JP7298336B2 - tire - Google Patents

Description

TECHNICAL FIELD The present invention relates to a tire, and more particularly to a tire having a tread portion provided with a plurality of blocks.

Patent Literature 1 below proposes a pneumatic tire having a tread portion provided with a plurality of blocks. In the pneumatic tire, the side wall of the block is provided with a gouged portion formed by recessing the side wall into the inside of the block. The gouged portion is useful for suppressing deterioration of drainage performance when the tread portion is worn.

JP-A-11-321238

In general, the grooves of the tread portion of a pneumatic tire are molded using projections of a vulcanization mold. For this reason, the gouged portion of the pneumatic tire as described above becomes a so-called undercut when viewed from the mold side, and the projection is likely to be caught by the rubber portion of the gouged portion on the outside in the tire radial direction during demolding. For this reason, for example, when two gouged portions face each other through a lateral groove, a large strain is generated around the gouged portions during demolding, which may cause molding defects such as cracks in the rubber.

SUMMARY OF THE INVENTION The present invention has been devised in view of the problems described above, and the main object of the present invention is to improve wet performance while suppressing molding defects in a tire having a tread portion provided with a plurality of blocks. .

The present invention provides a tire having a tread portion, the tread portion including first blocks and second blocks adjacent to the first blocks such that lateral grooves are formed between the first blocks. The block includes a tread surface and a first wall surface extending inward in the tire radial direction from an edge of the tread surface on the side of the lateral groove. The second block includes a tread surface and a second wall surface extending inward in the tire radial direction from an edge of the tread surface on the side of the lateral groove, and the second wall surface is recessed inwardly of the second block. A second recess is formed, and the second recess is provided at a position shifted in the longitudinal direction of the lateral groove with respect to the first recess.

In the tire of the present invention, each of the first recess and the second recess includes a first end on one side in the length direction and a second end on the other side in the length direction. The first end of the recess is located on one side in the length direction of the first end of the first recess, and the second end of the second recess is the second end of the first recess. preferably located on one side of said longitudinal direction.

In a plan view of the tread of the tire of the present invention, it is desirable that 0.50 times or more of the length of the second recess in the axial direction of the tire does not overlap with the imaginary region formed by extending the first recess in parallel with the tire circumferential direction. .

In the tire of the present invention, it is desirable that the entire second recessed portion does not overlap with the virtual region.

In the tire of the present invention, it is preferable that the second wall surface does not include a portion recessed inward of the block within the virtual area.

In the tire of the present invention, it is preferable that the first recess and the second recess are respectively provided at positions spaced radially inward from the edge of the lateral groove.

In the tire of the present invention, it is preferable that each of the first recess and the second recess is in contact with the bottom surface of the lateral groove.

In the tire of the present invention, the length of the first recess in the tire radial direction and the length of the second recess in the tire radial direction are each 0.30 to 0.80 of the maximum depth of the lateral groove. Preferably double.

In the tire of the present invention, it is preferable that the depth of the first recess gradually increases from the longitudinal end of the first recess toward the bottom of the first recess.

In the tire of the present invention, it is preferable that the depth of the second recess gradually increases from the longitudinal end of the second recess toward the bottom of the second recess.

In the tire of the present invention, it is preferable that the maximum depth of the first recess and the maximum depth of the second recess are 0.5 to 2.5 mm, respectively.

In the tire of the present invention, it is preferable that the first recess is separated from the axial end of the first wall surface.

In the tire of the present invention, the minimum distance from the end of the first wall surface to the first recess is 0.05 to 0.30 times the length of the first wall surface along the lateral groove. desirable.

In the tire of the present invention, it is preferable that the second recess is separated from the axial end of the second wall surface.

In the tire of the present invention, the minimum distance from the end of the second wall surface to the second recess is 0.05 to 0.30 times the length of the second wall surface along the lateral groove. desirable.

In the tire of the present invention, it is preferable that the volume of the first recess and the volume of the second recess are respectively 0.5% to 10% of the volume of the block.

In the tire of the present invention, the tread portion includes a tread central region having a width of 0.70 times the tread width and having a center in the tire axial direction on the tire equator; Preferably, the entirety of the two blocks are arranged within said tread central region.

In the tire of the present invention, the first wall surface of the first block is formed with a first recess that is recessed inward of the first block. The second wall surface of the second block is formed with a second recess that is recessed inward of the second block.

The first recess and the second recess can increase the groove volume of the lateral groove between the first block and the second block, thereby improving wet performance. Moreover, in the present invention, the second recess is provided at a position shifted in the longitudinal direction of the lateral groove with respect to the first recess. Therefore, it is possible to reduce the overlapping of the first recesses and the second recesses that cause undercuts, and to effectively suppress molding defects when removing the vulcanization mold for molding the tread portion.

1 is a developed view of a tread portion of a tire according to one embodiment of the present invention; FIG. It is an enlarged view of a 1st block and a 2nd block. FIG. 3 is a cross-sectional view taken along line AA of FIG. 2; FIG. 3 is a cross-sectional view taken along line BB of FIG. 2; It is an enlarged drawing of the 1st block and the 2nd block of the tire of a comparative example.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 shows a developed view of a tread portion 2 of a tire 1 of this embodiment. The tire 1 of the present embodiment is configured, for example, as a pneumatic tire for passenger cars, and is particularly suitable for off-road driving.

The tread portion 2 is provided with a plurality of main grooves 3 continuously extending in the tire circumferential direction and a plurality of lateral grooves 4 extending in the tire axial direction. Thus, the tread portion 2 includes a plurality of blocks 5 divided into main grooves 3 and lateral grooves 4 .

The tread portion of this embodiment has four block rows divided by one main groove 3 arranged on the tire equator C and two main grooves 3 provided so as to sandwich the main groove. contains. However, the present invention is not limited to such an aspect.

It is desirable that the main groove 3 extends, for example, in a zigzag shape. Specifically, the main groove 3 has a first inclined portion 3a inclined with respect to the tire circumferential direction and a second inclined portion 3b inclined in the opposite direction to the first inclined portion 3a with respect to the tire circumferential direction. It is included alternately in the tire circumferential direction. The groove width of the second inclined portion 3b is larger than the groove width of the first inclined portion 3a. Also, the length of the second inclined portion 3b is smaller than the length of the first inclined portion 3a. The main groove 3 including the first inclined portion 3a and the second inclined portion 3b can exhibit excellent off-road performance.

The lateral grooves 4 are desirably inclined, for example, at an angle of 45° or less with respect to the axial direction of the tire. The angle of the lateral grooves 4 of this embodiment with respect to the axial direction of the tire is, for example, 5 to 20 degrees. In this embodiment, each lateral groove 4 is inclined in the same direction with respect to the tire axial direction. Further, the lateral grooves 4 of this embodiment extend linearly. The length of the lateral groove 4 is preferably longer than the length of the first inclined portion 3a of the main groove 3. However, the lateral grooves 4 are not limited to such an aspect.

It is desirable that the block 5 has, for example, a length in the tire axial direction that is greater than a length in the tire circumferential direction. Such a block 5 can exhibit excellent traction on off-road. Moreover, the block 5 of this embodiment has, for example, a polygonal tread surface. For example, the tread surface is desirably rectangular to octagonal, and in this embodiment, it is configured as a hexagon. The tread surface of the block 5 in this embodiment is, for example, a hexagon having three pairs of two edges parallel to each other.

The axial width of the blocks 5 is, for example, 0.10 to 0.25 times the tread width TW. The tread width TW is the distance in the tire axial direction from one tread end Te to the other tread end Te in a normal state in which the tire is mounted on a normal rim, filled with a normal internal pressure, and in a no-load state. is. The tread edge Te is the outermost ground contact position in the tire axial direction when the normal load is applied to the tire in the normal state and the tire is grounded on a flat surface with a camber angle of 0°.

A "regular rim" is a rim defined for each tire in a standard system including the standard on which the tire is based. If there is, it is "Measuring Rim".

"Regular internal pressure" is the air pressure specified for each tire by each standard in the standard system including the standards on which tires are based. Maximum value described in VARIOUS COLD INFLATION PRESSURES", or "INFLATION PRESSURE" for ETRTO.

"Normal load" is the load defined for each tire by each standard in the standard system including the standards on which tires are based. AT VARIOUS COLD INFLATION PRESSURES", and for ETRTO, it is "LOAD CAPACITY".

The tread portion 2 includes first blocks 6 and second blocks 7 adjacent to each other such that lateral grooves 4 are formed between the first blocks 6 .

An enlarged view of the first block 6 and the second block 7 is shown in FIG. To facilitate understanding of the invention, the tread surface of each block is colored in FIG. As shown in FIG. 2, the first block 6 includes a tread surface and a first wall surface 6a extending inward in the tire radial direction from the edge of the tread surface on the lateral groove 4 side. A first recess 11 recessed inwardly of the first block 6 is formed in the first wall surface 6a.

The second block 7 includes a tread surface and a second wall surface 7a extending inward in the tire radial direction from the edge of the tread surface on the lateral groove 4 side. A second recess 12 recessed inward of the second block 7 is formed in the second wall surface 7a. In addition, in FIG. 2, the contours of the first recess 11 and the second recess 12 are indicated by broken lines.

The first recess 11 and the second recess 12 can increase the groove volume of the lateral groove 4 between the first block 6 and the second block 7 and improve the wet performance. In addition, the first recess 11 and the second recess 12 are also useful for increasing grip during off-road driving.

In the present invention, the second recess 12 is provided at a position shifted in the longitudinal direction of the lateral groove 4 with respect to the first recess 11 . Therefore, it is possible to reduce the overlapping of the first recesses 11 and the second recesses 12 that cause undercuts, and to effectively suppress molding defects when removing the vulcanization mold for molding the tread portion 2 .

The fact that the second recess 12 is displaced from the first recess 11 means that the second recess 12 is completely displaced from the first recess 11 in the longitudinal direction of the lateral groove. A part of the 2nd recessed part 12 includes the aspect which has overlapped with the 1st recessed part 11 and the tire axial direction. From the viewpoint of suppressing molding defects, the width of overlap between the imaginary region obtained by extending the first recess 11 in the tire circumferential direction and the second recess 12 is at most 20 mm, and along the lateral groove 4 of the second recess 12. less than 0.5 times its length.

The first concave portion 11 has a first end 11a on one side in the longitudinal direction of the lateral groove 4 (left side in FIG. 2) and a second end on the other side in the longitudinal direction (right side in FIG. 2). 11b. The second concave portion 12 includes a first end 12a on one side in the length direction and a second end 12b on the other side in the length direction. In the present embodiment, the first end 12a of the second recess 12 is positioned on one side of the length direction relative to the first end 11a of the first recess 11 . The second end 12b of the second recess 12 is located on one side in the length direction of the second end 11b of the first recess 11 .

In a tread plan view, it is desirable that 0.50 times or more of the length of the second recesses 12 in the axial direction of the tire does not overlap the imaginary region formed by extending the first recesses 11 parallel to the tire circumferential direction. As a more desirable aspect, in the present embodiment, the entire second concave portion 12 does not overlap the virtual region. In other words, the second end 12b of the second recess 12 is on one side in the length direction of the first end 11a of the first recess 11 . This reliably suppresses molding defects.

In order to further suppress molding defects, the second wall surface 7a is configured to be planar within the imaginary region without including a portion that is recessed inward of the block. Similarly, the first wall surface 6a does not include an inwardly recessed portion of the block and is planar within a virtual area formed by extending the second wall surface 7a parallel to the tire circumferential direction.

The first recess 11 is desirably separated from the axial end of the first wall surface 6a. Such a first concave portion 11 is unlikely to become a starting point of damage when the block is deformed, and can improve the durability of the block.

The minimum distance L2 from the end of the first wall surface 6a to the first recess 11 is preferably 0.05 to 0.30 times the length L1 along the lateral groove 4 of the first wall surface 6a.

From the same point of view, it is desirable that the second recessed portion 12 is separated from the end of the second wall surface 7a in the axial direction of the tire. The minimum distance L4 from the end of the second wall surface 7a to the second recess 12 is 0.05 to 0.30 times the length L3 along the lateral groove 4 of the second wall surface 7a. As a result, the first concave portion 11 and the second concave portion 12 can be appropriately spaced apart from each other while suppressing damage to the block, thereby suppressing defective molding.

FIG. 3 shows a cross-sectional view of the first recess 11 of FIG. 2 taken along the line AA. FIG. 4 shows a cross-sectional view of the second recess 12 of FIG. 2 taken along the line BB. As shown in FIGS. 3 and 4, the first recess 11 and the second recess 12 are provided at positions spaced radially inward from the edge 15 of the tread surface of the block on the side of the lateral groove 4, respectively. there is Also, the first recess 11 and the second recess 12 are in contact with the bottom surface 4d of the lateral groove 4, respectively. Such first recesses 11 and second recesses 12 help maintain wet performance when the tread portion 2 is worn.

The tire radial length L5 of the first recess 11 and the tire radial length L6 of the second recess 12 are each 0.30 to 0.80 times the maximum depth d1 of the lateral groove. is desirable. Such first recessed portion 11 and second recessed portion 12 can improve wet performance while suppressing molding defects.

As shown in FIG. 2 , the depth of first recess 11 gradually increases from the end of first recess 11 toward the bottom of first recess 11 . The depth of the second recess 12 gradually increases from the end of the second recess 12 toward the bottom of the second recess 12 . Such first concave portion 11 and second concave portion 12 prevent stress from concentrating on the bottom portion thereof, which helps to increase the durability of the block.

As for the first recess 11 and the second recess 12, it is desirable that the angle θ1 between the inner surface of the recess and the wall surface of the block at the end thereof is 45° or less.

As shown in FIGS. 3 and 4, the maximum depth d2 of the first recess 11 and the maximum depth d3 of the second recess 12 are preferably 0.5 to 2.5 mm, respectively. . As a result, wet performance is maintained when the tread portion 2 is worn while suppressing molding defects.

From the same point of view, the volume of the first recess 11 is preferably 0.5% to 10% of the volume of the first block 6 to which the first recess 11 belongs. Similarly, the volume of the second recess 12 is preferably 0.5% to 10% of the volume of the second block 7 to which the second recess 12 belongs. Note that the volume is defined by an imaginary plane extending parallel to the tire radial direction through the boundary 16 between the wall surface of the block and the first recess 11 or the second recess 12, and the inner surface of the first recess 11 or the second recess 12. Corresponds to the volume of the enclosed space.

As shown in FIG. 2, in the present embodiment, a wall surface 6b of the first block 6 opposite to the first wall surface 6a has a wall surface similar to the second wall surface 7a of the second block 7 described above. there is A wall surface 7b on the side opposite to the second wall surface 7a of the second block 7 has the same wall surface as the first wall surface 6a of the first block 6 described above. That is, in this embodiment, the first block 6 and the second block 7 are configured as substantially the same block, and are arranged in the tire circumferential direction.

Preferably, the entire first block 6 and second block 7 are arranged in the tread central region 20, as shown in FIG. The tread central region 20 means a region having a width that is 0.70 times the tread width TW and whose center in the tire axial direction is located on the tire equator. The blocks arranged in the tread central region 20 deform less during braking than the blocks on the tread edge Te side. Therefore, damage to the block originating from the first concave portion 11 and the second concave portion 12 is suppressed. In addition, in the present embodiment, blocks including recessed portions are not provided in the axially outer region of the tread central region 20, so damage to blocks in this region is suppressed.

Although the tire of one embodiment of the present invention has been described in detail above, the present invention is not limited to the specific embodiment described above, and can be implemented in various ways.

A passenger car pneumatic tire of size 265/70R17 having the basic tread pattern shown in FIG. As a comparative example, as shown in FIG. 5, a prototype tire was produced in which the first concave portion a and the second concave portion b faced each other. The comparative tire included a tread pattern similar to that of FIG. 1, except as noted above. Each test tire was tested for wet performance when the tread portion was worn by 50% and demoldability during vulcanization molding. Common specifications and test methods for each test tire are as follows.
Rim: 17 x 8.0J
Tire internal pressure: 180kPa
Test vehicle: 2500cc displacement, 4-wheel drive Tire mounting position: All wheels

<Wet Performance>
In a state where the tread portion was worn by 50%, the running performance when running on a wet road surface was evaluated by the senses of the driver. The results are scored with the comparative example being 100, and the larger the number, the better the wet performance when the tread portion is worn by 50%.

<Mold Releasability>
The rate of occurrence of defects occurring during demolding was measured. The results are indexed with the occurrence rate of the tire of Comparative Example set to 100. The smaller the numerical value, the smaller the occurrence rate, indicating that the tire has excellent demoldability.
Test results are shown in Table 1.

As a result of the test, it was confirmed that the tire of the example exhibits wet performance equivalent to that of the comparative example and effectively suppresses molding defects.

2 tread portion 4 lateral groove 6 first block 7 second block 6a first wall surface 7a second wall surface 11 first recess 12 second recess

Claims (12)

A tire having a tread portion,
The tread portion includes a first block and a second block adjacent to the first block such that a lateral groove is formed between the first block,
The first block includes a tread surface and a first wall surface extending inward in the tire radial direction from an edge of the tread surface on the side of the lateral groove. A recess is formed,
The second block includes a tread surface and a second wall surface extending inward in the tire radial direction from the lateral groove side edge of the tread surface. A recess is formed,
The second recess is provided at a position shifted in the longitudinal direction of the lateral groove with respect to the first recess,
Each of the first recess and the second recess is provided at a position spaced radially inward from the edge of the lateral groove,
each of the first recess and the second recess is in contact with the bottom surface of the lateral groove;
The tire radial length of the first recess and the tire radial length of the second recess are each 0.30 to 0.80 times the maximum depth of the lateral groove.
tire. A tire having a tread portion,
The tread portion includes a first block and a second block adjacent to the first block such that a lateral groove is formed between the first block,
The first block includes a tread surface and a first wall surface extending inward in the tire radial direction from an edge of the tread surface on the side of the lateral groove. A recess is formed,
The second block includes a tread surface and a second wall surface extending inward in the tire radial direction from the lateral groove side edge of the tread surface. A recess is formed,
The second recess is provided at a position shifted in the longitudinal direction of the lateral groove with respect to the first recess,
The maximum depth of the first recess and the maximum depth of the second recess are each 0.5 to 2.5 mm,
tire. A tire having a tread portion,
The tread portion includes a first block and a second block adjacent to the first block such that a lateral groove is formed between the first block,
The first block includes a tread surface and a first wall surface extending inward in the tire radial direction from an edge of the tread surface on the side of the lateral groove. A recess is formed,
The second block includes a tread surface and a second wall surface extending inward in the tire radial direction from the lateral groove side edge of the tread surface. A recess is formed,
The second recess is provided at a position shifted in the longitudinal direction of the lateral groove with respect to the first recess,
The first recess is spaced apart from the axial end of the first wall surface,
The minimum distance from the end of the first wall surface to the first recess is 0.05 to 0.30 times the length of the first wall surface along the lateral groove,
tire. A tire having a tread portion,
The tread portion includes a first block and a second block adjacent to the first block such that a lateral groove is formed between the first block,
The first block includes a tread surface and a first wall surface extending inward in the tire radial direction from an edge of the tread surface on the side of the lateral groove. A recess is formed,
The second block includes a tread surface and a second wall surface extending inward in the tire radial direction from the lateral groove side edge of the tread surface. A recess is formed,
The second recess is provided at a position shifted in the longitudinal direction of the lateral groove with respect to the first recess,
The second recess is spaced apart from the axial end of the second wall surface,
The minimum distance from the end of the second wall surface to the second recess is 0.05 to 0.30 times the length of the second wall surface along the lateral groove,
tire. A tire having a tread portion,
The tread portion includes a first block and a second block adjacent to the first block such that a lateral groove is formed between the first block,
The first block includes a tread surface and a first wall surface extending inward in the tire radial direction from an edge of the tread surface on the side of the lateral groove. A recess is formed,
The second block includes a tread surface and a second wall surface extending inward in the tire radial direction from the lateral groove side edge of the tread surface. A recess is formed,
The second recess is provided at a position shifted in the longitudinal direction of the lateral groove with respect to the first recess,
The volume of the first recess and the volume of the second recess are each 0.5% to 10% of the volume of the block,
tire. The first recess and the second recess each include a first end on one side in the length direction and a second end on the other side in the length direction,
The first end of the second recess is located on one side in the length direction of the first end of the first recess,
The tire according to any one of claims 1 to 5, wherein the second end of the second recess is located on one side in the longitudinal direction relative to the second end of the first recess. 7. The tire according to claim 6, wherein 0.50 times or more of the length of the second recess in the tire axial direction does not overlap with the imaginary region extending the first recess in parallel to the tire circumferential direction in a tread plan view. . 8. The tire of claim 7, wherein the second recess does not entirely overlap with the virtual area. The tire according to claim 8, wherein the second wall surface does not include a portion recessed inwardly of the block within the virtual area. 10. Tire according to any one of the preceding claims, wherein the depth of the first recess gradually increases from the longitudinal end of the first recess towards the bottom of the first recess. 11. Tire according to any one of the preceding claims, wherein the depth of the second recess gradually increases from the longitudinal end of the second recess towards the bottom of the second recess. The tread portion includes a tread central region having a width of 0.70 times the tread width and having a center in the tire axial direction on the tire equator,
12. A tire according to any preceding claim, wherein the first block and the second block are wholly disposed within the tread central region.

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