WO2014178182A1

WO2014178182A1 - Heavy duty pneumatic tire

Info

Publication number: WO2014178182A1
Application number: PCT/JP2014/002344
Authority: WO
Inventors: 吾空武居
Original assignee: 株式会社ブリヂストン
Priority date: 2013-04-30
Filing date: 2014-04-25
Publication date: 2014-11-06
Also published as: CN105163958B; JP5503775B1; JP2014213841A; CN105163958A

Abstract

Provided is a heavy duty pneumatic tire which has improved mud-channeling performance for the ground-contacting surface thereof so that the edges thereof are able to sufficiently exhibit a scraping effect without the rigidity of the blocks being significantly compromised, which would have worsened the abrasion-resistance performance thereof. In the case of this tire, a shallow groove (60) is provided on each block (6), and the shallow groove (60) includes multiple width-direction groove sections (61-63), connecting groove sections (64, 65), and circumferential-direction groove sections (66, 67).

Description

Heavy duty pneumatic tire

The present invention has a block which is partitioned on the tread surface by two or more circumferential grooves continuously extending in the tread circumferential direction and transverse grooves opening to the circumferential grooves adjacent to each other in the tread width direction. The present invention relates to a heavy duty pneumatic tire.

Heavy-duty tires are sometimes used in dump trucks that can be used at construction sites, mines, etc. This dump truck is a muddy area where a soft clay layer of several centimeters is formed on hard ground after rain. It may be used for traveling on the road surface.

When traveling on the road surface on which the clay layer is formed as described above, the tire mounted on the vehicle does not completely bury the tread in the clay layer, but the groove of the circumferential groove provided on the tread surface In this case, the traction force and braking force are applied to the road surface because of the soft clay layer between the tread tread and the hard ground. It is difficult to efficiently transmit the data.

In particular, this clay layer mud deposited on hard ground, on the rolling rolling of the tire, from the stepped side part of the tread tread surface that touches the ground first, and then to the kick side that touches the ground. Since it will be pushed out to the part and accumulates with the road surface at the part on the kicking side, the scratching effect by the block edge at the part on the kicking side of the block should be fully exhibited on such road surface As a result, the vehicle slips when inputting a traction force or a braking force. This, for example, may cause a decrease in traveling speed of a dump truck or the like used in a mine, a stagnation of transportation work by the dump truck or the like, and may reduce the work efficiency.

For this, as described in Patent Document 1, for example, by providing zigzag narrow grooves in the block, by increasing the tread width direction component of the tread tread edge, the soft clay layer It is also considered effective to improve the scratching effect on the existing road surface.

JP 2004-98914 A

However, simply adding the above-mentioned narrow groove in the block to increase the widthwise component of the edge, the mud of the soft clay layer remaining between the block surface and the road surface in the ground plane is sufficient. If it does not flow out, the scratching effect by the edge cannot be exhibited sufficiently, and the tire may slip, and the block rigidity may be reduced, and the wear resistance may be adversely affected.

An object of the present invention is to solve such problems of heavy-duty pneumatic tires that may be used in muddy roads. An object of the present invention is to provide a heavy-duty pneumatic tire capable of improving the mud repellency within the ground contact surface and sufficiently exhibiting the scratching effect by the edge without causing a significant decrease in block rigidity which causes deterioration.

A heavy-duty pneumatic tire according to the present invention is a pneumatic tire having a block which is partitioned by a circumferential groove and a transverse groove opening in each of the circumferential grooves adjacent to each other on a tread surface. A shallow groove having an average groove depth shallower than a groove depth of the circumferential groove adjacent to the block is provided, and the shallow groove has at least one end located in the block and is inclined with respect to the tread circumferential direction. A plurality of widthwise groove portions that extend in the above-mentioned direction, and a connecting groove portion that connects at least two of the plurality of widthwise groove portions, and one end is open to at least one of the circumferential groove and the transverse groove. The other end is connected to one of the plurality of widthwise groove portions, and includes a circumferential groove portion having a smaller inclination angle with respect to the tread circumferential direction than the widthwise groove portion. A.
According to the heavy-duty pneumatic tire of the present invention, the mud repellency in the ground contact surface is improved and the scratching effect by the edge is sufficiently obtained without incurring a significant decrease in the block rigidity that causes the wear resistance performance to deteriorate. It can be demonstrated.

The “tread surface” here refers to a tire that comes into contact with the road surface when rolling a tire that is assembled to the applicable rim and filled with the specified internal pressure while applying a load corresponding to the maximum load capacity. Means the outer peripheral surface of the entire circumference. “Applicable rim” refers to a standard rim defined in the following standard according to the tire size (specified as “Design Rim” in YEAR BOOK of TRA below. The "specified internal pressure" means the air pressure specified in accordance with the maximum load capacity in the following standards, and the "maximum load capacity" is allowed to be applied to the tire according to the following standards. The maximum mass. The standard is determined by an industrial standard effective in the region where the tire is produced or used. For example, in the United States, “THE TIRE AND RIM ASSOCIATION INC. (TRA)” “YEAR BOOK” In Europe, it is “STANDARDS MANUAL” of “The European Tire and Rim Technical Organization (ETRTO)”, and in Japan it is “JATMA YEAR BOOK” of “Japan Automobile Tire Association (JATMA)”.
“Tread width” means the length along the tread width direction between the outermost positions in the tire width direction of the tread tread when the tire is assembled to the applicable rim and filled with the specified internal pressure. To do.

In addition, the above-mentioned “groove depth” shall be measured in an unloaded state in which the tire is assembled to the applicable rim and filled with the specified internal pressure. The “shallow groove” referred to in the present invention has a groove width such that the facing groove walls are open to the tread tread surface without contacting each other in the tread ground surface. Here, the `` tread contact surface '' means a part of the tread tread surface in the circumferential direction that comes into contact with the road surface when the maximum load capacity is applied under the condition that the tire is assembled to the applicable rim and filled with the specified internal pressure. Say. In the present invention, “the inclination angle with respect to the tread circumferential direction is smaller” than the width direction groove portion includes the case where the inclination angle with respect to the tread circumferential direction is 0 degree. In addition, this inclination angle shall be measured along the tread surface as seen from the development view of the tread pattern in a no-load state in which the tire is assembled to the applicable rim and filled with the specified internal pressure. In the present invention, other dimensions and the like are measured under the same conditions unless otherwise specified.

In the heavy duty pneumatic tire of the present invention, it is preferable that the circumferential groove extends in a zigzag shape in the tread circumferential direction. Thereby, by increasing the tread width direction component of the edge of the tread surface, the scratching effect in the tread circumferential direction at the time of tire rolling can be further improved.

In the heavy duty pneumatic tire of the present invention, it is preferable that the connecting groove portion is inclined with respect to the tread circumferential direction. Thereby, the scratching effect in the tread circumferential direction at the time of load rolling of the tire can be further improved.

In the heavy duty pneumatic tire according to the present invention, the block further includes an auxiliary shallow groove having one end opened in at least one of the circumferential groove and the transverse groove and the other end terminated in the block. It is preferable to be provided. Thereby, the scratching effect in the tread circumferential direction at the time of load rolling of the tire can be further improved.

In the heavy duty pneumatic tire according to the present invention, the plurality of widthwise groove portions have first and second widthwise groove portions having one end positioned in the block and the other end opened in the transverse groove. And a third widthwise groove portion having both ends positioned in the block, and the connecting groove portion is positioned in the block at one end of the first and second widthwise groove portions. Including the first and second connecting groove portions, the other end being connected to one end of the third widthwise groove portion, and one end of the circumferential groove portion is the You may make it open to the circumferential groove and the other end may be connected with either one end of the said 3rd width direction groove part. Thereby, the mud repellency in the ground contact surface can be improved and the scratching effect by the edge can be sufficiently exhibited without causing a significant decrease in the block rigidity that causes the wear resistance performance to deteriorate.

In the heavy-duty pneumatic tire according to the present invention, the plurality of widthwise groove portions include two widthwise groove portions having one end located in the block and the other end opened to the circumferential groove, The connecting groove portion connects the two widthwise groove portions in the middle of their extension, and the circumferential groove portion has one end opened to the circumferential groove and the transverse groove, and the other end of the two widthwise groove portions. Any one of them may include two circumferential grooves connected to an end located in the block. Thereby, the mud repellency in the ground contact surface can be improved and the scratching effect by the edge can be sufficiently exhibited without causing a significant decrease in the block rigidity that causes the wear resistance performance to deteriorate.

In the heavy-duty pneumatic tire according to the present invention, the plurality of widthwise groove portions include two widthwise groove portions having one end located in the block and the other end opened to the circumferential groove, The connecting groove portion connects the two widthwise groove portions in the middle of their extension, and the circumferential groove portion has one end opened to the transverse groove and the other end is one of the two widthwise groove portions. Two circumferential grooves connected to one end located in the block may be included. Thereby, the mud repellency in the ground contact surface can be improved and the scratching effect by the edge can be sufficiently exhibited without causing a significant decrease in the block rigidity that causes the wear resistance performance to deteriorate.

According to the heavy-duty pneumatic tire of the present invention, the mud repellency in the ground contact surface is improved and the scratching effect by the edge is sufficiently obtained without incurring a significant decrease in the block rigidity that causes the wear resistance performance to deteriorate. A heavy-duty pneumatic tire that can be exhibited can be provided.

It is a partial development view of a tread pattern showing one embodiment of this invention. It is a partial expanded view which shows the tread pattern of the modification of one Embodiment of this invention. It is a partial expanded view which shows the tread pattern of the other modification of one Embodiment of this invention. 1 is a cross-sectional view in the tire width direction showing the tire internal structure of one embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described by way of example with reference to the drawings. In FIG. 1, reference numeral 1 denotes a tread tread included in a heavy duty pneumatic tire according to an embodiment of the present invention. In the present embodiment, the tread tread surface 1 is provided with two or more (two in the illustrated example) circumferential grooves 2 continuously extending in the circumferential direction of the tread in a zigzag shape as in the illustrated example, for example. . Further, the tread surface 1 is provided with a transverse groove 5 that opens in each of the circumferential grooves 2 adjacent to each other in the tread width direction at a bent portion that protrudes inward in the tread width direction of the circumferential groove 2 as shown in the example of the figure. ing. A plurality of blocks 6 are defined by the circumferential grooves 2 and the transverse grooves 5. In the example shown in the figure, the block 6 straddles the tire equatorial plane C.

Since the circumferential groove 2 extends in a zigzag shape in the tread circumferential direction as in the example of the figure, for example, the outer edge of the block 6 is more circumferential than in the case where the circumferential groove extends in parallel with the tread circumferential direction. Since the portion adjacent to the groove 2 is inclined with respect to the tread circumferential direction, the tread width direction component of the edge of the tread tread surface 1 is increased, and the scratching effect in the tread circumferential direction during load rolling of the tire is increased. Can be improved.

In the example shown in the figure, the transverse groove 5 is bent and extended at two places between the bent places protruding inward in the tread width direction of the two circumferential grooves 2. Thereby, the scratching effect by the edge is improved at the portion 40 of the outer edge of the block 6 adjacent to the transverse groove 5 and bent toward the inside of the block 6.

Further, in the example shown in the figure, a lug groove 3 extending from the tread end and opening to the circumferential groove 2 is provided on the tread tread surface 1. Thereby, the mud taken in the groove in the center region 50 of the tread surface 1 can flow out to the outside in the tread width direction through the lug groove 3 of the shoulder region 51. Furthermore, on the outer side of the tread tread surface 1 in the tread width direction from the circumferential groove 2, a lug 4 as a land portion is defined between the lug grooves 3 adjacent to each other in the tread circumferential direction. In addition, the lug 4 is provided with an opening groove 30 that has a groove depth shallower than that of the circumferential groove 2 and extends in a curved manner from the tread end toward the tread width direction and opens into the circumferential groove 2. Here, the “tread end” refers to the outermost position of the tread surface 1 in the tread width direction.

Each block 6 is provided with a shallow groove 60 and auxiliary

shallow grooves

31 and 32 having an average groove depth shallower than the groove depth of the circumferential groove 2 adjacent to the block 6. The shallow groove 60 includes a plurality of (three in the illustrated example) width direction groove portions 61 to 63,

connection groove portions

64 and 65, and circumferential direction groove portions 66 and 67. Note that the shallow groove 60 and the auxiliary

shallow grooves

31 and 32 are larger than 20% and less than 80% of the groove depth of the circumferential groove 2 from the viewpoint of improving mud drainage and securing sufficient rigidity for the block 6. And an average groove depth of 50 to 70% of the groove depth of the circumferential groove 2 is more preferable. Moreover, it is preferable that the shallow groove 60 and the auxiliary

shallow grooves

31 and 32 have an average groove width smaller than the groove width of the circumferential groove 2 as shown in the figure from the viewpoint of ensuring sufficient rigidity for the block 6. . Here, “the groove depth of the circumferential groove 2” and “the groove width of the circumferential groove 2” are respectively the circumferential groove 2 when the groove depth and the groove width are different in the course of the extension of the circumferential groove 2. The average value of the groove depth and the groove width over the entire length of is taken. In addition, the “average groove depth” and “average groove width” of each shallow groove are the shallow groove when the groove depth and groove width are different in the middle of the extension of the shallow groove provided in the block, respectively. Means the average value of the groove depth and the groove width over the entire length.

Each of the width direction grooves 61 to 63 has at least one end located in the block 6 and extends in a direction inclined with respect to the tread circumferential direction. By providing the width direction grooves 61 to 63, the tread width direction component of the edge of the tread surface can be increased, so that the scratching effect in the tread circumferential direction at the time of tire rolling can be improved. Therefore, the traction performance in a muddy area can be improved.

In the example of the figure, the

width direction grooves

61 and 63 have one end located in the block 6 and the other end opened to a portion 40 of the transverse groove 5 that bends inward of the block 6. . On the other hand, both ends of the width direction groove portion 62 are located in the block 6. However, although not shown, the width direction groove may be open to the circumferential groove 2 at the end opposite to the end located in the block 6.

The connecting

groove portions

64 and 65 respectively connect at least two of the plurality of width direction groove portions 61 to 63 (in the example shown in the figure, the width

direction groove portions

61 and 62 and the width direction groove portions 62 and 63). It extends like so. Here, the connecting

groove portions

64 and 65 have an inclination angle with respect to the tread circumferential direction smaller than each of the width direction groove portions 61 to 63. By providing the connecting

groove portions

64 and 65, mud that may enter the width direction groove portions 61 to 63 and clog at the time of load rolling of the tire can be released to the outside of the width direction groove portions 61 to 63. As a result, the mud repellency in the ground contact surface can be improved, and the edge scratching effect at the time of load rolling of the tire can be sufficiently exhibited.

Here, it is preferable that the connecting

groove portions

64 and 65 are inclined with respect to the tread circumferential direction as in the example of the figure. Accordingly, the tread width direction component of the tread tread edge can be increased as compared with the case where the connecting

groove portions

64 and 65 extend in parallel to the tread circumferential direction. Can improve the scratching effect.

In the example of the figure, one end of each of the connecting

groove portions

64 and 65 is connected to the end of the width

direction groove portions

61 and 63 located in the block 6, and the other end of each of the connecting

groove portions

64 and 65. The end is connected to one end of the width direction groove 62.

One end of each of the circumferential groove portions 66 and 67 opens into at least one of the circumferential groove 2 and the transverse groove 5 (the circumferential groove 2 in the example in the figure), and the other end of the plurality of width direction groove portions 61 to 63. One of them (in the example shown in the figure, the width direction groove portion 62) is connected, and the inclination angle with respect to the tread circumferential direction is smaller than that of the width direction groove portion 62. By providing the circumferential groove portions 66 and 67, mud that enters the width direction groove portions 61 to 63 and the connecting

groove portions

64 and 65 at the time of tire rolling can be discharged to the circumferential groove 2 and the transverse groove 5. As a result, the mud repellency in the ground contact surface can be improved, and the edge scratching effect at the time of load rolling of the tire can be sufficiently exhibited. Further, since the inclination angle of the circumferential groove portions 66 and 67 with respect to the tread circumferential direction is smaller than that of the width direction groove portions 61 to 63, the inclination angle of the circumferential groove portions 66 and 67 with respect to the tread circumferential direction is set to the width direction groove portions 61 to 63. Compared with the case where it is equal to or more than that, the mud that enters the widthwise grooves 66 and 67 is likely to flow out into the circumferential groove 2 and the transverse groove 5. In the example shown in the figure, the ends of the circumferential groove portions 66 and 67 opposite to the ends opening in the circumferential groove 2 are connected to either one of the widthwise groove portions 62 and the connecting groove portion 64. , 65 are also connected to one end.

The auxiliary

shallow grooves

31 and 32 each have one end opened to at least one of the circumferential groove 2 and the transverse groove 5 (circumferential groove 2 in the illustrated example) and the other end terminated in the block 6. Here, the other ends of the auxiliary

shallow grooves

31 and 32 are “terminated within the block”, and the other end is not connected to the shallow groove 60 and the land portion of the block 6 (of the block 6). It means that it is located in the part) except the shallow groove 60. By providing the auxiliary

shallow grooves

31, 32, the tread width direction component and / or the tread circumferential direction component of the edge of the tread surface can be increased without excessively reducing the rigidity of the block 6, so The scratching effect can be improved and the traction performance can be improved. On the contrary, if the other ends of the auxiliary

shallow grooves

31 and 32 are connected to the shallow groove 60, the block 6 is excessively subdivided and the rigidity of the block 6 may be reduced.

In the example shown in the figure, the

widthwise groove portions

61 and 63 and the circumferential groove portion are respectively formed at the ends of the

widthwise groove portions

61 and 63 and the circumferential groove portions 66 and 67 that open to the transverse groove 5 and the circumferential groove 2 respectively. The angles formed by the respective groove width center lines 66 and 67 and the respective groove width center lines of the transverse groove 5 and the circumferential groove 2 are set to be larger than 30 degrees. As a result, the angle of the corner of the block 6 defined by each of the width

direction groove portions

61 and 63 and the circumferential direction groove portions 66 and 67 and each of the transverse groove 5 and the circumferential groove 2 can be made larger than 30 degrees. Therefore, the rigidity of the block 6 can be prevented from becoming excessively small locally.

As shown in the example in the figure, the auxiliary

shallow grooves

31 and 32 are inclined with respect to the tread circumferential direction to increase the tread width direction component of the tread tread edge, so that the tread circumference at the time of load rolling of the tire is increased. The scratching effect in the direction can be improved. Further, as shown in the example in the figure, at the end of the auxiliary

shallow grooves

31, 32 that open to the circumferential groove 2, the groove width center line of the auxiliary

shallow grooves

31, 32 and the groove width center line of the circumferential groove 2 are By making the formed angle approximately 90 degrees, the angle of the corner of the block 6 defined by the auxiliary

shallow grooves

31, 32 and the circumferential groove 2 is approximately 90 degrees on both sides of the auxiliary

shallow grooves

31, 32, respectively. Therefore, the rigidity of the block 6 can be prevented from becoming excessively small locally. The angle formed between the groove width center line of the auxiliary

shallow grooves

31 and 32 and the groove width center line of the peripheral groove 2 at the end of the auxiliary

shallow grooves

31 and 32 that opens to the peripheral groove 2 is 90 degrees. However, from the viewpoint of ensuring sufficient rigidity for the block 6, it is preferably greater than 30 degrees.

In the illustrated example, the groove width center lines of the width direction groove portions 61 to 63, the groove width center lines of the

connection groove portions

64 and 65, and the groove width center lines of the circumferential groove portions 66 and 67 extend in parallel to each other. Yes. Further, the groove width center line of the width direction groove portions 61 to 63 and the groove width center line of a part of the transverse groove 5 extend in parallel to each other, and the groove width center lines of the connecting

groove portions

64 and 65 and the circumferential groove portions 66 and 67 are. And a groove width center line of a part of the circumferential groove 2 extend in parallel to each other. As a result, when the tire rolls, mud stably flows into the shallow groove 60 and then smoothly flows out into the circumferential groove 2 and the transverse groove 5. Can be further enhanced. From the same viewpoint, the groove width center lines of the auxiliary

shallow grooves

31 and 32 extend in parallel to each other as shown in the example of the figure, and the groove width center lines of the auxiliary

shallow grooves

31 and 32 and a part of the circumferential groove 2 are formed. It is preferable that the groove width center lines extend in parallel to each other.

Further, in the example of the figure, the groove width center lines of the width direction groove portions 61 to 63 extending in parallel to each other are arranged at substantially equal intervals in the tread circumferential direction, and thereby, the space direction groove portions 61 to 63 are partitioned. The lengths of the two sub-blocks 6a and 6b in the tread circumferential direction are substantially equal to each other. As a result, the uniformity of the rigidity of the block 6 is improved.

Here, in the example shown in the drawing, the groove widths of the circumferential groove portions 66 and 67 are larger than the groove widths of the width direction groove portions 61 to 63. As a result, the mud that enters the widthwise groove portions 61 to 63 and the connecting

groove portions

64 and 65 when the tire rolls is more likely to flow out into the circumferential groove 2. Although not shown, from the same viewpoint, the groove widths of the circumferential groove portions 66 and 67 may be increased only in the portion on the opening side to the circumferential groove 2, or the circumferential groove portions 66 and 67 may be increased. In addition, the groove widths of the connecting

groove portions

64 and 65 may be larger than the groove widths of the width direction groove portions 61 to 63.

As mentioned above, although this invention has been demonstrated based on the one embodiment, this invention is not limited to this embodiment, Various modifications are also included. In the following description of the modified example, the description will focus on parts different from the embodiment described above. In the modification shown in FIG. 2, the transverse groove 70 extends linearly without bending between the bent portions protruding inward in the tread width direction of the circumferential groove 2. Each block 71 is provided with a shallow groove 80. The shallow groove 80 has one end located in the block 71, the other end opened to the circumferential groove 2, and two width direction groove portions 81 extending in a direction inclined with respect to the tread circumferential direction, 82 and the width

direction groove portions

81 and 82 are connected to each other in the course of their extension, a connection groove portion 83, one end is opened in the circumferential groove 2 and the transverse groove 70, and the other end is formed in the width

direction groove portions

81 and 82. , And

circumferential grooves

84, 85 connected to the ends located within the block 71. Note that “opening in the circumferential groove 2 and the transverse groove 70” means opening in a portion where the circumferential groove 2 and the transverse groove 70 are connected to each other. The connecting groove 83 is inclined with respect to the tread circumferential direction. In this modification, the groove width center lines of the width

direction groove portions

81 and 82 and the groove width center lines of the circumferential

direction groove portions

84 and 85 extend in parallel to each other. Further, the groove width center line of the width

direction groove portions

81 and 82 and the groove width center line of the transverse groove 70 extend in parallel to each other, and the groove width center line of the

circumferential groove portions

84 and 85 and a groove of a part of the circumferential groove 2 The width center lines extend parallel to each other. Further, the respective groove width center lines of the transverse groove 70 and the width

direction groove portions

81 and 82 extending in parallel with each other are arranged at substantially equal intervals in the tread circumferential direction. The groove widths of the

circumferential groove portions

84 and 85 are larger than the groove widths of the width

direction groove portions

81 and 82.

On the other hand, in the modification shown in FIG. 3, the transverse groove 90 extends and bends at two places between the bent portions protruding inward in the tread width direction of the circumferential groove 2, and between the two bent portions. The portion has a longer extension length and a smaller inclination angle with respect to the tread width direction than the portion on the outer side in the tread width direction than the bent portion. As a result, the tread width direction component of the tread tread surface edge is increased at the portion 92 adjacent to the portion between the two bent portions of the transverse groove 90 on the outer edge of the block 91, so that the scratching effect in the tread circumferential direction can be obtained. It is improving. Each block 91 is provided with a shallow groove 100 and auxiliary

shallow grooves

106 and 107. One end of the shallow groove 100 is located in the block 91, and the other end is opened at a bent portion protruding inward in the tread width direction of the circumferential groove 2, and extends in a direction inclined with respect to the tread circumferential direction. Two widthwise

groove portions

101 and 102, a connecting groove portion 103 that connects these

widthwise groove portions

101 and 102 in the middle of their extension, and one end of the transverse groove 90 toward the inside of the block 91. The

circumferential groove portions

104 and 105 are opened at the bent portions and the other ends are connected to the ends of the width

direction groove portions

101 and 102 located in the block 91. The auxiliary

shallow grooves

106 and 107 each have one end opened to the circumferential groove 2 and the other end terminated in the block 91. The connecting groove 103 is inclined with respect to the tread circumferential direction. In the present modification, the groove width center lines of the width

direction groove portions

101 and 102, the groove width center lines of the

circumferential groove portions

104 and 105, and the groove width center lines of the auxiliary

shallow grooves

106 and 107 are parallel to each other. It extends to. Further, the groove width center line of the width

direction groove portions

101 and 102 and the groove width center line of a part of the transverse groove 90 extend in parallel to each other, and the groove width center line of the

circumferential groove portions

104 and 105, the circumferential groove 2 and the transverse groove. The groove width center line of each part of the groove 90 extends in parallel with each other, and the groove width center line of the connecting groove 103 and the auxiliary

shallow grooves

106 and 107 and the groove width center line of a part of the circumferential groove 2 are parallel to each other. It extends to. Furthermore, the respective groove width center lines of the transverse groove 90 and the width

direction groove portions

101 and 102 extending in parallel with each other are arranged at substantially equal intervals in the tread circumferential direction.

In each of the above-described examples, when the tire rolls, in order to ensure that mud is taken into the shallow groove within the contact time of the block that gradually contacts from the stepping-side portion toward the kick-out portion, the block Tb circumferential maximum length Lb and shallow grooves provided in the block (including auxiliary shallow grooves when auxiliary shallow grooves are provided; the same applies hereinafter in this paragraph). The circumferential distance Lm between the outer circumferential outer end points (outer circumferential grooves when the auxiliary shallow grooves are provided, the circumferential outer end points when viewing the shallow grooves and the auxiliary shallow grooves together) is In order to satisfy the relationship of Lm / Lb> 0.25, it is preferable to secure the extending length of the shallow groove along the tread circumferential direction.

The above-mentioned “maximum length Lb in the tread circumferential direction of the block” means a block length measured along the tread circumferential direction from one outermost position to the other outermost position in the tread circumferential direction of the block. .

In each of the above-described examples, the area Ab of the region surrounded by the outer edge of the block, that is, the surface area of the block and the shallow groove (auxiliary shallow groove provided in the block) in the plan view of FIGS. In this case, the area Ab including the auxiliary shallow grooves (the same applies hereinafter in this paragraph)) and the total groove area Am of the shallow grooves provided in the block are Am / Ab> 0. It is preferable to satisfy 20 relationships. Thereby, the required volume of the shallow groove for taking in mud on the block surface can be sufficiently secured.

Further, in each of the above examples, the arrangement of the shallow grooves increases the edge width direction component, effectively improving the traction performance and braking performance during muddy travel, The projected length Eb in the tread width direction and the projected length Em in the tread width direction of the edge of the shallow groove (including the auxiliary shallow groove when the auxiliary shallow groove is provided; the same applies to the following in this paragraph). And satisfy the relationship of Em / Eb> 0.8.
The “projected length of the edge in the tread width direction” herein means the total length of the components extending in the tread width direction of the edge extending in a predetermined direction.
The block circumferential maximum length Lb, the circumferential distance Lm between the circumferential outer end points of the shallow groove, the area Ab of the region surrounded by the block outer edge, the total groove area Am of the shallow groove, the block edge Each of the circumferential projection length Eb and the circumferential projection length Em of the shallow groove edge is an unloaded state in which the tire is assembled to the applicable rim and filled with the specified internal pressure, and is seen in the development view of the tread pattern. Measure along the tread surface.

FIG. 4 is a tire width direction cross-sectional view showing a tire internal structure of a pneumatic tire according to an embodiment of the present invention, particularly a heavy duty tire such as a construction vehicle. As shown in FIG. 4, the tire 100 has a thicker rubber gauge (rubber thickness) in the tread portion 500 than a pneumatic tire mounted on a passenger car or the like. Note that the tire internal structure described below can be applied to each tire having the tread pattern described with reference to FIGS.

Specifically, the tire 100 satisfies DC / OD ≧ 0.015 when the tire outer diameter is OD and the rubber gauge of the tread portion 500 at the position of the tire equatorial plane C is DC.

The tire outer diameter OD (unit: mm) is the diameter of the tire 100 at a portion (generally, the tread portion 500 in the vicinity of the tire equatorial plane C) where the outer diameter of the tire 100 is maximum. The rubber gauge DC (unit: mm) is the rubber thickness of the tread portion 500 at the position of the tire equatorial plane C. The rubber gauge DC does not include the thickness of the belt 300. In addition, when the circumferential groove | channel is formed in the position containing the tire equator surface C, it is set as the rubber thickness of the tread part 500 in the position adjacent to the circumferential groove | channel.

As shown in FIG. 4, the tire 100 includes a pair of bead cores 110, a carcass 200, and a belt 300 including a plurality of belt layers. 4 shows only the half width of the tire 100, the half width of the tire 100 not shown has the same structure.

The bead core 110 is provided in the bead unit 120. The bead core 110 is configured by a bead wire (not shown).

The carcass 200 forms the skeleton of the tire 100. The position of the carcass 200 passes from the tread portion 500 through the buttress portion 900 and the sidewall portion 700 to the bead portion 120.

The carcass 200 straddles between a pair of bead cores 110 and has a toroidal shape. The carcass 200 wraps the bead core 110 in this embodiment. The carcass 200 is in contact with the bead core 110. Both ends of the carcass 200 in the tire width direction twd are supported by a pair of bead portions 120.

The carcass 200 has a carcass cord extending in a predetermined direction when viewed in plan from the tread tread surface 1 side. In the present embodiment, the carcass cord extends along the tire width direction twd. For example, a steel wire is used as the carcass cord.

The belt 300 is disposed on the tread portion 500. The belt 300 is located outside the carcass 200 in the tire radial direction trd. The belt 300 extends in the tire circumferential direction. The belt 300 has a belt cord that is inclined with respect to a predetermined direction that is a direction in which the carcass cord extends. For example, a steel cord is used as the belt cord.

The belt 300 composed of a plurality of belt layers includes a first belt layer 301, a second belt layer 302, a third belt layer 303, a fourth belt layer 304, a fifth belt layer 305, and a sixth belt layer 306.

The first belt layer 301 is located outside the carcass 200 in the tire radial direction trd. The first belt layer 301 is located on the innermost side in the belt 300 composed of a plurality of belt layers in the tire radial direction trd. The second belt layer 302 is located outside the first belt layer 301 in the tire radial direction trd. The third belt layer 303 is located outside the second belt layer 302 in the tire radial direction trd. The fourth belt layer 304 is located outside the third belt layer 303 in the tire radial direction trd. The fifth belt layer 305 is located outside the fourth belt layer 304 in the tire radial direction trd. The sixth belt layer 306 is located outside the fifth belt layer 305 in the tire radial direction trd. The sixth belt layer 306 is located on the outermost side in the belt 300 composed of a plurality of belt layers in the tire radial direction trd. In the tire radial direction trd, from the inside toward the outside, the first belt layer 301, the second belt layer 302, the third belt layer 303, the fourth belt layer 304, the fifth belt layer 305, and the sixth belt layer 306 are arranged in this order. Be placed.

In the present embodiment, in the tire width direction twd, the width of the first belt layer 301 and the second belt layer 302 (the width measured along the tire width direction twd. The same applies hereinafter) is 25% or more of the tread width TW. And it is 70% or less. In the tire width direction twd, the widths of the third belt layer 303 and the fourth belt layer 304 are 55% or more and 90% or less of the tread width TW. In the tire width direction twd, the widths of the fifth belt layer 305 and the sixth belt layer 306 are 60% or more and 110% or less of the tread width TW.

In the present embodiment, in the tire width direction twd, the width of the fifth belt layer 305 is larger than the width of the third belt layer 303, and the width of the third belt layer 303 is equal to or larger than the width of the sixth belt layer 306. The width of the sixth belt layer 306 is larger than the width of the fourth belt layer 304, the width of the fourth belt layer 304 is larger than the width of the first belt layer 301, and the width of the first belt layer 301 is It is larger than the width of the second belt layer 302. In the tire width direction twd, among the belts 300 composed of a plurality of belt layers, the fifth belt layer 305 has the largest width and the second belt layer 302 has the smallest width. Accordingly, the belt 300 including a plurality of belt layers includes the shortest belt layer (that is, the second belt layer 302) having the shortest length in the tire width direction twd.

The second belt layer 302 which is the shortest belt layer has a belt end 300e which is an edge in the tire width direction twd.

In this embodiment, when viewed in plan from the tread tread surface 1 side, the inclination angles of the belt cords of the first belt layer 301 and the second belt layer 302 with respect to the carcass cord are 70 ° or more and 85 ° or less. The inclination angle of the belt cords of the third belt layer 303 and the fourth belt layer 304 with respect to the carcass cord is not less than 50 ° and not more than 75 °. The inclination angle of the belt cords of the fifth belt layer 305 and the sixth belt layer 306 with respect to the carcass cord is not less than 50 ° and not more than 70 °.

The belt 300 composed of a plurality of belt layers includes an inner cross belt group 300A, an intermediate cross belt group 300B, and an outer cross belt group 300C. In each cross belt group 300A to 300C, the belt cords constituting the respective belt layers in the group are between the belt layers adjacent to each other in the group (preferably, the tire equator) in a plan view from the tread tread surface 1 side. A group of multiple belt layers that intersect each other (with the plane in between).

The inner cross belt group 300A is composed of a pair of belt layers and is located outside the carcass 200 in the tire radial direction trd. The inner cross belt group 300 </ b> A includes a first belt layer 301 and a second belt layer 302. The intermediate cross belt group 300B includes a pair of belt layers and is located outside the inner cross belt group 300A in the tire radial direction trd. The intermediate crossing belt group 300 </ b> B includes a third belt layer 303 and a fourth belt layer 304. The outer cross belt group 300C includes a pair of belt layers and is located outside the intermediate cross belt group 300B in the tire radial direction trd. The outer cross belt group 300 </ b> C includes a fifth belt layer 305 and a sixth belt layer 306.

In the tire width direction twd, the inner cross belt group 300A has a width of 25% or more and 70% or less of the tread width TW. In the tire width direction twd, the width of the intermediate cross belt group 300B is 55% or more and 90% or less of the tread width TW. In the tire width direction twd, the width of the outer cross belt group 300C is 60% or more and 110% or less of the tread width TW.

When viewed in plan from the tread surface 1 side, the inclination angle of the belt cord of the inner cross belt group 300A with respect to the carcass cord is 70 ° or more and 85 ° or less. When viewed from the tread tread 1 side, the inclination angle of the belt cord of the intermediate cross belt group 300B with respect to the carcass cord is not less than 50 ° and not more than 75 °. When viewed in plan from the tread surface 1 side, the inclination angle of the belt cord of the outer cross belt group 300C with respect to the carcass cord is not less than 50 ° and not more than 70 °.

When viewed in plan from the tread surface 1 side, the inclination angle of the belt cord with respect to the carcass cord is the largest in the inner cross belt group 300A. The inclination angle of the belt cord with respect to the carcass cord of the intermediate intersection belt group 300B is equal to or greater than the inclination angle of the belt cord with respect to the carcass cord of the outer intersection belt group 300C.

The circumferential groove 2 is the innermost position in the tire width direction (that is, the tire width) of the groove width center line WL passing through the center in the width direction of the circumferential groove 2 when viewed from the belt end 300e from the tread tread surface 1 side of the tire 100. The length DL along the tire width direction twd up to the bent portion inward in the direction) is formed to be 200 mm or less.

Next, a pneumatic tire according to the present invention was prototyped and its performance was evaluated, which will be described below. The tire size was 27.00R49 for all tires.

Example tires

1 and 2 have patterns shown in FIGS. 1 and 2, respectively. The comparative tire 1 has a pattern excluding the circumferential grooves 66 and 67 in the pattern shown in FIG. The comparative example tire 2 has a pattern excluding the connecting groove 83 and the

circumferential grooves

84 and 85 in the pattern shown in FIG.

In order to evaluate the mud removal effect, each test tire was mounted on a dump truck and run on a muddy road surface under the same conditions, and then the volume of mud remaining in the lug groove was measured. In Tables 1 and 2, the reciprocal of the volume is represented by index values based on

Example Tires

1 and 2, respectively. The higher the index value, the better the mud removal effect.
On the other hand, in order to evaluate the edge effect of a tire not traveling in a muddy area, for each test tire not traveling in a muddy area, a shear strain was applied to the virtual tire by FEM calculation to determine the pressure at the edge of the block. Was measured. In Tables 1 and 2, the pressure is represented by an index value based on each of

Example Tires

1 and 2. The higher the index value, the better the edge effect.
Furthermore, in order to evaluate the slip suppression effect, each test tire is mounted on a dump truck and travels on a muddy road surface under the same conditions. The ratio with the distance calculated from the number was calculated. In Tables 1 and 2, the ratios are expressed as index values with reference to

Example tires

1 and 2, respectively. The higher the index value, the better the slip suppression effect.

As can be seen from the results shown in Tables 1 and 2, since the

Example Tires

1 and 2 are provided with more shallow grooves in the block than the

Comparative Example Tires

1 and 2, respectively, the mud removal effect and the edge Excellent in both effects. Further, as can be seen from the results shown in Tables 1 and 2,

Example Tires

1 and 2 have a larger ratio of the index value of the slip property to the index value of the edge effect than

Comparative Example Tires

1 and 2, respectively. Even in a muddy area, the scratching effect by the edge is not hindered and can be exhibited more greatly. That is, according to the pneumatic tire of the present invention, it has been found that the mud repellency in the contact surface can be improved and the scratching effect by the edge can be sufficiently exhibited.

The present invention can be applied to heavy load tires such as truck and bus tires, construction and mining vehicle tires, and is particularly suitable for use as construction and mining vehicle tires having a large load.

1: tread surface, 2: circumferential groove, 3: lug groove, 4: lug, 5, 70, 90: transverse groove, 6, 71, 91: block, 6a, 6b: sub-block, 60, 80, 100: shallow Groove, 30: opening groove, 31, 32, 106, 107: auxiliary shallow groove, 40, 92: part of the outer edge of the block, 50: center region, 51: shoulder region, 61, 62, 63, 81, 82, 101 , 102: width direction groove part, 64, 65, 83, 103: connecting groove part, 66, 67, 84, 85, 104, 105: circumferential groove part, 100: tire, 120: bead part, 200: carcass, 300: belt , 301: first belt layer, 302: second belt layer, 303: third belt layer, 304: fourth belt layer, 305: fifth belt layer, 306: 6 belt layers, 300A: inner cross belt group, 300B: intermediate cross belt group, 300C: outer cross belt group, 300e: belt end, 500: tread part, 700: sidewall part, 900: buttress part, TW: tread width , C: tire equator

Claims

A pneumatic tire having a block that is partitioned on a tread surface by two or more circumferential grooves continuously extending in the tread circumferential direction and transverse grooves opening to the circumferential grooves adjacent to each other in the tread width direction. There,
The block is provided with a shallow groove having an average groove depth shallower than a groove depth of the peripheral groove adjacent to the block,
The shallow groove is
A plurality of widthwise grooves extending at least one end in the block and extending in a direction inclined with respect to the tread circumferential direction;
A connecting groove for connecting at least two of the plurality of widthwise grooves;
One end is opened to at least one of the circumferential groove and the transverse groove, and the other end is connected to one of the plurality of width direction grooves, and the inclination angle with respect to the tread circumferential direction is more than the width direction groove. A small circumferential groove,
A heavy-duty pneumatic tire comprising:
The heavy duty pneumatic tire according to claim 1, wherein the circumferential groove extends in a zigzag shape in a tread circumferential direction.
The heavy duty pneumatic tire according to claim 1 or 2, wherein the connecting groove portion is inclined with respect to a tread circumferential direction.
The block is further provided with an auxiliary shallow groove having one end opened in at least one of the circumferential groove and the transverse groove and the other end terminating in the block. The heavy-duty pneumatic tire according to any one of the above.
The plurality of widthwise grooves are
First and second widthwise grooves, one end of which is located in the block and the other end is open in the transverse groove;
A third widthwise groove, both ends of which are located in the block;
Including
One end of the connecting groove is connected to the end of the first and second widthwise grooves located in the block, and the other end is one end of the third widthwise groove. Including first and second connecting grooves connected to each other;
The circumferential groove includes first and second circumferential grooves that have one end open to the circumferential groove and the other end connected to one of the third width grooves. The heavy duty pneumatic tire according to any one of claims 1 to 4.
The plurality of width direction groove portions include two width direction groove portions having one end located in the block and the other end opened to the circumferential groove,
The connecting groove portion connects the two widthwise groove portions in the middle of their extension,
One end of the circumferential groove is open to the circumferential groove and the transverse groove, and the other end is connected to one of the two widthwise grooves that is located in the block. The heavy duty pneumatic tire according to any one of claims 1 to 4, comprising two circumferential grooves.
The plurality of width direction groove portions include two width direction groove portions having one end located in the block and the other end opened to the circumferential groove,
The connecting groove portion connects the two widthwise groove portions in the middle of their extension,
The circumferential groove portion has two circumferential directions in which one end is open to the transverse groove and the other end is connected to one of the two widthwise groove portions that is located in the block. The heavy duty pneumatic tire according to any one of claims 1 to 4, comprising a groove.