JP2014213841A - Heavy load pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heavy load pneumatic tire which can sufficiently exhibit a scratch effect by an edge by improving mud removing performance in a grounding plane without largely lowering block rigidity causing the deterioration of wear resistance.SOLUTION: This tire includes: a plurality of width-direction groove parts 61 to 63 in which shallow grooves 60 having an average groove depth shallower than groove depths of circumferential grooves 2 which adjoin blocks are formed at the blocks 6, and the shallow grooves 60 are located in the blocks at their one-ends, and extend in directions inclined to tread circumferential directions; connecting groove parts 64, 65 which connect at least two of a plurality of the width-direction groove parts; and circumferential groove parts 66, 67 which are opened at least at either of the circumferential grooves 2 and traverse grooves 5 at their one-ends, connected to one of a plurality of the width-direction groove pats at the other ends, and smaller than the width-direction groove parts in inclination angles with respect to the tread circumferential directions.

Description

  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., and these dump trucks are muddy areas 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)”.

  In addition, the above-mentioned “groove depth” is measured in a no-load state in which a tire is assembled to an applicable rim and filled with a 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.

  Hereinafter, embodiments of the present invention will be described 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 drawing, the transverse groove 5 extends between two bent portions protruding inward in the tread width direction of the two circumferential grooves 2 at two locations. 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 that extends from the tread end and opens 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 have an average groove depth of 1/2 to 7/10 of the groove depth of the circumferential groove 2 from the viewpoint of ensuring sufficient rigidity in the block 6. Moreover, it is preferable to have an average groove width smaller than the groove width of the circumferential groove 2 as in the example of the figure. 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.

  At least one end of each of the width direction grooves 61 to 63 is located in the block 6 and extends in a direction inclined with respect to the tread circumferential direction. By providing the width direction groove portions 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 during load rolling of the tire 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 of the drawing, the width direction groove portions 61 and 62 and the width direction groove portions 62 and 63 are connected). It extends like so. Here, the connecting groove portions 64 and 65 have a smaller inclination angle with respect to the tread circumferential direction than each of the width direction groove portions 61 to 63. By providing the connection 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 connection groove parts 64 and 65 incline with respect to the tread circumferential direction like the example of a 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 illustrated example), and the other end of each 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. Moreover, since the inclination angle with respect to the tread circumferential direction of the circumferential groove portions 66 and 67 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.

  Each of the auxiliary shallow grooves 31 and 32 has one end opened to at least one of the circumferential groove 2 and the transverse groove 5 (the 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.

  Furthermore, in the example of the figure, the groove width center lines of the width direction groove portions 61 to 63 extending in parallel with each other are arranged at substantially equal intervals in the tread circumferential direction, and thereby, are partitioned between the width direction groove portions 61 to 63. 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 of the figure, 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 width direction groove portions 61 to 63 and the connection groove portions 64 and 65 at the time of tire rolling is further easily discharged to 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 to 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. Each of the auxiliary shallow grooves 106 and 107 has one end opening in the circumferential groove 2 and the other end terminating 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.

  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 duty tires such as truck / bus tires and construction / mine vehicle tires, and is particularly suitable for use as construction / mine 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: Connection groove part, 66, 67, 84, 85, 104, 105: Circumferential direction groove part, C: Tire equatorial plane

Claims (7)

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, wherein the connection 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 terminated 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.

Images