JP6023741B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire with improved rock performance.

  For example, a pneumatic tire traveling on a rocky road surface such as a rocky mountain is required to have a so-called rocky road performance (running performance) for running through the rocky field by exhibiting sufficient traction and braking force on the rocky road surface. In order to improve the rock performance, a block pattern tire having a plurality of blocks in the tread portion is employed. Such a pneumatic tire enhances traction and braking force and improves rock performance by sandwiching rocks between adjacent blocks.

  However, in recent years, there has been a demand for a pneumatic tire with further improved rock performance.

JP 2005-67246 A

  The present invention has been devised in view of the above problems, and has as its main object to provide a pneumatic tire capable of improving rock performance on the basis of improving the shape of the shoulder block. .

  The present invention is a pneumatic tire in which a shoulder block row in which shoulder blocks are arranged in the tire circumferential direction is formed on at least one tread end side of the tread portion, and the shoulder block includes a first shoulder block, a second shoulder block, and a second shoulder block. Shoulder blocks are alternately arranged, the first shoulder block has a first edge that defines a ground contact end on the outer side in the tire axial direction of the tread surface, and the second shoulder block is a tire on the tread surface. The first shoulder block has a second edge that defines an axially outer contact end and is located on the inner side in the tire axial direction than the first edge, and the first shoulder block extends inward in the tire axial direction from the first edge. In addition, a first lug groove that terminates inside the block is provided.

  In the pneumatic tire according to the present invention, it is preferable that the second shoulder block is provided with a second lug groove extending inward in the tire axial direction from the second edge and terminating in the block.

  In the pneumatic tire according to the present invention, it is preferable that the first edge and the second edge are separated by a distance in a tire axial direction of 4% to 7% of a tread contact width.

  In the pneumatic tire according to the present invention, the first lug groove has an axial portion extending along the tire axial direction from the first edge, and is connected to the axial portion and is 10 to 15 degrees with respect to the tire axial direction. It is desirable to have an inclined portion having an angle of

  In the pneumatic tire according to the present invention, it is preferable that the second lug groove includes an inclined portion that is inclined at an angle of 15 degrees or less with respect to the tire axial direction from the second edge.

  In the pneumatic tire according to the present invention, the inner end of the second lug groove in the tire axial direction is provided at the same position as the inner end of the first lug groove in the tire axial direction. Is desirable.

  In the pneumatic tire according to the present invention, the second shoulder block has a second buttress surface extending inward in the tire radial direction from the second edge toward the outer side in the tire axial direction, and the second buttress surface is It is desirable to have a concave arc surface having a center outside the tire.

  In the pneumatic tire according to the present invention, the height at the tread end of the second buttress surface is preferably 30% to 50% of the height of the shoulder block.

  In the pneumatic tire of the present invention, a shoulder block row in which the first shoulder block and the second shoulder block are alternately arranged is formed. The 1st shoulder block has the 1st edge which demarcates the grounding end of the tire axial direction outside of the tread. The second shoulder block has a second edge located on the inner side in the tire axial direction than the first edge. In such a pneumatic tire, the rock on the rocky road surface can be firmly sandwiched between the first shoulder blocks on both sides in the tire circumferential direction of the second shoulder block and the second edges of the second shoulder block. Thereby, the pneumatic tire of this invention has the outstanding rock performance.

  The first shoulder block is provided with a first lug groove extending inward in the tire axial direction from the first edge and terminating inside the block. Such a 1st lug groove reduces the rigidity of a 1st shoulder block, and accelerates | stimulates the deformation | transformation. For this reason, rocks can be further sandwiched between the first shoulder blocks on both sides and the second edges of the second shoulder blocks. Therefore, the pneumatic tire of the present invention has improved rock performance.

It is an expanded view of the tread part of the pneumatic tire of one embodiment of the present invention. It is an enlarged view of the shoulder block of FIG. It is a top view explaining the pinching of the rock by a shoulder block. It is a perspective view of a 2nd shoulder block. It is a perspective view of the 2nd shoulder block of other embodiments. It is an expanded view of the tread part which shows embodiment of a comparative example. It is an expanded view of the tread part which shows other embodiment of a comparative example.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a development view of a tread portion 2 of a pneumatic tire 1 showing an embodiment of the present invention. The pneumatic tire (hereinafter sometimes simply referred to as “tire”) 1 of the present embodiment is suitably used as an all-season tire for a four-wheel drive vehicle, for example.

  The tread portion 2 of the present embodiment includes a pair of shoulder block rows 3R in which a plurality of shoulder blocks 3 are arranged in the tire circumferential direction on the tread end Te side on both sides, and a plurality of center blocks 4 on both sides of the tire equator C. Are arranged in the tire circumferential direction, and a groove 5 extending between each shoulder block 3 or each center block 4 is provided.

  The “tread end” Te is obtained when a normal load is applied to a normal tire 1 that is assembled with a normal rim and filled with a normal internal pressure, and a normal load is applied to the flat tire with a camber angle of 0 degrees. It is determined as the ground contact position on the outermost side in the tire axial direction. In the normal state, the distance in the tire axial direction between the tread ends Te and Te is determined as the tread contact width TW. Unless otherwise noted, the dimensions and the like of each part of the tire are values measured in a normal state.

  The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, “Standard Rim” for JATMA, “Design Rim” for TRA, ETRTO Then "Measuring Rim".

  “Regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. “JAMATA” is the “maximum air pressure”, TRA is the table “TIRE LOAD LIMITS” The maximum value described in “AT VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” in the case of ETRTO. When the tire is for a passenger car, the normal internal pressure is 180 kPa.

  “Regular load” is a load determined by each standard for each tire in the standard system including the standard on which the tire is based. “JATMA” is “maximum load capacity”, TRA is “TIRE LOAD” The maximum value described in “LIMITS AT VARIOUS COLD INFLATION PRESSURES”, “LOAD CAPACITY” in the case of ETRTO. When the tire is for a passenger car, the normal load is a load corresponding to 88% of the load.

  When the groove width (measured at right angles to the groove center line) W1 of the groove 5 is small, the rock protrusion portion cannot be effectively sandwiched by the shoulder block 3 or the center block 4, and the rocky road running performance deteriorates. There is a fear. When the groove width W1 of the groove 5 is large, the rigidity of each of the blocks 3 and 4 is reduced, and the uneven wear resistance may be deteriorated. For this reason, the groove width W1 of the groove 5 is preferably 5% or more of the tread ground contact width TW, and preferably 15% or less.

  FIG. 2 is an enlarged view of the shoulder block 6 of FIG. As shown in FIG. 2, the shoulder block 3 of the present embodiment includes a first shoulder block 6 and a second shoulder block 7. These shoulder blocks 6 and 7 are arranged alternately in the tire circumferential direction.

  The first shoulder block 6 of the present embodiment has a tread surface 6a having a rectangular outer portion 6A and a substantially arc-shaped inner portion 6B provided on the inner side in the tire axial direction of the outer portion 6A. The first shoulder block 6 is not limited to such a shape.

  The first shoulder block 6 has a first edge 8 that defines a ground contact end 6t outside the tire axial direction of the tread 6a. The first edge 8 of this embodiment extends linearly and forms a tread end Te. Thereby, the capacity | capacitance of the 1st shoulder block 6 can be ensured large, and uneven wear-proof performance improves.

  The second shoulder block 7 of the present embodiment has a tread surface 7a having a rectangular outer portion 7A and a substantially arcuate inner portion 7B provided on the inner side in the tire axial direction of the outer portion 7A. The second shoulder block 7 is not limited to such a shape.

  The second shoulder block 7 has a second edge 9 that defines a ground contact end 7t outside the tire axial direction of the tread surface 7a. The second edge 9 extends along the tire circumferential direction.

  The second edge 9 is located on the inner side in the tire axial direction than the first edge 8. As a result, as shown in FIG. 3, the rocks R and the like on the rocky road surface are formed by the first shoulder blocks 6 and 6 on both sides in the tire circumferential direction of the second shoulder block 7 and the second edge 9 of the second shoulder block 7. Can be sandwiched greatly. Therefore, the tire 1 of the present embodiment exhibits great traction and braking force and has excellent rock performance.

  As shown in FIG. 2, the second edge 9 and the first edge 8 are preferably separated by a distance L1 in the tire axial direction that is 4% to 7% of the tread contact width TW. That is, when the distance L1 is less than 4% of the tread ground contact width TW, there is a possibility that the rock cannot be effectively sandwiched. When the distance L1 exceeds 7% of the tread contact width TW, the rigidity of the second shoulder block 7 is reduced, and the uneven wear resistance may be deteriorated.

Tio Ruda tire circumferential pitch P of the block 3 is preferably 20% to 40% of the tread width TW. Thereby, the above-mentioned rocky place traveling performance and uneven wear resistance can be improved in a well-balanced manner.

  The first shoulder block 6 is provided with a first lug groove 11 extending inward in the tire axial direction from the first edge 8 and terminating inside the block. Such a first lug groove 11 can effectively reduce the rigidity of the first shoulder block 6 and can deform the first shoulder block 6 in the tire circumferential direction by stress from the road surface. Therefore, since the tire 1 of this embodiment can further sandwich rocks or the like between the first shoulder blocks 6 and 6 on both sides, the rock performance is improved.

  In the present embodiment, the first lug groove 11 has an axial portion 11A extending from the first edge 8 along the tire axial direction, and an angle α1 that is continuous with the axial portion 11A and that is 10 to 15 degrees with respect to the tire axial direction. And an inclined portion 11B. The axial portion 11A and the inclined portion 11B can be greatly deformed in the tire circumferential direction while ensuring the rigidity of the first shoulder block 6 in the tire axial direction. Therefore, the uneven wear resistance and the rock performance are improved in a well-balanced manner. Further, by arranging the axial direction portion 11A on the outer side in the tire axial direction than the inclined portion 11B, the rigidity in the tire axial direction on the tread end Te side of the first shoulder block 6 on which a large lateral force acts during turning travel, It is further enhanced. The axial direction portion 11A and the inclined portion 11B of the present embodiment extend linearly.

  The second shoulder block 7 is provided with a second lug groove 12 extending inward in the tire axial direction from the second edge 9 and terminating inside the block. Such a second lug groove 12 can effectively reduce the rigidity of the second shoulder block 7 and can deform the second shoulder block 7 in the tire axial direction by stress from the road surface. Accordingly, since rocks and the like can be sandwiched between the first shoulder blocks 6 and 6 on both sides and the second edge 9 of the second shoulder block 7, the rock performance is further improved.

  In the present embodiment, the second lug groove 12 includes an inclined portion 12A that is inclined from the second edge 9 at an angle α2 of 15 degrees or less with respect to the tire axial direction. Such a second lug groove 12 can ensure large rigidity in the tire axial direction on the outer side in the tire axial direction of the second shoulder block 7, thereby improving uneven wear resistance.

  The inner end 12i of the second lug groove 12 in the tire axial direction is provided at the same position as the inner end 11i of the first lug groove 11 in the tire axial direction. As a result, the first shoulder block 6 and the second shoulder block 7 are ensured in a well-balanced rigidity, and the uneven wear resistance is further improved.

  The distance L2 in the tire axial direction between the inner end 11i, 12i in the tire axial direction of the first lug groove 11 and the second lug groove 12 and the tread end Te is preferably 10% to 20% of the tread contact width TW. . When the distance L2 is less than 10% of the tread contact width TW, deformation of the first shoulder block 6 and the second shoulder block 7 is suppressed, and there is a possibility that rocks or the like cannot be sandwiched greatly. When the distance L2 exceeds 20% of the tread contact width TW, the rigidity of the first shoulder block 6 and the second shoulder block 7 is excessively lowered, and the uneven wear resistance may be deteriorated.

An outer end 11e in the tire axial direction of the first lug groove 11 and an outer end 12e in the tire circumferential direction of the second lug groove 12 are connected to a substantially intermediate position of the first edge 8 or the second edge 9 in the tire circumferential direction. Yes. Thereby, the rigidity of the tire circumferential direction of the 1st shoulder block 6 and the 2nd shoulder block 7 is ensured with sufficient balance, and also uneven wear-proof performance improves. The “substantially intermediate position” refers to a position that is 40% to 60% of the length La, Lb in the tire circumferential direction of each edge 8 , 9 from one end of the first edge 8 or the second edge 9.

  The groove width W2 of the first lug groove 11 is preferably 3.0 to 8.0 mm. When the groove width W2 of the 1st lug groove 11 exceeds 8.0 mm, the rigidity of the 1st shoulder block 6 deteriorates and there exists a possibility that uneven wear-proof performance may deteriorate. When the groove width W2 of the 1st lug groove 11 is less than 3.0 mm, the deformation | transformation of the 1st shoulder block 6 is small, a rock cannot be pinched | interposed effectively and there exists a possibility that a rocky road performance cannot be improved. From the same viewpoint, the groove width W3 of the second lug groove 12 is preferably 3.0 to 8.0 mm. The first lug groove 11 and the second lug groove 12 of the present embodiment extend with a constant groove width W2, W3.

  In order to effectively exhibit the above-described action, the groove depth (not shown) of the first lug groove 11 and the second lug groove 12 is preferably 1 to 4 mm.

  FIG. 4 is a perspective view of the second shoulder block 7 having a cross section along the tread end Te. As shown in FIG. 4, the second shoulder block 7 has a second buttress surface 13 extending inward in the tire radial direction from the second edge 9 toward the outer side in the tire axial direction.

  The second buttress surface 13 of the present embodiment is formed by a concave arc surface having a center outside the tire. Such a second buttress surface 13 increases the space for sandwiching the rock formed between the first shoulder blocks 6 and 6 on both sides in the tire circumferential direction, thereby further improving the rock performance.

  The height H1 of the second buttress surface 13 at the tread end Te is preferably 30% to 50% of the height Ha of the shoulder block 3. When the height H1 of the second buttress surface 13 is less than 30% of the height Ha of the shoulder block 3, the rigidity of the outer portion in the tire axial direction of the second shoulder block 7 on which a large lateral force acts becomes excessively small. There is a risk that uneven wear resistance will deteriorate. When the height H1 of the second buttress surface 13 exceeds 50% of the height Ha of the shoulder block 3, the above-described effect of enlarging the space is not exhibited, and there is a possibility that the rock performance cannot be improved.

  The second buttress surface 13 of the present embodiment is provided with a narrow groove 14 extending from the second edge 9 to the outside in the tire axial direction. Such a narrow groove 14 further reduces the rigidity of the second shoulder block 7 more effectively, facilitates deformation of the second shoulder block 7 inward in the tire axial direction, and improves rock performance.

  The narrow groove 14 is connected to the outer end 12e of the second lug groove 12 in the tire axial direction. The narrow groove 14 extends along the tire axial direction. Thereby, the excessive rigidity fall of the 2nd shoulder block 7 is suppressed, and uneven wear-proof performance is maintained high.

  Such a narrow groove 14 desirably has the same groove width as that of the second lug groove 12, and the groove width W4 (shown in FIG. 2) is 3.0 to 8.0 mm. Similarly, the groove depth D of the narrow groove 14 is desirably the same as that of the second lug groove 12, and the groove depth D is 1 to 4 mm.

  As shown in FIG. 2, the first shoulder block 6 further includes a first inner edge 17A, a first long inclined edge 18A, and a first short inclined edge 19A. The first inner edge 17A is disposed on the innermost side of the tread surface 6a in the tire axial direction. The first long inclined edge 18A joins one end of the first edge 8 in the tire circumferential direction and one end of the first inner edge 17A in the tire circumferential direction. The first short inclined edge 19A connects the other end of the first edge 8 in the tire circumferential direction and the other end of the first inner edge 17A in the tire circumferential direction. The first long inclined edge 18A and the first short inclined edge 19A are inclined in the opposite direction to the tire circumferential direction from the first inner edge 17A.

  The first long inclined edge 18A and the first short inclined edge 19A are respectively a gently inclined portion 20A inclined at an angle θ1 of 15 degrees or less with respect to the tire axial direction from the first edge 8, and 15 degrees with respect to the tire axial direction. And a steeply inclined portion 20B that is inclined at an angle θ2 that exceeds. Such a gently inclined portion 20A increases the rigidity in the tire axial direction on the tread end Te side of the shoulder blocks 6 and 7 on which the greatest lateral force acts, and thus can greatly improve the uneven wear resistance. Further, the gently inclined portion 20A is useful for effectively sandwiching the rock.

  Similarly, the second shoulder block 7 further includes a second inner edge 17B, a second long inclined edge 18B, and a second short inclined edge 19B. The second inner edge 17B is disposed on the innermost side in the tire axial direction of the tread surface 7a. The second long inclined edge 18B joins one end of the second edge 9 in the tire circumferential direction and the other end of the second inner edge 17B in the tire circumferential direction. The second short inclined edge 19B joins the other end of the second edge 9 in the tire circumferential direction and the other end of the second inner edge 17B in the tire circumferential direction.

  In the present embodiment, the tread surface 6a of the first shoulder block 6 and the tread surface 7a of the second shoulder block 7 have the same shape except that the arrangement positions of the first edge 8 and the second edge 9 are different. For this reason, since the rigidity of the 1st shoulder block 6 and the 2nd shoulder block 7 is improved with a sufficient balance, it has the outstanding partial wear-proof performance.

  The first shoulder block 6 is provided with a first sipe 21 that connects the inner end 11i of the first lug groove 11 in the tire axial direction and the first inner edge 17A. Similarly, the second shoulder block 7 is provided with a second sipe 22 that connects the inner end 12i of the second lug groove 12 in the tire axial direction and the second inner edge 17B. Such sipes 21 and 22 can accelerate the deformation of the first shoulder block 6 and the second shoulder block 7 and can improve the rock performance.

  The first sipe 21 and the second sipe 22 extend substantially parallel to the first long inclined edge 18A or the second long inclined edge 18B, respectively. As a result, uneven wear resistance is ensured without excessively reducing the rigidity of the first shoulder block 6 and the second shoulder block 7.

  The first sipe 21 and the second sipe 22 are connected to substantially intermediate positions of the inner edges 17A and 17B, respectively. The substantially intermediate position is 40% to 60% of the length of each inner edge 17A, 17B from one end of each inner edge 17A, 17B. Thereby, the above-mentioned operation is more effectively exhibited.

  In this specification, the 1st sipe 21 and the 2nd sipe 22 are defined as what has the width | variety smaller than the groove width W2, W3 of each lug groove 11,12. In order to effectively exhibit the above-described action, in the present embodiment, the width of the first sipe 21 and the second sipe 22 is preferably less than 1.0 mm.

  As shown in FIG. 1, the center block 4 includes a first inclined portion 25A whose tread surface 4a is inclined from the tire equator C to one side in the tire circumferential direction and a first inclined portion 25A opposite to the first inclined portion 25A. It is substantially V-shaped including the second inclined portion 25B larger than the inclined portion 25A. The shape of the center block 4 is not limited to such a mode.

  The center block 4 according to the present embodiment is arranged point-symmetrically with respect to the center block 4 adjacent to the tire equator C with respect to an arbitrary point on the tire equator C. Thereby, also in the center block 4, rigidity is ensured with good balance and uneven wear resistance is improved.

  The height Ha of such a shoulder block 3 is preferably 12 to 18 mm.

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

Tires for a four-wheel drive vehicle having the basic pattern of FIG. 1 were prototyped based on the specifications in Table 1, and the rock performance and uneven wear resistance of each sample tire were tested. The main common specifications and test methods for each sample tire are as follows.
Tread contact width TW: 240mm
Height of each block Ha: 17.1 mm

<Iwaji running performance>
Each sample tire was mounted on all wheels of a 3600cc four-wheel drive vehicle under the following conditions. Then, a test driver drove a test course on a rocky road surface such as a rocky mountain, and the running characteristics related to traction and braking force at this time were evaluated by the sensuality of the test driver. The results are displayed with a score of Comparative Example 1 being 100. The larger the value, the better.
Size: 37 × 12.50R17
Rim: 9.0JJ
Internal pressure: 100kPa
<Uneven wear resistance>
After the above test run, the difference in wear amount between the long slope edge and the short slope edge was measured in the shoulder blocks of all the wheels. The measurement was performed at three locations on the tire circumference, and the average value was obtained. The result is evaluated by the reciprocal of the average value, and is displayed as an index with the value of Comparative Example 1 being 100. The larger the value, the better.

  As a result of the test, it can be confirmed that the tire of the example has improved rock performance while maintaining uneven wear resistance compared to the tire of the comparative example. In addition, tests were performed on tire sizes different from the above, but the same tendency was shown.

2 tread portion 3 shoulder block 3R shoulder block row 6 first shoulder block 6a tread surface 7 second shoulder block 7a tread surface 8 first edge 9 second edge 11 first lug groove 12 second lug groove

Claims (8)

A pneumatic tire in which a shoulder block row in which shoulder blocks are arranged in the tire circumferential direction is formed on at least one tread end side of the tread portion,
The shoulder block has first shoulder blocks and second shoulder blocks arranged alternately,
The first shoulder block has a first edge that defines a ground contact end on the outer side in the tire axial direction of the tread surface,
The second shoulder block has a second edge that defines a ground contact end on the outer side in the tire axial direction of the tread surface and is located on the inner side in the tire axial direction with respect to the first edge,
The first shoulder block is provided with a first lug groove extending inward in the tire axial direction from the first edge and terminating inside the block ,
The second shoulder block is provided with a second lug groove extending inward in the tire axial direction from the second edge and terminating inside the block,
The first lug groove includes an axial portion extending along the tire axial direction from the first edge, and an inclined portion that is continuous with the axial portion and has an angle of 10 to 15 degrees with respect to the tire axial direction. ,
The pneumatic tire is characterized in that the second lug groove is configured by an inclined portion that is inclined at an angle of 15 degrees or less with respect to the tire axial direction from the second edge . The tire axial distance between the inner end and the tread end of the tire axial direction of the first lug grooves, the pneumatic tire according to claim 1, wherein Ru 10% to 20% der the tread width.   The pneumatic tire according to claim 1 or 2, wherein the first edge and the second edge are separated by a distance in a tire axial direction of 4% to 7% of a tread contact width. The pneumatic tire according to any one of claims 1 to 3, wherein a distance in the tire axial direction between an inner end in the tire axial direction of the second lug groove and a tread end is 10% to 20% of a tread contact width . The second shoulder block has a second inner edge arranged on the innermost side in the tire axial direction of the tread, and
The pneumatic tire according to any one of claims 1 to 4, wherein a second sipe that connects an inner end of the second lug groove in the tire axial direction and the second inner edge is provided .   The tire axial direction inner end of the second lug groove is provided at the same position as the tire axial direction inner end of the first lug groove in the tire axial direction. Pneumatic tires. The second shoulder block has a second buttress surface extending inward in the tire radial direction from the second edge toward the outside in the tire axial direction,
The pneumatic tire according to claim 1, wherein the second buttress surface is a concave arc surface having a center outside the tire. The pneumatic tire according to claim 7, wherein a height at a tread end of the second buttress surface is 30% to 50% of a height of the shoulder block.

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