JP5559595B2 - tire - Google Patents

Description

  The present invention relates to a tire that effectively suppresses uneven wear of a block-shaped land portion provided on a tread surface.

  Conventionally, various improved technologies have been proposed for suppressing uneven wear that occurs in tires mounted on vehicles such as automobiles. For example, the tire described in Patent Document 1 has a block-like land portion defined by a plurality of circumferential grooves extending along the tire circumferential direction and a lateral groove extending along the tread width direction. In the land portion, the angle α between the tread side groove wall located on the front side in the tire rotation direction and the tread ground surface and the angle β between the kick side groove wall located on the rear side in the tire rotation direction and the tread ground surface are , Α> β. Furthermore, the rigidity of the block-shaped land portion is within a predetermined range from various conditions such as the length of the block-shaped land portion in the tire circumferential direction, the height from the groove bottom, and the Young's modulus of rubber. According to this, the compressive deformation of the block-shaped land portion that occurs when the block-shaped land portion contacts the road surface reaches the entire block-shaped land portion without concentrating on the kicking-out end portion. As a result, it is possible to suppress the slip that occurs when the kicked-out end portion leaves the road surface, and avoids uneven wear (so-called heel and toe wear).

JP-A-5-270214

  However, the conventional tire described above has the following problems. That is, in the block-shaped land portion, a predetermined effect can be obtained with respect to suppressing heel and toe wear in which the kicked-out end portion on the rear side in the tire rotation direction is worn, but a tread pattern is used to improve driving force and braking force. In recent years, the wear of the block-like land portions of tires has become complicated, and further improvements are required.

  Then, this invention aims at provision of the tire which suppresses the uneven wear of the block-shaped land part provided in the tread surface effectively.

  As a result of earnest research on the uneven wear that occurs in the block-shaped land portion of the tire, the inventor has found that there are mainly two causes for the occurrence and progress of uneven wear.

  The first cause is initial wear that occurs at the kicking end portion on the shoulder side of the block-shaped land portion due to input in the tread width direction from the shoulder side. Usually, the road surface is provided with a slope whose height decreases toward the road shoulder for the purpose of discharging rainwater or the like. For this reason, the vehicle tends to travel to the shoulder side due to the inclination of the road surface. Therefore, it is necessary to generate a lateral force from the road shoulder side to the road center line side by giving a slip angle to the tire and to make the vehicle go straight. For this reason, shear strain is generated in the block land portion in contact with the road surface, and as a result, initial wear is likely to occur. In particular, the ground contact pressure increases at the kicking end on the shoulder side of the block-shaped land portion, and initial wear tends to occur.

  The second cause is that the wear progresses forward in the tire rotation direction due to a force acting in the direction opposite to the vehicle traveling direction (hereinafter referred to as braking force). Usually, the compressive deformation of the block-shaped land portion during vehicle travel concentrates on the kicking end of the block-shaped land portion. Moreover, a shearing strain is generated at the kicking end of the block-shaped land portion by the braking force. As a result, when the kick-out end portion is separated from the road surface, a large amount of slip occurs between the block-shaped land portion and the road surface. In addition, the kicking end of the worn block-shaped land portion has a lower contact pressure with the road surface than other portions of the block-shaped land portion, and moves easily within the contact area with the road surface. It becomes slippery and promotes wear of this part.

  Accordingly, it is understood that if the shear strain of the block-shaped land portion due to the lateral force caused by the inclination provided on the road surface and the braking force is suppressed, the uneven wear of the block-shaped land portion is greatly suppressed. As a result of further research, the inventors have completed the present invention.

  First, the first feature of the present invention is defined by a plurality of circumferential grooves (circumferential grooves 50) extending along the tire circumferential direction and a plurality of lateral grooves (lateral grooves 60) extending along the tread width direction. A tire (pneumatic tire 1) having a block-like land portion (block-like land portion 10), one circumferential side wall (circumferential wall 12) of the block-like land portion formed by a circumferential groove, and a block The gist of the invention is that the circumferential side wall angle (wall angle θ1) formed by the tread surface in contact with the road surface is reduced as it goes from one end of the block land portion to the other end in the tire circumferential direction.

  According to such a feature, by arranging the other end of the block-shaped land portion having a small circumferential side wall angle so as to correspond to a portion where the initial wear is likely to occur, the occurrence of the initial wear and the wear from the initial wear are reduced. It becomes possible to suppress progress.

  The second feature of the present invention relates to the first feature, wherein the circumferential side wall angle (wall angle θ2) formed by the other circumferential side wall and the tread surface is different from one end of the block-shaped land portion in the tire circumferential direction. The gist is that it grows as it goes to the end.

  A third feature of the present invention relates to the first feature or the second feature, and is a widthwise side wall formed by a widthwise side wall of a block-like land portion formed by a transverse groove at the other end of the block-like land portion and a tread surface. The gist is that the angle (wall angle θ3) increases from one circumferential side wall toward the other circumferential side wall.

  A fourth feature of the present invention relates to any one of the first to third features, and includes a circumferential side wall angle of one circumferential side wall, a circumferential side wall angle of the other circumferential side wall, and a lateral side wall angle. At least one of them is summarized to change linearly continuously.

  A fifth feature of the present invention relates to any one of the first to fourth features, wherein a circumferential side wall angle of one circumferential side wall is 70 degrees to 110 degrees at the other end of the block-shaped land portion. It is a summary.

  The sixth feature of the present invention is related to any one of the first to fifth features, and the gist of the width direction side wall angle is 70 to 110 degrees in one circumferential side wall.

  A seventh feature of the present invention relates to any one of the first to sixth features, and is summarized in that the block-like land portion has a parallelogram shape in a tread surface view.

  The eighth feature of the present invention relates to the first or second feature, wherein one circumferential side wall is located on the shoulder side of the road, and the other circumferential side wall (circumferential wall 13) is on the center line side of the road. And is mounted on the vehicle so that one end of the block-shaped land portion is located on the front end side in the tire rotation direction.

  According to the characteristics of the present invention, it is possible to provide a tire that effectively suppresses uneven wear of the block-shaped land portion provided on the tread surface.

FIG. 1 is a partial plan view showing a tread pattern constituting the pneumatic tire 1 according to the first embodiment of the present invention. FIG. 2 is an enlarged perspective view of the block-shaped land portion 10 configured in the pneumatic tire 1 according to the first embodiment. FIG. 3A is a plan view seen from the tread surface of the block-shaped land portion 10 configured in the pneumatic tire 1 according to the first embodiment. FIG. 3B is a cross-sectional view taken along line A-A ′ of FIG. FIG. 3C is a cross-sectional view taken along line B-B ′ of FIG. FIG. 3D is a cross-sectional view taken along line C-C ′ in FIG. FIG. 4 is a partial cross-sectional view in the tread width direction showing the state of the block-shaped land portion 10 according to the first embodiment when the vehicle is running. FIG. 5A is a partial plan view showing a tread pattern constituting the pneumatic tire 1X according to the first modification. FIG. 5B is a cross-sectional view taken along line A-A ′ of FIG. FIG. 5C is a cross-sectional view taken along line B-B ′ of FIG. FIG. 5D is a cross-sectional view taken along line C-C ′ in FIG. FIG. 6 is a partial plan view showing a tread pattern constituting the pneumatic tire 2 according to the second embodiment. FIG. 7 is an enlarged perspective view of the block-shaped land portion 20 configured in the pneumatic tire 2 according to the second embodiment. FIG. 8A is a plan view seen from the tread surface of the block-shaped land portion 20 configured in the pneumatic tire 2 according to the second embodiment. FIG. 8B is a cross-sectional view taken along line A-A ′ of FIG. FIG. 8C is a cross-sectional view taken along line B-B ′ of FIG. FIG. 8D is a cross-sectional view taken along line C-C ′ in FIG. FIG. 8E is a cross-sectional view taken along line D-D ′ in FIG. FIG. 8F is a cross-sectional view taken along line E-E ′ of FIG. FIG. 8G is a cross-sectional view taken along line F-F ′ in FIG. FIG. 9A is a partial plan view showing a tread pattern constituting the pneumatic tire 2Y according to the second modification. FIG. 9B is a cross-sectional view taken along line A-A ′ of FIG. FIG. 9C is a cross-sectional view taken along line B-B ′ of FIG. FIG. 9D is a cross-sectional view taken along line C-C ′ in FIG. FIG. 9E is a cross-sectional view taken along line D-D ′ in FIG. FIG. 9F is a cross-sectional view taken along line E-E ′ of FIG. FIG. 9G is a cross-sectional view taken along line F-F ′ in FIG. FIG. 10A is a partial plan view showing a tread pattern constituting the pneumatic tire 3 according to the third embodiment. FIG. 10B is a cross-sectional view taken along line A-A ′ of FIG. FIG. 10C is a cross-sectional view taken along line B-B ′ of FIG. FIG. 10D is a cross-sectional view taken along line C-C ′ in FIG. FIG. 10E is a cross-sectional view taken along line D-D ′ in FIG. FIG. 10F is a cross-sectional view taken along line E-E ′ of FIG. FIG. 10G is a cross-sectional view taken along line F-F ′ in FIG.

  Next, the first embodiment, the second embodiment, the third embodiment, comparative evaluation, and modified examples according to the present invention will be described with reference to the drawings.

  In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones.

  Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, the part from which the relationship and ratio of a mutual dimension differ also in between drawings may be contained.

  The tire according to the first to third embodiments is a pneumatic tire including a beat portion, a carcass layer, and a belt layer (not shown).

(1) 1st Embodiment In 1st Embodiment, (1.1) The structure of a tread pattern, (1.2) The structure of a block-shaped land part, (1.3) The effect | action and effect are demonstrated.

(1.1) Configuration of Tread Pattern FIG. 1 is a partial plan view showing a tread pattern constituting the pneumatic tire 1 according to the first embodiment of the present invention.

  As shown in FIG. 1, the pneumatic tire 1 communicates with a plurality of circumferential grooves 50 extending along the tire circumferential direction and adjacent circumferential grooves 50 in the tread surface view, and extends along the tread width direction. It has a plurality of horizontal grooves 60 and a plurality of block-shaped land portions 10 that are defined by the circumferential grooves 50 and the horizontal grooves 60.

  In the first embodiment, the pneumatic tire 1 is distinguished from the stepping-in side and the kicking-out side, and the tire rotation direction when traveling forward of the vehicle is specified.

(1.2) Configuration of Block-Land Land Next, the configuration of the block-like land 10 will be described with reference to the drawings. FIG. 2 is an enlarged perspective view of the block-shaped land portion 10 configured in the pneumatic tire 1 according to the first embodiment. FIG. 3A is a plan view seen from the tread surface of the block-shaped land portion 10 configured in the pneumatic tire 1 according to the first embodiment. FIG. 3B is a cross-sectional view taken along line AA ′ of FIG. FIG. 3C is a cross-sectional view taken along line BB ′ in FIG. FIG. 3D is a cross-sectional view taken along the line CC ′ of FIG.

  As shown in FIG. 2, the block-shaped land portion 10 includes a tread surface 11 that comes into contact with the road surface, a circumferential wall 12 that is located on the road shoulder side, a circumferential wall 13 that is located on the road center line side, and a tire rotation direction. It has the width direction wall 14 located in the back side, and the width direction wall 15 located in the tire rotation direction front side. The circumferential wall 12 and the circumferential wall 13 are configured in parallel with each other, and the width direction wall 14 and the width direction wall 15 are configured in parallel with each other.

  As shown in FIGS. 2 to 3, the tread surface 11 of the block-shaped land portion 10 is a rectangle having a long side as a side along the tire circumferential direction.

  The bottom surface (not shown) of the block-shaped land portion 10 that is on the inner side in the tire radial direction is parallel four sides that incline so as to approach the road center line side from the front side in the tire rotation direction toward the rear side in the tire rotation direction in the tread width direction. It is a shape. That is, the groove bottom 51 which is the bottom of the circumferential groove 50 is not linear, but is inclined with respect to the tire circumferential direction between the block-shaped land portions 10 adjacent to each other in the tread width direction. A certain groove bottom 61 extends linearly along the tread width direction.

  In the block-shaped land portion 10, the boundary side between the circumferential wall 12 and the tread surface 11 is located on the outer side in the tire radial direction and is defined as an upper end side 12 </ b> A. Further, in the block-shaped land portion 10, a boundary side between the circumferential wall 12 and the groove bottom portion 51 of the circumferential groove 50 adjacent to the circumferential wall 12 is defined as a bottom side 12 </ b> B.

  As shown in FIG. 3A, in the tread surface view, the upper end side 12A is located on the road center line side in the tread width direction from the bottom side 12B on the front side in the tire rotation direction. On the other hand, on the rear side in the tire rotation direction, the upper end side 12A is positioned on the road shoulder side in the tread width direction from the bottom side 12B. That is, the upper end side 12A and the bottom side 12B are configured to intersect at the approximate center in the tire rotation direction of the block-shaped land portion 10 in the tread surface view.

  That is, the upper end side 12A is configured along the tire circumferential direction, the bottom side 12B is configured to go toward the road center line side toward the rear side in the tire rotation direction, and the circumferential wall 12 has a twisted shape. It has become.

  In the pneumatic tire 1 according to the first embodiment, the wall angle θ1 that is an angle formed by the tread surface 11 and the circumferential wall 12 is a block shape from the step-in end 10A located on the front side in the tire rotation direction in the block-shaped land portion 10. It is comprised so that it may become small as it goes to the kicking end 10B located in the tire rotation direction back side in the land part 10. FIG. Specifically, as shown in FIG. 2C, the wall angle θ1 is approximately 90 degrees at the center portion in the tire rotation direction, and as shown in FIG. 2B, the wall angle θ1 is 90 at the step-in end 10A side. As shown in FIG. 2D, it is configured to be smaller than 90 degrees on the kicking end 10B side.

  The step-in end 10 </ b> A and the kick-out end 10 </ b> B are outer ends in the tire radial direction of the width direction wall 15 and the width direction wall 14, respectively.

  In the pneumatic tire 1 according to the first embodiment, the wall angle θ1 at the depression end 10A is 100 degrees, and the wall angle θ1 at the kicking end 10B is 80 degrees.

  In addition, wall angle (theta) 1 is not limited to the angle of 1st Embodiment. The wall angle θ1 is preferably in the range of 70 degrees to 110 degrees. Furthermore, the wall angle θ1 is more preferably in the range of 75 degrees to 95 degrees.

  In the first embodiment, the wall angle θ3 that is the angle formed by the tread surface 11 and the width direction wall 14 and the wall angle θ4 that is the angle formed by the tread surface 11 and the width direction wall 15 are the road center from the shoulder side. It is unified at 95 degrees across the line side.

  In the first embodiment, the wall angle θ1 is configured to continuously change linearly.

(1.3) Actions and Effects Next, actions and effects when the pneumatic tire 1 of the first embodiment is used will be described with reference to the drawings.

  FIG. 4 is a partial cross-sectional view in the tread width direction showing the state of the block-shaped land portion 10 located closest to the shoulder side when the vehicle is running.

  As shown in FIG. 4, when the vehicle travels, the block-like land portion 10 bulges toward the road shoulder due to gravity, contact pressure due to the weight of the vehicle, and rubber incompressibility. Further, when the vehicle goes straight on a road surface that is inclined so as to become lower as it goes toward the road shoulder side, a lateral force acts on the block-like land portion 10 by giving a slip angle to the pneumatic tire 1. For this reason, when a lateral force acts on the bulging block land portion 10, shear strain is generated in the block land portion 10.

  Specifically, when the block-shaped land portion 10 is separated from the road surface at the time of kicking, a large shear strain is generated on the tread surface 11 due to the bulged portion of the block-shaped land portion 10. As a result, the tread surface 11 slides on the road surface, and the block-shaped land portion 10 is likely to be initially worn at the road shoulder side kick end 10B. Further, when wear progresses in accordance with the travel distance of the vehicle, the road shoulder side kicking end 10B has a weak ground contact pressure with the road surface, and as a result, the road surface becomes more slippery. For this reason, the wear of the block-shaped land portion 10 further progresses toward the front side in the tire rotation direction.

  That is, in order to suppress wear, it is effective to reduce the bulging amount of the block land portion 10. As a result of earnest research on the bulging amount of the block-like land portion 10 in the ground contact state when the vehicle is traveling, the bulging amount of the block-like land portion 10 in a state where the ground pressure is loaded is the same as that of the tread surface 11. It was found that the greater the angle formed by the groove wall of the block-shaped land portion 10, the larger the bulge amount, and the smaller the angle formed by the groove wall of the tread surface 11 and the block-shaped land portion 10, the smaller the bulge amount.

  Specifically, when verified by FEM (finite element method), the block-shaped land portion 10 during vehicle traveling is suppressed from bulging to the road shoulder side on the kicking end 10B side, and on the stepping end 10A side. It was found that the bulge to the shoulder side becomes larger.

  Further, since the rubber constituting the block-shaped land portion 10 has a small bulge at the kicking end 10B and a large bulge at the step-in end 10A, the block-shaped land in the tire circumferential direction is caused by the non-compressibility of the rubber. It was found that the fluid flowed from the kicking end 10B side to the stepping end 10A side around the center of the portion 10. That is, on the tread surface 11 of the block-shaped land portion 10, the rubber flows so as to cancel the braking force, and by reducing the shear strain in the tire circumferential direction, the initial wear generated in the block-shaped land portion 10 causes the tire rotation. It turned out that it restrains progressing to the direction front side.

  The pneumatic tire 1 according to the first embodiment described above includes a block-shaped land portion 10 defined by a plurality of circumferential grooves 50 extending along the tire circumferential direction and a plurality of lateral grooves 60 extending along the tread width direction. The wall angle θ1 formed by the circumferential wall 12 of the block-like land portion 10 formed by the circumferential groove and the tread surface 11 with which the block-like land portion 10 contacts the road surface is expressed as block-like land in the tire circumferential direction. It is comprised so that it may become small as it goes to the kicking end 10B from 10A of stepping-in ends of the part 10. FIG.

  According to this, in the state where the contact pressure is applied to the block-shaped land portion 10, the wall angle θ <b> 1 is larger as it is closer to the stepping end 10 </ b> A, and thus the amount of bulge of the block-shaped land portion 10 toward the road shoulder increases. On the other hand, as the wall angle θ1 decreases toward the kicking end 10B, the amount of bulging of the block-shaped land portion 10 toward the road shoulder decreases. For this reason, the shear strain of the block-shaped land portion 10 becomes smaller as it approaches the kicking end 10B. As a result, it is possible to suppress the occurrence of initial wear at the road shoulder side kick end 10B and the progress of wear from the initial wear to the front side in the tire rotation direction.

  Moreover, in 1st Embodiment, wall angle (theta) 2 which is the angle which the circumferential direction wall 13 and the tread surface 11 comprise so that it may become large as it goes to the kicking end 10B from the depression end 10A of the block-shaped land part 10. FIG. It is configured.

  According to this, even if the user installs the pneumatic tire 1 in the vehicle with the tire rotating direction wrong, the angle formed by the groove wall on the road shoulder side and the tread surface 11 in the block-like land portion 10 is It becomes smaller as it goes from 10A to the kicking end 10B. Therefore, since the same effect as the case where the pneumatic tire 1 is correctly mounted on the vehicle is obtained for the user, it can be mounted on the vehicle without being aware of the tire rotation direction.

  In the first embodiment, the wall angle θ1 of the circumferential wall 12 and the wall angle θ2 of the circumferential wall 13 continuously change linearly. According to this, the rubber constituting the block-shaped land portion 10 is stepped on from the kicking end 10B side in the tire rotation direction as compared with the case where the wall angle θ1 and the wall angle θ2 do not change linearly continuously. It becomes easy to flow to the end 10A side. Therefore, the swelling of rubber at the road shoulder side kick end 10B of the block-shaped land portion 10 is further suppressed, and the effect of suppressing the occurrence of initial wear and the progress of wear from the initial wear to the front side in the tire rotation direction is increased. To do.

  In the first embodiment, the wall angle θ <b> 1 of the circumferential wall 12 is configured to be 70 degrees to 110 degrees at the kicking end 10 </ b> B of the block-shaped land portion 10.

  According to this, the effect which suppresses generation | occurrence | production of the initial wear in the kicking end 10B of the block-shaped land part 10, and progress to the tire rotation direction front side of wear from initial wear can be enlarged. When the wall angle θ <b> 1 at the kicking end 10 </ b> B is larger than 110 degrees, the effect of suppressing uneven wear that occurs in the block-shaped land portion 10 becomes insufficient. On the other hand, when the wall angle θ1 is smaller than 70 degrees, there is a possibility that a risk of the block-like land portion 10 being missing occurs.

  In the first embodiment, the block land portion 10 has a rectangular shape on the tread surface 11 and is formed in a parallelogram shape on the bottom surface. That is, the circumferential wall 12 and the circumferential wall 13 are configured in parallel with each other, and the width direction wall 14 and the width direction wall 15 are configured in parallel with each other. According to this, on the rear side in the tire rotation direction, the wall angle θ2 is set so that the block-shaped land portion 10 is easily bulged toward the road center line side, and the wall angle θ1 is used to suppress the bulge toward the roadside. Is easy to set. For this reason, progress to the tire rotation direction front side of wear can be controlled.

  In the pneumatic tire 1 according to the first embodiment, the circumferential wall 12 is located on the shoulder side of the road, the circumferential wall 13 is located on the center line side of the road, and the step-in end of the block-shaped land portion 10 10A is mounted on the vehicle so as to be positioned on the front end side in the tire rotation direction. According to this, in the state where the contact pressure is applied to the block-shaped land portion 10, the wall angle θ <b> 1 is larger as it is closer to the stepping end 10 </ b> A. On the other hand, as the wall angle θ1 decreases toward the kicking end 10B, the amount of bulging of the block-shaped land portion 10 toward the road shoulder decreases. Therefore, the effect of suppressing the initial wear that tends to occur at the road shoulder side kicking end 10B is increased.

[Modification 1]
Next, a pneumatic tire 1X according to Modification 1 of the present invention will be described with reference to FIG. In addition, the same number is attached | subjected to the structure same as 1st Embodiment, and detailed description is abbreviate | omitted.

  FIG. 5A is a partial plan view showing a tread pattern constituting the pneumatic tire 1X according to the first modification. FIG. 5B is a cross-sectional view taken along line A-A ′ of FIG. FIG. 5C is a cross-sectional view taken along line B-B ′ of FIG. FIG. 5D is a cross-sectional view taken along line C-C ′ in FIG.

  The block-shaped land portion 10X configured in the pneumatic tire 1X according to the modification 1 is different in the shape of the tread surface and the bottom surface from the block-shaped land portion 10 according to the first embodiment.

  In the block-shaped land portion 10X, the tread surface 11 is a parallelogram that is inclined so as to approach the road shoulder side in the tread width direction from the front side in the tire rotation direction toward the rear side in the tire rotation direction. The bottom surface (not shown) of the block-shaped land portion 10 </ b> X, which is the inner side in the tire radial direction, is a rectangle having a side along the tire circumferential direction as a long side.

  That is, the groove bottom 51X, which is the bottom of the circumferential groove 50X, extends linearly along the tire circumferential direction.

(2) Second Embodiment Next, a pneumatic tire 2 according to a second embodiment of the present invention will be described with reference to FIGS. In addition, the same number is attached | subjected to the structure same as 1st Embodiment, and detailed description is abbreviate | omitted.

  FIG. 6 is a partial plan view showing a tread pattern constituting the pneumatic tire 2 according to the second embodiment. FIG. 7 is an enlarged perspective view of the block-shaped land portion 20 configured in the pneumatic tire 2 according to the second embodiment. FIG. 8A is a plan view seen from the tread surface of the block-shaped land portion 20 configured in the pneumatic tire 2 according to the second embodiment. FIG. 8B is a cross-sectional view taken along line A-A ′ of FIG. FIG. 8C is a cross-sectional view taken along line B-B ′ of FIG. FIG. 8D is a cross-sectional view taken along line C-C ′ in FIG. FIG. 8E is a cross-sectional view taken along line D-D ′ in FIG. FIG. 8F is a cross-sectional view taken along line E-E ′ of FIG. FIG. 8G is a cross-sectional view taken along line F-F ′ in FIG.

  As shown in FIGS. 6 to 8, the block-shaped land portion 20 of the pneumatic tire 2 according to the second embodiment includes not only the circumferential wall 12 and the circumferential wall 13 but also the width wall 14 and the width wall 15. However, the point that each groove wall angle changes linearly is different from the pneumatic tire 1 of the first embodiment.

  In the block-shaped land portion 20 according to the second embodiment, the tread surface 11 is a rectangle having a long side as a side along the tire circumferential direction. The bottom surface (not shown) of the block-shaped land portion 20 that is on the inner side in the tire radial direction is inclined so as to approach the road center line side from the front side in the tire rotation direction toward the rear side in the tire rotation direction, and from the road center line side to the road shoulder. It is a parallelogram which inclines so that it may approach the tire rotation direction front side as it goes to the side.

  That is, the groove bottom 53 which is the bottom of the circumferential groove 52 is not linear, but is inclined with respect to the tire circumferential direction between the block-shaped land portions 20 adjacent in the tread width direction. Further, the groove bottom 63 which is the bottom of the lateral groove 62 is not linear, but is inclined with respect to the tread width direction between the block-shaped land portions 20 adjacent in the tire circumferential direction.

  In the block-shaped land portion 20 of the pneumatic tire 2 according to the second embodiment, the wall angle θ3 that is an angle formed between the tread surface 11 and the width direction wall 14 is increased from the road shoulder side end 20C toward the center line side end 20D. It is configured to be large. Further, the wall angle θ4 that is an angle formed between the tread surface 11 and the width direction wall 15 is configured to become smaller from the road shoulder side end 20C toward the center line side end 20D. The road shoulder side end 20C and the center line side end 20D are located at the tire radial direction upper end portions of the circumferential wall 12 and the circumferential wall 13, respectively.

  The pneumatic tire 2 according to the second embodiment is configured such that the wall angle θ3 is 80 degrees at the road shoulder side end 20C and 100 degrees at the center line side end 20D. The wall angle θ3 is preferably configured within a range of 70 degrees to 110 degrees.

  According to the pneumatic tire 2 according to the second embodiment described above, the width direction wall 14 of the block-shaped land portion 20 formed by the circumferential groove 52 at the kicking end 20B of the block-shaped land portion 20, and the tread surface 11. The wall angle θ3 formed by is configured to increase from the circumferential wall 12 toward the circumferential wall 13. According to this, by setting the road shoulder side wall angle θ3 on which initial wear is likely to occur to be small, it is possible to suppress bulging to the rear side in the tire rotation direction. Specifically, since the rubber constituting the block-shaped land portion 20 flows from the kicking-side end 20B toward the stepping-side end 20A, the braking force can be reduced, and as a result, initial wear is reduced. Can be prevented from progressing forward in the tire rotation direction.

  In the second embodiment, the wall angle θ3 is configured to be 70 degrees to 110 degrees. According to this, the effect which suppresses generation | occurrence | production of the initial wear in the kicking end 20B of the block-shaped land part 20, and the progress to the tire rotation direction front side of wear from initial wear can be enlarged. When the wall angle θ3 at the kicking end 20B is larger than 110 degrees, the effect of suppressing the uneven wear that occurs in the block-shaped land portion 20 becomes insufficient. On the other hand, when the wall angle θ3 is smaller than 70 degrees, there is a possibility that a risk such as lack of the block land portion 20 may occur.

  In the second embodiment, the wall angle θ3 and the wall angle θ4 change linearly and continuously. According to this, the rubber constituting the block-shaped land portion 20 has a road shoulder side end 20C side in the tread width direction as compared with the case where the wall angle θ3 and the wall angle θ4 do not change linearly and continuously. It becomes easy to flow toward the center line side end 20D side. Therefore, in the block-shaped land portion 20, bulging of the kick-out side end 20B toward the road shoulder can be suppressed, and the occurrence of initial wear can be suppressed.

[Modification 2]
Next, a pneumatic tire 2Y according to Modification 2 will be described with reference to FIG. In addition, the same number is attached | subjected to the structure same as 2nd Embodiment, and detailed description is abbreviate | omitted.

  FIG. 9A is a partial plan view showing a tread pattern constituting the pneumatic tire 2Y according to the second modification. FIG. 9B is a cross-sectional view taken along line A-A ′ of FIG. FIG. 9C is a cross-sectional view taken along line B-B ′ of FIG. FIG. 9D is a cross-sectional view taken along line C-C ′ in FIG. FIG. 9E is a cross-sectional view taken along line D-D ′ in FIG. FIG. 9F is a cross-sectional view taken along line E-E ′ of FIG. FIG. 9G is a cross-sectional view taken along line F-F ′ in FIG.

  The block-like land portion 20Y configured in the pneumatic tire 2Y according to the modified example 2 is different in the shape of the tread surface and the bottom surface from the block-like land portion 20 according to the second embodiment.

  In the block land portion 20Y, the tread surface 11 is inclined so as to approach the tread width direction road shoulder side from the tire rotation direction front side to the tire rotation direction rear side, and the tread width direction road center line side from the tread width direction road shoulder. It is a parallelogram which inclines so that it may approach the tire rotation direction back side as it goes to the side. The bottom surface (not shown) of the block-shaped land portion 20 </ b> Y that is the inner side in the tire radial direction is a rectangle having a side along the tire circumferential direction as a long side. That is, the groove bottom portion 53Y that is the bottom of the circumferential groove 52Y extends linearly along the tire circumferential direction, and the groove bottom portion 63Y that is the bottom of the lateral groove 62Y linearly extends along the tread width direction. It is extended.

(3) Third Embodiment Next, a pneumatic tire 3 according to a third embodiment will be described with reference to FIG. In addition, the same number is attached | subjected to the structure same as 1st Embodiment, and detailed description is abbreviate | omitted.

  FIG. 10A is a partial plan view showing a tread pattern constituting the pneumatic tire 3 according to the third embodiment. FIG. 10B is a cross-sectional view taken along line A-A ′ of FIG. FIG. 10C is a cross-sectional view taken along line B-B ′ of FIG. FIG. 10D is a cross-sectional view taken along line C-C ′ in FIG. FIG. 10E is a cross-sectional view taken along line D-D ′ in FIG. FIG. 10F is a cross-sectional view taken along line E-E ′ of FIG. FIG. 10G is a cross-sectional view taken along line F-F ′ in FIG.

  The block-like land portion 30 configured in the pneumatic tire 3 according to the third embodiment is compared with the block-like land portion 10 according to the first embodiment and the block-like land portion 20 according to the second embodiment. The tread surface and the bottom surface are both parallelograms.

  In the block-shaped land portion 30, the tread surface 11 is inclined so as to approach the tread width direction road shoulder side from the tire rotation direction front side to the tire rotation direction rear side, and the tread width direction road center line side from the tread width direction road shoulder. It is a parallelogram which inclines so that it may approach the tire rotation direction back side as it goes to the side. The bottom surface (not shown) of the block-shaped land portion 30 which is the inner side in the tire radial direction is inclined so as to approach the road center line side in the tread width direction from the front side in the tire rotation direction toward the rear side in the tire rotation direction. It is a parallelogram which inclines so that it may approach the tire rotation direction front side as it goes to the tread width direction road shoulder side from the road center line side.

  That is, the groove bottom 55 which is the bottom of the circumferential groove 54 is not linear, but is inclined with respect to the tire circumferential direction between the block-shaped land portions 30 adjacent in the tread width direction. Further, the groove bottom portion 65 which is the bottom of the lateral groove 64 is not linear, but is inclined with respect to the tread width direction between the block-shaped land portions 30 adjacent in the tire circumferential direction.

  In the block-shaped land portion 30 according to the third embodiment, the wall angle θ3 is configured to be 80 degrees at the road shoulder side end 30C and 100 degrees at the center line side end 30D.

  Further, in the block land portion 30 according to the third embodiment, the wall angle θ1 is configured to be 100 degrees at the step-on side end 30A and 80 degrees at the kick-out side end 30B.

  According to the pneumatic tire 3 according to the third embodiment described above, in the block-shaped land portion 30, the rubber constituting the block-shaped land portion 30 is prevented from bulging on the kick-side end 30B side, The bulging on the stepping side end 30A side becomes larger. Therefore, similarly to the pneumatic tire 1 of the first embodiment, it is possible to suppress the occurrence of initial wear that is likely to occur at the kick-out side end 30B and the progress of wear from the initial wear to the front side in the tire rotation direction. Become.

(4) Comparative Evaluation Next, in order to further clarify the effect of the present invention, comparative evaluation performed using pneumatic tires according to the following comparative examples and examples will be described. Specifically, (4.1) Evaluation method and (4.2) Evaluation result will be described. In addition, this invention is not limited at all by these examples.

(4.1) Evaluation method Tests were performed using 13 types of pneumatic tires, and the amount of uneven wear and distortion at the block end were evaluated.

  In addition, about evaluation of the amount of uneven wear, the volume of the block-shaped land part with the largest volume of an uneven wear part is measured and indexed in the pneumatic tire after driving | running | working. In Table 1, it is shown that the smaller the numerical value, the smaller the amount of uneven wear.

  As for the distortion at the block end, the maximum value of the distortion at the groove bottom calculated by the FEM (finite element method) calculation is indexed in the pneumatic tire after running. Table 1 shows that the larger the numerical value, the greater the distortion at the block end.

Moreover, the data regarding the pneumatic tire used for the test were measured on the conditions shown below.
・ Tire size: 11R22.5
・ Rim wheel size: 7.5 × 22.5
・ Tire type: Heavy load tire ・ Vehicle: Tractor (fixed volume state)
・ Test tire mounting position: Steering wheel ・ Distance traveled at final evaluation: Approximately 50,000 km
・ Characteristics of driving route: Expressway

In Table 1, Example 1 uses the pneumatic tire 1 of the first embodiment of the present invention. Examples 2, 3, 9, and 10 have the same configuration as that of the first embodiment, but the wall angle θ1 and the wall angle θ2 are different. In Example 4, the pneumatic tire 2 of the second embodiment of the present invention is used. Examples 5, 6, 11, and 12 have the same configuration as that of the second embodiment, but the wall angle θ3 and the wall angle θ4 are different. Example 7 has the same configuration as that of the pneumatic tire 1 of the first embodiment, but the lateral groove is configured by a sipe (not shown). In Example 8, the pneumatic tire 3 according to the third embodiment of the present invention is used. Moreover, the conventional example uses a pneumatic tire having a general block-shaped land portion.
(4.2) Evaluation Results The evaluation results of each pneumatic tire will be described with reference to Table 1.

  As a result, it can be seen that the pneumatic tires according to Examples 1 to 12 are drastically improved in suppressing the amount of uneven wear as compared with the conventional example. However, as can be seen from Examples 10 and 12, when the configuration is such that the circumferential side wall angle and the width side wall angle of the pneumatic tire of the present invention are not included in the above-described appropriate ranges, the distortion at the block end is large. There is also one side.

  Therefore, in the pneumatic tire of the present invention, by configuring the circumferential side wall angle and the width direction side wall angle of the block-shaped land portion within the above-described appropriate range, while suppressing the distortion of the block end portion from increasing, It was proved that the effect of suppressing the occurrence and progress of uneven wear was great.

[Other embodiments]
Although the contents of the present invention have been disclosed through the embodiments of the present invention as described above, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples, and operational techniques will be apparent to those skilled in the art.

  For example, the embodiment of the present invention can be modified as follows.

  Specifically, the tire may be a pneumatic tire 1 filled with air, nitrogen gas, or the like, or may be a solid tire that is not filled with air, nitrogen gas, or the like.

  Further, the shape of the block-shaped land portion 10 at the tread surface 11 that is the outer side in the tire radial direction and the bottom portion may not be a parallelogram.

  Moreover, in embodiment of this application, although the circumferential wall 12, the circumferential wall 13, the width direction wall 15, and the width direction wall 14 shall change linearly continuously, it is limited to this. The change is not necessarily linear. Moreover, on the structure of the block-shaped land part 10, there may be a non-linear part in the vicinity of the stepping end 10A and the kicking end 10B.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is determined only by the invention specifying matters according to the scope of claims reasonable from the above description.

1, 1X, 2, 2Y, 3 ... Pneumatic tires, 10, 10X, 20, 20Y, 30 ... Block-shaped land portion, 10A, 20A, 30A ... Step-in end, 10B, 20B, 30B ... Kick-out end, 11 ... Tread surface, 12, 13 ... circumferential wall, 14, 15 ... width direction wall, 20C, 30C ... road shoulder side end, 20D, 30D ... center line side end, 50, 50X, 52, 52Y, 54 ... circumferential groove, 51, 51X, 53, 53Y, 55 ... groove bottom, 60, 62, 62Y, 64 ... horizontal groove, 61, 63, 63Y, 65 ... groove bottom, θ1, θ2, θ3, θ4, wall angle

Claims (5)

A tire including a block-like land portion defined by a plurality of circumferential grooves extending along a tire circumferential direction and a plurality of lateral grooves extending along a tread width direction,
The block-shaped land portion includes one circumferential side wall formed by one circumferential groove, and the other circumferential side wall formed by the other circumferential groove disposed in parallel with the one circumferential groove. Have
The circumferential side wall angle formed by one circumferential side wall of the block-shaped land portion formed by the circumferential groove and the tread surface where the block-shaped land portion is in contact with the road surface is the block-shaped land portion in the tire circumferential direction. Ri a smaller take from one end toward its other end,
The circumferential side wall angle formed by the other circumferential side wall and the tread surface increases from one end of the block-shaped land portion in the tire circumferential direction toward the other end,
The width-direction side wall angle formed by the width-direction side wall of the block-shaped land portion formed by the lateral groove at the other end of the block-shaped land portion and the tread surface is determined from the one circumferential side wall to the other circumferential direction. As you go to the side walls,
The one circumferential side wall is located on the shoulder side of the road, the other circumferential side wall is located on the center line side of the road, and one end of the block-like land portion is located on the front end side in the rotation direction of the tire The tire according to claim 1, wherein the tire is mounted on a vehicle as described above. Circumferential sidewall angle of the one circumferential side wall, at least one of the circumferential sidewall angles and the width direction sidewall angle of the other circumferential side wall, a tire according to claim 1 that varies linearly continuous. The tire according to claim 1 or 2 , wherein a circumferential side wall angle of the one circumferential side wall is 70 degrees to 110 degrees at the other end of the block-shaped land portion. The tire according to any one of claims 1 to 3 , wherein the width-direction side wall angle is 70 degrees to 110 degrees on the one circumferential side wall. The tire according to any one of claims 1 to 4 , wherein the block land portion has a parallelogram shape in a tread surface view.

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