JP2018144653A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of achieving both on-ice performance and dry performance.SOLUTION: A pneumatic tire comprises: a plurality of circumferential grooves 20 extending in a tire circumferential direction; a land part 10 with at least one end in the tire width direction partitioned by the circumferential grooves 20; a bent lug groove 31 having a bent part 34 formed in the land part 10, having one end being open in the circumferential grooves 20 and the other end terminated in the land part 10, and bending at an acute angle in the land part 10; a bottom-up part 41 provided at least in the bent part 34 of the bent lug groove 31 and formed by the bottom of a groove bottom 40 of the bending lug groove 31 being raised; and a through sipe 65 formed in the land part 10 while opening in the circumferential grooves 20 partitioning the land part 10 and formed so as to pass through the groove bottom 40 of the bent part 34 and penetrate between a superior angle side edges 45 of the bent part 34 in the bent lug groove 31.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a pneumatic tire.

  Pneumatic tires have grooves on the tread surface mainly to ensure drainage, but some conventional pneumatic tires have sipes and narrow grooves on the tread surface for the purpose of further improving performance. There is something that forms. For example, in the pneumatic tire described in Patent Document 1, an auxiliary groove having one end opened in the circumferential groove and the other end terminating in the land portion is formed on the tread surface, and the auxiliary groove is further communicated with the land portion. By providing the sipe, the uneven wear resistance is improved. Moreover, in the pneumatic tire described in Patent Document 2, the snow performance is improved by providing an auxiliary groove that is bent in the land portion and further providing a narrow groove that intersects the auxiliary groove.

Japanese Patent Laid-Open No. 2006-128297 JP 2014-205410 A

  Here, when improving snow performance in all-season tires, a bending lug groove that bends in the land is provided, and the edge component by the groove acts in multiple directions to ensure steering stability on the road surface on snow. The technique to do is mentioned. However, when the lug groove is bent in the land portion, the rigidity of the land portion near the bent portion is lowered, and accordingly, the steering stability on the dry road surface may be lowered.

  There is a method to raise the bottom of the lug groove bottom to suppress the decrease in rigidity of the land part near the bent part of the lug groove, but the rigidity of the land part near the raised part is locally too high The trackability of the tread surface located in the vicinity of the raised bottom portion to the road surface is deteriorated. In this case, the edge component of the lug groove hardly acts on the snowy road surface, so that it is difficult to effectively improve the steering stability on the snowy road surface. In this way, on-snow performance, which is steering stability on snowy road surface, and dry performance, which is steering stability on dry road surface, are contradictory to each other, it is very difficult to achieve both of them. It was.

  This invention is made | formed in view of the above, Comprising: It aims at providing the pneumatic tire which can make a snow performance and dry performance compatible.

  In order to solve the above-described problems and achieve the object, the pneumatic tire according to the present invention includes a plurality of circumferential grooves extending in the tire circumferential direction, and at least one end in the tire width direction is formed by the circumferential groove. A bent lug groove having a land portion to be partitioned, a bent portion formed in the land portion, one end opening in the circumferential groove, the other end terminating in the land portion, and bending at an acute angle in the land portion And at least the bent portion of the bent lug groove, the bottom raised portion formed by raising the groove bottom of the bent lug groove, and the circumferential groove defining the land portion, A sipe formed on a land portion and passing through the groove bottom of the bent portion and penetrating between the edges of the bent portion in the bent lug groove. To do.

  Further, in the pneumatic tire, the sipe is a minor angle side bending point that is a bending point of a minor angle side edge of the bent portion in the bent lug groove, and a dominant angle that is a bending point of a dominant angle edge. When the distance from the side bending point is A1, and the distance between the intersection of the sipe and the virtual line connecting the minor angle side bending point and the dominant angle side bending point and the minor angle side bending point is A2. A1 * (1/10) ≦ A2 ≦ A1 * (8/10) is preferably passed through the position.

  In the pneumatic tire, the relationship between the groove depth D1 at a position other than the raised bottom portion and the groove depth D2 at the position of the raised bottom portion is D1 * (2/10). ) ≦ D2 ≦ D1 * (7/10), and the sipe has a relationship between a depth D3 of the sipe and a groove depth D2 of the bent lug groove at the position of the raised portion. * It is preferable to be within the range of 1.5 ≦ D3 ≦ D2 * 3.0.

  In the pneumatic tire, the sipe preferably has an inclination angle θ in the tire width direction with respect to the tire circumferential direction in a range of 60 ° ≦ θ ≦ 90 °.

  In the pneumatic tire, it is preferable that at least one end of the sipe is raised.

  In the pneumatic tire, it is preferable that the bottom-up portion is not formed at an end portion of the bent lug groove that terminates in the land portion.

  In the pneumatic tire, it is preferable that the bottom-up portion is further raised at an end portion of the bent lug groove that terminates in the land portion.

  The pneumatic tire according to the present invention has an effect that both on-snow performance and dry performance can be achieved.

FIG. 1 is a plan view showing a tread surface of a pneumatic tire according to an embodiment. FIG. 2 is a detailed view of part A of FIG. FIG. 3 is a detailed view of part B of FIG. 4 is a cross-sectional view taken along the line C-D-C in FIG. FIG. 5 is a detailed view of a portion E in FIG. 6 is a cross-sectional view taken along line FF in FIG. FIG. 7 is a modified example of the pneumatic tire according to the embodiment, and is an explanatory diagram in the case where the folded portion has a portion where the bottom raised portion is not formed. FIG. 8 is a G-G-G cross-sectional view of FIG. FIG. 9 is a modified example of the pneumatic tire according to the embodiment, and is an explanatory diagram in a case where the height of the bottom raised portion changes. 10 is a cross-sectional view taken along the line KK in FIG. FIG. 11A is a chart showing the results of a performance test of a pneumatic tire. FIG. 11B is a chart showing the results of a performance test of a pneumatic tire.

  Hereinafter, an embodiment of a pneumatic tire according to the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be replaced by those skilled in the art and can be easily conceived, or those that are substantially the same.

  In the following description, the tire width direction means a direction parallel to the rotation axis of the pneumatic tire, the inner side in the tire width direction means the direction toward the tire equator line in the tire width direction, and the outer side in the tire width direction means the tire width. The direction opposite to the direction toward the tire equator line. Further, the tire radial direction means a direction orthogonal to the tire rotation axis, and the tire circumferential direction means a direction rotating around the tire rotation axis.

  FIG. 1 is a plan view showing a tread surface of a pneumatic tire according to an embodiment. A pneumatic tire 1 shown in FIG. 1 is provided with a tread portion 2 at the outermost portion in the tire radial direction, and the surface of the tread portion 2, that is, a vehicle on which the pneumatic tire 1 is mounted (not shown). The portion that comes into contact with the road surface during travel is formed as a tread surface 3. A plurality of circumferential grooves 20 extending in the tire circumferential direction are formed on the tread surface 3, and a plurality of land portions 10 are formed on the tread surface 3 by the circumferential grooves 20. Specifically, four circumferential grooves 20 are formed side by side in the tire width direction, two first circumferential grooves 21 positioned on both sides of the tire equator line CL in the tire width direction, and two Two second circumferential grooves 22 located on the outer sides in the tire width direction of the first circumferential grooves 21 are provided. The circumferential groove 20 here has a groove width in the range of 7 mm or more and 15 mm or less, and a groove depth in the range of 5 mm or more and 10 mm or less.

  The land portion 10 has at least one end in the tire width direction defined by a circumferential groove 20, and as the land portion 10, a center land portion 11, a second land portion 12, a shoulder land portion 13, Is provided. Among these, the center land portion 11 is located between the two first circumferential grooves 21, and both end portions in the tire width direction are partitioned by the first circumferential grooves 21. For this reason, the center land part 11 is located on the tire equator line CL. Further, the second land portion 12 is located between the adjacent first circumferential groove 21 and the second circumferential groove 22, and the end portion on the inner side in the tire width direction is partitioned by the first circumferential groove 21. An end portion on the outer side in the tire width direction is partitioned by the second circumferential groove 22. Further, the shoulder land portion 13 is located outside the second circumferential groove 22 in the tire width direction, and the end portion on the inner side in the tire width direction is partitioned by the second circumferential groove 22. Each of these land portions 10 is formed as a rib-like land portion 10 extending in the tire circumferential direction.

  Further, lug grooves 30 extending in the tire width direction are formed on the tread surface 3. The lug groove 30 includes a bent lug groove 31 formed in the second land portion 12 and a shoulder lug groove 32 formed in the shoulder land portion 13, and a plurality of them are formed side by side in the tire circumferential direction. ing. Among these, the shoulder lug groove 32 is formed as a substantially linear groove extending in the tire width direction and inclined in the tire circumferential direction, and both ends are terminated in the shoulder land portion 13. Further, the bent lug groove 31 has one end opened to the second circumferential groove 22 and the other end terminated in the second land portion 12. Further, the bent lug groove 31 has a bent portion 34 that bends at an acute angle in the second land portion 12. The lug groove 30 here has a groove width in the range of 1.5 mm to 7.0 mm and a groove depth in the range of 5.0 mm to 10.0 mm.

  A plurality of sipes 60 extending in the tire width direction are formed on the tread surface 3. The sipe 60 has a center sipe 61 formed on the center land portion 11, a second sipe 62 formed on the second land portion 12, and a shoulder sipe 63 formed on the shoulder land portion 13, respectively. A plurality are formed side by side in the tire circumferential direction.

  Among these, the center sipe 61 is formed to be inclined in the tire circumferential direction while extending in the tire width direction between the two first circumferential grooves 21 defining the center land portion 11. Each center sipe 61 has a notch 61a formed on one end side in the tire width direction so that the width in the width direction of the center sipe 61 is increased. The notches 61a are formed on the end sides different from each other in the tire width direction between the adjacent center sipes 61 in the tire circumferential direction. That is, the notches 61a are formed in a plurality of center sipes 61 arranged in the tire circumferential direction, with the ends where the notches 61a are formed alternately in the tire circumferential direction.

  The second sipe 62 is formed between the first circumferential groove 21 and the second circumferential groove 22 that define the second land portion 12 and is inclined in the tire circumferential direction while extending in the tire width direction. Yes. Further, the shoulder sipe 63 is formed to be inclined in the tire circumferential direction while extending in the tire width direction, and both ends are terminated in the shoulder land portion 13. Further, two shoulder sipes 63 are formed between the shoulder lug grooves 32 adjacent in the tire circumferential direction.

  Here, the sipe 60 is formed in a narrow groove shape on the tread surface 3, and the pneumatic tire 1 is assembled to a regular rim to form a narrow groove when no load is applied under normal internal pressure conditions. When the narrow groove is located in the part of the ground contact surface formed on the flat plate when loaded in the vertical direction on the flat plate, or when the land part where the narrow groove is formed falls, The wall surface which comprises the said fine groove, or at least one part of the site | part provided in a wall surface says what mutually contacts by deformation | transformation of a land part. The regular rim is “standard rim” defined by JATMA, “Design Rim” defined by TRA, or “Measuring Rim” defined by ETRTO. The normal internal pressure is “maximum air pressure” defined by JATMA, the maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO. In this embodiment, the sipe 60 has a width in the range of 0.5 mm to 1.5 mm and a depth in the range of 1.0 mm to 10.0 mm.

  FIG. 2 is a detailed view of part A of FIG. The bent lug groove 31 terminates in the second land portion 12 and the main body portion 35 that is a portion from the opening side end portion 37 to the bent portion 34 that is an end portion on the side opened to the second circumferential groove 22. And a folded portion 36 that is a portion from the end side end portion 38 that is a side end portion to the bent portion 34. Among these, the main body portion 35 is curved in a direction in which the inclination angle in the tire circumferential direction with respect to the tire width direction increases as it goes from the opening side end portion 37 side to the bent portion 34 side. The main body portions 35 of the bent lug grooves 31 provided in the two second land portions 12 are inclined in the tire circumferential direction with respect to the tire width direction from the opening side end portion 37 side toward the bent portion 34 side. The directions of inclination in the circumferential direction of the tire are opposite to each other.

  On the other hand, the folded portion 36 extends substantially linearly from the bent portion 34 side toward the opening side end portion 37 side. Further, in the folded portion 36, the inclination direction in the tire circumferential direction with respect to the tire width direction is the same as the inclination direction in the tire circumferential direction with respect to the tire width direction of the main body portion 35. For this reason, the bent portion 34 is formed with an acute angle such that the relative angle between the main body portion 35 and the folded portion 36 is less than 90 °.

  FIG. 3 is a detailed view of part B of FIG. In this case, the angle of the bent portion 34 is the angle of the dominant-side edge 46 that is the dominant-side edge 45 of the bent portion 34 among the edges 45 of the bent lug groove 31 or the minor angle of the bent portion 34. The angle of the minor angle side edge 47 which is the side edge 45 is set. In addition, the angle of the curved main body portion 35 with respect to the folded portion 36 is such that the edge 45 of the main body portion 35 is connected to the edge 45 of the folded portion 36 at the bent portion 34. The angle is a relative angle between the tangent line 45 and the edge 45 of the folded portion 36.

  In other words, the angle of the dominant angle side edge 46 of the bent portion 34 is the angle of the dominant angle side of the main body portion 35 at a portion where the dominant angle side edge 46 of the main body portion 35 is connected to the dominant angle side edge 46 of the folded portion 36. The angle is a relative angle between the tangent line 46 and the dominant edge 46 of the folded portion 36. Similarly, the angle of the minor angle side edge 47 of the bent portion 34 is such that the minor angle side edge 47 of the main body portion 35 is connected to the minor angle side edge 47 of the folded portion 36. The angle is a relative angle between the tangent line of the edge 47 and the minor angle side edge 47 of the folded portion 36. The angle of the bent part 34 defined as described above is preferably in the range of 20 ° to 75 °.

  Further, in the bent lug groove 31, the groove width W <b> 2 (see FIG. 5) of the folded portion 36 is smaller than the groove width W <b> 1 (see FIG. 5) of the main body portion 35. The main body portion 35 and the folded portion 36 of the bent lug groove 31 have a relationship between the groove width W1 of the main body portion 35 and the groove width W2 of the folded portion 36 in the range of W1 * 0.5 ≦ W2 ≦ W1 * 0.8. Is preferably within.

  The bent lug groove 31 is provided with a raised portion 41 formed by raising the groove bottom 40 of the bent lug groove 31. The bottom raised portion 41 is provided at least in the bent portion 34 of the bent lug groove 31, and is provided in the entire folded portion 36 in the bent lug groove 31 and in a position near the bent portion 34 in the main body portion 35. Specifically, the raised portion 41 provided in the main body portion 35 is formed in a predetermined range from the bent portion 34 toward the opening side end portion 37, and the length of the range in which the raised portion 41 in the main body portion 35 is provided. Is shorter than the length of the folded portion 36.

  The length of the bottom raising portion 41 provided in the main body portion 35 in the extending direction of the main body portion 35 is from the minor angle side bending point 52 which is the bending point 50 of the minor angle side edge 47 of the bent portion 34 in the bent lug groove 31. The length L in the direction opposite to the direction in which the bent portion 34 is located is in the range of W1 * 1.0 ≦ L ≦ W1 * 5.0 with respect to the groove width W1 of the main body 35 (see FIG. 5). Is preferably within.

  4 is a cross-sectional view taken along the line C-D-C in FIG. The bottom raised portion 41 is formed by bringing the groove bottom 40 closer to the tread surface 3 than the groove bottom 40 other than the portion where the bottom raised portion 41 is formed in the main body portion 35. Thus, the groove depth of the bent lug groove 31 where the bottom raised portion 41 is formed is shallower than the groove depth of the main body portion 35 other than the portion where the bottom raised portion 41 is formed. As described above, the bent lug groove 31 in which the bottom raised portion 41 is formed has a relationship between the groove depth D1 at a position other than the bottom raised portion 41 and the groove depth D2 at the position of the bottom raised portion 41 as D1 * ( 2/10) ≦ D2 ≦ D1 * (7/10).

  The second sipe 62 formed in the second land portion 12 is formed by opening both ends of the first circumferential groove 21 and the second circumferential groove 22 that define the second land portion 12, and the tire in the tire circumferential direction. The inclination angle θ in the width direction is in the range of 60 ° ≦ θ ≦ 90 °. Further, among the plurality of second sipes 62, some of the second sipes 62 are penetrating sipes 65 that are formed so as to penetrate between the dominant-side edges 46 of the bent portions 34 in the bent lug grooves 31. The penetrating sipe 65 is formed through the groove bottom 40 of the bent portion 34 from the angled edge 46 side of the folded portion 36 to the angled edge 46 side of the main body 35 at the position of the bent portion 34.

  That is, the penetration sipe 65 has a depth deeper than the groove depth of the bent lug groove 31 at the position of the bottom raised portion 41. For this reason, the second land portion 12 is formed between the first circumferential groove 21 and the second circumferential groove 22, and the dominant side of the main body portion 35 from the dominant edge 46 side of the folded portion 36. The through sipe 65 formed toward the edge 46 is formed through the groove bottom 40 of the bent portion 34. In the penetration sipe 65, the relationship between the depth D3 of the penetration sipe 65 and the groove depth D2 of the bent lug groove 31 at the position of the bottom raised portion 41 is in the range of D2 * 1.5 ≦ D3 ≦ D2 * 3.0. It is inside.

  FIG. 5 is a detailed view of a portion E in FIG. The penetrating sipe 65 includes a minor angle side bending point 52 which is a bending point 50 of the minor angle side edge 47 of the bent portion 34 in the bent lug groove 31 and a major angle side bending which is the bending point 50 of the dominant angle edge 46. It is formed through a predetermined range between the point 51 and the point 51. Specifically, the penetration sipe 65 has a distance A1 between the minor angle side bending point 52 and the major angle side bending point 51 when the virtual line 71 connecting the minor angle side bending point 52 and the dominant angle side bending point 51 is defined. And the relationship between the intersection 72 of the virtual line 71 and the penetrating sipe 65 and the distance A2 between the inferior angle side bending point 52 is within the range of A1 * (1/10) ≦ A2 ≦ A1 * (8/10). Is going through. In this case, the intersection 72 of the virtual line 71 and the penetrating sipe 65 is the intersection 72 of the center line 73 and the virtual line 71 in the width direction of the penetrating sipe 65.

  In the present embodiment, the bent portion 34 refers to a region on the dominant angle side bend point 51 side with respect to the inferior angle side bend point 52 in the extending direction of the main body portion 35, and an inferior angle in the extending direction of the folded portion 36. This is a region obtained by combining the region on the dominant angle side bending point 51 side with respect to the side bending point 52.

  6 is a cross-sectional view taken along line FF in FIG. The penetrating sipe 65 has at least one end portion 66 raised at the bottom, that is, has a bottom raised portion 67 on the one end portion 66 side. Specifically, the penetrating sipe 65 has a bottom raised portion 67 on the end 66 side opened in the second circumferential groove 22. In addition, it is preferable that the depth of the penetration sipe 65 in the position of the bottom raising part 67 is 1 mm or more.

  When the pneumatic tire 1 configured as described above is mounted on a vehicle and travels, the pneumatic tire 1 rotates while the tread surface 3 positioned below the tread surface 3 is in contact with the road surface. When driving on a dry road surface with a vehicle equipped with pneumatic tires 1, the driving force or braking force is transmitted to the road surface or the turning force is generated mainly by the frictional force between the tread surface 3 and the road surface. To drive. Further, when traveling on a wet road surface, water between the tread surface 3 and the road surface enters the circumferential groove 20, the lug groove 30, etc., and the water between the tread surface 3 and the road surface is drained by these grooves. Drive while draining. As a result, the tread surface 3 is easily grounded to the road surface, and the vehicle can travel by the frictional force between the tread surface 3 and the road surface.

  Further, when traveling on a snowy road surface, the pneumatic tire 1 compresses the snow on the road surface with the tread surface 3, and the snow on the road surface enters the circumferential grooves 20 and the lug grooves 30. It will be in a state of being pressed and hardened in the groove. In this state, a driving force or a braking force is applied to the pneumatic tire 1 or a force in the tire width direction is applied by turning of the vehicle, whereby the shearing force is applied to the snow in the groove. A so-called snow column shearing force is generated, and a resistance is generated between the pneumatic tire 1 and the road surface by the shearing force in the snow, so that the driving force and the braking force can be transmitted to the snowy road surface. Driving on the road becomes possible.

  Further, when traveling on a snowy road surface, the vehicle travels using the edge effect of the circumferential groove 20, the lug groove 30, and the sipe 60. That is, when traveling on a snowy road surface, the vehicle travels using resistance caused by the edge of the circumferential groove 20 and the lug groove 30 and the edge of the sipe 60 being caught on the snow surface. As a result, the tread surface 3 is increased in resistance between the road surface on snow due to frictional force and edge effect, and the traveling performance of the vehicle equipped with the pneumatic tire 1 can be ensured. In the present embodiment, the bent lug groove 31 has a bent portion 34, and the edge 45 is formed orthogonal to a plurality of directions on the tread surface 3. The effect can be exhibited, and the driving stability on the road surface on snow can be ensured.

  Furthermore, since the bent portion 34 of the bent lug groove 31 is bent at an acute angle, it is possible to generate a higher resistance against the road surface on snow. For example, when the pneumatic tire 1 rotates in a direction in which the bent lug groove 31 contacts the ground from the bent portion 34 side, the bent lug groove 31 has snow on the road surface on the minor angle side bending point 52 side of the bent portion 34. As a result, the lower edge 47 can exert a higher edge effect. On the other hand, when the pneumatic tire 1 rotates in the direction in which the bent portion 34 of the bent lug groove 31 is finally grounded, the snow that has entered the bent lug groove 31 accompanies the rotation of the pneumatic tire 1. Thus, when the inside of the bent lug groove 31 is moved in the tire circumferential direction, the movement is blocked by the bent portion 34. For this reason, a larger snow column shear force can be generated. Accordingly, the bent lug groove 31 can generate a larger resistance between the pneumatic tire 1 and the road surface, and can improve the steering stability on the road surface on snow.

  Here, since the bent portion 34 of the bent lug groove 31 has an acute angle, the rigidity of the vicinity of the bent portion 34 in the second land portion 12 where the bent lug groove 31 is formed increases as the groove area ratio increases. It tends to be lower. On the other hand, in the present embodiment, the bent lug groove 31 is provided with the bottom raised portion 41 at least in the bent portion 34, so that the rigidity in the vicinity of the bent portion 34 in the second land portion 12 can be ensured. As a result, the rigidity of the second land portion 12 can be secured, the steering stability when traveling on a dry road surface, that is, a dry road surface, can be secured, and the dry performance can be secured.

  On the other hand, when the raised portion 41 is provided in the bent portion 34 of the bent lug groove 31, the rigidity of the second land portion 12 around the bent lug groove 31 is locally increased only around the raised portion 41. When the tread surface 3 sequentially contacts the road surface with the rotation of the vehicle, the followability to the road surface may be reduced. That is, when the tread surface 3 positioned on the road surface side comes into contact with the ground when the pneumatic tire 1 rotates, the land portion 10 is deformed by a load acting on the tread surface 3 to be contacted, and the tread surface 3 moves along the road surface. Ground while deforming. At that time, when the raised portion 41 is provided in the bent portion 34 of the bent lug groove 31 and the rigidity of the second land portion 12 is locally increased only around the raised portion 41, in the vicinity of the raised portion 41. The tread surface 3 is difficult to deform along the road surface. Specifically, it is difficult for the tread surface 3 to be deformed following the road surface at the stepping side end portion or the kicking side end portion when the tread surface 3 contacts the ground. In this case, the edge 45 of the bent lug groove 31 is also less likely to be deformed following the road surface, so that it is difficult to properly ground along the road surface. The bent lug groove 31 is effective for the edge effect on the snowy road surface. It becomes difficult to demonstrate.

  On the other hand, in the present embodiment, the second land portion 12 is formed with a through sipe 65 that passes through the bottom raised portion 41 and passes through the bent portion 34 by passing through the groove bottom 40 of the bent portion 34 of the bent lug groove 31. ing. For this reason, since the rigidity of the second land portion 12 can be appropriately reduced in the portion where the penetrating sipe 65 is formed, the rigidity of the second land portion 12 is locally increased only around the raised portion 41. Can be suppressed. Accordingly, the bent lug groove 31 can be appropriately deformed following the road surface even at the stepped-side end portion and the kick-out side end portion when the tread surface 3 contacts the ground. Therefore, the edge effect of the bent lug groove 31 on the road surface on snow can be effectively exhibited, and the performance on snow, which is the steering stability on the road surface on snow, can be improved. As a result, both on-snow performance and dry performance can be achieved.

  The penetrating sipe 65 has a distance A1 between the minor angle side bending point 52 and the major angle side bending point 51, and a distance A2 between the intersection 72 between the virtual line 71 and the penetrating sipe 65 and the minor angle side bending point 52. Since the relationship passes through a position within the range of A1 * (1/10) ≦ A2 ≦ A1 * (8/10), it is effective that the rigidity of the second land portion 12 is locally increased by the raised portion 41. Can be relaxed. That is, when A2 <A1 * (1/10) or A2> A1 * (8/10), the distance between the penetrating sipe 65 and the bending point 50 is too short. There is a possibility that the penetration sipe 65 makes it difficult to relax the locally increased rigidity of the second land portion 12 due to the formation of the raised bottom portion 41. In this case, it may be difficult to appropriately deform the bent lug groove 31 following the road surface, and it may be difficult to effectively exhibit the edge effect of the bent lug groove 31 on the road surface on snow. There is.

  On the other hand, when the penetrating sipe 65 passes through a position within the range of A1 * (1/10) ≦ A2 ≦ A1 * (8/10), the bent portion 34 is provided with the bottom raised portion 41. Thus, locally increasing the rigidity of the second land portion 12 can be effectively mitigated. Thereby, the rigidity of the second land portion 12 is increased by providing the bottom raising portion 41 at the bent portion 34, thereby improving the driving stability on the dry road surface and the snowy road surface due to the edge effect of the bent lug groove 31. Improvement in handling stability can be achieved more reliably. As a result, both on-snow performance and dry performance can be achieved more reliably.

  Further, in the bent lug groove 31, the relationship between the groove depth D1 at a position other than the bottom raised portion 41 and the groove depth D2 at the position of the bottom raised portion 41 is D1 * (2/10) ≦ D2 ≦ D1 *. Since it is within the range of (7/10), it is possible to ensure both the snow column shearing force by the bent lug groove 31 and the rigidity of the second land portion 12 near the bent portion 34. That is, when the relationship between the groove depth D1 at a position other than the bottom raised portion 41 of the bent lug groove 31 and the groove depth D2 at the position of the bottom raised portion 41 is D2 <D1 * (2/10). Since the height of the bottom raised portion 41 is too high, the groove volume of the bent lug groove 31 at the position where the bottom raised portion 41 is provided may be too small. In this case, since the amount of snow that can enter the bent lug groove 31 is reduced, it may be difficult to improve the steering stability on the road surface on snow. Further, when the relationship between the groove depth D1 at a position other than the raised portion 41 of the bent lug groove 31 and the groove depth D2 at the position of the raised portion 41 is D2> D1 * (7/10) In addition, since the height of the raised portion 41 is too low, there is a possibility that it is difficult to ensure the rigidity of the second land portion 12 near the bent portion 34 by the raised portion 41. In this case, it may be difficult to improve the handling stability on the dry road surface.

  On the other hand, the relationship between the groove depth D1 at a position other than the raised portion 41 of the bent lug groove 31 and the groove depth D2 at the position of the raised portion 41 is D1 * (2/10) ≦ D2 ≦ D1. * When within the range of (7/10), the bottom raised portion 41 can secure the rigidity of the second land portion 12 near the bent portion 34 while ensuring the groove volume at the position where the raised portion 41 is provided. it can. As a result, it is possible to secure the steering stability on the dry road surface while ensuring the snow column shear force by the bent lug groove 31 to ensure the steering stability on the snowy road surface. As a result, both on-snow performance and dry performance can be achieved more reliably.

  Further, in the through sipe 65, the relationship between the depth D3 of the through sipe 65 and the groove depth D2 of the bent lug groove 31 at the position of the bottom raised portion 41 is D2 * 1.5 ≦ D3 ≦ D2 * 3.0. Therefore, the rigidity of the second land portion 12 can be effectively reduced locally while suppressing the rigidity near the bent portion 34 from becoming too low. That is, when the relationship between the depth D3 of the through sipe 65 and the groove depth D2 of the bent lug groove 31 at the position of the bottom raised portion 41 is D3 <D2 * 1.5, the depth of the through sipe 65 Since D3 is too shallow, the penetration sipe 65 may make it difficult to relax the locally increased rigidity of the second land portion 12 due to the formation of the raised portion 41 in the bent portion 34. In this case, it may be difficult to appropriately deform the bent lug groove 31 following the road surface, and it may be difficult to effectively exhibit the edge effect of the bent lug groove 31 on the road surface on snow. There is. Further, when the relationship between the depth D3 of the penetration sipe 65 and the groove depth D2 of the bent lug groove 31 at the position of the bottom raised portion 41 is D3> D2 * 3.0, the depth of the penetration sipe 65 Since D3 is too deep, the rigidity in the vicinity of the bent portion 34 in the second land portion 12 may be too low. In this case, it may be difficult to ensure the driving stability on the dry road surface.

  On the other hand, the relationship between the depth D3 of the through sipe 65 and the groove depth D2 of the bent lug groove 31 at the position of the bottom raised portion 41 is within the range of D2 * 1.5 ≦ D3 ≦ D2 * 3.0. In this case, it is possible to effectively mitigate that the rigidity of the second land portion 12 is locally increased while suppressing the rigidity in the vicinity of the bent portion 34 from becoming too low. Thereby, the improvement of the steering stability on the dry road surface and the improvement of the steering stability on the snowy road surface can be achieved more reliably. As a result, both on-snow performance and dry performance can be achieved more reliably.

  Further, since the depth D3 of the through sipe 65 is deeper than the groove depth D2 of the bent lug groove 31 at the position of the bottom raised portion 41, even when the tread surface 3 is worn, the through sipe 65 is kept for a long time. Can leave. Thereby, the edge effect by the penetration sipe 65 can be exhibited over a long time. As a result, it is possible to minimize the decrease in performance on snow due to wear of the tread surface 3.

  Further, since the through-sipe 65 has an inclination angle θ in the tire width direction with respect to the tire circumferential direction within a range of 60 ° ≦ θ ≦ 90 °, the second through the portion where the through-sipe 65 opens into the circumferential groove 20. It can suppress that the rigidity of the land part 12 becomes low too much. That is, when the inclination angle θ of the through sipe 65 with respect to the tire circumferential direction in the tire width direction is θ <60 °, the rigidity of the second land portion 12 near the portion where the through sipe 65 opens into the circumferential groove 20. May be too low. In this case, it may be difficult to ensure the driving stability on the dry road surface.

  On the other hand, when the inclination angle θ in the tire width direction of the through sipe 65 with respect to the tire circumferential direction is within the range of 60 ° ≦ θ ≦ 90 °, the vicinity of the portion where the through sipe 65 opens into the circumferential groove 20 The rigidity of the vehicle can be suppressed from becoming too low, and the steering stability on the dry road surface can be more reliably ensured. Further, when the inclination angle θ of the through sipe 65 with respect to the tire circumferential direction in the tire width direction is within a range of 60 ° ≦ θ ≦ 90 °, the direction in which the through sipe 65 extends is close to the tire width direction. The edge component of the penetrating sipe 65 has more edge components with respect to the tire circumferential direction. Thereby, the edge effect at the time of braking / driving when traveling on a snowy road surface can be improved. As a result, both on-snow performance and dry performance can be more reliably achieved.

  Further, since at least one end 66 of the penetrating sipe 65 is raised, even when the distance between the end 66 of the penetrating sipe 65 and the bent lug groove 31 is short, the penetrating sipe 65 is bent with the penetrating sipe 65 in the second land portion 12. It can suppress that the rigidity of the part between the lug grooves 31 becomes too low. That is, the penetrating sipe 65 is raised to the end 66 side on the side opened to the second circumferential groove 22, which is the circumferential groove 20 in which the bent lug groove 31 is opened, of both ends 66 of the penetrating sipe 65. A portion 67 is provided. Thereby, even when the distance between the penetrating sipe 65 and the bent lug groove 31 is short, it is possible to prevent the rigidity of the portion between the penetrating sipe 65 and the bent lug groove 31 in the second land portion 12 from becoming too low. it can. As a result, the steering stability on the dry road surface can be ensured more reliably, and the dry performance can be improved more reliably.

  In the pneumatic tire 1 according to the above-described embodiment, the bottom raised portion 41 formed in the folded portion 36 is provided in the entire folded portion 36, but the bottom raised portion 41 is provided in the entire folded portion 36. It does not have to be. FIG. 7 is a modified example of the pneumatic tire according to the embodiment, and is an explanatory diagram in the case where the folded portion has a portion where the bottom raised portion is not formed. FIG. 8 is a G-G-G cross-sectional view of FIG. As shown in FIGS. 7 and 8, the raised portion 41 of the bent lug groove 31 may not be formed at the terminal end 38 of the folded portion 36. That is, the raised portion 41 of the folded portion 36 is formed in a predetermined range from the bent portion 34 side toward the terminal end 38, and may not be formed near the terminal end 38. In this case, the height in the tire radial direction of the groove bottom 40 in the vicinity of the terminal end 38, that is, the distance from the tread surface 3 is the groove bottom 40 located in the portion where the bottom raising portion 41 is not provided in the main body portion 35. The distance from the tread surface 3 is almost the same. That is, the groove depth of the portion where the bottom raised portion 41 is not provided in the folded portion 36 is substantially the same as the groove depth of the portion where the bottom raised portion 41 is not provided in the main body portion 35.

  As the snow column shear force of the bent lug groove 31 is larger, the larger the volume of the bent lug groove 31, the more snow can be taken into the bent lug groove 31, so that a larger force can be obtained. For this reason, the range which provides the bottom raising part 41 formed in the bending lug groove 31 is kept to the minimum range in the vicinity of the bending part 34, and the bottom raising part 41 is not provided in the other range. While mitigating locally high rigidity, the snow column shear force by the bent lug groove 31 can be more reliably ensured, and the steering stability on the road surface on snow can be improved. As a result, both on-snow performance and dry performance can be more reliably achieved, and in particular, on-snow performance can be improved.

  Moreover, in the pneumatic tire 1 which concerns on embodiment mentioned above, although the height of the bottom raising part 41 formed in the bending lug groove 31 is constant, the height of the bottom raising part 41 may be changing. FIG. 9 is a modified example of the pneumatic tire according to the embodiment, and is an explanatory diagram in a case where the height of the bottom raised portion changes. 10 is a cross-sectional view taken along the line KK in FIG. As shown in FIGS. 9 and 10, the bottom raised portion 41 of the bent lug groove 31 may be further raised at the end side end portion 38 of the folded portion 36. That is, the bottom raised portion 41 of the folded portion 36 may have a second bottom raised portion 42 that is raised further than the other portions of the bottom raised portion 41 in a predetermined region near the terminal end 38. In other words, by providing the second raised portion 42 in the raised portion 41, the groove depth in the vicinity of the end side end portion 38 of the bent lug groove 31 can be set to a portion other than the second raised portion 42 in the portion where the raised portion 41 is provided. You may make it shallower than the groove depth in a part.

  As described above, by providing the second raised portion 42 in the raised portion 41 and further reducing the groove depth in the vicinity of the end side end portion 38 of the bent lug groove 31, the rigidity in the vicinity of the bent portion 34 becomes too high. Even when it is suppressed by the penetrating sipe 65, it is possible to ensure the rigidity in the vicinity of the terminal end 38 that is slightly away from the bent portion 34. As a result, both on-snow performance and dry performance can be more reliably achieved, and in particular, dry performance can be improved.

  Further, in the pneumatic tire 1 according to the above-described embodiment, the bent lug groove 31 has the main body portion 35 curved and the folded portion 36 formed in a substantially linear shape. It may be formed in a form. For example, the main body portion 35 may be formed in a substantially linear shape, and the folded portion 36 may be curved. Or both the main-body part 35 and the folding | returning part 36 may be curving, or both may be formed in substantially linear form. Regardless of the shape of the main body portion 35 and the folded-back portion 36, the bent lug groove 31 only needs to be formed at an acute angle relative to both edges 45. It is only necessary that the relative angle between the tangent line of the edge 45 and the tangent line of the other edge 45 or the other edge 45 is formed at an acute angle.

  In the pneumatic tire 1 according to the above-described embodiment, four circumferential grooves 20 are formed on the tread surface 3, and shoulder lug grooves 32 are provided as lug grooves 30 in addition to the bent lug grooves 31. The configurations of the circumferential groove 20 and the lug groove 30 may be other configurations.

  Further, in the pneumatic tire 1 according to the above-described embodiment, the bent lug groove 31 is provided in the second land portion 12, and the through sipe 65 is configured by the second sipe 62 provided in the second land portion 12. The bent lug groove 31 and the through sipe 65 may be provided in addition to the second land portion 12. Regardless of the land portion 10 provided, the bent lug groove 31 and the penetrating sipe 65 have the bent portion 34 where the bent lug groove 31 bends at an acute angle, and at least the bent portion 34 is provided with a bottom raising portion 41, and the bent portion 34 is provided. By providing the through sipe 65 that penetrates the bottom raised portion 41, it is possible to achieve both on-snow performance and dry performance.

〔Example〕
11A and 11B are tables showing the results of performance tests of pneumatic tires. Hereinafter, the performance evaluation test performed on the pneumatic tire 1 of the conventional example and the comparative example and the pneumatic tire 1 according to the present invention will be described. In the performance evaluation test, tests were conducted on snow handling stability, which is steering stability on a snowy road surface, and dry stability, which is steering stability on a dry road surface.

  In the performance evaluation test, a pneumatic tire 1 with a nominal size of 225 / 50R18 stipulated by JATMA is assembled on a rim wheel of a 18 × 7 J size JATMA standard rim, and the air pressure is the maximum pneumatic pressure stipulated by JATMA. The test was carried out by mounting it on a front-wheel drive (front engine / front drive) test vehicle. As for the evaluation method of each test item, the snow maneuverability was evaluated by a sensory evaluation by a test driver when a test vehicle was run on a test course assuming an urban area made on snow, and was evaluated by a 10-step evaluation. The larger the value, the better the snow maneuverability. The dry maneuverability was evaluated by a sensory evaluation by a test driver when traveling on a test course on a dry road surface by a test vehicle, and evaluated by a 10-step evaluation. The larger the value, the better the dry operability.

  An evaluation test compares with the pneumatic tire of the conventional example which is an example of the conventional pneumatic tire 1, Examples 1-10 which are the pneumatic tire 1 which concerns on this invention, and the pneumatic tire 1 which concerns on this invention. It carried out about 12 types of pneumatic tires with the comparative example which is a pneumatic tire. Among these pneumatic tires 1, the conventional pneumatic tire is not provided with the raised portion 41 in the bent lug groove 31, and is not provided with the through sipe 65. Moreover, although the penetration sipe 65 is provided in the pneumatic tire of the comparative example, the bottom raised portion 41 is not provided in the bent lug groove 31.

  On the other hand, in Examples 1 to 10 which are examples of the pneumatic tire 1 according to the present invention, the bent lug groove 31 is provided with the bottom raised portion 41 and the through sipe 65 is also provided. Further, the pneumatic tire 1 according to Examples 1 to 10 penetrates the intersection 72 of the imaginary line 71 and the penetrating sipe 65 with respect to the distance A2 from the inferior angle side bending point 52 and the groove depth D2 at the bottom raised portion 41. The depth D3 of the sipe 65, the inclination angle θ of the through sipe 65 with respect to the tire circumferential direction, the presence or absence of the bottom up of the through sipe 65, and the shape of the raised portion 41 at the end side end portion 38 of the bent lug groove 31 are different. .

  As a result of performing an evaluation test using these pneumatic tires 1, as shown in FIGS. 11A and 11B, the pneumatic tires 1 of Examples 1 to 10 are better in snow handling and dryness than conventional examples. It has been found that at least one of the performances is improved without deteriorating any of the performances with the maneuverability. That is, the pneumatic tire 1 according to Examples 1 to 10 can achieve both on-snow performance and dry performance.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Tread surface 10 Land part 20 Circumferential groove 30 Lug groove 31 Bending lug groove 34 Bending part 35 Main body part 36 Folding part 37 Opening side edge part 38 Termination side edge part 40 Groove bottom 41 Bottom raising part 42 Second bottom raised portion 45 Edge 46 Major angle side edge 47 Major angle side edge 50 Bending point 51 Major angle side bending point 52 Minor angle side bending point 60 Sipe 65 Penetration sipe 66 End portion 67 Bottom raising portion 71 Virtual line 72 Intersection 73 Center line

Claims (7)

A plurality of circumferential grooves extending in the tire circumferential direction;
A land portion in which at least one end in the tire width direction is partitioned by the circumferential groove;
A bent lug groove having a bent portion formed at the land portion and having one end opened in the circumferential groove and the other end terminated in the land portion and bent at an acute angle in the land portion;
A bottom raised portion provided by at least the bent portion of the bent lug groove and formed by raising the groove bottom of the bent lug groove;
An opening is formed in the land portion that opens to the circumferential groove that divides the land portion, and passes between the groove bottom of the bent portion and between the edges on the dominant angle side of the bent portion in the bent lug groove. A sipe formed through,
A pneumatic tire characterized by comprising: The sipe is
A1 is a distance between an inferior angle side bend point that is a bend point of an inferior angle side edge of the bent portion in the bent lug groove and a bend angle side bend point that is a bend point of a dominant angle side edge;
When the distance between the imaginary line connecting the minor angle side bending point and the major angle side bending point and the sipe and the minor angle side bending point is A2,
The pneumatic tire according to claim 1, which passes through a position that falls within a range of A1 * (1/10) ≦ A2 ≦ A1 * (8/10). In the bent lug groove, the relationship between the groove depth D1 at a position other than the bottom raised portion and the groove depth D2 at the bottom raised portion is D1 * (2/10) ≦ D2 ≦ D1 * (7 / 10),
In the sipe, the relationship between the sipe depth D3 and the groove depth D2 of the bent lug groove at the position of the bottom raised portion is within the range of D2 * 1.5 ≦ D3 ≦ D2 * 3.0. The pneumatic tire according to claim 1 or 2.   The pneumatic tire according to claim 1, wherein the sipe has an inclination angle θ in the tire width direction with respect to the tire circumferential direction in a range of 60 ° ≦ θ ≦ 90 °.   The pneumatic tire according to any one of claims 1 to 4, wherein at least one end of the sipe is raised.   The pneumatic tire according to any one of claims 1 to 5, wherein the bottom raised portion is not formed at an end portion of the bent lug groove that terminates in the land portion.   The pneumatic tire according to any one of claims 1 to 5, wherein the bottom raised portion is an end portion on a side of the bent lug groove that terminates in the land portion, and the groove bottom is further raised.

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