JP6911389B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire.

Pneumatic tires have grooves formed on the tread surface mainly to ensure drainage, but some conventional pneumatic tires have sipes or 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, one end is opened in a circumferential groove, the other end is formed on the tread surface with an auxiliary groove terminating in the land portion, and the auxiliary groove is further communicated with the land portion. By providing a sipe, the uneven wear resistance is improved. Further, in the pneumatic tire described in Patent Document 2, the snow performance is improved by providing an auxiliary groove that bends in the land portion and further providing a narrow groove that intersects the auxiliary groove.

Japanese Unexamined Patent Publication No. 2016-128297 Japanese Unexamined Patent Publication No. 2014-205410

Here, when improving snow performance in all-season tires, a bending lug groove that bends in the land area is provided, and the edge component of the groove acts in a plurality of directions to ensure steering stability on a snowy road surface. There is a method to do. However, when the lug groove bends in the land portion, the rigidity of the land portion in the vicinity of the bent portion decreases, and as a result, the steering stability on a dry road surface may decrease.

In order to suppress the decrease in the rigidity of the land area near the bent part of the lug groove, there is a method of raising the bottom of the lug groove, but when the rigidity of the land area near the bottom raising part becomes too high locally. The tread surface located near the bottom raising portion has poor followability to the road surface. In this case, since it becomes difficult for the edge component of the lug groove to effectively act on the snowy road surface, it becomes difficult to effectively improve the steering stability on the snowy road surface. In this way, the snow performance, which is the steering stability on the snowy road surface, and the dry performance, which is the steering stability on the dry road surface, are mutually contradictory performances, so it is very difficult to achieve both. It was.

The present invention has been made in view of the above, and an object of the present invention is to provide a pneumatic tire capable of achieving both on-snow performance and dry performance.

In order to solve the above-mentioned problems and achieve the object, the pneumatic tire according to the present invention has a plurality of circumferential grooves extending in the tire circumferential direction and at least one end in the tire width direction by the circumferential groove. A bent lug groove having a land portion to be partitioned and a bent portion formed in the land portion and having an opening at one end in the circumferential groove, ending at the other end in the land portion, and bending sharply in the land portion. And, at least, the bottom raising portion provided at the bending portion of the bending lug groove and formed by raising the bottom of the bending lug groove, and the circumferential groove that partitions the land portion are opened to the above. It is characterized by including a sipe formed on the land portion, passing through the groove bottom of the bending portion, and penetrating between the edges on the dominant angle side of the bending portion in the bending lug groove. do.

Further, in the pneumatic tire, the sipes are a bending point on the inferior angle side, which is a bending point on the inferior angle side of the bending portion in the bending lug groove, and a superior angle, which is a bending point on the edge on the dominant angle side. When the distance to the side bending point is A1, and the distance between the intersection of the virtual line connecting the inferior angle side bending point and the superior angle side bending point and the sipe and the inferior angle side bending point is A2. , It is preferable to pass through a position within the range of A1 * (1/10) ≦ A2 ≦ A1 * (8/10).

Further, in the pneumatic tire, in the bent lug groove, the relationship between the groove depth D1 at a position other than the bottom raising portion and the groove depth D2 at the position of the bottom raising portion is D1 * (2/10). ) ≤ D2 ≤ D1 * (7/10), and the relationship between the sipe depth D3 and the groove depth D2 of the bent lug groove at the position of the bottom raising portion is D2. It is preferably within the range of * 1.5 ≦ D3 ≦ D2 * 3.0.

Further, in the pneumatic tire, it is preferable that the sipe has an inclination angle θ in the tire width direction with respect to the tire circumferential direction within a range of 60 ° ≦ θ ≦ 90 °.

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

Further, in the pneumatic tire, it is preferable that the bottom raising portion is not formed at the end portion of the bent lug groove on the side that terminates in the land portion.

Further, in the pneumatic tire, it is preferable that the bottom of the groove is further raised at the end of the bent lug groove on the side that ends in the land.

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

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. FIG. 4 is a cross-sectional view taken along the line CDC of FIG. FIG. 5 is a detailed view of part E of FIG. FIG. 6 is a cross-sectional view taken along the line FF of FIG. FIG. 7 is a modified example of the pneumatic tire according to the embodiment, and is an explanatory view in the case where the folded-back portion has a portion where the bottom-raising portion is not formed. FIG. 8 is a cross-sectional view taken along the line GHG of FIG. FIG. 9 is a modified example of the pneumatic tire according to the embodiment, and is an explanatory view when the height of the bottom raising portion changes. FIG. 10 is a cross-sectional view taken along the line JKJ of FIG. FIG. 11A is a chart showing the results of performance tests of pneumatic tires. FIG. 11B is a chart showing the results of performance tests of pneumatic tires.

Hereinafter, embodiments of the pneumatic tire according to the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment. In addition, the components in the following embodiments include those that can be easily conceived by those skilled in the art, 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 inside in the tire width direction is the direction toward the tire equatorial line in the tire width direction, and the outside in the tire width direction is the tire width. The direction opposite to the direction toward the tire equatorial line. The tire radial direction means a direction orthogonal to the tire rotation axis, and the tire circumferential direction means a direction of rotation about the tire rotation axis.

FIG. 1 is a plan view showing a tread surface of a pneumatic tire according to an embodiment. In the pneumatic tire 1 shown in FIG. 1, a tread portion 2 is arranged on 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). ) Is formed as a tread surface 3 at a portion that comes into contact with the road surface during traveling. 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, the circumferential groove 20 is formed by arranging four grooves in the tire width direction, and two first circumferential grooves 21 and two grooves located on both sides of the tire equatorial line CL in the tire width direction. Two second circumferential grooves 22 located outside each tire width direction of the first circumferential groove 21 are provided. Further, the circumferential groove 20 referred to here has a groove width within a range of 7 mm or more and 15 mm or less, and a groove depth within a range of 5 mm or more and 10 mm or less.

At least one end of the land portion 10 in the tire width direction is partitioned by a circumferential groove 20, and the land portion 10 includes a center land portion 11, a second land portion 12, and a shoulder land portion 13. Is provided. Of these, the center land portion 11 is located between the two first circumferential groove 21s, and both end portions in the tire width direction are partitioned by the first circumferential groove 21. Therefore, the center land portion 11 is located on the tire equatorial 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 inner end portion in the tire width direction is partitioned by the first circumferential groove 21. The outer end 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 inner end portion in the tire width direction is partitioned by the second circumferential groove 22. Each of these land portions 10 is formed as a rib-shaped land portion 10 extending in the tire circumferential direction.

Further, a lug groove 30 extending in the tire width direction is formed on the tread surface 3. The lug groove 30 has 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 lug grooves 30 are formed side by side in the tire circumferential direction. ing. Of these, the shoulder lug groove 32 is formed as a substantially linear groove that extends in the tire width direction and inclines in the tire circumferential direction, and both ends are terminated within the shoulder land portion 13. Further, one end of the bent lug groove 31 opens in the second circumferential direction groove 22, and the other end ends 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. Further, the lug groove 30 referred to here has a groove width in the range of 1.5 mm or more and 7.0 mm or less, and a groove depth in the range of 5.0 mm or more and 10.0 mm or less.

Further, 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 of tires are formed side by side in the tire circumferential direction.

Of these, the center sipe 61 is formed so as to extend in the tire width direction and be inclined in the tire circumferential direction over between the two first circumferential groove 21s that partition the center land portion 11. Further, each center sipe 61 has a notch portion 61a formed on one end side in the tire width direction so that the width of the center sipe 61 becomes wider in the width direction. The notch portions 61a are formed on end portions that are adjacent to each other in the tire circumferential direction and are different from each other in the tire width direction. That is, the notch portions 61a are formed in a plurality of center sipes 61 arranged in the tire circumferential direction, and the end portions where the notch portions 61a are formed are alternately formed in the tire circumferential direction.

Further, the second sipe 62 is formed so as to extend in the tire width direction and be inclined in the tire circumferential direction between the first circumferential groove 21 and the second circumferential groove 22 for partitioning the second land portion 12. There is. Further, the shoulder sipe 63 is formed so as to extend in the tire width direction and be inclined in the tire circumferential direction, and both ends thereof are terminated in the shoulder land portion 13. Further, two shoulder sipes 63 are formed between the shoulder lug grooves 32 adjacent to each other in the tire circumferential direction.

The sipe 60 referred to here is formed in a fine groove shape on the tread surface 3, and the pneumatic tire 1 is rim-assembled on a regular rim to form a fine groove under normal internal pressure internal pressure conditions when no load is applied. When the wall surfaces do not come into contact with each other, but when a fine groove is located on the ground contact surface formed on the flat plate when the load is applied in the vertical direction on the flat plate, or when the land part where the fine groove is formed collapses. It means that the wall surfaces constituting the narrow groove or at least a part of the portion provided on the wall surface come into contact with each other due to the deformation of the land portion. The regular rim is a "standard rim" specified by JATTA, a "Design Rim" specified by TRA, or a "Measuring Rim" specified by ETRTO. The normal internal pressure is the "maximum air pressure" specified by JATTA, the maximum value described in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified by TRA, or "INFLATION PRESSURES" specified by ETRTO. In the present embodiment, the sipe 60 has a width of 0.5 mm or more and 1.5 mm or less, and a depth of 1.0 mm or more and 10.0 mm or less.

FIG. 2 is a detailed view of part A of FIG. The bending lug groove 31 terminates in the second land portion 12 with the main body portion 35 which is a portion from the opening side end portion 37 which is the end portion on the side opening to the second circumferential direction groove 22 to the bending portion 34. It has a folded-back portion 36 which is a portion from the terminal side end portion 38 which is a side end portion to the bent portion 34. Of these, the main body 35 is curved in a direction in which the inclination angle in the tire circumferential direction with respect to the tire width direction increases from the opening side end 37 side toward the bent portion 34 side. The main body 35 of each of the bending lug grooves 31 provided in the two second land portions 12 is inclined in the tire circumferential direction with respect to the tire width direction from the opening side end portion 37 side toward the bending portion 34 side. The directions of inclination in the tire circumferential direction are opposite to each other.

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

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 angle side edge 46, which is the dominant angle side edge 45 of the bent portion 34, or the inferior angle of the bent portion 34 among the edges 45 of the bent lug groove 31. The angle is the inferior angle side edge 47, which is the side edge 45. Further, the angle of the curved main body 35 with respect to the folded-back portion 36 is the edge of the main body 35 at the portion where the edge 45 of the main body 35 is connected to the edge 45 of the folded-back portion 36 at the bent portion 34. The angle is relative to the tangent of 45 and the edge 45 of the folded portion 36.

That is, the angle of the dominant angle side edge 46 of the bent portion 34 is the dominant angle side edge 46 of the main body portion 35 in the 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. It is a relative angle between the tangent line of 46 and the dominant angle side edge 46 of the folded portion 36. Similarly, the angle of the inferior angle side edge 47 of the bent portion 34 is the inferior angle side of the main body portion 35 in the portion where the inferior angle side edge 47 of the main body portion 35 is connected to the inferior angle side edge 47 of the folded portion 36. The angle is relative to the tangent line of the edge 47 and the inferior angle side edge 47 of the folded portion 36. The angle of the bent portion 34 defined as described above is preferably in the range of 20 ° or more and 75 ° or less.

Further, in the bent lug groove 31, the groove width W2 (see FIG. 5) of the folded-back portion 36 is smaller than the groove width W1 (see FIG. 5) of the main body portion 35. The relationship between the main body 35 of the bent lug groove 31 and the folded-back portion 36 between the groove width W1 of the main body 35 and the groove width W2 of the folded-back portion 36 is in the range of W1 * 0.5 ≦ W2 ≦ W1 * 0.8. It is preferably inside.

The bent lug groove 31 is provided with a bottom raising portion 41 formed by raising the bottom of the groove bottom 40 of the bent lug groove 31. The bottom raising portion 41 is provided at least in the bent portion 34 of the bent lug groove 31, and is provided at the entire folded portion 36 in the bent lug groove 31 and at a position near the bent portion 34 in the main body portion 35. The bottom raising portion 41 provided in the main body portion 35 is specifically formed in a predetermined range from the bent portion 34 toward the opening side end portion 37 side, and is the length of the range in which the bottom raising portion 41 is provided in the main body portion 35. Is shorter than the length of the folded-back 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 inferior angle side bending point 52 which is the bending point 50 of the inferior angle side edge 47 of the bending portion 34 in the bending lug groove 31. , The length L directed 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 (see FIG. 5) of the main body 35. It is preferably inside.

FIG. 4 is a cross-sectional view taken along the line CDC of FIG. The bottom raising 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 raising portion 41 is formed in the main body portion 35. As a result, the groove depth of the portion of the bent lug groove 31 where the bottom raising portion 41 is formed is shallower than the groove depth of the main body portion 35 other than the portion where the bottom raising portion 41 is formed. In the bent lug groove 31 on which the bottom raising portion 41 is formed, the relationship between the groove depth D1 at a position other than the bottom raising portion 41 and the groove depth D2 at the position of the bottom raising portion 41 is D1 * ( It is within the range of 2/10) ≦ D2 ≦ D1 * (7/10).

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

That is, the depth of the penetrating sipe 65 is deeper than the groove depth of the bent lug groove 31 at the position of the bottom raising portion 41. Therefore, it is formed in the second land portion 12 between the first circumferential direction groove 21 and the second circumferential direction groove 22, and is formed from the dominant angle side edge 46 side of the folded-back portion 36 to the dominant angle side of the main body portion 35. The penetrating sipe 65 formed toward the edge 46 side is formed through the groove bottom 40 of the bent portion 34. The penetrating sipe 65 has a relationship between the depth D3 of the penetrating sipe 65 and the groove depth D2 of the bent lug groove 31 at the position of the bottom raising portion 41 in the range of D2 * 1.5 ≦ D3 ≦ D2 * 3.0. It is inside.

FIG. 5 is a detailed view of part E of FIG. Further, the penetrating sipe 65 has an inferior angle side bending point 52 which is a bending point 50 of the inferior angle side edge 47 of the bending portion 34 in the bending lug groove 31, and a dominant angle side bending point 50 which is a bending point 50 of the dominant angle side edge 46. It is formed through a predetermined range between the point 51 and the point 51. Specifically, the penetrating sipe 65 defines the distance A1 between the inferior angle side bending point 52 and the superior angle side bending point 51 when the virtual line 71 connecting the inferior angle side bending point 52 and the dominant angle side bending point 51 is defined. 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). It passes through the position. The intersection 72 between the virtual line 71 and the penetrating sipe 65 in this case is the intersection 72 between the center line 73 in the width direction of the penetrating sipe 65 and the virtual line 71.

In the present embodiment, the bent portion 34 is a region on the superior angle side bending point 51 side of the inferior angle side bending point 52 in the extending direction of the main body portion 35, and the inferior angle in the extending direction of the folded portion 36. It refers to a region including a region on the dominant angle side bending point 51 side with respect to the side bending point 52.

FIG. 6 is a cross-sectional view taken along the line FF of FIG. The penetrating sipe 65 has at least one end 66 raised, that is, has a bottom raised 67 on the one end 66 side. Specifically, the penetrating sipe 65 has a bottom raising portion 67 on the end portion 66 side that is open to the second circumferential direction groove 22. The depth of the penetrating sipe 65 at the position of the bottom raising portion 67 is preferably 1 mm or more.

When the pneumatic tire 1 configured as described above is mounted on the vehicle and traveled, the pneumatic tire 1 rotates while the tread surface 3 located below the tread surface 3 is in contact with the road surface. When traveling on a dry road surface with a vehicle equipped with pneumatic tires 1, the driving force and braking force are transmitted to the road surface and turning force is generated mainly by the frictional force between the tread surface 3 and the road surface. It runs by letting it run. 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, and the like, and these grooves allow water between the tread surface 3 and the road surface to flow. Run while draining. This makes it easier for the tread surface 3 to come into contact with the road surface, and the frictional force between the tread surface 3 and the road surface allows the vehicle to travel.

Further, when traveling on a snowy road surface, the pneumatic tire 1 compacts the snow on the road surface with the tread surface 3, and the snow on the road surface enters the circumferential groove 20 and the lug groove 30, so that these snows are also removed. It will be in a state of being compacted in the groove. In this state, a driving force or a braking force acts on the pneumatic tire 1, or a force acts in the tire width direction due to the turning of the vehicle, so that the shearing force acts on the snow in the groove. , So-called snow column shearing force is generated, and resistance is generated between the pneumatic tire 1 and the road surface due to the shearing force in the snow, so that the driving force and braking force can be transmitted to the snowy road surface, and the vehicle is on the snow. It will be possible to drive on the road surface.

Further, when traveling on a snowy road surface, the edge effect of the circumferential groove 20, the lug groove 30, and the sipe 60 is also used. That is, when traveling on a snowy road surface, the edge of the circumferential groove 20 and the lug groove 30 and the edge of the sipe 60 are caught on the snow surface, and the resistance is also used. As a result, the resistance of the tread surface 3 to the snowy road surface increases due to the frictional force and the edge effect, and the running 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, so that the edge is formed in more directions. It can be effective and ensure steering stability on snowy roads.

Further, since the bent portion 34 of the bent lug groove 31 is bent at an acute angle, it is possible to generate higher resistance to the road surface on snow. For example, when the pneumatic tire 1 is rotating in the direction in which the bent lug groove 31 comes into contact with the ground from the bent portion 34 side, the bent lug groove 31 has snow on the road surface on the inferior angle side bending point 52 side of the bending portion 34. By biting into, a higher edge effect can be exhibited by the inferior angle side edge 47. On the contrary, when the bent portion 34 side of the bent lug groove 31 is rotating in the direction in which the pneumatic tire 1 finally touches the ground, the snow that has entered the bent lug groove 31 accompanies the rotation of the pneumatic tire 1. When the tire is moved in the bending lug groove 31 in the circumferential direction of the tire, the movement is blocked by the bending portion 34. Therefore, a larger snow column shearing force can be generated. As a result, 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 snowy road surface.

Here, since the bent portion 34 of the bent lug groove 31 has an acute angle, the vicinity of the bent portion 34 in the second land portion 12 where the bent lug groove 31 is formed becomes rigid due to a large groove area ratio. It tends to be low. On the other hand, in the present embodiment, since the bottom raising portion 41 is formed at least in the bent portion 34 in the bent lug groove 31, it is possible to secure the rigidity in the vicinity of the bent portion 34 in the second land portion 12. As a result, the rigidity of the second land portion 12 can be ensured, the steering stability when traveling on a dry road surface, that is, a dry road surface can be ensured, and the dry performance can be ensured.

On the other hand, when the bottom raising portion 41 is provided in the bending portion 34 of the bending lug groove 31, the rigidity of the second land portion 12 around the bending lug groove 31 is locally increased only around the bottom raising portion 41, so that the pneumatic tire 1 When the tread surface 3 sequentially touches the road surface with the rotation of the tire, the followability to the road surface may decrease. That is, when the tread surface 3 located on the road surface side touches the ground when the pneumatic tire 1 rotates, the land portion 10 is deformed by the load acting on the grounded tread surface 3, and the tread surface 3 moves along the road surface. Ground while deforming. At that time, if the bottom raising portion 41 is provided in the bending portion 34 of the bending lug groove 31 and the rigidity of the second land portion 12 is locally increased only around the bottom raising portion 41, in the vicinity of the bottom raising portion 41 , The tread surface 3 is less likely to be deformed along the road surface. Specifically, when the tread surface 3 touches the ground, it becomes difficult for the tread surface 3 to be deformed to follow the road surface at the stepping side end portion and the kicking side end portion. 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 touch the ground along the road surface, and the bent lug groove 31 has an effect of edge effect on a snowy road surface. It becomes difficult to demonstrate it.

On the other hand, in the present embodiment, the second land portion 12 is formed with a penetrating sipe 65 that passes through the bottom raising portion 41 and penetrates the bent portion 34 by passing through the groove bottom 40 of the bent portion 34 of the bent lug groove 31. ing. Therefore, in the portion where the penetrating sipe 65 is formed, the rigidity of the second land portion 12 can be appropriately reduced, so that the rigidity of the second land portion 12 is locally increased only around the bottom raising portion 41. It can be suppressed. As a result, the bent lug groove 31 can be appropriately deformed following the road surface even at the stepping-side end and the kicking-side end when the tread surface 3 touches the ground. Therefore, the edge effect of the bent lug groove 31 on the snowy road surface can be effectively exerted, and the snow performance, which is the steering stability on the snowy road surface, can be improved. As a result, both on-snow performance and dry performance can be achieved at the same time.

Further, the penetrating sipe 65 is a distance A1 between the inferior angle side bending point 52 and the dominant 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 inferior 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 bottom raising portion 41 locally increases the rigidity of the second land portion 12. 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 close, so that the bending portion 34 It may be difficult for the penetrating sipe 65 to alleviate the local increase in the rigidity of the second land portion 12 due to the formation of the bottom raising 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 exert the edge effect of the bent lug groove 31 on a snowy road surface. 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 raising portion 41. It is possible to effectively alleviate the local increase in the rigidity of the second land portion 12. As a result, the rigidity of the second land portion 12 is increased by providing the bottom raising portion 41 in the bent portion 34, thereby improving the steering stability on the dry road surface and the edge effect of the bent lug groove 31 on the snowy road surface. It is possible to more reliably achieve both improvement in steering stability. As a result, both on-snow performance and dry performance can be more reliably achieved.

Further, in the bent lug groove 31, the relationship between the groove depth D1 at a position other than the bottom raising portion 41 and the groove depth D2 at the position of the bottom raising portion 41 is D1 * (2/10) ≤ D2 ≤ D1 *. Since it is within the range of (7/10), it is possible to secure both the snow column shearing force due to the bending lug groove 31 and the rigidity of the second land portion 12 in the vicinity of the bending portion 34. That is, when the relationship between the groove depth D1 at a position other than the bottom raising portion 41 of the bent lug groove 31 and the groove depth D2 at the position of the bottom raising portion 41 is D2 <D1 * (2/10). Since the height of the bottom raising portion 41 is too high, the groove volume of the bent lug groove 31 at the position where the bottom raising portion 41 is provided may become 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 snowy road surface. Further, when the relationship between the groove depth D1 at a position other than the bottom raising portion 41 of the bent lug groove 31 and the groove depth D2 at the position of the bottom raising portion 41 is D2> D1 * (7/10). Since the height of the bottom raising portion 41 is too low, it may be difficult for the bottom raising portion 41 to secure the rigidity of the second land portion 12 near the bent portion 34. In this case, it may be difficult to improve the steering stability on a dry road surface.

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

Further, in the penetrating sipe 65, the relationship between the depth D3 of the penetrating sipe 65 and the groove depth D2 of the bent lug groove 31 at the position of the bottom raising portion 41 is D2 * 1.5 ≦ D3 ≦ D2 * 3.0. Since it is within the range of, it is possible to effectively alleviate the local increase in the rigidity of the second land portion 12 while suppressing the rigidity in the vicinity of the bent portion 34 from becoming too low. That is, when the relationship between the depth D3 of the penetrating sipe 65 and the groove depth D2 of the bending lug groove 31 at the position of the bottom raising portion 41 is D3 <D2 * 1.5, the depth of the penetrating sipe 65. Since D3 is too shallow, it may be difficult for the penetrating sipe 65 to alleviate the local increase in rigidity of the second land portion 12 due to the formation of the bottom raising 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 exert the edge effect of the bent lug groove 31 on a snowy road surface. There is. Further, when the relationship between the depth D3 of the penetrating sipe 65 and the groove depth D2 of the bending lug groove 31 at the position of the bottom raising portion 41 is D3> D2 * 3.0, the depth of the penetrating sipe 65 Since D3 is too deep, the rigidity near the bent portion 34 in the second land portion 12 may become too low. In this case, it may be difficult to ensure steering stability on a dry road surface.

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

Further, since the depth D3 of the penetrating sipe 65 is deeper than the groove depth D2 of the bending lug groove 31 at the position of the bottom raising portion 41, even when the tread surface 3 is worn, the penetrating sipe 65 can be used for a long time. Can be left. As a result, the edge effect of the penetrating sipe 65 can be exhibited over a long period of time. As a result, the deterioration of the performance on snow due to the wear of the tread surface 3 can be minimized.

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

On the other hand, when the inclination angle θ of the penetrating sipe 65 in the tire circumferential direction with respect to the tire circumferential direction is within the range of 60 ° ≦ θ ≦ 90 °, the vicinity of the portion where the penetrating sipe 65 opens in the circumferential groove 20. It is possible to prevent the tire from becoming too low, and it is possible to more reliably ensure steering stability on a dry road surface. Further, when the inclination angle θ of the penetrating sipe 65 in the tire width direction with respect to the tire circumferential direction is within the range of 60 ° ≦ θ ≦ 90 °, the direction in which the penetrating sipe 65 extends is close to the tire width direction. The edge component of the penetrating sipe 65 has a large edge component in the tire circumferential direction. As a result, it is possible to improve the edge effect at the time of control drive when traveling on a snowy road surface. As a result, it is possible to more reliably achieve both snow performance and dry performance.

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

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

As for the snow column shearing force of the bent lug groove 31, 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. Therefore, the range in which the bottom raising portion 41 formed in the bending lug groove 31 is provided is limited to the minimum range in the vicinity of the bending portion 34, and the bottom raising portion 41 is not provided in the other range. It is possible to more reliably secure the snow column shearing force due to the bent lug groove 31 and improve the steering stability on the snowy road surface while alleviating the local increase in rigidity. As a result, both the snow performance and the dry performance can be more reliably achieved, and in particular, the snow performance can be improved.

Further, in the pneumatic tire 1 according to the above-described embodiment, the height of the bottom raising portion 41 formed in the bent lug groove 31 is constant, but the height of the bottom raising portion 41 may be changed. FIG. 9 is a modified example of the pneumatic tire according to the embodiment, and is an explanatory view when the height of the bottom raising portion changes. FIG. 10 is a cross-sectional view taken along the line JKJ of FIG. As shown in FIGS. 9 and 10, the bottom raising portion 41 of the bent lug groove 31 may be a terminal end portion 38 of the folded-back portion 36, and the groove bottom 40 may be further raised. That is, the bottom-raising portion 41 of the folded-back portion 36 may have a second bottom-raising portion 42 that is further raised than other portions in the bottom-raising portion 41 in a predetermined region near the end side end portion 38. In other words, by providing the bottom raising portion 42 in the bottom raising portion 41, the groove depth in the vicinity of the terminal end portion 38 of the bent lug groove 31 can be adjusted to the portion other than the second bottom raising portion 42 in which the bottom raising portion 41 is provided. It may be shallower than the groove depth at the portion.

In this way, by providing the second bottom raising portion 42 in the bottom raising portion 41 and further reducing the groove depth near the terminal end portion 38 of the bending lug groove 31, the rigidity in the vicinity of the bending portion 34 becomes too high. Is suppressed by the penetrating sipe 65, the rigidity in the vicinity of the terminal end portion 38 slightly away from the bent portion 34 can be ensured. 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 main body portion 35 of the bent lug groove 31 is curved and the folded-back portion 36 is formed substantially linearly, but the bent lug groove 31 is other than this. It may be formed in a form. For example, the main body portion 35 may be formed in a substantially straight line, and the folded-back portion 36 may be curved. Alternatively, both the main body portion 35 and the folded-back portion 36 may be curved, or both may be formed in a substantially linear shape. Regardless of the form of the main body portion 35 and the folded portion 36, the bent lug groove 31 may be formed with an acute angle relative to both edges 45, and if it is curved, the other edge 45 may be formed. It is sufficient that the relative angle between the tangent line of the edge 45 of the portion connected to the other edge 45 or the tangent line of the other edge 45 is formed at an acute angle.

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

Further, in the pneumatic tire 1 according to the above-described embodiment, the bending lug groove 31 is provided in the second land portion 12, and the penetrating sipe 65 is composed of the second sipe 62 provided in the second land portion 12. The bending lug groove 31 and the penetrating sipe 65 may be provided in addition to the second land portion 12. The bent lug groove 31 and the penetrating sipe 65 have a bent portion 34 in which the bent lug groove 31 bends at an acute angle regardless of the land portion 10 provided, 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 penetrating sipe 65 penetrating the bottom raising portion 41 of the above, both on-snow performance and dry performance can be achieved at the same time.

〔Example〕
11A and 11B are charts showing the results of performance tests of pneumatic tires. Hereinafter, the performance evaluation test of the above-mentioned pneumatic tire 1 with respect to the pneumatic tires 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, the maneuverability on snow, which is the steering stability on the snowy road surface, and the dry maneuverability, which is the maneuvering stability on the dry road surface, were tested.

In the performance evaluation test, the tire nominal of 225 / 50R18 size specified by JATTA is assembled to the rim wheel of the JATMA standard rim of 18 x 7J size, and the air pressure is the maximum air pressure specified by JATTA. It was adjusted to the above and mounted on a front-wheel drive (front engine / front drive) test vehicle for a test run. As for the evaluation method of each test item, for the maneuverability on snow, a sensory evaluation was carried out by a test driver when the test vehicle was driven on a test course assuming an urban area created on snow, and the evaluation was made on a 10-point scale. The larger the value, the better the maneuverability on snow. The dry maneuverability was evaluated by a sensory evaluation by a test driver when the test course on a dry road surface was driven by a test vehicle, and was evaluated on a 10-point scale. The larger the value, the better the dry maneuverability.

The evaluation test compares the conventional pneumatic tire, which is an example of the conventional pneumatic tire 1, the pneumatic tires 1 according to the present invention, Examples 3 to 10, and the pneumatic tire 1 according to the present invention. A comparative example of a pneumatic tire and 12 types of pneumatic tires of Reference Examples 1 and 2 were performed. Among these pneumatic tires 1, the conventional pneumatic tire is not provided with the bottom raising portion 41 in the bending lug groove 31 and is not provided with the penetrating sipe 65. Further, in the pneumatic tire of the comparative example, although the penetrating sipe 65 is provided, the bottom raising portion 41 is not provided in the bent lug groove 31.

On the other hand, in Examples 3 to 10, which are examples of the pneumatic tire 1 according to the present invention, the bottom raising portion 41 is provided in the bent lug groove 31, and the penetrating sipe 65 is also provided. Further, the pneumatic tires 1 according to Examples 3 to 10 and Reference Examples 1 and 2 have a distance A2 from the inferior angle side bending point 52 at the intersection 72 between the virtual line 71 and the penetrating sipe 65, and the bottom raising portion 41. The depth D3 of the penetrating sipe 65 with respect to the groove depth D2, the inclination angle θ of the penetrating sipe 65 with respect to the tire circumferential direction, the presence or absence of raising the bottom of the penetrating sipe 65, and the bottom raising portion 41 at the terminal end 38 of the bending lug groove 31. The shapes are different.

As a result of conducting an evaluation test using these pneumatic tires 1, as shown in FIGS. 11A and 11B, the pneumatic tires 1 of Examples 3 to 10 have higher maneuverability on snow and dryness as compared with the conventional examples. It was found that the performance of at least one of them was improved without deteriorating any of the performance with the maneuverability. That is, the pneumatic tire 1 according to Examples 3 to 10 can achieve both snow performance and dry performance.

1 Pneumatic tire 2 Tread part 3 Tread surface 10 Land part 20 Circumferential groove 30 Rug groove 31 Bending lug groove 34 Bending part 35 Main body part 36 Folded part 37 Opening side end 38 Ending side end 40 Groove bottom 41 Bottom raising part 42 2nd bottom raising part 45 edge 46 superior angle side edge 47 inferior angle side edge 50 bending point 51 dominant side bending point 52 inferior angle side bending point 60 sipes 65 through sipe 66 end 67 bottom raising part 71 virtual line 72 intersection 73 center line

Claims (6)

Multiple 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, and a land portion.
A bending lug groove formed in the land portion, one end opening in the circumferential groove, the other end ending in the land portion, and having a bent portion that bends at an acute angle in the land portion.
At least a bottom raising portion provided at the bending portion of the bending lug groove and formed by raising the bottom of the bending lug groove.
It is formed in the land portion by opening in the circumferential groove that partitions the land portion, and also passes through 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. Sipe formed through and
Equipped with a,
The sipe is
The distance between the inferior angle side bending point, which is the bending point of the inferior angle side edge of the bending portion in the bending lug groove, and the dominant angle side bending point, which is the bending point of the dominant angle side edge, is defined as A1.
When the distance between the intersection of the virtual line connecting the inferior angle side bending point and the superior angle side bending point and the sipe and the inferior angle side bending point is A2,
A pneumatic tire characterized by passing through a position within the 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 raising portion and the groove depth D2 at the position of the bottom raising portion is D1 * (2/10) ≤ D2 ≤ D1 * (7). It is within the range of / 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 raising portion is within the range of D2 * 1.5 ≦ D3 ≦ D2 * 3.0. The pneumatic tire according to claim 1. The pneumatic tire according to claim 1 or 2 , wherein the sipe 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 pneumatic tire according to any one of claims 1 to 3 , wherein the sipe has at least one end raised. The pneumatic tire according to any one of claims 1 to 4 , wherein the bottom raising portion is not formed at the end portion of the bent lug groove on the side ending in the land portion. The pneumatic tire according to any one of claims 1 to 4 , wherein the bottom raising portion is an end portion of the bent lug groove on the side ending in the land portion, and the groove bottom is further raised.

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