JP6217405B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire in which braking performance on a wet road surface (hereinafter referred to as “wet braking performance”) and steering stability performance on a dry road surface (hereinafter referred to as “dry safety performance”) are improved in a well-balanced manner.

  Conventionally, as disclosed in Patent Document 1, in order to improve drainage performance, it is known to arrange sipes in land portions defined by circumferential main grooves.

JP 2013-139193 A

  However, in the technique disclosed in Patent Document 1, since the groove area of the sipe is small, the drainage performance cannot be sufficiently ensured, and the excellent wet braking performance may not be exhibited. On the other hand, if the groove area is increased to ensure drainage performance, the rigidity of the land portion is lowered and the dry steering performance is deteriorated.

  Then, an object of this invention is to provide the pneumatic tire which improved wet braking performance and dry steering performance in a good balance.

  In the first aspect of the present invention, a plurality of circumferential main grooves are provided, and the circumferential main grooves are provided on the outermost first land portion on each side in the tire width direction and on the inner side in the tire width direction from the first land portion. In the pneumatic tire in which the two land portions are defined, a plurality of lateral grooves including a chamfered sipe and a first width direction groove are disposed in the second land portion, and one end of the first width direction groove is circumferential. The other end of the first widthwise groove communicates with one end of the chamfered sipe, the other end of the chamfered sipe terminates inside the second land portion, and a lateral groove in each second land portion. However, in the tire circumferential direction, a pneumatic tire is provided that extends alternately from adjacent circumferential main grooves.

  In the second aspect of the present invention, the lateral groove terminates without reaching the center position in the tire width direction of each second land portion.

  In the 3rd mode of the present invention, the transverse groove in each 2nd land part inclines in the tire circumferential direction opposite direction from the circumferential direction main groove which adjoins.

  In the fourth aspect of the present invention, the pneumatic tire includes at least three circumferential main grooves, and the lateral grooves extending from the same circumferential main groove into different second land portions are alternately arranged in the tire circumferential direction. It extends to.

  In the fifth aspect of the present invention, the second width direction groove is disposed in the first land portion.

  In the sixth aspect of the present invention, the second width direction groove does not communicate with the circumferential main groove.

  In the seventh aspect of the present invention, the second land portion is provided with a non-chamfered sipe extending from the circumferential main groove and terminating inside the second land portion, and the tire width of each second land portion. On each side of the direction, non-chamfered sipes and transverse grooves are alternately arranged in the tire circumferential direction, and non-chamfered sipes not communicating with the circumferential main groove are disposed on the first land portion. Two width direction grooves are alternately arranged in the tire circumferential direction.

  In the eighth aspect of the present invention, the number of lateral grooves in each second land portion is twice the number of second width direction grooves in each first land portion.

  According to the present invention, a plurality of lateral grooves including a chamfered sipe and a first width direction groove are disposed in a land portion near the center in the tire width direction, so that wet braking performance and dry steering performance are well balanced. An improved pneumatic tire is provided.

FIG. 1 is a plan development view showing a tread surface of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of a chamfer sipe. FIG. 3 is a cross-sectional view of another form of chamfer sipe. FIG. 4 is a developed plan view showing a tread surface of a pneumatic tire according to another embodiment of the present invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention (the following basic forms and additional forms 1 to 8) will be described in detail with reference to the accompanying drawings. In the accompanying drawings, the same components are denoted by the same reference numerals. Note that these embodiments do not limit the present invention. In addition, constituent elements of the above embodiment include those that can be easily replaced by those skilled in the art and those that are substantially the same. Furthermore, various forms included in the above embodiment can be implemented in any combination.

  First, terms used in the description of the embodiments are defined as follows. The tire radial direction means a direction orthogonal to the rotation axis of the pneumatic tire. The inner side in the tire radial direction means the side toward the rotation axis in the tire radial direction. The outer side in the tire radial direction means the side away from the rotation axis in the tire radial direction. The tire circumferential direction means a direction around the rotation axis as a central axis. The tire width direction means a direction parallel to the rotation axis. The inner side in the tire width direction means the side toward the tire equatorial plane in the tire width direction. The outer side in the tire width direction means the side away from the tire equatorial plane in the tire width direction. The tire equatorial plane means a plane that is orthogonal to the rotational axis of the pneumatic tire and passes through the center of the tire width of the pneumatic tire.

[Basic form]
Hereinafter, the basic form of the pneumatic tire according to the present invention will be described. FIG. 1 is a plan development view showing a tread surface of a pneumatic tire according to an embodiment of the present invention. In addition, the code | symbol E of FIG. 1 shows a tire grounding end.

  The tread portion of the pneumatic tire 1a is made of a rubber material (tread rubber). The surface of the tread portion (tread surface 3a) located at the outermost portion in the tire radial direction comes into contact with the road surface when the vehicle travels. As shown in FIG. 1, a tread pattern having a predetermined pattern is engraved on the tread surface 3a.

  Four circumferential main grooves 6 are disposed on the tread surface 3a. The circumferential main groove has a groove width of 3 mm or more and 25 mm or less. In this specification, the groove width means a groove dimension (maximum value) measured in a direction perpendicular to the direction in which the groove extends. Moreover, the circumferential main groove has a groove depth of 5 mm or more and 10 mm or less. In this specification, the groove depth means the groove dimension (maximum value) measured in the tire radial direction from the profile line when there is no groove.

  Further, the circumferential main groove 6 defines a first land portion 30 on the outermost side on each side in the tire width direction and three second land portions 32 on the inner side in the tire width direction from the first land portion 30. Yes. In the example of FIG. 1, the first land portion 30 and the second land portion 32 are ribs. The first land portion 30 may be a block defined by the circumferential main groove 6 and a width direction groove (not shown).

  A plurality of lateral grooves 8 are disposed in the second land portion 32. The lateral groove 8 includes a chamfered sipe (chamfered sipe 12a) and a first widthwise groove 10. In this specification, the width direction groove means a groove inclined with respect to the tire circumferential direction, and is not only a groove extending in parallel with the tire width direction but also inclined with respect to the tire width direction as shown in FIG. Including the groove. Further, the width direction groove has a groove width of 0.8 mm or more and 5.0 mm or less and a groove depth of 3 mm or more and 9 mm or less.

  FIG. 2 is a cross-sectional view of a chamfer sipe. As shown in FIG. 2, the chamfer sipe 12a is chamfered in a tapered shape. The chamfered sipe 12a includes a chamfered portion 121a and a sipe portion 123a. The groove width of the chamfered portion 121a is larger than that of the sipe portion 123a. By disposing the lateral groove 8 composed of the chamfered sipe 12a and the first widthwise groove 10, the drainage performance can be enhanced while suppressing a decrease in rigidity of the second land portion 32. As a result, in the pneumatic tire 1a, the wet braking performance and the dry steering performance can be improved with a good balance.

  Note that the dimension L1 of the chamfered portion 121a in the direction perpendicular to the extending direction of the chamfered sipe 12a can be set to 0.5 mm to 3.0 mm. The dimension D1 of the chamfered portion 121a in the tire radial direction can be set to 1 mm to 4 mm. The dimension L2 of the sipe part 123a in the direction perpendicular to the extending direction of the chamfered sipe 12a can be set to 0.3 mm to 2.0 mm. The dimension D2 of the sipe part 123a in the tire radial direction can be set to 2 mm to 5 mm. The depth (D1 + D2) from the top surface of the second land portion 32 to the groove bottom of the chamfered sipe 12a can be made 1.7 mm shorter than the depth of the circumferential main groove 6.

  FIG. 3 is a cross-sectional view of another form of chamfer sipe. As shown in FIG. 3, the chamfer sipe 12b may be chamfered in an R shape. In addition, the curvature radius of the chamfered part 121b can be set to 1 mm to 5 mm. The dimensions of the sipe part 123b are the same as those of the sipe part 123a in FIG.

  As shown in FIG. 1, one end of the first widthwise groove 10 communicates with the circumferential main groove 6, and the other end of the first widthwise groove 10 communicates with one end of the chamfered sipe 12a. Further, the other end of the chamfered sipe 12 a is terminated inside the second land portion 32. That is, only one end of the lateral groove 8 communicates with the circumferential main groove 6. For this reason, the rigidity of the 2nd land part 32 is improved rather than the time of the both ends of the horizontal groove 8 communicating with the circumferential direction main groove. Further, the drainage performance is improved as compared with the case where both ends of the lateral groove 8 are not in communication with the circumferential main groove. As a result, in the pneumatic tire 1a, the wet braking performance and the dry steering performance can be improved with a good balance.

  Further, the chamfered sipe 12a is continuously chamfered from one side in the width direction to the other side in the width direction through the end portion in the extending direction. Thereby, the local rigidity change of a land part can be made small especially in the extension direction edge part, generation | occurrence | production of a crack etc. can be suppressed and eventually durability performance can be improved.

  Further, as shown in FIG. 1, the lateral grooves 81 and 82 in the second land portions 32 alternately extend from the adjacent circumferential main grooves 6 in the tire circumferential direction. In other words, the lateral grooves 81 and 82 extend from different tire circumferential positions of the adjacent circumferential main grooves 6. This makes it possible to make the contact area at the time of tire rolling more uniform, and the lateral force when the tire has a slip angle becomes more constant at the time of tire rolling. As a result, in the pneumatic tire 1a, the dry steering performance can be improved.

  In addition, although not shown in figure, the pneumatic tire 1a has the same meridional cross-sectional shape as the conventional pneumatic tire. Here, the meridional cross-sectional shape of the pneumatic tire refers to a cross-sectional shape of the pneumatic tire that appears on a plane perpendicular to the tire equatorial plane CL. The pneumatic tire 1a has a bead portion, a sidewall portion, a shoulder portion, and a tread portion from the inner side in the tire radial direction toward the outer side in a tire meridional sectional view. In addition, the pneumatic tire 1a is formed sequentially from the tread portion to the bead portions on both sides and wound around the pair of bead cores, and on the outer side in the tire radial direction of the carcass layer in the tire meridional section. A belt layer and a belt reinforcing layer.

  The pneumatic tire 1a is obtained through normal manufacturing processes, that is, a tire material mixing process, a tire material processing process, a green tire molding process, a vulcanization process, and an inspection process after vulcanization. In the manufacturing process of the pneumatic tire 1a, in particular, concave portions and convex portions corresponding to the tread pattern shown in FIG. 1 are formed on the inner wall of the vulcanization mold, and vulcanization is performed using this mold. Further, the chamfered sipe may be formed by directly carving the chamfered portion on the tread surface before the inspection process after vulcanization. In this case, the chamfer sipe can be formed on the tread surface without changing the existing vulcanization mold.

[Additional form]
Next, with reference to FIG. 4, additional modes 1 to 8 that can be optionally implemented in the basic mode of the pneumatic tire according to the present invention will be described. FIG. 4 is a developed plan view showing a tread surface of a pneumatic tire according to another embodiment of the present invention. In addition, the code | symbol E of FIG. 4 shows a tire grounding end.

(Additional form 1)
In the basic configuration, it is preferable that the lateral groove 8 terminates without reaching the center position in the tire width direction of each second land portion 32 (additional configuration 1).

  Since the lateral groove 8 terminates without reaching the center position in the tire width direction of each second land portion 32, the groove area in the second land portion 32 does not become excessive, so that the rigidity of the second land portion 32 decreases. Can be further suppressed. As a result, dry steering performance can be ensured.

(Additional form 2)
In the basic form or the like (the basic form or the form in which the additional form 1 is combined with the basic form), as shown in FIG. 4, the circumferential groove 8 in each second land portion 32 is adjacent to the circumferential main groove 6 to the tire circumference. It is preferable to be inclined in the opposite direction (additional form 2).

  Since the lateral groove 8 in each second land portion 32 is inclined from the adjacent circumferential main groove 6 in the opposite direction to the tire circumferential direction, the rigidity balance of the second land portion 32 is further enhanced. As a result, the dry steering performance can be further improved.

(Additional form 3)
In the basic form or the like (the basic form or the form in which the additional form 1 or 2 is combined with the basic form), as shown in FIG. 4, the pneumatic tire 1b includes at least three circumferential main grooves 6 and is the same. It is preferable that the lateral grooves 83 and 84 extending from the circumferential main grooves 6 to the insides of the different second land portions 32 alternately extend in the tire circumferential direction (additional form 3). In other words, it is preferable that the lateral grooves 83 and 84 extend from different tire circumferential positions of the same circumferential main groove 6.

  The lateral grooves 83 and 84 extending from the same circumferential main groove 6 into the different second land portions 32 alternately extend from the same circumferential main groove 6 in the tire circumferential direction. The contact area at the time of rolling of the tire can be made more uniform, and the lateral force when the tire has a slip angle becomes more constant at the time of rolling of the tire. As a result, the dry steering performance can be further improved. Moreover, the contact surface pressure at the time of tire rolling can be made more uniform, and as a result, uneven wear resistance can be improved.

(Additional form 4)
In a basic form or the like (a basic form or a form in which at least one of the additional forms 1 to 3 is combined with the basic form), as shown in FIG. 14 is preferably provided (additional form 4).

  By disposing the second width direction groove 14 in the first land portion 30, the groove area on the tread surface 3b can be increased, and the drainage performance can be further improved. As a result, the wet braking performance can be further improved.

(Additional form 5)
In the form in which the additional form 4 is combined with the basic form, it is preferable that the second width direction groove 14 does not communicate with the circumferential main groove 6 (additional form 5) as shown in FIG. . That is, it is preferable that the first land portion 30 is partitioned as a rib.

  Since the second width direction groove 14 is not in communication with the circumferential main groove 6, a decrease in rigidity of the first land portion 30 can be suppressed. As a result, dry steering performance can be ensured.

(Additional form 6)
In the form in which the additional form 4 is combined with the basic form, the non-chamfered sipe 16a extending from the circumferential main groove 6 and terminating inside the second land part 32 is arranged on the second land part 32. Non-chamfered sipes 16a and lateral grooves 8 are alternately arranged in the tire circumferential direction on each side in the tire width direction of each second land portion 32, and communicated with the circumferential main groove 6 in the first land portion 30. It is preferable that the non-chamfered sipe 16b is disposed and the non-chamfered sipe 16b and the second width direction groove 14 are alternately disposed in the tire circumferential direction (additional form 6). The non-chamfered sipe means a sipe that is not chamfered. The non-chamfered sipes 16a and 16b have a groove width of 0.3 mm to 1.5 mm and a groove depth of 3 mm to 9 mm.

  A non-chamfered sipe 16a is disposed on the second land portion 32, and on each side in the tire width direction of each second land portion 32, the non-chamfered sipe 16a and the lateral groove 8 are alternately disposed in the tire circumferential direction. The non-chamfered sipe 16b is disposed on the land portion 30, and the non-chamfered sipe 16b and the second width direction groove 14 are alternately disposed in the tire circumferential direction, thereby increasing the groove area on the tread surface 3b. The drainage performance can be further improved. As a result, the wet braking performance can be further improved. On the other hand, since the groove width of the non-chamfered sipes 16a and 16b is small, a decrease in the rigidity of the land portion due to the arrangement of the non-chamfered sipes 16a and 16b is minimal. As a result, dry steering performance can be ensured.

  In addition, since the non-chamfered sipe 16a terminates without reaching the center position in the tire width direction of each second land portion 32, the above effect can be achieved at a higher level.

(Additional form 7)
In the form in which the additional form 4 is combined with the basic form, as shown in FIG. 4, the number of the lateral grooves 8 in each second land part 32 is equal to the second width direction groove 14 in each first land part 30. (Additional form 7) is preferred.

  Since the number of the lateral grooves 8 in each second land portion 32 is twice the number of the second width direction grooves 14 in each first land portion 30, a large number of lateral grooves 8 are formed in each second land portion 32. Edges can be formed. For this reason, the tire width direction component of these edges can further exert a resistance against stress applied in the tire circumferential direction, and wet braking performance can be further improved. In addition, the number of the lateral grooves 8 in each second land portion 32 is twice the number of the second width direction grooves 14 in each first land portion 30, so that the first land portion 30 and the second land portion 32. And the difference in rigidity can be reduced. As a result, uneven wear performance can be improved.

(Additional form 8)
In the basic form or the like (the basic form or a form in which at least one of the additional forms 1 to 7 is combined with the basic form), as shown in FIG. 4, the shallow groove 18 is disposed in the second land portion 32. (Additional form 8) is preferred. The shallow groove 18 has a groove width of 0.5 mm to 5 mm and a groove depth of 0.5 mm to 1 mm.

  By disposing the shallow groove 18 in the second land portion 32, the surface area of the tread surface 3b can be increased and the heat generation performance can be improved.

  As shown in Table 1, each condition relating to the second land portion (type of groove, communication with the circumferential main groove of the groove, arrangement of the transverse groove in the same land portion, extension length of the groove, transverse groove in the tire circumferential direction Extending direction, arrangement of transverse grooves in different land portions), each condition relating to the first land portion (type of groove, communication with the circumferential main groove of the groove), the number of transverse grooves in each second land portion, and each A total of 10 tires of Conventional Examples 1 and 2 and Examples 1 to 8 were manufactured by changing the ratio with the number of width direction grooves in the first land portion. For all tires, the number of circumferential main grooves was four.

  In the tires of Examples 1 to 8, the lateral grooves were arranged so as to alternately extend from adjacent circumferential main grooves into the same second land portion in the tire circumferential direction. In the tires of Examples 1 to 3, the lateral grooves were arranged so as to extend from the same circumferential main groove into different second land portions at the same position in the tire circumferential direction. In the tires of Examples 4 to 8, the lateral grooves were disposed so as to alternately extend from the same circumferential main groove into the different second land portions in the tire circumferential direction. In the tires of Examples 7 and 8, on each side in the tire width direction of each second land portion, non-chamfered sipes and lateral grooves are alternately arranged in the tire circumferential direction, and in the first land portion, non-chamfered sipes and widths are arranged. Directional grooves were alternately arranged in the tire circumferential direction.

  For the tires (test tires) of Conventional Examples 1 and 2 and Examples 1 to 8, the tire size was 195 / 65R15, and each test tire was assembled in four 15 × 6JJ rims with an air pressure of 220 kPa. It was mounted on a sedan type vehicle with a displacement of 1500CC. All these test tires were evaluated for wet braking performance and dry steering performance as follows. These results are also shown in Table 1.

(Wet braking performance)
On a wet road surface, braking was performed from a state where the vehicle traveled at a speed of 100 km / h, and a braking distance until the vehicle completely stopped was measured, and an index evaluation was performed using a conventional example as a reference (100). This evaluation shows that wet braking performance is excellent, so that a numerical value is large.

(Dry steering performance)
A sensory evaluation was performed by a paneler when traveling on a predetermined test course that was a dry road surface, and an index evaluation was performed using the conventional example as a reference (100). This evaluation shows that the larger the index, the higher the dry steering performance.

  According to Table 1, the pneumatic tires of Examples 1 to 8 belonging to the technical scope of the present invention are all the pneumatic tires of Conventional Examples 1 and 2 that do not belong to the technical scope of the present invention. On the other hand, it can be seen that wet braking performance and dry steering performance are improved in a well-balanced manner.

  The present invention includes the following aspects.

  (1) A plurality of circumferential main grooves are provided, and the circumferential main grooves form a first land portion on the outermost side on each side in the tire width direction and a second land portion on the inner side in the tire width direction from the first land portion. In the partitioned pneumatic tire, a plurality of lateral grooves including a chamfered sipe and a first width direction groove are disposed in the second land portion, and one end of the first width direction groove communicates with the circumferential main groove. The other end of the first widthwise groove communicates with one end of the chamfered sipe, the other end of the chamfered sipe terminates inside the second land portion, and the lateral groove in each second land portion has a tire circumferential direction. A pneumatic tire characterized by alternately extending from adjacent circumferential main grooves.

  (2) The pneumatic tire according to (1), wherein the lateral groove terminates without reaching the center position in the tire width direction of each second land portion.

  (3) The pneumatic tire according to (1) or (2), wherein the lateral groove in each second land portion is inclined in the opposite direction of the tire circumferential direction from adjacent circumferential main grooves.

  (4) At least three circumferential main grooves are provided, and lateral grooves extending from the same circumferential main groove into different second land portions are alternately extended in the tire circumferential direction. The pneumatic tire according to any one of 1) to (3).

  (5) The pneumatic tire according to any one of (1) to (4), wherein a second width direction groove is disposed in the first land portion.

  (6) The pneumatic tire according to (5), wherein the second width direction groove does not communicate with the circumferential main groove.

  (7) In the second land portion, a non-chamfered sipe extending from the circumferential main groove and terminating inside the second land portion is disposed, and on each side in the tire width direction of each second land portion, Non-chamfered sipes and transverse grooves are alternately arranged in the tire circumferential direction, and non-chamfered sipes and second widthwise grooves are arranged on the first land portion, which are not communicated with the circumferential main grooves. The pneumatic tire according to (5) or (6), wherein and are alternately arranged in the tire circumferential direction.

  (8) The number of transverse grooves in each second land portion is twice the number of second width direction grooves in each first land portion, according to any one of (5) to (7) above Pneumatic tire.

DESCRIPTION OF SYMBOLS 1a, 1b Pneumatic tire 3a, 3b Tread surface 6 Circumferential main groove 8, 81, 82, 83, 84 Lateral groove 10 First width direction groove 12a, 12b Chamfer sipe 121a, 121b Chamfer 123a, 123b Sipe 14 2 width direction grooves 16a, 16b non-chamfered sipe 18 shallow groove 30 first land part 32 second land part E grounding end L1 dimension of chamfered part 121a in the direction perpendicular to the extending direction of chamfered sipe 12a L2 of chamfered sipe 12a Dimensions of sipe portion 123a in the direction perpendicular to the extending direction D1 Dimensions of chamfered portion 121a in the tire radial direction D2 Dimensions of sipe portion 123a in the tire radial direction

Claims (8)

A plurality of circumferential main grooves are provided, and the circumferential main grooves define first outermost land portions on each side in the tire width direction and second land portions on the inner side in the tire width direction from the first land portions. In the formed pneumatic tire,
In the second land portion, a plurality of lateral grooves including a chamfered sipe and a first width direction groove are disposed,
One end of the first widthwise groove communicates with the circumferential main groove, the other end of the first widthwise groove communicates with one end of the chamfered sipe, and the other end of the chamfered sipe is the second land. Terminated inside the part,
The pneumatic tire according to claim 1, wherein the lateral grooves in the second land portions alternately extend from the adjacent circumferential main grooves in the tire circumferential direction.   The pneumatic tire according to claim 1, wherein the lateral groove terminates without reaching the center position in the tire width direction of each second land portion.   The pneumatic tire according to claim 1 or 2, wherein the lateral groove in each second land portion is inclined in the opposite direction of the tire circumferential direction from the adjacent circumferential main groove.   4. The transverse groove that includes at least three circumferential main grooves and extends from the same circumferential main groove into different second land portions extends alternately in the tire circumferential direction. The pneumatic tire according to any one of the above.   The pneumatic tire according to any one of claims 1 to 4, wherein a second width direction groove is disposed in the first land portion.   The pneumatic tire according to claim 5, wherein the second width direction groove does not communicate with the circumferential main groove. In the second land portion, a non-chamfered sipe extending from the circumferential main groove and terminating inside the second land portion is disposed, and on each side in the tire width direction of each second land portion, The non-chamfered sipes and the lateral grooves are alternately arranged in the tire circumferential direction,
Non-chamfered sipes not communicating with the circumferential main groove are disposed in the first land portion, and the non-chamfered sipes and the second widthwise grooves are alternately disposed in the tire circumferential direction. The pneumatic tire according to claim 5 or 6.   The pneumatic tire according to any one of claims 5 to 7, wherein the number of the lateral grooves in each second land portion is twice the number of the second width direction grooves in each first land portion.

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