JP6364781B2 - 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 chamfered sipes are disposed in the second land portion, the chamfered sipes extend from the circumferential main groove and terminate in the second land portion, A pneumatic tire is provided in which chamfered sipes in each second land portion alternately extend from adjacent circumferential main grooves in the tire circumferential direction.

  In the second aspect of the present invention, the chamfer sipe ends without reaching the center position in the tire width direction of each second land portion.

  In the 3rd mode of the present invention, the chamfer sipe in each 2nd land part inclines in the direction opposite to the tire peripheral direction from the adjacent main groove in the circumferential direction.

  In the fourth aspect of the present invention, the pneumatic tire includes at least three circumferential main grooves, and the chamfered sipe extending from the same circumferential main groove into the different second land portion is in the tire circumferential direction. It extends alternately.

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

  In the sixth aspect of the present invention, the 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 sipe and chamfered sipe are alternately arranged in the tire circumferential direction, and a non-chamfered sipe that is not in communication with the circumferential main groove is disposed on the first land portion. The width direction grooves are alternately arranged in the tire circumferential direction.

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

  ADVANTAGE OF THE INVENTION According to this invention, the pneumatic tire which improved wet-braking performance and dry steering performance in good balance is provided by arrange | positioning a chamfering sipe in the land part near the tire width direction center.

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 10 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.

  The circumferential main groove 10 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. 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 10 and a width direction groove (not shown).

  The second land portion 32 is provided with a plurality of chamfered sipe (chamfer sipe) 12a. 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 chamfered sipe 12a in place of the chamfered sipe (non-chamfered sipe), the drainage performance can be enhanced while suppressing the 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 10.

  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, the chamfered sipe 12 a extends from the circumferential main groove 10 and terminates inside the second land portion 32. That is, only one end of the chamfered sipe 12 a communicates with the circumferential main groove 10. For this reason, the rigidity of the 2nd land part 32 is improved rather than when both ends communicate with the circumferential direction main groove. Further, the drainage performance is improved as compared with the case where both ends do not communicate 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.

  The chamfered sipe 12a extends from the circumferential main groove 10 not only when the entire chamfered sipe 12a (the chamfered portion 121a and the sipe portion 123a) communicates with the circumferential main groove 10, but also with the chamfered sipe 12a. The case where only a part (for example, the chamfered portion 121a) communicates with the circumferential main groove 10 is also included. When the end of the chamfered sipe 12a on the circumferential main groove 10 side is raised and only the chamfered portion 121a communicates with the circumferential main groove 10, the rigidity of the second land portion 32 is further enhanced.

  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.

  As shown in FIG. 1, the chamfered sipes 112 and 212 in each second land portion 32 alternately extend from the adjacent circumferential main grooves 10 in the tire circumferential direction. In other words, the chamfered sipes 112 and 212 extend from different tire circumferential positions of adjacent circumferential main grooves 10. 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.

  Further, the second land portion 32 is not provided with a widthwise groove having a groove width larger than that of the sipe portion 123a. As a result, in the pneumatic tire 1a, the rigidity of the second land portion 32 can be further increased.

  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, as shown in FIG. 4, it is preferable that the chamfered sipe 12a terminates without reaching the center position in the tire width direction of each second land portion 32 (additional configuration 1).

  Since the chamfered sipe 12a 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. The decrease 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 chamfer sipe 12 a in each second land portion 32 is adjacent to the adjacent circumferential main groove 10 to the tire. Inclining in the opposite direction in the circumferential direction (additional form 2) is preferred.

  Since the chamfered sipe 12a in each second land portion 32 is inclined in the opposite direction of the tire circumferential direction from the adjacent circumferential main groove 10, 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 10 and is the same. It is preferable that the chamfering sipes 312 and 412 extending from the circumferential main groove 10 to the inside of different second land portions 32 alternately extend in the tire circumferential direction (additional form 3). In other words, the chamfered sipes 312 and 412 preferably extend from different tire circumferential positions of the same circumferential main groove 10.

  Chamfering sipes 312 and 412 extending from the same circumferential main groove 10 into different second land portions 32 alternately extend from the same circumferential main groove 10 in the tire circumferential direction. Thus, the contact area during rolling of the tire can be made more uniform, and the lateral force when the slip angle is given to the tire becomes more constant during 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 the basic configuration or the like (the basic configuration or a configuration in which at least one of the additional configurations 1 to 3 is combined with the basic configuration), the width direction groove 14 is arranged in the first land portion 30 as shown in FIG. It is preferable (additional form 4). 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. The width direction groove has a groove width of 1.5 mm or more and 5 mm or less and a groove depth of 3 mm or more and 9 mm or less.

  Since the width direction groove 14 is disposed 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 width direction groove 14 does not communicate with the circumferential main groove 10 (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 width direction groove 14 does not communicate with the circumferential direction main groove 10, it is possible to suppress a decrease in rigidity of the first land portion 30. 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 second land portion 32 is provided with a non-chamfered sipe 16a extending from the circumferential main groove 10 and terminating inside the second land portion 32. The chamfered sipes 16a and the chamfered sipes 312 and 412 are alternately arranged in the tire circumferential direction on each side in the tire width direction of each second land portion 32, and the circumferential main groove is formed in the first land portion 30. It is preferable that the non-chamfered sipe 16b that does not communicate with 10 is disposed, and the non-chamfered sipe 16b and the width direction groove 14 are alternately disposed in the tire circumferential direction (additional form 6). 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.

  Non-chamfered sipes 16a are disposed on the second land portions 32, and non-chamfered sipes 16a and chamfered sipes 312 and 412 are alternately disposed in the tire circumferential direction on each side in the tire width direction of each second land portion 32. The non-chamfered sipe 16b is disposed in the first land portion 30, and the non-chamfered sipe 16b and the 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.

  As shown in FIG. 4, the non-chamfered sipe 16a terminates without reaching the center position in the tire width direction of each second land portion 32, so that 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 chamfered sipes 12 a in each second land portion 32 is equal to the number of widthwise grooves 14 in each first land portion 30. (Additional form 7) is preferred.

  The number of chamfered sipes 12a in each second land portion 32 is twice the number of widthwise grooves 14 in each first land portion 30, so that each second land portion 32 has many edges due to the chamfered sipes 12a. 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. Moreover, since the number of chamfered sipes 12a in each second land portion 32 is twice the number of the width direction grooves 14 in each first land portion 30, the first land portion 30 and the second land portion 32 The rigidity difference between them 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 the 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 first land part 30 and the second land part 32 It is preferable that the shallow grooves 18a and 18b are disposed (additional form 8). The shallow grooves 18a and 18b have 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 grooves 18a and 18b in the first land portion 30 and the second land portion 32, respectively, 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 chamfer sipe of the same land portion, extension length of the groove, tire circumferential direction Chamfering sipe extending direction, arrangement of chamfering sipe of different land part), each condition regarding first land part (type of groove, communication with circumferential main groove of groove), and chamfering sipe in each second land part A total of ten tires of Conventional Examples 1 and 2 and Examples 1 to 8 were manufactured by changing the ratio of the number of the first and second grooves and the number of widthwise grooves in each first land portion. For all tires, the number of circumferential main grooves was four.

  In the tires of Examples 1 to 8, the chamfered sipes 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 chamfer sipe was disposed so as to extend from the same circumferential main groove into the different second land portion at the same position in the tire circumferential direction. In the tires of Examples 4 to 8, the chamfered sipes were arranged so as to alternately extend from the same circumferential main groove into different second land portions in the tire circumferential direction. In the tires of Examples 7 and 8, non-chamfered sipe and chamfered sipe are alternately arranged in the tire circumferential direction on each side in the tire width direction of each second land portion, and in the first land portion, non-chamfered sipe and The width direction 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. A plurality of chamfered sipes are arranged in the second land portion, and the chamfered sipes extend from the circumferential main groove and terminate in the second land portion in each of the partitioned pneumatic tires. The pneumatic tire according to claim 1, wherein the chamfered sipes extend alternately from adjacent circumferential main grooves in the tire circumferential direction.

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

  (4) The chamfering sipes provided with at least three circumferential main grooves and extending from the same circumferential main groove into different second land portions alternately extend 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 widthwise groove is disposed in the first land portion.

  (6) The pneumatic tire according to (5), wherein the 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 chamfered sipes are alternately arranged in the tire circumferential direction, non-chamfered sipes not communicating with the circumferential main groove are disposed on the first land portion, The pneumatic tire according to (5) or (6), wherein the pneumatic tire is alternately arranged in a tire circumferential direction.

  (8) The air according to any one of (5) to (7), wherein the number of chamfered sipes in each second land portion is twice the number of widthwise grooves in each first land portion. tire.

1a, 1b Pneumatic tire 3a, 3b Tread surface 10 Circumferential main groove 12a, 12b, 112, 212, 312, 412 Chamfered sipe 121a, 121b Chamfered portion 123a, 123b Sipe portion 14 Width direction groove 16a, 16b Non-chamfered sipe 18a 18b Shallow groove 30 First land portion 32 Second land portion E Grounding end L1 Dimensions of chamfered portion 121a in a direction perpendicular to the extending direction of chamfered sipe 12a L2 Sipe portion in a direction perpendicular to the extending direction of chamfered sipe 12a Dimension of 123a D1 Dimension of chamfered portion 121a in tire radial direction D2 Dimension of sipe portion 123a in 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,
A plurality of chamfer sipes are disposed on the second land portion,
The chamfer sipe extends from the circumferential main groove and terminates inside the second land portion;
The chamfered sipe in each second land portion alternately extends from the adjacent circumferential main grooves in the tire circumferential direction ,
The pneumatic tire according to claim 1, wherein the chamfered sipe includes a chamfered portion and a sipe portion, and only the chamfered portion communicates with the circumferential main groove .   The pneumatic tire according to claim 1, wherein the chamfered sipe 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 chamfered sipe in each second land portion is inclined in the opposite direction of the tire circumferential direction from the adjacent circumferential main groove.   The chamfering sipe comprising at least three circumferential main grooves and extending from the same circumferential main groove into different second land portions alternately extends in the tire circumferential direction. 4. The pneumatic tire according to any one of 3 above.   The pneumatic tire according to any one of claims 1 to 4, wherein a width direction groove is disposed in the first land portion.   The pneumatic tire according to claim 5, wherein the width direction groove does not communicate with the circumferential direction 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 sipe and the chamfered sipe are alternately arranged in the tire circumferential direction,
The non-chamfered sipe that does not communicate with the circumferential main groove is disposed in the first land portion, and the non-chamfered sipe and the widthwise groove are alternately disposed in the tire circumferential direction. Or the pneumatic tire of 6.   The pneumatic tire according to any one of claims 5 to 7, wherein the number of the chamfered sipes in each second land portion is twice the number of the width direction grooves in each first land portion.

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