JP5159652B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire provided on a tread surface with a main groove that extends continuously in the circumferential direction and a lateral groove that intersects the main groove at a non-right angle.

  In recent years, with the development of analysis technology such as contact pressure in each part of the tread pattern, an asymmetric pattern in which different tread patterns are formed on the inside and outside when the vehicle is mounted may be used for the purpose of optimizing the design. . At that time, drainage on a wet road surface (WET road surface) and steering stability on a dry road surface (DRY road surface) are important performance requirements for a pneumatic tire.

  In order to satisfy both the drainage performance on the WET road surface and the steering stability on the DRY road surface, in Patent Document 1 below, as shown in FIG. 8, a tread from the vicinity of the tire equator CL at an inclination angle substantially symmetrical to the tire equator CL is shown. A tread pattern of a rotation direction designating type having a plurality of inclined main grooves 51 extending so as to gradually expand the arrival side after rotation toward the end side is described. However, in this tread pattern, the land portion of the shoulder portion C is continuous to the mediate portion B, and the interval between the inclined main grooves 51 continuous to the shoulder portion C is widened in the shoulder portion C. The rigidity of the land portion 59 increases, and the pattern noise due to the hitting sound tends to increase.

  Moreover, in the following Patent Document 2, in a pneumatic tire provided with at least one circumferential groove in the vicinity of the equator line of the tire that extends parallel to or substantially parallel to the tire circumferential direction, (1) the circumferential groove A large number of isosceles or nearly isosceles triangular regions are formed adjacent to each other at intervals in the circumferential direction. (2) One of the vertices and isosceles of the isosceles triangular region is the circumferential groove. (3) chamfered over a length of 5 mm or more so that the chamfering depth gradually decreases from the apex to the base of the isosceles triangle region, and (4) the two There is a description that when the apex angle of the apex of the equilateral triangular region is 5 to 40 degrees, the deterioration of the noise (pattern noise) level of the pneumatic tire can be prevented or suppressed. However, in this pneumatic tire, since the triangular chamfered region is connected to the lateral groove only through the inclined sipe, the opening of the inclined sipe narrows or closes when a load is applied during tire travel. Tend to. For this reason, in this pneumatic tire, drainage on the WET road surface is not sufficient.

JP 08-1113015 A JP 2000-52715 A

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a pneumatic tire with improved handling stability on a wet road surface (WET road surface) and a dry road surface (DRY road surface) and with improved drainage. There is to do.

  The above object can be achieved by the present invention as described below. That is, the pneumatic tire of the present invention includes a main groove extending continuously in the circumferential direction on the tread surface, an obtuse side wall surface that intersects the main groove at a non-perpendicular angle and extends at an obtuse angle with respect to the main groove, and the In the pneumatic tire comprising a lateral groove having an acute angle side wall surface extending at an acute angle with respect to the main groove, the obtuse angle side wall surface extends while inclining in a direction in which the groove width of the horizontal groove widens toward the main groove, And having a first wall surface opened in the main groove, the acute-side wall surface starting from the vicinity of a ridge line with the tread surface of the lateral groove and extending while being inclined toward the bottom of the first wall surface, and It has the 2nd wall surface opened to a main groove, It is characterized by the above-mentioned.

  In the pneumatic tire, the obtuse side wall surface of the lateral groove has a first wall surface that extends while inclining in the direction in which the groove width of the lateral groove widens toward the main groove and opens into the main groove. Thereby, since the water flow path of a main groove and a horizontal groove is ensured smoothly, the drainage property on a WET road surface can be improved. As a result, the hydroplaning resistance of the pneumatic tire and the steering stability on the WET road surface can be improved. Further, in the pneumatic tire described above, the acute side wall surface of the lateral groove starts from the vicinity of the ridge line with the tread surface of the lateral groove, extends while inclining toward the bottom of the first wall surface, and has a second wall surface that opens to the main groove. Have. Thereby, the acute angle part of the land part adjacent to this horizontal groove can be reinforced, without impairing the drainage property on the WET road surface. As a result, the steering stability of the pneumatic tire on the DRY road surface can be improved, and uneven wear of the pneumatic tire can be prevented. In addition, since the acute-angle side wall surface of the lateral groove has the second wall surface, generation of pattern noise of the pneumatic tire due to air columnar resonance in the groove can be suppressed.

  In the pneumatic tire, it is preferable that the second wall surface has a triangular shape in plan view. According to such a configuration, since the second wall surface has a triangular shape in a plan view, the acute angle portion of the land portion adjacent to the lateral groove can be more reliably reinforced without impairing the drainage performance on the WET road surface. it can. As a result, the handling stability of the pneumatic tire on the DRY road surface can be further improved, and uneven wear of the pneumatic tire can be more effectively prevented.

  In the pneumatic tire, it is preferable that H / 4 ≦ H1, where H is the groove depth of the main groove and H1 is the distance from the tread surface to the bottom of the second wall surface on the main groove side. According to such a configuration, the reinforcing effect of the second wall surface and the drainage performance on the WET road surface with respect to the acute angle portion of the land portion adjacent to the lateral groove can be improved with a particularly good balance.

Schematic development view of a tread pattern of an example of the pneumatic tire of the present invention Partial enlarged view of the vicinity of the opening to the main groove of the horizontal groove In FIG. 1, the perspective view which shows the wall surface of the horizontal groove 3 seen from the main groove 22out side Schematic development view of a tread pattern of another example of the pneumatic tire of the present invention Schematic development view of a tread pattern of another example of the pneumatic tire of the present invention Schematic development of the tread pattern of the pneumatic tire of Comparative Example 2 BB arrow sectional view of FIG. Schematic development of a tread pattern of an example of a conventional pneumatic tire

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic development view of a tread pattern of an example of the pneumatic tire of the present invention, and FIG. 2 is a partially enlarged view of the vicinity of the opening of the lateral groove with respect to the main groove. FIG. 3 is a perspective view showing the wall surface of the lateral groove 3 as viewed from the main groove 22out side in FIG.

  The pneumatic tire of the present invention has a main groove extending continuously in the circumferential direction on the tread surface, a non-right angle with respect to the main groove, and an obtuse side wall surface and the main groove extending at an obtuse angle with respect to the main groove. A transverse groove having an acute angle side wall surface extending at an acute angle. As shown in FIG. 1, the pneumatic tire of the present embodiment has an asymmetric pattern in which the mounting direction to the vehicle is specified, and continuously extends in the tire circumferential direction PD on both sides of the tire equator CL. Main grooves 21in and 21out and main grooves 22in and 22out that extend continuously in the tire circumferential direction are disposed between the main grooves and the tread ends. In the drawing, the arrow IN indicates the inner side of mounting and the arrow OUT indicates the outer side of mounting. This pneumatic tire is a type in which the mounting direction is designated, but in the present invention, it may be a tire in which the rotational direction is designated at the same time according to the shape of the tread pattern.

  In the present invention, “continuously extending in the tire circumferential direction PD” is not limited to a groove extending linearly in the tire circumferential direction PD, and even a zigzag or curved groove in the tire circumferential direction PD Anything that extends continuously is included.

  In the tread surface 1 of the present embodiment, a central land portion 41 is defined between the main groove 21in and the main groove 21out. Further, an intermediate land portion 42out is defined between the main groove 21out and the main groove 22out, and a shoulder land portion 43out is defined between the main groove 22out and the tread end on the outer side of the mounting. Further, an intermediate land portion 42in is defined between the main groove 21in and the main groove 22in, and a shoulder land portion 43in is defined between the main groove 22in and the tread end on the inner side of the mounting.

  In this embodiment, the groove width of the main groove 22out closest to the tread end on the outer side of the mounting is set narrower than the other main grooves 21in, 21out, and 22in. Specifically, the groove width of the main groove 22out is set to 4 mm, the groove widths of the other main grooves 21in and 21out are set to 14.5 mm, and the groove width of 22in is set to 13.2 mm. In the pneumatic tire set in this way, the ground contact areas of the intermediate land portion 42out and the shoulder land portion 43out are increased on the outer side of the mounting, so that the steering stability of the pneumatic tire on the DRY road surface is further improved. In the present invention, in order to further improve the handling stability on the DRY road surface of the pneumatic tire, the groove width of the main groove closest to the tread end on the outer side of the mounting is set to the average groove width of all the main grooves provided in the tread surface It is more preferable to set it to be narrower, and it is particularly preferably set to 30 to 80% of the average groove width of all the main grooves provided in the tread surface.

  As shown in FIGS. 1 and 2, the tread surface 1 of the present embodiment intersects with the main groove 22out at a non-right angle and extends at an obtuse angle (specifically, 120 °) with respect to the main groove 22out. And a lateral groove 3 having an acute angle side wall surface 3A extending at an acute angle (specifically, 60 °) with respect to the main groove 22out. Here, the angle formed between the obtuse side wall surface 3B and the main groove 22out means the angle formed between the center line C of the lateral groove 3 and the main groove 22out, and the angle formed between the acute side wall surface 3A and the main groove 22out is also as follows. Similarly, it means the angle formed by the center line C of the lateral groove 3 and the main groove 22out.

  In the present embodiment, the lateral groove 3 includes one extending from the main groove 21out and intersecting the main groove 22out at a non-right angle, and one extending from the tread end on the outer side of the mounting and intersecting the main groove 22out at a non-right angle. In the present embodiment, the groove width and groove depth of the lateral groove 3 are not particularly limited, but examples include a groove width of 3 to 8 mm and a groove depth of 4 to 8 mm.

  In the present invention, the angle between the main groove and the center line of the lateral groove is preferably 30 ° to 80 ° in order to further improve the drainage of the pneumatic tire. The “angle at which the main groove and the transverse groove intersect” here refers to the smaller angle among the angles formed by the intersection of the main groove and the center line of the transverse groove.

  As shown in FIGS. 1 to 3, the obtuse side wall surface 3 </ b> B has a first wall surface F <b> 1 that extends while inclining in the direction in which the groove width of the lateral groove 3 increases toward the main groove 22 out and opens into the main groove 22 out. Thereby, since the water flow path of the main groove 22out and the horizontal groove 3 is ensured smoothly, the drainage property on the WET road surface can be improved. As a result, the hydroplaning resistance of the pneumatic tire and the steering stability on the WET road surface can be improved. The acute-angle side wall surface 3A has a second wall surface F2 that starts from the vicinity of the ridge line with the tread surface 1 of the lateral groove 3 and extends while inclining toward the bottom of the first wall surface F1 and opens to the main groove 22out. Thereby, the acute angle portion of the intermediate land portion 42out adjacent to the lateral groove 3 can be reinforced without impairing the drainage performance on the WET road surface. As a result, the steering stability of the pneumatic tire on the DRY road surface can be improved, and uneven wear of the pneumatic tire can be prevented. In addition, since the acute-angle side wall surface 3A of the lateral groove 3 has the second wall surface F2, it is possible to suppress generation of pattern noise of the pneumatic tire due to air column resonance in the groove.

  As shown in FIG. 3, in this embodiment, the groove depth H of the main groove 22out is set to 8 mm, and the distance H1 from the tread surface 1 to the bottom of the second wall surface F2 on the main groove 22out side is set to 6 mm. In the present invention, the relationship between H and H1 is preferably H / 4 ≦ H1. According to such a configuration, it is possible to improve the reinforcing effect of the second wall surface F2 on the acute angle portion of the intermediate land portion 42out adjacent to the lateral groove 3 and the drainage on the WET road surface with a particularly good balance.

  In the present embodiment, as shown in FIGS. 1 and 2, the second wall surface F2 is formed so as to have a triangular shape in plan view. According to this configuration, the acute angle portion of the land portion adjacent to the lateral groove can be reliably reinforced by the second wall surface F2 without impairing the drainage performance on the WET road surface. As a result, the handling stability of the pneumatic tire on the DRY road surface can be further improved, and uneven wear of the pneumatic tire can be more effectively prevented. In the present embodiment, as shown in FIGS. 1 and 2, the second wall surface F <b> 2 has a triangular shape with a straight line including the entire bottom portion of the first wall surface F <b> 1 as one side. In this case, drainage performance of the pneumatic tire, steering stability on the WET road surface, and steering stability on the DRY road surface can be improved in a balanced manner, which is preferable.

  As described above, in the present embodiment, the groove width of the main groove 22out closest to the tread end on the outer side of the mounting is set to be narrower than the average groove width of all the main grooves provided in the tread surface 1, so that the pneumatic tire Steering stability on the DRY road surface is further improved. Here, if the groove width of the main groove is narrowed, the drainage performance tends to decrease in the main groove. Therefore, both the steering stability on the DRY road surface and the drainage performance and the steering stability on the WET road surface are compatible. It is generally difficult to do. However, in the present embodiment, the tread surface 1 is a main groove 22out having a groove width set narrower than the average groove width of all the main grooves provided in the tread surface 1, and a wall surface in the vicinity of the opening with respect to the main groove 22out. By providing the horizontal groove 3 having the wall surface F1 and the second wall surface F2, a water flow path between the main groove 22out and the horizontal groove 3 is ensured smoothly. As a result, the steering stability on the DRY road surface can be particularly improved, and the drainage performance and the steering stability on the WET road surface can also be improved in a balanced manner.

  In the present embodiment, in addition to the lateral groove 3, the tread surface 1 includes a termination groove 3 ′ that extends substantially parallel to the lateral groove 3 from the main groove 21out toward the main groove 22out and terminates before the main groove 22out. . In the present embodiment, in particular, the number of the lateral grooves 3 and the terminal grooves 3 'is set to be approximately equal. In the pneumatic tire set as described above, the steering stability on the WET road surface and the DRY road surface can be improved while ensuring the drainage. The groove widths and groove depths of these terminal grooves 3 ′ can be made substantially equal to the lateral grooves 3 described above.

  In the tread surface 1 of the present embodiment, the central land portion 41 has a rib shape. Further, a termination groove 5 extending from the main groove 22in toward the main groove 21in and terminating before the main groove 21in, and a termination groove 6 extending from the tread end on the inner side of the mounting toward the main groove 22in and terminating before the main groove 22in. And comprising. The groove widths and groove depths of these terminal grooves 5 and 6 can be made substantially equal to those of the lateral groove 3 described above.

  The pneumatic tire of the present invention is the same as a conventionally known pneumatic tire except that the main groove and the lateral groove as described above are provided in the tread portion, and any conventionally known shape, structure, material, manufacturing method, etc. Can also be adopted.

  Although not shown in the drawings, such a pneumatic tire includes, for example, a pair of bead portions, a sidewall portion extending outward in the tire radial direction from the bead portion, a tread portion provided between the sidewall portions, and the tread thereof. And a belt layer disposed below the portion.

  Specifically, for example, the carcass layer is arranged between a pair of bead portions. The carcass layer is a radial carcass formed from a rubberized layer of a cord such as polyester, and a rubber layer is formed outside the carcass layer. In the tubeless tire, an inner liner layer is formed as the innermost layer. A belt layer that reinforces by the effect is disposed on the outer side in the tire radial direction of the carcass layer, and the tread portion 1 is formed on the outer side in the tire radial direction of the belt layer. The belt layer is formed by laminating layers of rubberized steel cords arranged in parallel at an inclination angle of about 20 ° with respect to the tire equator line so that the steel cords intersect with each other across the tire equator line.

  Examples of the raw material for the tread rubber forming the tread portion include natural rubber, styrene butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), butyl rubber (IIR), and the like. These rubbers are reinforced with fillers such as carbon black and silica, and a vulcanizing agent, a vulcanization accelerator, a plasticizer, an antiaging agent, and the like are appropriately blended.

  The pneumatic tire of the present invention can be used widely as a summer tire, an all-season tire, a competition tire, etc., because it can improve the handling stability on the WET road surface and the DRY road surface and improve the drainage performance. Can do.

[Other Embodiments]
(1) In the above-described embodiment, the example in which the tread surface 1 is provided with the four main grooves has been described. However, in the present invention, the tread surface may be provided with at least four main grooves.

  (2) In the above-described embodiment, in addition to the lateral groove 3, the tread surface 1 extends from the main groove 21out toward the main groove 22out substantially in parallel with the lateral groove 3, and terminates in front of the main groove 22out. In this example, the number of the lateral grooves 3 and the terminal grooves 3 ′ is set to be approximately equal. However, in the embodiment shown in FIG. 1, the lateral groove 3 may be adopted instead of the terminal groove 3 ′. In this case, since only the lateral groove that communicates with the main groove 22out at a non-right angle is provided, the drainage of the pneumatic tire is improved, so that the hydroplaning resistance of the pneumatic tire is particularly improved.

  (3) In the above-described embodiment, the tread surface 1 has the main groove 22out having a groove width set narrower than the average groove width of all the main grooves provided in the tread surface 1, and the wall surface near the opening with respect to the main groove 22out. The example provided with the horizontal groove 3 which has the 1st wall surface F1 and the 2nd wall surface F2 was shown. However, in the present invention, as shown in FIG. 4, the groove width of the main groove 22in is set to be narrow like the groove width of the main groove 22out, and the first wall surface F1 and the first wall surface as the wall surface near the opening with respect to the main groove 22in are used. The lateral groove 3 having two wall surfaces F2 may be provided. In this case, since the ground contact area becomes large even inside the wearing, the steering stability of the pneumatic tire on the DRY road surface is particularly improved.

  (4) In the above-described embodiment, as shown in FIG. 1, an example of a pneumatic tire having an asymmetric pattern in which the mounting direction to the vehicle is specified is shown, but air having a symmetric pattern as shown in FIG. 5 is shown. The present invention can also be applied to an entering tire.

  Examples and the like specifically showing the configuration and effects of the present invention will be described below. In addition, the evaluation item in an Example etc. measured as follows.

(1) Hydroplaning resistance The hydroplaning generation speed when running on a WET road surface with a water depth of 8 mm was measured and evaluated. In addition, evaluation is shown by the index display when the tire of the comparative example 1 is set to 100, and a favorable result is shown, so that a numerical value is large.

(2) Steering stability on DRY road surface Two test drivers evaluated the feeling of the driver when driving on the DRY road surface in various driving modes. In addition, evaluation is shown by the index display when the tire of the comparative example 1 is set to 100, and a favorable result is shown, so that a numerical value is large.

(3) Steering stability on the WET road surface Two test drivers evaluated the feeling when driving on the WET road surface with a water depth of 1 mm in various driving modes. In addition, evaluation is shown by the index display when the tire of the comparative example 1 is set to 100, and a favorable result is shown, so that a numerical value is large.

(4) Uneven wear resistance performance After running at 12,000 km, the wear amount difference between the blocks (to-and-heel ratio) was measured. The measurement result is digitized and evaluated, and the closer the value is to 1.0, the better the result.

(5) Pattern noise The test noise was evaluated by two test drivers using the feeling when driving on the DRY road surface in various driving modes. The evaluation is based on 10 points, and the larger the value, the better the result.

Example 1
In the tread surface 1 shown in FIG. 1, the groove width of the main groove 22out is set to 4 mm, the groove widths of the other main grooves 21in and 21out are set to 14.5 mm, the groove width of 22in is set to 13.2 mm, The groove depth H is set to 8 mm, the distance H1 from the tread surface 1 to the bottom of the second wall surface F2 on the main groove 22out side is set to 6 mm, and the number of the horizontal grooves 3 and the terminal grooves 3 ′ are set to be equal (all the horizontal grooves 3 are A pneumatic tire having a first wall surface F1 and a second wall surface F2 on the main groove 22out side was manufactured, and the performance was evaluated. The results are shown in Table 1.

Example 2
In the tread surface 1 shown in FIG. 1, except that the lateral groove 3 is employed instead of the terminal groove 3 ′ (all lateral grooves 3 have the first wall surface F <b> 1 and the second wall surface F <b> 2 on the main groove 22 out side). A pneumatic tire having the same configuration as that of No. 1 was produced, and the above performance was evaluated. The results are shown in Table 1.

Comparative Example 1
In the tread surface 1 shown in FIG. 1, a pneumatic tire having the same configuration as that of Example 1 was produced except that a lateral groove without a second wall surface having a triangular shape in plan view was adopted instead of the lateral groove 3. The above performance was evaluated. The results are shown in Table 1.

Comparative Example 2
In the tread surface 10 shown in FIG. 6, the reinforcing bridge B is provided in the lateral groove 30 and in the vicinity of the opening to the main groove 22out, the groove width of the main groove 22out is 4 mm, and the other main grooves 21in and 21out are 14 .5 mm, the width of 22 inches is set to 13.2 mm, the groove depth H of the main groove 22out and the lateral groove 30 is 8 mm, and the distance H1 from the tread surface 1 to the bottom of the second wall surface F2 on the main groove 22out side is 4 mm. The set pneumatic tire was produced and the said performance was evaluated. The results are shown in Table 1.

  From the results of Table 1, compared to the pneumatic tire of Comparative Example 1, the pneumatic tires of Example 1 and Example 2 are resistant to hydroplaning, steering stability on the WET road surface and DRY road surface, and uneven wear resistance. It can be seen that the performance is improved and the occurrence of pattern noise is suppressed. On the other hand, the pneumatic tire of Comparative Example 2 includes the reinforcing bridge B in the lateral groove 30 and in the vicinity of the opening to the main groove 22out, so that the steering stability on the DRY road surface is improved, but on the WET road surface. There is a tendency for the drainage of the water to deteriorate. For this reason, compared with the pneumatic tire of Comparative Example 1, the hydroplaning resistance and the steering stability on the WET road surface were deteriorated.

1: Tread surface 21in, 21out, 22in, 22out: Main groove 3: Horizontal groove

Claims (3)

A main groove extending continuously in the circumferential direction on the tread surface;
In a pneumatic tire comprising: an obtuse-angle side wall surface that intersects at a non-right angle with respect to the main groove and has an obtuse-angle side wall surface that extends at an obtuse angle with respect to the main groove and an acute-angle side wall surface that extends at an acute angle with respect to the main groove.
The obtuse side wall surface has a first wall surface that extends while inclining in the direction in which the groove width of the lateral groove widens toward the main groove and opens to the main groove,
The acute-angle side wall surface has a second wall surface that starts from the vicinity of the ridge line with the tread surface of the lateral groove, extends while inclining toward the bottom of the first wall surface, and opens to the main groove. Pneumatic tire characterized by.   The pneumatic tire according to claim 1, wherein the second wall surface has a triangular shape in plan view.   3. The air according to claim 1, wherein H / 4 ≦ H1, where H is a groove depth of the main groove and H1 is a distance from the tread surface to the bottom of the second wall surface on the main groove side. tire.

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