JP3447367B2 - Pneumatic tire having a directional inclined groove - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire for passenger cars, and more particularly to a high athletic performance tire which emphasizes athletic performance capable of supporting sports running, and which has a pattern without sacrificing wet performance. The present invention relates to a pneumatic tire for passenger cars, which has low noise.

[0002]

2. Description of the Related Art FIG. 4 shows a typical conventional tread pattern of a pneumatic tire for a high-performance passenger car. As shown in the figure, the conventional tire has several tires (four tires in the illustrated example,
The tread pattern is composed of circumferential grooves (generally about 2 to 8) and a large number of directional inclined grooves arranged at intervals in the circumferential direction. In the present specification, the circumferential groove means a straight groove or a substantially straight groove continuously extending in the circumferential direction, and the directional inclined groove is a groove extending obliquely with respect to the circumferential direction. Then, the side of the groove near the tire equatorial plane that extends obliquely contacts the ground first,
It means a groove in which a so-called directional tread pattern is formed, in which the direction of rotation of the tire when it is mounted on a vehicle is specified so that the side farther from the equatorial plane will come into contact with the ground later.

In order to improve steering stability and hydroplaning characteristics on a wet road surface in the conventional tire as described above, the number of grooves and the groove width are increased to obtain a negative ratio (area of the groove surface with respect to the area of the tread contact surface). It is effective to increase the ratio), and in particular, to increase the negative ratio of the directional tilted groove, which is a frequently adopted design method. However, it has been found that the pattern noise is deteriorated in the pneumatic tire having the directional tread pattern excellent in wet performance designed by this method. The pattern noise of the tire is composed of various elements, and one of them is the impact sound generated when the tire comes into contact with the road surface when the tire rotates under load.
It was found that the pattern noise of this striking component was extremely large in the case of a tire having a directional inclined groove with a high negative ratio.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-performance tire which is capable of coping with sports running and emphasizes the dynamic performance, and which is excellent in wet performance and is used for passenger cars having a low pattern noise. It is to provide a novel tread pattern for use in pneumatic tires.

[0005]

In order to achieve the above object, a pneumatic tire of the present invention comprises several circumferential grooves and a large number of directional slanted grooves arranged at intervals in the circumferential direction. In a pneumatic tire having a directional tread pattern, (1) the circumferential groove includes one or two circumferential main grooves provided at or near the tread central portion, and tread center from both ends of the tread. A pair of left and right circumferential sub-grooves provided at a position corresponding to about 1/4 of the tread width toward the portion. (2) A pair of circumferential sub-grooves formed by the circumferential main groove and the circumferential sub-groove. A main rib is formed, (3) a pair of circumferential sub-ribs is formed by the circumferential sub-groove and the tread end, and (4) the directional inclined groove has a narrow width such that the groove closes just under a load. Directional inclined slit groove and groove closes just under load (5) The directional inclined wide groove has a large inclination angle with respect to the circumferential direction, and the directional inclined wide groove has a small inclination angle. (6) In the circumferential sub-rib, the directional slant groove extends from the both ends of the tread to almost the central portion of the circumferential sub-rib by the directional high-gradient wide groove, and The directional low-inclination wide groove extends in a stepwise manner, and then the directional-inclination slit groove extends to the circumferential sub-groove. (7) The circumferential main rib also has the same shape as the circumferential sub-rib. In addition, the directional high-inclination wide groove extends from the circumferential sub-groove to almost the central portion of the circumferential main rib, where it changes to the directional low-inclination wide groove and extends stepwise, and then the directional inclination slit groove. And extends to the circumferential main groove instead of That a passenger high driving performance pneumatic tire for having a directional tread pattern.

To achieve the above object, in the tread pattern of the pneumatic tire for passenger cars of the present invention, the direction of inclination of the directional high-inclination wide groove is 45 degrees or more with respect to the circumferential direction, and It is preferable that the inclination angle of the wide groove with low inclination is 20 degrees or less with respect to the circumferential direction.

In order to achieve the above object, in the tread pattern of the pneumatic tire for passenger cars of the present invention, the width of the directional inclined slit groove is such that the groove closes just below the load on the side close to the tread surface. Narrow 0.5 mm to 1.
Although the width is 5 mm, it is preferable that the width near the groove bottom is wide enough to ensure drainage in the grounded state.

[0008]

Since the pneumatic tire for passenger cars of the present invention has the tread pattern as described above, the circumferential groove and the directional inclined groove provide a temporary drainage property. (See, for example, FIG. 4) is also the same. In a pneumatic tire for passenger cars equipped with a tread pattern having directional inclined grooves, in order to have excellent wet performance and suppress pattern noise to a low level,
It is effective to avoid the use of directional high-inclination wide groove as directional inclination groove as much as possible, and conversely use a large amount of directional low-inclination wide groove, but this is easy to adopt because it causes a decrease in block rigidity. It is not a design tool that should be done. In the pneumatic tire for passenger cars of the present invention, only the directional inclined slit grooves are arranged on the tread center side of each of the pair of circumferential main ribs and the pair of circumferential sub ribs, and any directional inclined wide groove is formed. Since it is not arranged, the pattern of the impact sound of the directional inclined groove (impact component) generated when the tire tread smoothly touches the ground at these points and comes into contact with the road surface when the tire rotates under load -Noise is suppressed.

On the other hand, with respect to drainage performance on the wet road surface, the directionality having a small inclination angle with respect to the circumferential direction arranged at the substantially central portion of each of the pair of circumferential main ribs and the pair of circumferential sub-ribs. The drainage channel is composed of the low-inclination wide groove and the directional high-inclination wide groove continuous in the kicking direction, and finally, in the circumferential main rib, to the pair of circumferential sub-grooves, and in the circumferential sub-rib, Drained to both ends of tread. Further, if the circumferential continuity of the circumferential main ribs and the circumferential sub ribs is maintained, the rib rigidity of these ribs is too high to obtain uniform ground contact. In order to block the directional continuity, directional inclined grooves consisting of the directional inclined slit groove and the directional inclined wide groove are provided in the respective ribs at intervals in the circumferential direction and are discontinuous ribs, in other words, , It has a row of blocks, so it shows a smooth grounding behavior.

Further, the width of the slit-shaped transverse groove is 0.5 mm to 1.5 mm on the side close to the tread surface so that the groove closes just below the load, but on the side close to the groove bottom it is in a grounded state. Since the width is wide enough to ensure drainage, the drainage performance on the wet road surface is significantly improved. This is effective in suppressing pattern noise because the drainage performance is significantly improved without increasing the negative ratio of the directional inclined groove.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described with reference to the drawings. FIGS. 1 to 3 are tread patterns of Examples 1 to 3 of a pneumatic tire for passenger cars according to the present invention, in which the tire size is Both are 225 / 50R16
The tread width TW is about 200 mm.

The pneumatic tire of Example 1 shown in FIG.
Two circumferential main grooves (1 near the center of the tread)
1 and 12) and a pair of left and right circumferential sub-grooves (13, 14) provided at a location corresponding to approximately 1/4 of the tread width from both ends of the tread toward the central portion of the tread and the circumferential spacing. With a tread pattern consisting of a number of directional slanted grooves arranged side by side.
1, 12) and the circumferential sub-grooves (13, 14) form a pair of circumferential main ribs (21, 22), and further the circumferential sub-grooves (13, 14) and the tread end (TE). A pair of circumferential sub-ribs (23, 24) are formed. The circumferential main groove (11, 12) and the circumferential sub groove (13, 1)
The widths of 4) are all 9 mm, the direction of the grooves is the same as the circumferential direction, in other words, the inclination angle of these grooves with respect to the circumferential direction is 0 degree. The directional tilted groove has a width narrow enough to close the groove just below the load.
42, 43, 44) and the directional inclined wide groove (31, 32, 33, 3) having a wide width such that the groove does not close even under the load.
4, 35, 36, 37, 38). In this embodiment, the directional tilt slit grooves (41, 42, 43, 4
The groove width of 4) is 1 mm in all, the groove width of the directional inclined wide groove (31, 32, 33, 34) is 4 mm, and the groove width of the directional inclined wide groove (37, 38) is 5 mm. The groove width of the directional inclined wide groove (35, 36) is equal to the circumferential sub-rib (23,
24) The width is 5 mm in the vicinity of the central portion, but gradually widens to 5.5 mm at both ends of the tread. This directional inclined wide groove (31, 32, 33, 34, 35, 36,
37, 38) are directional high inclination wide grooves (31, 32, 35, 36) having a large inclination angle with respect to the circumferential direction and directional low inclination wide grooves (33, 34, 33) having a small inclination angle.
37, 38). Directional high inclination wide groove (3
1, 32) has an inclination angle of 45 to 55 degrees with respect to the circumferential direction, and the directional high inclination wide groove (35, 36) has an inclination angle of 70 to 90 degrees with respect to the circumferential direction. ing. On the other hand, the directional low-tilt wide groove (33, 34) and the directional low-tilt wide groove (37, 38) are respectively 6 in the circumferential direction.
And a tilt angle of 5 degrees. In the circumferential sub-ribs (23, 24), the directional high-inclination wide groove (35, 36) extends from both ends of the tread to almost the central portion, and there is changed to the directional low-inclination wide groove (37, 38) in the stairs. Shaped, then directional inclined slit grooves (43, 44)
To the sub-grooves (13, 14) in the circumferential direction.
Also in the circumferential main ribs (21, 22), the directional high-inclination wide grooves (31, 32) extend from the circumferential sub-grooves (13, 14) to almost the central portion, and the directional low-inclination wide grooves (33) are there. , 34) and extends stepwise, and then changes to directional inclined slit grooves (41, 42) and extends to the circumferential main groove. In any case, all the directional tilted grooves are grooves extending obliquely with respect to the circumferential direction,
The direction of rotation of the tire when it is mounted on the vehicle is designated so that the side of the inclined and extended portion closer to the equatorial plane contacts the ground first, and the side farther from the equatorial surface contacts the ground later.

The pneumatic tire of Example 2 shown in FIG.
It is basically the same as the pneumatic tire of Example 1 shown in FIG. The main difference is that the slit grooves (51, 52, 5
3, 54) is added to improve the drainage property.

The pneumatic tire of Example 3 shown in FIG.
It is basically the same as the pneumatic tire of Example 1 shown in FIG. The main difference is the circumferential main ribs (21, 22)
And the directional low-inclination wide grooves (33, 34, 37, 38) of the circumferential sub-ribs (23, 24) are alternately extended.

The conventional pneumatic tire shown in FIG. 4 is a typical example of the tread pattern of the conventional pneumatic tire. As shown in the drawing, five circumferential grooves and a large number of directional inclined grooves are provided. Are arranged at intervals in the circumferential direction. The tire size is 225 / 50R16, and the tread width TW is about 200 mm, both of which are the same as those in the above embodiment. The circumferential groove (63) in the center of the tread has a width of 4
Although it is a narrow groove of mm, a pair of circumferential grooves (62, 64) with a groove width of 11 mm is provided on the left and right sides, and further, it is equivalent to about 1/4 of the tread width from both ends of the tread toward the center of the tread. A pair of circumferential grooves (61, 65) having a groove width of 10 mm are provided at the positions to be formed, and these four thick circumferential grooves and a large number of directional inclined grooves (71, 72, 73, 74, 75,
76) greatly contributes to drainage performance when the tire travels on a wet road surface.

Hydroplaning characteristics, pattern noise, and dryness of the passenger vehicle pneumatic tires of Examples 1 to 3 according to the present invention shown in FIGS. 1 to 3 and the conventional passenger vehicle pneumatic tire shown in FIG. An evaluation test of steering stability on the road surface was conducted. The test conditions were a tire internal pressure of 2.3 kg / cm ² , and hydro-planing characteristics were a test driver's feeling evaluation result by the response of the steering wheel when passing through a wet road surface with a water depth of 10 mm. Feeling evaluation result of the in-vehicle sound when the car is turned as it is, and driving stability on dry road surface is the feeling evaluation result of the test driver when running sports on the dry circuit course in various driving modes. . The evaluation results are shown in index representation with the result of the pneumatic tire of Conventional Example as 100, and the larger the number, the better the performance. Table 1 shows a summary of the evaluation results.

[0017]

[Table 1]

From the results shown in Table 1, the pneumatic tires for passenger cars of Examples 1 to 3 according to the present invention have hydro-planing characteristics and steering on a dry road surface as compared with the pneumatic tires for passenger cars of the above-mentioned conventional examples. It was found that the stability was about the same, but the pattern noise was much better.

[0019]

According to the present invention, only the directional inclined slit groove is arranged on the tread central side of each of the pair of circumferential main ribs and the pair of circumferential sub ribs, and any directional inclined wide groove is also arranged. Since the tire tread smoothly touches the ground at these points, the pattern of the impact sound of the directional tilt groove (impact component) that occurs when the tire comes into contact with the road surface when the tire rotates under load. Noise is suppressed. On the other hand, with regard to drainage performance on the wet road surface, a directional low inclination wide width with a small inclination angle with respect to the circumferential direction, which is arranged at approximately the center of each of the pair of circumferential main ribs and the pair of circumferential sub ribs. The drainage channel is composed of the groove and the directional high-inclination wide groove that is continuous to the kicking direction, and finally the circumferential main rib is formed into a pair of circumferential sub-grooves, and the circumferential sub-rib is provided with both ends of the tread. Drained to.

[Brief description of drawings]

FIG. 1 is a tread pattern diagram of a pneumatic tire according to the present invention.

FIG. 2 is a tread pattern diagram of a pneumatic tire according to the present invention.

FIG. 3 is a tread pattern diagram of a pneumatic tire according to the present invention.

FIG. 4 is a tread pattern diagram of a conventional typical pneumatic tire.

[Explanation of symbols]

D Tire rotation direction TE tread edge TW tread width 11 circumferential main groove 12 circumferential main groove 13 Circumferential sub groove 14 circumferential auxiliary groove 21 Circumferential main rib 22 Circumferential main rib 23 Circumferential sub rib 24 Circumferential sub rib 31 Directional inclined groove (directional high inclined wide groove) 32 directional inclined groove (directional high inclined wide groove) 33 Directional inclined groove (directional low inclination wide groove) 34 Directional inclined groove (directional low inclination wide groove) 35 Directional inclined groove (directional high inclination wide groove) 36 Directional inclined groove (directional high inclination wide groove) 37 Directional inclined groove (directional low inclination wide groove) 38 Directional inclined groove (directional low inclination wide groove) 41 Directional inclined slit groove 42 Directional inclined slit groove 43 Directional inclined slit groove 44 Directional inclined slit groove 51 slit groove 52 slit groove 53 slit groove 54 slit groove

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B60C 11/04 B60C 11/113 B60C 11/12

Claims (3)

(57) [Claims] 1. A pneumatic tire having a directional tread pattern, comprising a plurality of circumferential grooves and a large number of directional inclined grooves arranged at intervals in the circumferential direction, comprising: (1)
The circumferential groove is provided in one or two circumferential main grooves provided at or near the center of the tread, and at a location corresponding to approximately 1/4 of the tread width from both ends of the tread toward the center of the tread. A pair of left and right circumferential sub-grooves, (2) the circumferential main groove and the circumferential sub-groove form a pair of circumferential main ribs, and (3) the circumferential sub-groove and tread end. And a pair of circumferential sub-ribs are formed by
(4) The directional inclined groove is composed of a directional inclined slit groove having a width narrow enough to close the groove immediately below the load, and a wide directional inclined groove having a width wide enough not to close the groove even directly below the load, (5) The directional inclined wide groove is composed of a directional high inclined wide groove having a large inclination angle with respect to the circumferential direction and a directional low inclined wide groove having a small inclination angle. (6) The circumferential sub-rib Then, the directional inclined groove extends from the both ends of the tread to almost the central portion of the circumferential sub-rib by a directional high inclined wide groove, where it changes to a directional low inclined wide groove and extends stepwise, and then the direction Characteristic slit slit groove, extending to the circumferential sub groove, (7) also in the circumferential main rib,
Similarly to the circumferential sub-ribs, a directional high-inclination wide groove extends from the circumferential sub-groove to almost the central portion of the circumferential main rib.
Then, instead of wide directional low-inclination wide groove, it extends in a staircase,
Then, a pneumatic tire having a tread pattern characterized by extending to the circumferential main groove instead of the directional inclined slit groove. 2. The tilt direction of the directional high-inclination wide groove is 45 degrees or more with respect to the circumferential direction, and the tilt direction of the directional low-inclination wide groove is 20 degrees or less with respect to the circumferential direction. The pneumatic tire according to claim 1. 3. The directional slanted slit groove has a width of 0.5 mm to 1.5 mm on the side close to the tread surface, which is narrow enough to close the groove immediately below the load, but on the side close to the groove bottom, it is grounded. The pneumatic tire according to claim 1 or 2, wherein the width is wide enough to ensure drainage in a state.