JP3397450B2 - Pneumatic tire - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-performance pneumatic tire, which is compatible with improvement of wet performance and reduction of pattern noise at a high level without sacrificing the main function of the tire. .

[0002]

2. Description of the Related Art In order to improve the performance on a wet road surface, that is, the so-called wet performance, it is essential to enhance the drainage performance of the tread pattern. As the tread pattern with improved drainage performance, for example, as shown in FIGS. 1 and 2, there is a so-called directivity in which a circumferential groove that extends linearly in the tire circumferential direction and a specific direction with respect to the rotation direction of the tire are provided. A combination of inclined grooves is generally used.
In other words, the relatively wide circumferential groove provides excellent drainage performance, the contact pressure distribution is appropriate, and the steering stability is good, but vibration due to collision with the road surface on the tread side during tire rolling There is a problem of pattern noise that is amplified by the wide circumferential groove and leaks from the circumferential groove to the outside.

Further, the tread pattern shown in FIGS. 3 and 4 is a combination of one or two circumferential grooves arranged in the central region of the tread with an inclined groove, and has excellent drainage like the above-mentioned tread pattern. While the performance is obtained, noise is generated due to the circumferential groove, and the contact pressure distribution becomes inadequate, so that there is a disadvantage that steering stability is deteriorated and uneven wear is likely to occur.

[0004]

In the conventional tread pattern, good drainage performance can be ensured by the wide circumferential groove, but in addition to the deterioration of pattern noise, in some cases, the required land rigidity is required. Cannot be achieved, and this causes a problem that uneven wear resistance and turning performance are deteriorated.

Therefore, an object of the present invention is to provide a pneumatic tire in which pattern noise is advantageously reduced without impairing main tire functions such as steering stability, wear resistance, and wet performance. .

[0006]

SUMMARY OF THE INVENTION The present invention is directed to a tread end side from respective positions separated on both sides of a tire equatorial plane.
A pneumatic tire in which a large number of inclined main grooves that are inclined with respect to the tire circumferential direction and extend in mutually opposite directions are arranged in the tire circumferential direction, wherein each of the inclined main grooves is 15 with respect to the tire circumferential direction.
It extends at an inclination angle of ~ 45 ° and extends at an inclination angle of 75 to 105 ° with respect to the tire circumferential direction near the end on the tread end side and opens at a narrow width at the tread end, while near the end on the tire equatorial side. With this, toward the intermediate portion of the inclined main groove adjacent in the tire circumferential direction, to the adjacent inclined main groove extending in an arc shape convex on the tire equatorial plane side, open in the adjacent inclined main groove, in the side area of the tread,
Each of the inclined main grooves arranged in parallel in the tire circumferential direction is communicated with an auxiliary groove having a width narrower than that of the inclined main groove, and a rib continuous on the tire equatorial plane in the tire circumferential direction and both sides of the rib in the tire circumferential direction. The pneumatic tire is formed by dividing a plurality of blocks arranged in parallel and gradually decreasing the negative ratio of the tread tread portion from the central portion of the tread toward the tread end. The side area of the tread is an area within a range of 5 to 15% of the tread tread width from the tread end to the tire equatorial plane side.

Here, the arcuate portion of each of the inclined main grooves on the tire equatorial plane side forms a series extending substantially in the tire circumferential direction, and the width of the inclined main groove is gradually reduced toward each terminal. The inclined main grooves are alternately arranged on both sides of the tire equatorial plane, and the auxiliary groove is substantially in the tire circumferential direction when a part of the inclined main groove is interposed between the auxiliary grooves arranged in the tire circumferential direction. Arranging in a position where a groove continuously extending to
The opening position of the auxiliary groove in the inclined main groove is 50 to 85% of the half width of the tread tread from the tread edge to the tire equatorial side.
Range, at least a part of the auxiliary groove has a depth shallower than the inclined main groove, the maximum width of the rib is 10 to 30% of the tread width, and the block has the same direction as the auxiliary groove. Splitting with sipes extending to each is advantageous in each implementation.

The present invention will be specifically described below with reference to FIG. The basic structure of a pneumatic tire to which the tread pattern shown in the figure is applied is that a pair of sidewall portions and a crown portion interconnecting the sidewall portions are embedded in a bead portion at an inner peripheral edge of the sidewall portion. A plurality of cords arranged in parallel with each other that are reinforced by a carcass of a radial structure made up of plies of cords that are wound around and fixed around the bead core, and that intersect around the crown portion at a small angle to the circumferential direction. A tread arranged in the crown portion is reinforced by arranging a belt made of a crossed laminated body of layers.

The illustrated tread pattern shows the entire tread tread portion, and T _C is a tread central area that spreads on both sides of the tire equatorial plane O by 5 to 15% of the tread tread width W,
T _M is tread tread width W on both sides of the tread central area T _C
The tread intermediate region extending from 0 to 40%, and T _S is the tread side region extending between the tread intermediate region T _M and the tread edge E.

In the figure, reference numeral 1 designates inclined main grooves which are alternately arranged on both sides of the tire equatorial plane and are arranged in parallel in the tire circumferential direction. The inclined main groove 1 is formed on each side of the tire equatorial plane O from each position separated by a predetermined distance from each tread end E.
Side, with respect to the tire circumferential direction, more preferably 15 to 45 °
The terminal region 1a extending in the opposite directions at the inclination angle α of 20 to 40 ° and extending in the vicinity of the end on the tread end E side, specifically, the tread side region T _S , is 75 to 105 ° with respect to the tire circumferential direction. Of the tire equatorial plane O side, specifically, a terminal region 1b extending in the tread central region T _C is adjacent to the tread end E in the tire circumferential direction while extending at an inclination angle β of 1. Toward the middle of the inclined main groove 1, the tire equatorial plane O
Ribs 2 continuous in the tire circumferential direction are defined on the tire equatorial plane O by opening in adjacent inclined main grooves 1 that extend in an arc shape that is convex toward the side.

Further, the inclined main grooves 1 arranged in parallel in the tire circumferential direction are narrower than the inclined main groove 1 on the end region 1a side and extend at an inclination angle γ of 25 ° or less with respect to the tire circumferential direction. By communicating with the auxiliary groove 3, a plurality of blocks 4 arranged in parallel in the tire circumferential direction are defined on both sides of the rib 2.
In the illustrated example, the auxiliary groove 3 is arranged near the boundary between the tread intermediate region T _M and the tread side region T _S. This block 4
The sipe 5 extending in the same direction as the auxiliary groove 3 adjacent thereto, preferably in the direction substantially orthogonal to the inclined main groove 1, is divided into a plurality of sections, and in the illustrated example, three sipe 5 is divided into four sections. Further, in each tread side area T _S , a side block 6 is defined by the terminal area 1a of the inclined main groove 1 which is juxtaposed in the tire circumferential direction, the auxiliary groove 3 and the tread end E, and the side block 6 is It has a notch groove 7 extending from the tread end E.

Here, the inclined main groove 1 has a depth of 5 to 10 mm.
Then, in the middle of the tread T_MAt width W ₀Tread tread
It extends 3 to 7% of the width W, and the tread edge E in the terminal area 1a.
Width W of the terminal at₁Is 1 to 4% of the tread tread width W
While decreasing gradually until it becomes adjacent to the slope in the terminal area 1b
Opening width W of terminal in main groove 1₂Is the tread tread width W of 1
It is preferable to gradually reduce it to 4%. In addition, Thailand
The radius of curvature R of the terminal area 1b, which has an arc shape on the equatorial plane O side, is
30 to 150 mm is suitable, and it is divided between these terminal areas 1b.
The rib 2 to be defined has the maximum width W_FourIs tread tread width W of 5
~ 15% and minimum width W_FiveAround 3-12% of the same W around the tire
It becomes a land part that extends in a zigzag shape toward the front.

The width W _{3 of the} auxiliary groove 3 is equal to the tread width W of 1
-3% and depth: 4-7 mm, and the notch groove 7 formed to optimize the rigidity near the tread edge is preferably formed with a width according to the opening width of the terminal area 1b. . Further, the sipe 5 has a width such that the sipe 5 is closed during grounding due to load rolling, specifically, about 1 to 3 mm.

In this tire in which the tread is divided under the groove arrangement as described above, the negative ratio of the tread tread is 25 to 35%, and the negative ratio at each position in the width direction of the tread is set. Is maximized in the area adjacent to the rib 2 as shown in the graph of FIG. 6, and is gradually decreased toward the tread end side from the area, and more preferably,
Area where more than 70% of the negative rate of the tread tread exists, for example, 70% of the tread width at the center of the tread.
In the area that occupies ~ 90%, the negative rate of the tread side area in that area is 50-80% of the maximum negative rate, and the negative rate of the part on the tread edge side of the area is 15-30% of the maximum negative rate. %. For comparison, the distribution of the negative rate in the tread patterns shown in FIGS. 1 to 4 described above is shown in each figure (b).

[0015]

[Operation] Now, the behavior of water on the tread tread on a wet road surface is 20% in the tire circumferential direction or in the circumferential direction near the tread tread near the tread central area.
Less than °, then forward in the middle tread area at 20-40 ° to the tire circumference, and in the tread side area to more than 40 ° to the tire circumference to the outside of the tire. Flows. Therefore, in this tire, in the middle region of the tread, extending at an inclination angle of 15 to 45 ° with respect to the tire circumferential direction, and in an arc shape at the terminal extending in the central region of the tread, that is, while reducing the inclination with respect to the tire circumferential direction, the tread The terminal extending in the side area is almost in the tread width direction,
That is, by increasing the inclination with respect to the tire circumferential direction and partitioning the tread surface with the inclined main groove extending in the direction that matches the behavior of water in the tread surface, excellent drainage performance was secured.

Here, if the inclination of the inclined main groove with respect to the tire circumferential direction in the middle region of the tread is less than 15 °, the block between the inclined main grooves cannot be provided with the required rigidity and the steering stability is deteriorated and uneven wear is caused. On the other hand, the inclination is 45 °
If it exceeds, the above drainage performance cannot be secured. Similarly, the inclination of the end of the inclined main groove in the tread side region with respect to the tire circumferential direction is set to 75 to 105 ° because traction is insufficient at less than 75 ° and uneven wear occurs at more than 105 °. . The reason why the width of the inclined main groove is wide in the middle region of the tread and gradually decreased toward the ends on both sides thereof is to change the negative ratio, which will be described in detail later.

Further, a rib is formed in the central region of the tread by forming an arcuate end region extending in the central region of the tread of the inclined main groove and connecting it to an adjacent inclined main groove. By forming the ribs, it is possible to suppress the impact component in the central region of the tread, which has a great influence on the pattern noise, so that the noise can be reduced. Here, if the radius of curvature of the arc in the terminal region is too large, the inclined main groove causes the occurrence of air column resonance, similarly to the straight groove extending in the circumferential direction, while if it is too small, near the end of the inclined main groove. Rigidity of the land portion is extremely reduced, and uneven wear is likely to occur. Therefore, the radius of curvature of the circular arc in the terminal area is preferably 30 to 150 mm.

Particularly, in the tread pattern of the present invention,
The arcuate end regions of the inclined main groove in the central region of the tread extend in a continuous manner, and the extension of the auxiliary groove in the tread side region in which a part of the inclined main groove intervenes extends substantially in a zigzag manner in the tire circumferential direction. The feature is that the groove is formed. First, the drainage performance is further improved by making the grooves substantially continuous in the tire circumferential direction. Also, by extending in a zigzag shape in the tire circumferential direction,
Vibration energy due to the collision with the road surface on the stepping side during rolling of the tire is absorbed by the side wall of the groove, which is effective for noise reduction. Further, the rigidity of ribs and blocks defined by these grooves is optimized to improve steering stability and avoid uneven wear.

That is, the position in the tread width direction of the portion where the rigidity decreases due to the presence of the groove changes on the circumference, so that the width of the portion is smaller than that when a portion with low rigidity such as a straight groove exists on the same circumference. Concentration of tread deformation in the low-rigidity portion in the direction is suppressed, and the ground contact pressure can be made uniform. Further, when the groove is straight, the corner portion of the block becomes a more acute angle to promote uneven wear, but by making the groove zigzag, this uneven wear can be avoided.

Here, the auxiliary groove in the tread side area is
The opening position is preferably in the range of 50 to 85% of the half width of the tread tread portion from the tire equatorial plane side to the tread edge. Because, if it exceeds 85%, the rigidity of the side block decreases, leading to a lack of traction and deterioration of maneuverability, which impairs steering stability, while below 50%,
The desired ground pressure distribution cannot be obtained. More preferably, 60-
75%.

Similarly, it is preferable that the arcuate end spacing of the inclined main groove in the central region of the tread sandwiching the tire equatorial plane, that is, the maximum width of the rib is 10 to 30% of the half width of the tread tread portion. . Because, if it is less than 10%, the negative rate in the central region of the tread becomes extremely large, so that steering stability and linearity at the time of steering (the relationship between the steering angle and the steering force changes linearly) deteriorates, while 30% Beyond that, improvement in drainage performance cannot be expected. More preferably, it is 7 to 13%.

Further, the negative ratio of the tread tread is gradually reduced from the center of the tread toward the tread end. That is, when observing the hydroplaning phenomenon, since a water film is generated from the central region of the tread tread portion to the intermediate region, here, the negative tread of the negative rate due to the inclined main groove formed from the tread central region to the intermediate region is used. The ratio to the overall negative ratio is made sufficiently large to contribute to drainage, the negative ratio on both sides of the rib is maximized, and the negative ratio is gradually reduced to the tread end side.

Here, the tread tread width, which accounts for 70% or more of the negative ratio of the entire tread tread, is, for example, 70 to
In the 90% tread central region and the intermediate region, the negative rate of the tread end side portion within the area is preferably 50 to 80% of the maximum negative rate of the portion adjacent to the rib, in terms of drainage, In addition, since the part on the tread end side of the tread intermediate region side is a part that has a greater effect on steering stability than drainage, the negative ratio of that part is the maximum negative ratio in order to secure tread rigidity. of
It is preferably set to 15 to 30%.

[0024]

Example A tire having a size of 235 / 45ZR17 was prototyped under the specifications shown in Table 1 according to the tread pattern shown in FIG. The tread tread width W was 190 mm and the tread contact length was 126 mm. The negative ratio of the entire tread surface was 30%, and the negative ratio of each part in the tire width direction was as shown in FIG. Further, as a comparison, a tire according to the tread pattern shown in FIGS. In these tires, the circumferential groove was 15 mm wide and 8.5 mm deep, and the inclined groove was 12 mm wide and 7.5 mm deep, and the inclination angle was 30 °. The negative rate is as shown in the figure corresponding to each tire.

[0025]

[Table 1]

Each tire thus obtained has an internal pressure of 2.5 k.
After filling with gf / cm ² and mounting it on the actual vehicle, under the load condition of two passengers, the pattern noise is the noise when coasting from a position of 7.5 mm from the installed microphone on a straight smooth road from 55 km / h. Measured and evaluated, drainage performance is evaluated by measuring the speed at which hydroplaning occurs by running on a wet road with a water depth of 10 mm, and the steering stability on dry road surface is
We evaluated the feeling when driving in a dry circuit with a radius of 50 m in various driving modes. The results are shown in Table 2. In addition, the results are shown as an index with the conventional tire as a control, and the larger the index value, the better the result.

[0027]

[Table 2]

It can be seen from Table 2 that each of the invention tires can effectively reduce the pattern noise without sacrificing the drainage performance while maintaining the steering stability on dry road surface sufficiently high.

[0029]

According to the present invention, it is possible to reduce pattern noise without sacrificing excellent drainage performance and steering stability.

[Brief description of drawings]

FIG. 1 is a diagram showing a conventional tread pattern and a negative rate distribution.

FIG. 2 is a diagram showing a conventional tread pattern and a negative rate distribution.

FIG. 3 is a diagram showing a conventional tread pattern and a negative rate distribution.

FIG. 4 is a diagram showing a conventional tread pattern and a negative rate distribution.

FIG. 5 is a schematic view showing a tread pattern of the present invention.

FIG. 6 is a graph showing a negative ratio distribution in the tire width direction.

[Explanation of symbols]

1 inclined main groove 1a, 1b terminal area 2 ribs 3 auxiliary grooves 4 blocks 5 sipes 6 side blocks 7 Notch groove

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B60C 11/04 B60C 11/117 B60C 11/12

Claims (9)

(57) [Claims] 1. Air in which a large number of inclined main grooves are arranged in the tire circumferential direction, which are inclined from the respective positions separated from both sides of the tire equatorial plane toward the tread end side and extend in opposite directions to each other with respect to the tire circumferential direction. A filled tire, wherein each of the inclined main grooves extends at an inclination angle of 15 to 45 ° with respect to the tire circumferential direction, and has an inclination angle of 75 to 105 ° with respect to the tire circumferential direction near the terminal on the tread end side. While opening at a narrow width at the tread end while extending toward the middle of the inclined main groove adjacent to this at the end on the tire equatorial plane side in the tire circumferential direction, in an arc shape convex to the tire equatorial plane side. It extends and opens in the adjacent inclined main groove, and in the side area of the tread, the inclined main grooves that are parallel to each other in the tire circumferential direction communicate with each other by an auxiliary groove that is narrower than the inclined main groove, and on the tire equatorial plane. A rib that is continuous in the tire circumferential direction and the tire circumferential direction on both sides of the rib A pneumatic tire in which a plurality of blocks arranged in parallel are sectioned and the negative ratio of the tread surface is gradually reduced from the center of the tread toward the tread edge. 2. The pneumatic tire according to claim 1, wherein an arcuate portion of each of the inclined main grooves on the tire equatorial plane side forms a series extending substantially in the tire circumferential direction. 3. The pneumatic tire according to claim 1, wherein the width of the inclined main groove is gradually reduced toward each end. 4. The pneumatic tire according to claim 1, wherein the inclined main grooves are alternately arranged on both sides of the tire equatorial plane. 5. The auxiliary groove is located at a position where a groove extending substantially continuously in the tire circumferential direction is formed when a part of the inclined main groove is interposed between the auxiliary grooves arranged in the tire circumferential direction. The pneumatic tire according to claim 1, which is arranged. 6. The opening position of the auxiliary groove in the inclined main groove is
From the tire equatorial side to the tread edge, 1 / of the tread tread
2. The pneumatic tire according to claim 1, which is in the range of 50 to 85% of the width. 7. The pneumatic tire according to claim 1, wherein at least a part of the auxiliary groove is shallower than the inclined main groove. 8. The maximum width of the rib is 10 to 10 times the tread tread width.
The pneumatic tire according to claim 1, which is 30%. 9. The pneumatic tire according to claim 1, wherein the block is divided by sipes extending in the same direction as the auxiliary groove.