JP4488457B2 - Pneumatic tires for passenger cars - Google Patents

Description

表１の結果が示すように、実施例のタイヤでは、ドライ操縦安定性、耐ハイドロプレーニング性能を損なうことなく、ウエット制動距離性能と偏摩耗性能を改善することができる。これに対して、先着側壁面の角αが５°未満の比較例１では、ドライ操縦安定性、ウエット制動距離性能、偏摩耗性能が低下し、また、先着側壁面の角αが２５°を超える比較例２では、耐ハイドロプレーニング性能が低下した。
【図面の簡単な説明】
【図１】本発明の乗用車用空気入りタイヤの一例のトレッドパターンを示す概略展開図
【図２】図１のＩ−Ｉ断面を示す要部断面図
【図３】乗用車用空気入りタイヤの他のトレッドパターンを示す概略展開図
【図４】乗用車用空気入りタイヤの他のトレッドパターンを示す概略展開図
【図５】乗用車用空気入りタイヤの他のトレッドパターンを示す概略展開図
【符号の説明】
１ トレッド面
２ 傾斜主溝
３ 傾斜主溝
６ 周方向溝
７ 周方向溝
Ｌ１〜８ 陸部
ＥＱ タイヤ赤道
α 回転先着側壁面と踏面法線となす角度
β 回転後着側壁面と踏面法線となす角度
Ｓα 回転先着側壁面
Ｓβ 回転後着側壁面
Ｒ タイヤの正回転方向[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire for a passenger car provided with a tread pattern of a rotation direction designation type having a substantially V-shaped inclined groove.
[0002]
[Prior art]
Conventionally, as a tread pattern of a pneumatic tire for passenger cars, various patterns exist according to the required performance of the tire. In particular, while reducing the tire noise, it is possible to rotate from the vicinity of the tire equator to the tread edge at an inclination angle substantially symmetrical to the tire equator, as it satisfies both drainage on wet road surfaces and steering stability on dry road surfaces. There is known a tread pattern of a rotation direction designation type having a plurality of inclined main grooves extending so as to spread the rear arrival side. And since the land part divided by such an inclination main groove becomes the shape extended along the inclination direction (however, it is divided by sipe if necessary), the land part blocked by the surrounding groove is It is distinguished from so-called block type patterns having a large number.
[0003]
For the tread pattern as described above, the angle between the tread surface normal of the stepping side (first arrival side) and the tread surface normal of the land side wall on the kicking side (rear arrival side) When the angle formed is β (however, a negative angle indicates that the land wall surface is inclined inward), it is known that the angles α and β satisfy the following relationship.
[0004]
That is, JP-A-8-142613 discloses a tread pattern having a substantially V-shaped inclined groove that satisfies the relationship of α ≧ β ≧ 0 ° in order to improve toe-and-heel wearability. Yes. Japanese Patent Laid-Open No. 10-278515 discloses a tread pattern having a substantially V-shaped inclined groove, and in particular, assists the land portion along the inclined groove in order to improve uneven wear of the land portion on the tread end side. A tire that satisfies the relationship of β ≧ α ≧ 0 ° on the tire equator side from the groove and α ≧ β ≧ 0 ° on the tread end side from the auxiliary groove is disclosed.
[0005]
[Problems to be solved by the invention]
However, in the technique disclosed in the above publication, since both angles α and β are both 0 ° or more, the rigidity of the land portion is increased, but the groove volume tends to decrease, and the drainage on the wet road surface is insufficient. Further, according to the study by the present inventors, it has been found that the wet braking performance is not sufficient and the effect of improving the uneven wear is not sufficient.
[0006]
In various tread patterns, in general, making the angle α or β negative is advantageous in terms of drainage, but it is easy to reduce the rigidity of the land portion. It was considered undesirable.
[0007]
Japanese Patent Laid-Open No. 8-268809 discloses a so-called block-type pattern that satisfies the relationship of α ≧ 0 ° ≧ β and faces the circumferential grooves on both sides in order to improve uneven wear of heavy duty tires in particular. Although a pneumatic tire in which the wall surface of the block is similarly inclined is disclosed, since the pattern type and the tire application are different, the effect when applied to the above-mentioned pattern is difficult to predict.
[0008]
Accordingly, an object of the present invention is to provide a pneumatic tire for a passenger car that can improve wet braking performance and toe-and-heel wear performance while maintaining tire handling stability and drainage.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present inventors have conducted intensive research on the inclination angle of the side wall of the land portion in a specific tread pattern. As a result, the angles α and β are 5 ° ≦ α ≦ 25 ° and −20 ° ≦ β. The inventors have found that the above object can be achieved by satisfying the relation of ≦ 0 °, and have completed the present invention.
[0010]
That is, the present invention has a plurality of inclined main grooves extending on the tread surface having a rotation direction designation so that the arrival side after rotation extends from the vicinity of the tire equator to the tread end side at an inclination angle substantially symmetrical to the tire equator, A pneumatic tire for a passenger car having 1 to 4 circumferential grooves that communicate with the inclined main groove and extend in the tire circumferential direction, and a rotation first landing side wall surface and a tread surface of a land portion divided by the inclined main groove 5 ° ≦ α ≦ 25 ° and −20 ° ≦ β ≦ 0 °, where α is the angle to the normal line, and β is the angle to the normal to the tread surface after the rotation. part walls meet the relationship shown) if that slopes inwardly, the inclined main grooves, in the boundary vicinity of the shoulder start position to narrow the groove width between the up ground terminal, a narrow portion of the groove width The angles α and β are smaller than those of the wide groove width, and 5 ° ≦ α ≦ 10 ° and −5 ° ≦ β ≦. ° and satisfies the. Here, the circumferential groove refers to a groove that is projected through a groove surface without overlapping when a groove for one pitch is projected in the tire circumferential direction (see-through).
[0011]
In the above, the circumferential groove is one or two grooves communicating with the tire equator side end portion of the inclined main groove, and the deepest portion of the groove depth is 50 of the groove depth of the inclined main groove. It is preferable to have a shallow groove portion that is ˜85%, and that the shallow groove portion is provided at least over substantially the entire land between the land portions separated by the circumferential groove.
[0012]
The circumferential groove is one or two grooves communicating with the tire equator side end of the inclined main groove, and the groove width ranges from 4 mm to 15% of the tire ground contact width. The deepest portion of the groove depth has a shallow groove portion that is 50 to 85% of the groove depth of the inclined main groove and a deep groove portion that extends from the tire equator side end portion of the inclined main groove at the same groove depth. Preferably there is.
[0013]
[Function and effect]
According to the present invention, as shown in the results of the examples, a pneumatic tire for a passenger car is provided that can improve wet braking performance and toe-and-heel wear performance while maintaining tire handling stability and drainage performance. be able to. In other words, by increasing the angle α, the angle β is decreased (negatively), so that the land portion is tilted to the arrival side after rotation while maintaining drainage and land portion rigidity. By increasing the rigidity of the side (α), wet braking performance and toe-and-heel wear performance can be improved. The circumferential groove is one or two grooves communicating with the tire equator side end portion of the inclined main groove, and the deepest portion of the groove depth is 50 to 50 of the groove depth of the inclined main groove. When having a shallow groove portion that is 85%, and the shallow groove portion is provided at least substantially between the land portions separated by the circumferential groove, the shallow groove portion of the circumferential groove is interposed between the land portions. For this reason, the lateral rigidity of the land portion is increased, the steering stability is improved, and the shallow groove portion has an appropriate groove depth, so that drainage performance and noise prevention performance are also improved.
[0014]
The circumferential groove is one or two grooves communicating with the end of the inclined main groove on the tire equator side, and the groove width ranges from 4 mm to 15% of the tire ground contact width. When the deepest portion of the groove has a shallow groove portion that is 50 to 85% of the groove depth of the inclined main groove and a deep groove portion that extends at the same groove depth from the tire equator side end portion of the inclined main groove. In addition to the above, since the groove width of the circumferential groove is appropriate and the shallow groove portion is provided, steering stability, drainage performance, noise prevention performance, and the like can be further improved.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
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 a pneumatic tire for passenger cars of the present invention.
[0016]
The pneumatic tire for passenger cars of the present invention includes a tread surface 1 having a rotation direction designation such that an arrow R indicates the normal rotation direction of the tire. As shown in FIG. 1, the tread surface 1 has a plurality of inclined main grooves 2, each extending so that the arrival side after rotation extends from the vicinity of the tire equator EQ to the tread end side at an inclination angle substantially symmetrical to the tire equator EQ. 3 and 1 to 4 circumferential grooves 6 and 7 communicating with the inclined main grooves 2 and 3 and extending in the tire circumferential direction. In this embodiment, as shown in FIG. 1, the circumferential grooves 6 and 7 are two grooves communicating with the tire equator side end portions of the inclined main grooves 2 and 3, and the shallow groove portions 6a and 7a and the deep groove portion. An example of having 6b and 7b is shown.
[0017]
The inclined main grooves 2 and 3 are curved such that the tangential direction of the center line gradually increases as the inclination angle (angle with respect to the tire equator EQ) increases toward the tread end side. The inclined main grooves 2 and 3 are once narrowed in the vicinity of the shoulder start position SI, extend to the ground end 5 with substantially the same width, and widen outside the ground end 5. The shoulder start position SI corresponds to a position of about 65% of the ground contact width, but can be changed in a range of a position of 50 to 80% of the ground contact width.
[0018]
The deepest portion of the shallow groove portions 6a, 7a of the circumferential grooves 6, 7 is preferably 50 to 85% of the groove depth of the inclined main grooves 2, 3. The deep groove portions 6b and 7b extend from the end portions of the inclined main grooves 2 and 3 at the tire equator side at the same groove depth, and the shallow groove portions 6a and 7a are separated by the circumferential grooves 6 and 7. It is provided in almost the entire area between the land. The groove width of the shallow groove portions 6a and 7a is preferably in the range of 4 mm to 15% of the tire ground contact width.
[0019]
The circumferential grooves 6 and 7 are not completely straight grooves but have curved groove portions (corresponding to the shallow groove portions 6a and 7a) extending from the tire equator side end portions of the inclined main grooves 2 and 3, and the curved groove portions are the tire equator. The center line has a convexly curved side. In addition, the width of the curved groove is not constant, but slightly widens on the rotation first arrival side. A circumferential land portion L2 exists between the two circumferential grooves 6 and 7.
[0020]
The oblique land portion L1 divided by the inclined main grooves 2 and 3 extends along the two inclined main grooves 2 or the two inclined main grooves 3 while gradually widening the width toward the tread end side. Near the center of the oblique land portion L1, an inclined auxiliary groove 10 extending from slightly inside the shoulder start position SI to near the tread end is formed. The inclined auxiliary groove 10 has an average groove width narrower than that of the inclined main grooves 2 and 3, and the groove depth is shallower than that of the inclined main groove. Further, the oblique land portion L1 is divided by a sipe 4 provided in the vicinity of the shoulder start position SI.
[0021]
The pneumatic tire for a passenger car of the present invention has an angle formed between the rotation first landing side wall surface Sα of the land portion L1 divided by the inclined main groove 2 and the tread normal line in the tread pattern as described above, as shown in FIG. α, 5 ° ≦ α ≦ 25 ° and −20 ° ≦ β ≦ 0 °, where β is the angle formed between the post-rotation landing wall surface Sβ and the tread surface normal line. It is characterized by satisfying the relationship of 2 shows the II cross section of FIG. 1, and the arrow R ′ indicates the direction in which the tire rotation direction is projected onto the II cross section.
[0022]
Not limited to the above tread pattern, if the angle α is less than 5 °, the rigidity of the land portion becomes too small, the collapse of the land portion becomes large at the time of braking, and the ground contact area is reduced, so the braking force is reduced and the toe and heel Wear performance deteriorates. On the other hand, if the angle α exceeds 25 °, the drainage performance decreases due to the decrease in the groove volume.
[0023]
In addition to the above tread pattern, if the angle β is less than −20 °, the mold groove protrusion is caught by the tread rubber at the time of vulcanization molding of the tire, and it becomes difficult to remove the tire from the vulcanizer. On the other hand, when the angle β exceeds 0 °, the drainage performance decreases due to the decrease in the groove volume, the land portion rigidity at the time of braking becomes too large, and the to-and-heel wear performance deteriorates.
[0024]
In the tread pattern shown in FIG. 1, it is preferable to change the angles α and β between the inside and outside of the shoulder start position SI. That is, 5 ° ≦ α ≦ 25 ° and −20 ° ≦ β ≦ 0 ° inside the shoulder start position SI having a wide groove width, and 5 ° in the region between the shoulder start position SI having a narrow groove width and the ground contact edge. It is preferable that ° ≦ α ≦ 10 ° and −5 ° ≦ β ≦ 0 °.
[0025]
Thus, by making the angles α and β smaller in the region between the shoulder start position SI and the ground contact end, the groove volume can be ensured and the drainage can be further improved.
[0026]
The pneumatic tire for passenger cars of the present invention has the tread surface 1 as described above, but the other parts are the same as those of the conventional tire, and the formation of the tread surface 1 is also in accordance with the molding method of the conventional tire. It can be carried out.
[0027]
[Other Embodiments]
Hereinafter, other embodiments of the present invention will be described. The present invention is not limited to the tread pattern shown in FIG. 1 but can be applied to tread patterns as shown in FIGS.
[0028]
(1) Tread pattern shown in FIG. 3 In the tread pattern shown in FIG. 3, two linear circumferential grooves 6 and 7 are formed in the vicinity of the shoulder start position SI and intersect with the inclined main grooves 2 and 3. is doing. The intersecting portions of the circumferential grooves 6 and 7 are deep groove portions 6b and 7b having the same depth as the inclined main grooves 2 and 3, and the other portions are shallow groove portions 6a and 7a as described above. .
[0029]
The inclined main grooves 2 and 3 are bent such that the direction of the center line gradually increases as the direction of the center line extends toward the tread end side (the angle with respect to the tire equator EQ). The inclined main grooves 2 and 3 and the circumferential grooves 6 and 7 are formed by dividing the shoulder land portions 8 and 9, and the shoulder land portions 8 and 9 are further divided by the lateral grooves 11 deeper than the circumferential grooves 6 and 7. Has been. Further, a central land portion L3 is formed between the circumferential grooves 6 and 7 and is partially divided by the inclined main grooves 2 and 3.
[0030]
(2) Tread pattern shown in FIG. 4 The tread pattern shown in FIG. 4 is the same as that shown in FIG. 3 except that two circumferential grooves 12 and 13 extending in the tire circumferential direction are formed on both sides near the tire equator EQ. It is the same. The circumferential grooves 12 and 13 are formed to have a narrower groove width than the circumferential grooves 6 and 7. The portions of the circumferential grooves 12, 13 intersecting the inclined main grooves 2, 3 are deep groove portions 12b, 13b having the same depth as the inclined main grooves 2, 3, and the other portions are shallow groove portions as described above. 12a and 13a.
[0031]
A mediate land portion L5 is formed between the circumferential groove 6 and the circumferential groove 12, and a mediate land portion L6 is formed between the circumferential groove 7 and the circumferential groove 13. Further, a central land portion L3 is formed between the circumferential grooves 12 and 13, and is partially divided by the inclined main grooves 2 and 3.
[0032]
(3) Tread pattern shown in FIG. 5 In the tread pattern shown in FIG. 5, one more circumferential groove 16 extending in the tire circumferential direction is formed in the vicinity of the tire equator EQ, and is substantially V-shaped symmetrical to the tire equator EQ. The inclined main grooves 17 are bent so that the inclination angle (angle with respect to the tire equator EQ) increases stepwise as they extend from the vicinity of the tire equator EQ toward the tread ends. The rest is the same as the tread pattern shown in FIG. The portion of the circumferential groove 16 intersecting the inclined main groove 17 is a deep groove portion 16b having the same depth as the inclined main groove 17, and the other portion is the shallow groove portion 16a as described above.
[0033]
A mediate land portion L7 is formed between the circumferential groove 6 and the circumferential groove 16, and a mediate land portion L8 is formed between the circumferential groove 7 and the circumferential groove 16. It is divided by an inclined main groove 17.
[0034]
(4) Other Tread Patterns The two circumferential grooves 6 and 7 in the tread pattern shown in FIG. 1 may be linear circumferential grooves, and instead of the two circumferential grooves 6 and 7, FIG. One circumferential groove 16 near the tire equator EQ in the tread pattern shown in FIG. Further, the circumferential grooves 6 and 7 in the tread pattern shown in FIG. 5 may be omitted.
[0035]
【Example】
Examples and the like specifically showing the configuration and effects of the present invention will be described below.
[0036]
As tires of the tire size 215 / 45ZR17 having the tread pattern of FIG. 1, tires of Examples, Comparative Examples, and Conventional Examples as shown in Table 1 are prototyped, mounted on a test rim 17 × 7-JJ, and pneumatic pressure 220 KPa, and the following performance evaluation tests of dry steering stability, hydroplaning performance, wet braking distance performance, and uneven wear performance were performed.
[0037]
[Dry handling stability]
The tires were mounted on a real vehicle and evaluated by the driver's feelings when driving on dry roads in various driving modes under the load conditions of one passenger. In addition, evaluation is shown by an index display when the conventional example is set to 100, and a larger value indicates a better result.
[0038]
[Hydroplaning resistance]
The tire was mounted on a real vehicle, and the hydroplaning generation speed and the driver's feeling when traveling on a wet road surface with a water depth of 8 mm under the load condition of one passenger were evaluated. In addition, evaluation is shown by an index display when the conventional example is set to 100, and a larger value indicates a better result.
[0039]
[Wet braking distance performance]
A tire was mounted on an actual vehicle, and the distance required to stop when a braking force was applied to a wet road surface with a depth of 1 mm at an initial speed of 90 km / h under the load condition of one passenger was measured and evaluated. In addition, evaluation is shown by an index display when the conventional example is set to 100, and a larger value indicates a better result.
[0040]
[Uneven wear performance]
The tire was mounted on a real vehicle, and the vehicle was run under the load condition of one passenger, and the to-and-heel ratio (depressed portion wear amount / kick-out portion wear amount) when the average wear amount reached 50% was measured. In addition, evaluation is shown by an index display when the conventional example is set to 100, and a larger value indicates a better result.
[0041]
The results are shown in Table 1.
[0042]
[Table 1]

As shown in the results of Table 1, in the tire of the example, the wet braking distance performance and the uneven wear performance can be improved without impairing the dry steering stability and the hydroplaning performance. On the other hand, in Comparative Example 1 in which the angle α of the first sidewall surface is less than 5 °, the dry steering stability, the wet braking distance performance, and the uneven wear performance are degraded, and the angle α of the first sidewall surface is 25 °. In the comparative example 2 which exceeds, the hydroplaning performance declined.
[Brief description of the drawings]
FIG. 1 is a schematic development view showing a tread pattern of an example of a pneumatic tire for passenger cars of the present invention. FIG. 2 is a cross-sectional view of a main part showing a II cross section of FIG. FIG. 4 is a schematic development view showing another tread pattern of a pneumatic tire for passenger cars. FIG. 5 is a schematic development view showing other tread patterns of a pneumatic tire for passenger cars. ]
DESCRIPTION OF SYMBOLS 1 Tread surface 2 Inclined main groove 3 Inclined main groove 6 Circumferential groove 7 Circumferential groove L1-8 Land part EQ Tire equator α Angle formed between rotation first sidewall surface and tread surface normal β Rear rotation sidewall surface and tread surface normal Angle Sα formed Rotation first side wall surface Sβ Rotation first side wall surface R Tire forward rotation direction

Claims (3)

A plurality of inclined main grooves extending on the tread surface having a rotation direction designation so as to spread the arrival side after rotation from the vicinity of the tire equator to the tread end side at an inclination angle substantially symmetrical to the tire equator, and communicated with the inclined main grooves A pneumatic tire for a passenger car having 1 to 4 circumferential grooves extending in the tire circumferential direction,
5 ° ≦ α ≦ 25 °, where α is an angle between the rotation first landing side wall surface and the tread normal line of the land portion divided by the inclined main groove, and β is an angle between the rotation first landing wall surface and the tread normal line. and -20 ° ≦ β ≦ 0 ° (provided that the negative angle are shown when the land portion wall inclined inwardly) meets the relationship,
The inclined main groove has a narrower groove width between the vicinity of the shoulder start position and the ground contact end, and the angle α and β are smaller at the narrow groove portion than the wide groove portion at 5 °. A pneumatic tire for passenger cars that satisfies ≦ α ≦ 10 ° and −5 ° ≦ β ≦ 0 ° .   The circumferential groove is one or two grooves communicating with the tire equator side end portion of the inclined main groove, and the deepest portion of the groove depth is 50 to 85% of the groove depth of the inclined main groove. The pneumatic tire for a passenger car according to claim 1, further comprising: a shallow groove portion that is at least substantially provided between the land portions separated by the circumferential groove.   The circumferential groove is one or two grooves communicating with the end of the inclined main groove on the tire equator side, and the groove width ranges from 4 mm to 15% of the tire ground contact width. The deepest part has a shallow groove part that is 50 to 85% of the groove depth of the inclined main groove and a deep groove part that extends at the same groove depth from the tire equator side end part of the inclined main groove. Item 2. A pneumatic tire for a passenger car according to Item 1.

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