JP3393802B2 - Pneumatic tire - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a pneumatic tire capable of improving braking performance and drivability while maintaining wet performance.

[0002]

2. Description of the Related Art In a tread pattern of a block type or the like in which a vertical groove and a horizontal groove are crossed to improve wet performance, generally, a hitting sound at the time of contact with the ground or a tread edge side is reduced. In order to improve drainage, it is widely practiced to incline the lateral groove with respect to the tire axial direction. Therefore, the block has a non-rectangular shape, for example, a rhombus, whose acute-angled side apex faces forward and backward in the tire rotation direction.

As a result, the rigidity of the block in the circumferential direction is reduced due to the sharp-angled side apex, which tends to impair the braking performance and drivability of the tire.

Conventionally, in order to improve the braking performance and drivability, for example, the length of the block in the circumferential direction is increased. However, this method has a problem that the sea area ratio, which is the ratio of the groove area to the ground contact area of the tread, is decreased by the increase in the block length, and the wet performance is deteriorated.

Therefore, the present invention is based on the fact that a predetermined change is made to the inclination angle of the groove wall surface, the circumferential rigidity of the block can be improved without changing the sea area ratio, and the deterioration of wet performance can be minimized. However, it is an object of the present invention to provide a pneumatic tire that can improve braking performance and drivability.

[0006]

In order to achieve the above object, the invention according to claim 1 is to provide vertical grooves extending continuously in the circumferential direction on a tread surface, and between the vertical grooves or between the vertical grooves and the tread edge. A pneumatic tire in which a tread surface is divided into a plurality of blocks by providing a lateral groove that connects between the lateral groove and the lateral groove, and the groove length direction line on the tread surface is inclined with respect to the tire axial direction line. Thus, the block is
One end in the tire axial direction and the other end include a non-rectangular block having a slant side that is circumferentially displaced on the tread surface, and a groove that is continuous with the slant side on the tread surface of the non-rectangular block. The wall surface is inclined so that the lateral groove opens outward in the radial direction, and the circumference of the non-rectangular block.
The angle δ with respect to tread <br/> de surface normal of the groove wall surface continuous to the two said inclined side forming a pair in the direction, it on the occasion to the tire rotation
The angle δs of the wall surface of the first-arrival side groove connected to the edge of the first-arrival side with respect to the normal to the tread surface is set larger than the angle δe of the groove wall surface of the last-arrival side connected to the edge of the trailing-side, and The angle δs is in the range of 15 to 40 degrees and the angle δe is 0.
The feature is that the range is set to -10 degrees.

From the viewpoint of uneven wear and drainage, it is preferable that the angle δ be continuously changed from the groove wall surface at the end of the oblique side on the first arrival side to the groove wall surface at the end of the oblique side on the rear arrival side.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a plan view of a tread surface 2 of a pneumatic tire 1, and the tread surface 2
And the vertical groove 3 extending continuously in the circumferential direction, and the vertical groove 3,
The tread surface 2 is divided into a plurality of blocks B by providing a lateral groove 4 connecting between the three or the vertical groove 3 and the tread edge Te.

More specifically, in this example, four vertical grooves 3 are provided, which are the internal vertical grooves 3A and 3A located on both sides of the tire equator C and the external vertical grooves 3B and 3B arranged outside thereof. It This vertical groove 3 has the same siping S (groove width 2.0 m) as the horizontal groove 4.
The groove is wider than (m or less) and has, for example, a zigzag shape or a linear shape. The vertical groove 3 and the horizontal groove 4 arranged on one side of the tire equator C are substantially line-symmetrical with the vertical groove 3 and the horizontal groove 4 arranged on the other side, whereby the tread pattern is arranged in the rotational direction. Make a direction to.

The horizontal groove 4 is formed by connecting the inner vertical grooves 3A, 3A to form a row of the inner block B1 and the inner and outer vertical grooves 3A, 3B. It comprises an inner lateral groove 4B forming a row of blocks B2 and an outer lateral groove 4C forming an outer row of blocks B3 by joining the outer lateral groove 4B and the tread edge Te. In this example, the lateral grooves 4A, 4B, 4C adjacent to each other in the tire axial direction are provided.
Are arranged substantially in a line to form a single lateral groove body extending between the tread edges Te and Te in a V-shape or a U-shape.
In order to give the block B the necessary rigidity in the circumferential direction, at least the groove wall of the lateral groove 4 is inclined from the groove bottom toward the tread surface, that is, toward the radially outer side in the direction of opening in a V shape. is necessary.

Further, the inner lateral groove 4A has an arc shape centering on the tire equator C in the present embodiment, and therefore the block B1 has opposite sides 21a, 21b facing each other in the circumferential direction.
(It refers to the opposite sides that form a pair in the circumferential direction in a block.
Same) is formed in a substantially rectangular block that is substantially perpendicular to the tire equator C.

On the other hand, the inner and outer lateral grooves 4B, 4C are rearward of the tire rotation when the groove length direction line L on the tread surface 2 has an angle θ of, for example, 0 to 45 degrees with respect to the tire axial direction line. It is an inclined groove that extends to the side. In the present example, the inner and outer lateral grooves 4B, 4C have a curved shape in which the angle θ is gradually reduced outward in the tire axial direction, and together with forming one lateral groove body, the tread edge Te Drainage to

As a result, the blocks B2 and B3 are
Of the four sides 10 that surround the periphery of the block, the opposite sides 10a and 10b facing in the circumferential direction are the hypotenuses 11a and 1 respectively.
It is formed in a non-rectangular block forming 1b.

Here, as will be described on behalf of the block B2 in the above, in this block B2, opposite sides 10a and 10b facing each other in the circumferential direction are substantially parallel to each other as shown in FIG. 2, and one side 10a. Forms an oblique side 11a in which one end E1 of the side 10a in the tire axial direction and the other end E2 are displaced in the circumferential direction. The other side 1
0b also forms a hypotenuse 11b in which one end E1 and the other end E2 are displaced in the circumferential direction.

Therefore, in FIG. 2, the block B2 is caused by, for example, the tire rotation K1 (lower side in the figure) during forward movement.
When the ground touches the ground, the hypotenuse 11a becomes the rotation direction side (lower side)
In the direction of rotation (lower side), the hypotenuse end E1a
Is the first-arrival side, and the other hypotenuse edge E2a is the last-arrival side for grounding. When the tire rotates in reverse (upper side in the figure), the hypotenuse edge E1b, which is the rotational direction side (upper side) of the hypotenuse 11b, is the first arrival side, and the other hypotenuse edges E2b are the last arrival side.

A groove wall surface Sa connected to the oblique side 11a
At the angle δ with respect to the tread surface normal line N, the groove wall surface S1a on the first arrival side that is continuous with the oblique side end E1a on the first arrival side.
Is larger than the angle δe of the groove wall surface S2a on the rear end side that is continuous with the oblique side end E2a on the rear end side (δs> δe).
I am trying.

Similarly, for the hypotenuse 11b side, the hypotenuse 1
In the angle δ of the groove wall surface Sb connected to 1b with respect to the tread surface normal N, the angle δs of the groove wall surface S1b on the first arrival side that is continuous to the oblique side end E1b that is the first arrival side is connected to the oblique side end E2b that is the last arrival side. Angle δe of groove wall surface S2b on the trailing side
Larger than (δs> δe), and thus paired in the circumferential direction.
Whichever of the opposite sides is
It is set to be larger than the angle δe on the trailing side .

This makes it possible to increase the circumferential rigidity near the hypotenuse end E1a and near the hypotenuse end E1b, that is, near the top of the non-rectangular block that comes in advance at the time of each ground contact during forward movement and reverse movement, and braking performance and drivability. Can be improved.

Here, the first-arrival-side groove wall surfaces S1a and S1b and the second-arrival-side groove wall surfaces S2a and S2b are the oblique sides 11.
A distance of 0.3 times each length of a and 11b is set to the end E1 of the hypotenuse side.
a, E1b and the edge surfaces E2a, E2b of the groove wall surfaces Sa, Sb, respectively, in the range of 15 degrees or more and 40 degrees or less for the first arrival side angle δs , or the second arrival side The angle δe is in the range of 0 degree or more and 10 degrees or less.

Regarding the angle δ, the groove wall surface S
The angle δ in 1a, S1b, S2a, S2b
s and δe may be substantially constant, or the angle δ between the groove wall surfaces S1a and S2a and the intermediate region between the groove wall surfaces S1b and S2b may be substantially constant. However, as in this example, the entire angle δ is changed from the oblique side end E1 on the first-arrival side to the oblique side end E2 on the rear-end side.
It is preferable to continuously change toward. As a result, it is possible to suppress the occurrence of uneven wear and the decrease in drainage property due to the change in the inclination gradient of the groove wall surfaces Sa and Sb.

The difference between the angle δs and the angle δe is
It is preferably 10 degrees or more, and more preferably 15 degrees or more in order to uniformly increase the circumferential rigidity. On the other hand, if the angle δs exceeds 40 degrees , the groove depth becomes too small or the groove width becomes too large, resulting in deterioration of dry steering stability or wet performance. Also when the angle δs is less than 15 degrees, and the angle δ
When e is less than 0 degrees, the effect of improving the braking performance and drivability can not be expected . Also when the angle δe exceeds 10 degrees, sleeping impairing the uniformity of stiffness.

Further, in this example, in order to maintain the smooth flow of water in the vertical grooves 3A, 3B, the inclination angles of the groove wall surfaces Sc, Sd connected to the opposite sides 10c, 10d facing each other in the tire axial direction in the block B2 are set. , Is substantially constant over the entire length.

The same applies to the outer block B3.
The opposite sides 10a and 10b facing each other in the circumferential direction are substantially parallel to each other as shown in FIG.
1a and 11b are formed, and in the groove wall surface Sa connected to the oblique side 11a, the angle δs of the groove wall surface S1a on the first arrival side connected to the oblique end E1a is changed to the angle δs of the groove wall surface S2a on the rear side connected to the oblique end E2a. Greater than δe (δs> δ
e). Similarly, the groove wall surface S extending to the hypotenuse 11b
In b, the groove wall surface S on the first-arrival side that is continuous with the hypotenuse end E1b
The angle δs of 1b is larger than the angle δe of the groove wall surface S2b on the rear end side that is continuous with the oblique side end E2b (δs> δe), and the angle δs is in the range of 15 degrees or more and 40 degrees or less, or the angle δe is in the range of 0 degrees or more and 10 degrees or less.

In the present example, the outer and inner blocks B2 and B3 are of two types by forming the outer vertical groove 3B in a zigzag shape and intersecting the lateral grooves 4B and 4C at the protruding corner and the entering corner of the zigzag. Blocks B2x, B2y, B3
x, B3y, but opposite sides 10a, 1 in the circumferential direction
If 0b constitutes the hypotenuses 11a and 11b, the block shape is not particularly limited.

As shown in FIG. 2, the substantially rectangular block B1 has opposite sides 21a, 2 facing each other in the circumferential direction, as described above.
1b is curved in an arc shape protruding in the tire rotation K1 (lower side) direction. Therefore, when moving forward, the vehicle first arrives at the central portion P1a (position of the tire equator) of the side 21a and both end portions P
2a arrives later. Further, at the time of reverse travel, both end portions P2b of the side 21b come first and the central portion P1b comes later.

Therefore, in this example, in the groove wall surface Sc connected to the hypotenuse 21a, the angle γs of the groove wall surface of the first arrival side connected to the central portion P1a is larger than the angle γe of the groove wall surface of the last arrival side connected to both ends P2a. (Γs> γe) and hypotenuse 21b
In the groove wall surface Sd connected to, the angle γs of the groove wall surface on the first arrival side that is connected to both ends P2b is larger than the angle γe of the groove wall surface on the last arrival side that is connected to the central portion P1b (γs> γe). As a result, the rigidity in the circumferential direction is increased even in the substantially rectangular block B1, and the effect of improving braking performance and drivability is further enhanced.

The angles γs and γe are the angles δ.
Similarly to s and δe, it is preferable to set the range of 15 to 40 degrees and 0 to 10 degrees.

In the present application, it is not necessary to set the angle δs> angle δe for all non-rectangular blocks.
It is desirable to carry out for more blocks.
Further, the groove width and the groove depth of the vertical groove 3 and the horizontal groove 4 are not particularly limited, but the same range as in the case of a general radial tire for passenger cars can be used, and the groove depth is 6.0 to 6.0, respectively.
The range of 9.0 mm is preferable, and the groove width is 3.0, respectively.
The range of 12.0 mm is preferable.

[0029]

EXAMPLES A radial tire for passenger cars having a tire size of 235 / 45R17 and a tread pattern shown in FIG. 1 was prototyped according to the specifications shown in Table 1, and dry steering stability, wet performance, braking performance, and The drivability was measured and the results are shown in Table 1. The tire internal structures are the same. Also, as a comparative example product,
As shown in FIG. 4, the same pattern is adopted in which only the groove width of the lateral groove is reduced by half.

The A-A 'cross section and B- of each sample tire
B'section, C-C 'section, D-D' section, E-E 'section, F-F' section, G-G 'section, H-H' section, I-
Table 2 shows the values of the angles δ and γ of the groove wall surface in the I ′ cross section and the JJ ′ cross section. The test method is as follows.

Dry steering stability test and wet performance test: A test tire was mounted on a vehicle under the conditions of a rim (8JJ × 17) and an internal pressure (2.0 kgf / cm ² ), and dry asphalt on a tire test course. The vehicle was run on a road surface and a wet asphalt road surface, respectively, and the runnability in terms of steering wheel response, rigidity, grip, etc. was scored by a 5-point method with a "3" as the average value by sensory evaluation of the driver. The larger the number, the better.

Braking performance and drivability test: Using the vehicle equipped with the test tires, the driving performance when suddenly starting on a dry asphalt road surface and the braking performance when sudden braking is applied are 100 Was evaluated by the index. The larger the number, the better.

[0033]

[Table 1]

[0034]

[Table 2]

As shown in Table 1, the tires of the examples maintained dry steering stability, braking performance and drivability while maintaining a high level of wet performance substantially equal to that of a conventional tire having the same tread pattern with the same sea area ratio. It can be confirmed that and can be greatly improved.

[0036]

Since the present invention is constructed as described above,
The circumferential rigidity of the block can be effectively increased without reducing the sea area ratio, and braking performance and drivability can be greatly improved while minimizing deterioration of wet performance.

[Brief description of drawings]

FIG. 1 is a development view showing a tread pattern according to an embodiment of the present invention.

FIG. 2 is an enlarged plan view showing a block therein.

FIG. 3 is an enlarged plan view showing an outer block.

FIG. 4 is a development view showing a tread pattern of a comparative example used in Table 1.

5 (A) to (D) are A-A 'cross-sections, B-B' cross-sections, C-C 'cross-sections, and D-D' cross-sections in FIGS.

6 (E) to (H) are an EE ′ cross section, an FF ′ cross section, a GG ′ cross section, and an HY ′ cross section ′ in FIGS.

7 (I) to (J) are cross sections taken along the line II ′ of FIG.
-J'section '.

[Explanation of symbols]

2 tread surface 3, 3A, 3B vertical groove 4, 4A, 4B, 4C Lateral groove 11a, 11b hypotenuse B, B1, B2, B3 blocks E1, E1a, E1b The edge of the hypotenuse on the first-arrival side E2, E2a, E2b End of hypotenuse on the rear side L groove length direction line Sa, Sb Groove wall connected to the hypotenuse S1a, S1b Groove wall surface on the first arrival side S2a, S2b Groove wall surface on the trailing side Te tread edge

Claims (2)

(57) [Claims] 1. A tread surface is divided into a plurality of blocks by providing vertical grooves extending continuously in the circumferential direction and lateral grooves connecting between the vertical grooves or between the vertical groove and a tread edge. In the pneumatic tire, the lateral groove has one end portion in the tire axial direction and the other end portion because the groove length direction line on the tread surface is inclined with respect to the tire axial direction line. And includes a non-rectangular block having a slanted side that is displaced in the circumferential direction on the tread surface, and a groove wall surface continuous with the slanted side on the tread surface of the non-rectangular block has a direction in which the lateral groove opens outward in the radial direction. The two hypotenuses that are inclined to each other and are paired in the circumferential direction of the non-rectangular block
Angle δ with respect to the tread surface normal of the groove wall surface continuous to the angle δs respect to the tread surface normal of arrival side of the groove wall surface continuous with the oblique end portion serving as the respective first arrival side on the occasion to the tire rotation
Is greater than the angle δe of the wall surface of the groove on the rear side that is continuous with the end of the hypotenuse side, and the angle δs is 15 to 40.
A pneumatic tire having a degree range and an angle δe of 0 to 10 degrees. 2. The pneumatic tire according to claim 1, wherein the angle δ continuously changes from the groove wall surface at the end of the oblique side on the front end side to the groove wall surface at the end of the oblique side on the rear end side. .