JP3058590B2 - 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 pneumatic tire which can improve steering stability and noise performance in a so-called non-directional flow pattern and can be preferably used for a passenger car.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4 (A), left and right inclined lug grooves a extending from the left and right tread edges E, E toward the tire equator C on both sides of the tire equator C on the tread surface. Has been proposed at a substantially point-symmetric position about a point on the tire equator.

[0003] This non-directional flow pattern is a pattern in which the direction of rotation when mounted on a vehicle is usually not specified, and the inclination angle β formed by the inclined lug groove a with the tire circumferential direction line.
Is often set to 50 ° or more.

[0004]

In order to improve the noise characteristics and the drainage performance of the non-directional flow pattern as described above, the present inventor has found that the inclined lug groove b as shown in FIG. Attempts were made to improve the inclination angle β, which is a line with the tire circumferential direction, to reduce the angle, for example, β ≦ 45 °.

[0005] Then, it has been found that the blocks c formed between the inclined lug grooves b, b have a vertically long shape, and that the rigidity of the blocks is reduced, so that the blocks c slide on the ground contact surface during running. .

[0006] The sliding of the block not only reduces the steering stability performance but also, as shown by the solid line in FIG.
The generation of a "slip noise" having a sharp peak e near 6 KHz causes a problem that the noise performance is also reduced.

The inventor of the present invention has conducted intensive studies on a specific problem which occurs in such a non-directional flow pattern in which the inclination angle β of the inclined lug groove with respect to the tire circumferential line is reduced, and as a result, the radial direction of the tire has been studied. By specifying the cord angle of the outermost belt ply and the inclined lug groove in association with each other, the rigidity in the ground contact surface is increased even if the block is vertically elongated, so that the above-described block is formed. It has been found that the slippage can be suppressed.

As described above, according to the present invention, in the non-directional flow pattern in which the inclination angle β of the inclined lug groove with respect to the tire circumferential direction is reduced, the noise performance and the steering stability can be improved by suppressing the slip of the block. The aim is to provide pneumatic tires that can be enhanced.

[0009]

According to the first aspect of the present invention, there is provided an organic fiber cord which is folded and locked around a bead core of a bead portion from a tread portion through a sidewall portion.
Comprising a carcass and, arranged in the radially outer side of the tread portion inward and the carcass, moreover metals are arranged inclined code at an angle of 10 to 35 ° with respect to the tire equator Co
A belt layer which at least two belt plies superimposed in the direction of the code cross each other consisting of de, 該Be
Low elasticity cord arranged radially outside the tire layer 7 in the tire radial direction
That are arranged substantially parallel to the tire circumferential line
And the band layer is a belt layer.
A narrow edge band that covers only the left and right edge areas
Around the entire width of the belt layer.
And a full band, and in the tread portion,
The groove width extending along the tire circumferential direction at a position near the tire equator C and on both sides thereof is 4 to 20 mm , and the groove depth is 5 to 10 mm.
By forming a straight groove , a straight rib is formed therebetween, and the tread portion extends on both sides of the tire equator from the left and right tread edges toward the tire equator, and opens and terminates at the straight groove. the left and right tilt lug grooves to form a non-directional flow pattern arranged substantially point-symmetrical positions around the point on the tire equator, and before
Each inclined lug groove, in the total length from the tread edge,
From the tread edge to the tire equator side,
The inclination angle β is β1> β2 >>...> βmin
And sea urchin decreasing, yet minimum angle βmin of the inclination angle β of the inclined lug grooves makes with the tire circumferential direction line is a 45 ° or less.

According to the first aspect of the present invention, the groove width of the inclined lug groove is provided.
Gradually from the tread edge E toward the tire equator C.
And make the groove depth uniform in the length direction.
The inclined lug groove is disposed on the outermost side in the radial direction of the belt layer.
When the belt is inclined in the opposite direction to the cord
In both cases, the minimum angle βmin and the outer belt ply
The cord angle α that the cord forms with the tire circumferential direction satisfies the relationship of | βmin−α | ≦ 25 ° .

In the invention according to claim 2, the inclined lug groove has
The minimum angle β and the cord angle α of the outer belt ply
Is characterized by satisfying the relationship | βmin−α | ≦ 20 ° .

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, a pneumatic tire 1
In the present embodiment, the carcass 6 is folded back around the bead core 5 of the bead portion 4 from the tread portion 2 to the sidewall portion 3 through the sidewall portion 3 and is locked. This illustrates a radial tire for a passenger car having a tough belt layer 7 that gives the carcass 6 a hoop effect by being disposed on the side.

The carcass 6 comprises one or more plies having a radial structure in which carcass cords are arranged at an angle of 75 ° to 90 ° with respect to the tire equator C. As the carcass cord, an organic fiber cord such as nylon, rayon or polyester is preferably employed .

In the present embodiment, the carcass 6 has a main body 6a extending from the tread portion 2 to the bead core 5 of the bead portion 4 through the side wall portion 3; The folded part 6 to be folded
b) and is formed by so-called (1-0) high turn-up in which the end of the folded portion 6b is located outside half of the tire section height.

A bead apex 8 extending from the bead core 5 in the tire radial direction and made of hard rubber is disposed between the main body 6a and the turn-back portion 6b of the carcass 6 to reinforce the bead. .

The belt layer 7 is disposed inside the tread portion 2 and radially outside the carcass 6 in the tire radial direction, and has a cord inclined at an angle of 10 to 35 ° with respect to the tire equator. In this example, two belt plies 7A and 7B are overlapped in the direction in which the cords cross each other.

The belt cord uses a metal cord of high elasticity such as steel .

Further, in the tire radial direction outside of the belt layer 7, and the organic fiber cord of low elasticity, for example, a band layer 10 that are substantially parallel arranged nylon cord with respect to the tire circumferential direction lines are provided . This band layer 10 can improve high-speed durability by suppressing lifting of both edges of the belt layer during high-speed running.

The band layer 10 includes, for example, a belt layer 7.
Edge band 10 covering only the left and right edge areas
A and a full band 10B disposed outside the edge band 10A and covering almost the entire width of the belt layer 7. Note that the band layer 10 may be a jointless band in which a so-called tape-like ply is spirally wound, or may be omitted.

Next, as shown in FIG. 2, the tread portion 2 is provided on both sides of the tire equator C on the tread surface 2A so as to extend from left and right tread edges E, E toward the tire equator C. The inclined lug grooves 12L and 12R (referred to collectively as the inclined lug grooves 12) are arranged at substantially point symmetric positions with respect to a point on the tire equator C. In the present example, the inclined lug grooves flow from the upper left side to the lower right side in the figure. Forming a non-directional flow pattern.

[0021] Then, the straight grooves 13 extending along the tire circumferential direction in the vicinity and on both sides thereof tire equator C,
The inclined lug groove 12 is open to the straight grooves 13 and terminates. And
Straight ribs 14 are formed between the straight grooves 13. The straight groove 13 preferably has a groove width of about 4 to 20 mm and a groove depth of about 5 to 10 mm, for example.

[0022] Each of the inclined lug grooves 12L, 12R, the inclination angle formed in the entire length L of the preparative Les <br/> Ddoen E, the tire circumferential direction line toward the tire equator C side from the tread edge E β gradually decreases, that is, β1>β2>.
The inclined lug groove 1 is shown.
2 has a minimum angle βmin of 45 ° or less, preferably 15 to
The angle is set to 40 °, more preferably 20 ° to 35 °.

As a result, it is possible to secure a large inclination angle β in the shoulder region of the tread portion 2 which affects the cornering, and to increase the rigidity of a block formed between the inclined lug grooves 12 to improve the steering stability. At the same time, the inclination angle can be reduced in the crown region of the tread portion 2 having a high contact pressure, which helps to improve drainage.

The total length L of the inclined lug groove 12 is 55 to 100% of the half width tW of the tread, preferably 60 to 90%.
%, More preferably 70 to 85%.

The tread surface 2A has blocks 17 and 19 defined between the inclined lug grooves 12 by appropriately providing auxiliary grooves 15 and narrow grooves 16 for connecting the inclined lug grooves 12 adjacent to each other in the tire circumferential direction. Can be formed.

Further, the inclined lug grooves 12 are arranged so as to intersect with the cords 7C by being inclined in a direction opposite to the cords 7C of the outer belt plies 7B arranged on the outermost side in the radial direction of the belt layer 7. Is established.

In general, a belt layer of a radial tire has a structure in which the cords of overlapping belt plies cross each other to increase rigidity and prevent deformation when the tire is in contact with the ground. By intersecting the groove 12 and the cord 7C of the outermost belt ply 7B of the belt layer 7, the inclined lug groove 1
Since the direction of the block 7 and the like between the points 2 and 12 and the direction of the cord 7C can be crossed, the rigidity of the grounding surface is increased, and the generation of the “slip noise” having a peak at about 1.6 KHz, which has conventionally occurred, is generated. Can be prevented.

At this time, the relationship between the minimum angle βmin of the inclined lug groove 12 and the cord angle α that the cord 7C of the outer belt ply 7B makes with the tire circumferential direction is: | βmin−α | ≦ 25 °. It is necessary to satisfy

When | βmin−α | exceeds 25 °,
The effect of improving the rigidity of the ground contact surface of the tire is inferior, the slip noise cannot be reduced, and the steering stability is also reduced, so that it cannot be adopted.

Preferably, the minimum angle β of the inclined lug groove and the cord angle α of the outer belt ply satisfy a relation of | βmin−α | ≦ 20 °, and the lower limit is 0. It is.

The inclined lug groove 12 preferably has a groove width Ge measured at the tread edge E of not less than 4 mm and not more than 25 mm. In this example, the groove is formed to have a width of about 6 mm. The inclined lug groove 12 preferably has a groove depth of preferably 4 mm or more and 10 mm or less, and approximately 8 mm in this example.

In this embodiment, as described above, the groove width of the inclined lug groove 12 is also changed from the tread edge E in response to the inclination angle β of the inclined lug groove 12 gradually decreasing toward the tire equator C. An example is shown in which the value gradually decreases toward the tire equator C, and is reduced to about 25% at the tire equatorial end. This can prevent the rigidity of the block on the tire equator C side from being significantly reduced.

[0033] described above, but the pneumatic tire of the present invention may appropriately modified in addition to the embodiment shown FIG.

[0034]

EXAMPLES Various tires having a tire size of 195 / 65R15 and having a structure shown in FIG. 1 and a tread pattern as shown in FIG. 2 were manufactured (Examples 1 to 7), and the performance was tested. Also, a conventional tire (conventional example) in which the inclined lug groove and the cord of the outer belt ply are inclined in the same direction,
Furthermore, tires other than the present invention (Comparative Examples 1 to 3) were also prototyped and tested. The test method is as follows.

A) Maneuvering stability and ride comfort test A test tire was applied to a 15 × 6-JJ wheel rim with an internal pressure of 20
After assembling the rim at 0 kpa (same fore and aft), it was mounted on four wheels of a 2,500 cc front wheel drive vehicle, traveled on a tire test course with only one driver riding alone, and according to the sensory evaluation of the driver, 10 points each of the conventional example as 6 It was evaluated by the method.
The higher the value, the better.

(B) Outside noise test According to JASO / Z101-83, the vehicle is coasted on a straight test course (ISO road surface) for a distance of 50 m at a passing speed of 60 km / h and a running center line at an intermediate point of the course. 7.5m to the side from and 1.2m from the road
The level of the passing noise is measured by the stationary microphone installed at the position of the maximum sound pressure level dB (A) and 1.6.
The sound pressure level dB (A) at KHz was compared. The results are expressed as relative values, both of which are 0 in the conventional example. A minus indicates a decrease in noise and a plus indicates an increase. Table 1 shows the test results.
Shown in

[0037]

[Table 1]

As a result of the test, it was confirmed that each of the examples had better noise performance than the conventional example. In particular, in Examples 1 to 3, since | βmin−α | was 10 ° or less, the rigidity in the ground contact surface was further increased. As a result, all of the steering stability was excellent and the sound of 1.6 KHz was obtained. It was confirmed that the pressure level, that is, the “slip noise” was greatly reduced. The noise of Example 1 was subjected to frequency analysis to find that the noise was 1.6 KH as indicated by the chain line in FIG.
No z peak was observed. Also, by reducing the "slip noise", the maximum level of the entire noise could be greatly reduced. Therefore, | βmin -α |
Is preferably 10 ° or less.

[0039]

As described above, according to the present invention, in a pneumatic tire having a non-directional flow pattern, the inclination direction of the inclined lug groove is changed to the outer belt disposed radially outermost of the belt layer. The minimum angle βmin of the inclination of the inclined lug groove and the cord angle α formed by the cord of the outer belt ply with the tire circumferential direction are | βmin−α | ≦ 25 °. By satisfying the relationship, the rigidity of the tread contact surface can be increased, the steering stability can be improved, and the generation of “slip noise” having a peak near 1.6 KHz can be prevented, so that the noise performance can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a pneumatic tire showing an embodiment of the present invention.

FIG. 2 is a developed plan view showing a tread pattern of the pneumatic tire of FIG. 1;

FIG. 3 is a graph showing noise measurement results.

FIGS. 4A and 4B are plan views of tread patterns showing a conventional technique.

[Explanation of symbols]

 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 7 Belt layer 7B Outside belt ply 12 Inclined lug groove E Tread edge C Tire equator β Inclined angle of inclined lug βmin Minimum angle α Cord angle of external belt ply

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI B60C 11/04 D (56) References JP-A-4-271906 (JP, A) JP-A-4-271905 (JP, A) JP-A-4-208608 (JP, A) JP-A-7-52612 (JP, A) JP-A-7-186631 (JP, A) JP-A-58-39438 (JP, A) JP-A-7-246806 (JP, A) JP-A-59-45203 (JP, A) JP-A-59-230807 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60C 11/00-11 / 11 B60C 9/18 B60C 9/22

Claims (2)

(57) [Claims] 1. A folded around the bead cores of bead portions through sidewall portions from a tread portion locked chromatic
A carcass made of machine fiber cords , and the cords are arranged inside the tread portion and outside of the carcass in the tire radial direction.
A belt layer in which at least two belt plies made of a metal cord and arranged at an angle of 5 ° are overlapped in a direction in which the cords cross each other , Low elasticity
Are arranged substantially parallel to the tire circumferential line
And a band layer covering only the left and right edge regions of the belt layer.
Edge band with a small width and placed outside this edge band
And a full band that covers almost the entire width of the belt layer.
And a groove width extending in the circumferential direction of the tire on the tread portion at a position near the tire equator C and on both sides thereof.
By forming a straight groove of 0 mm and a groove depth of 5 to 10 mm , a straight rib is formed therebetween,
The tread portion, on both sides of the tire equator, extending from the right and left tread edge inclined towards the tire equator the storage
The left and right tilt lug groove that opens to terminate at preparative grooves, to form a non-directional flow pattern arranged substantially point-symmetrical positions around the point on the tire equator, and each inclined lug grooves, tread
From the tread edge to the tire equator
The inclination angle β that forms a tire circumferential direction line toward the side is β1
>Β2>...> gradually decreases and so that .beta.min, yet minimum angle βmi inclination angle β of the inclined lug grooves makes with the tire circumferential direction line
n is 45 ° or less and the groove width of the inclined lug groove is
Gradually decrease from E to the tire equator C
The depth is made uniform in the length direction, and the inclined lug groove is inclined in the opposite direction to the cord of the outer belt ply arranged on the outermost side in the radial direction of the belt layer. A pneumatic tire characterized by satisfying a relationship of | βmin−α | ≦ 25 ° with a cord angle α formed by a cord of an outer belt ply with a tire circumferential direction line. 2. The air according to claim 1, wherein a minimum angle β of the inclined lug groove and a cord angle α of the outer belt ply satisfy a relation of | βmin−α | ≦ 20 °. Containing tires.