JPS60161204A - Aired tire - Google Patents

Abstract

PURPOSE:To average the variation of tread rigidity in circumferential direction of tire thus to reduce the pattern noise considerably by providing a bent section at the intermediate section of sub-groove while directing the sub-groove in the directionof 30-60 deg. against the circumferential direction of tire. CONSTITUTION:Main grooves 10 linear against the circumferential direction of tire are arranged in the step face of tire then coupled through sub-grooves 20. A bent section 21 is provided at the intermediate section of sub-groove 20 while the angle theta of sub-groove 20 against the circumferential direction of tire is set within 30-60 deg. when measured from acute side. Consequently, the fluctuation of tread rigidy in the circumferential direction of tire can be further uniformed while the minimum rigidity level of tread can be increased resulting in improvement of abrasion-resistance of block and considerable reduction of pattern noise.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a pneumatic tire, and more particularly, a pneumatic tire with an improved tread pattern (1) to reduce pattern noise without impairing wear resistance. It is related to tires.

[Conventional technology]

The sound generated between the tires and the road surface while the vehicle is running is
It is called pattern noise because the influence of the trend pattern provided on the 1st to 10th red surface of the tire is very large, and it mainly has a frequency of 500 to 1000 Hz.
The noise is in the range of .

Therefore, experiments and studies have been conducted to reduce the noise caused by this tread pattern.

In the first place, one of the major causes of pattern noise generation is that the rigidity of the tread pattern changes greatly along the circumferential direction of the tire while the vehicle is running.

When the tread pattern is a block pattern in which a plurality of linear main grooves 10 are arranged in the tire circumferential direction on the tread surface of the tire, and sub-grooves 20 connecting the main grooves 10 are arranged. As shown in C1 Figure 1 fal,
When the groove direction angle (2) degree θ of the sub-groove 20 is 90° with respect to the tire circumferential direction, the tread of the tire that is in contact with the road surface while the vehicle is running is suddenly short-circuited by the sub-groove 20. When this tire passes over the road surface, the tread rigidity changes greatly and rapidly in the tire circumferential direction, as shown in FIG. 1 (bl), and large pattern noise is generated.

Therefore, while the vehicle is running, the tread surface of the tire is
In order to prevent the trend stiffness from short-circuiting due to large and rapid changes in the tire circumferential direction, conventionally, as shown in FIG. By bringing the groove direction angle θ closer to the tire circumferential direction, as shown in FIG.
Efforts are being made to reduce pattern noise.

However, as described above, if the sub-grooves 20 connecting the main grooves 10 are made to be inclined and the groove direction angle θ is brought closer to the tire circumferential direction, pattern noise can be reduced, but wear resistance is reduced and uneven wear occurs. (3) At present, there are still problems such as the occurrence of cassoping and the like, which impairs the durability of the tire.

[Purpose of the invention]

The present invention was achieved as a result of experiments and studies aimed at solving the two problems.

Therefore, an object of the present invention is to provide an excellent pneumatic tire that can reduce pattern noise without impairing wear resistance by devising the structure of the sub-grooves.

[Structure of the invention]

That is, the present invention provides a pneumatic tire having a block pattern in which a plurality of substantially linear main grooves in the tire circumferential direction are arranged on the tire tread, and sub-grooves connecting the plurality of main grooves are arranged. The pneumatic tire is characterized in that the sub-groove is provided with a bent part in the middle thereof, and the angle of the sub-groove in the groove direction is 30° to 60° with respect to the circumferential direction of the tire. be.

〔Example〕

The present invention will be described below by way of example with reference to the drawings. Explain physically.

FIG. 3 is an explanatory plan view showing a part of the tread of a pneumatic tire according to an embodiment of the present invention, FIG. 4 is a partially enlarged plan view explanatory view of the same, and FIG. 5(a) is the present pneumatic tire. The basic pattern of the tread pattern arranged on the tread surface of
Figure fb) is a diagram showing the rigidity change of the same basic pattern, No. 6
The figure is a diagram showing the relationship between the groove direction angle of the sub-groove and noise.

In the figure, E indicates a pneumatic tire according to an embodiment of the present invention, in which a plurality of main grooves 10 that are substantially straight in the tire circumferential direction are arranged on the tire tread, and a sub-groove that connects the plurality of main grooves 10. In particular, in the present invention, the sub-grooves 20 are arranged in a block pattern.
A bent portion 21 is provided at the intermediate portion of the tire, and the groove direction angle θ of the sub-groove 20 is set in the range of 30° to 60° with respect to the tire circumferential direction, as measured from the acute angle side.

Therefore, in the present invention, the groove direction angle θ with respect to the tire circumferential direction is
A block pattern is formed on the tire tread by the main groove 10 and the sub-groove 20 which is inclined in the range of 30° to 60'' as measured from the acute angle side and has a bent part 21 in the middle part (5). As a result, compared to the conventional tire shown in FIG. 2, which has a block pattern formed by simply slanting the sub-grooves 20 connecting the main grooves 10, As shown in Figure 2, changes in tread stiffness in the tire circumferential direction can be further averaged, and pattern noise can be significantly reduced, while the minimum tread stiffness level is increased compared to the conventional tires mentioned above. It is possible to improve the wear resistance of the block, prevent uneven wear and occurrence of cassoping, and improve the durability of the tire.

Further, as described above, forming a block pattern on the tire tread by the sub-groove 20 having the bent portion 21 in the intermediate portion greatly contributes to reducing pattern noise. This is because it is possible to alleviate a sudden change in the trend stiffness in the tire circumferential direction while the vehicle is running.

(6) In particular, the ratio of the projected length A of the sub-groove 20 in the tire circumferential direction to the projected length a of the bent portion 21 in the tire circumferential direction is 1/10≦a
/A≦4/10 is particularly preferable for the pattern noise reduction effect.

Note that when the ratio a/A becomes less than 1/IO, the bent portion 21
This is not preferable because the projected length a in the tire circumferential direction becomes too short, and the shape of the sub-groove 20 in plan view becomes straight as shown in FIG. When the ratio a/A exceeds 4/10, the projected length a of the bent portion 21 in the tire circumferential direction becomes too long, reducing the rigidity of the block and reducing the durability of the tire, such as uneven wear and cassoping. So I don't like it.

Note that the projected length A of the minor groove 20 in the tire circumferential direction and the projected length a of the bent portion 21 in the tire circumferential direction are values measured at the distance between the centers of the minor grooves 20, respectively, as shown in FIG. This is because the opposing groove walls of the sub-groove 20 are not necessarily formed in parallel as shown in the figure.

Furthermore, in the present invention, the groove direction angle θ of the sub-groove 20 with respect to the tire circumferential direction (7) is set in the range of 30° to 60° because the groove direction angle θ is 30° with respect to the tire circumferential direction.
If it is less than this, the rigidity of the block will decrease, and the durability of the tire will decrease, such as uneven wear and cassoping, which is undesirable. Also, the effect of reducing pattern noise by providing the bent portion 21 will decrease. It is. On the other hand, if the groove direction angle θ exceeds 60° with respect to the tire circumferential direction, this is undesirable because the trend stiffness short circuit in the tire circumferential direction, that is, the discontinuity of tread stiffness increases, and the pattern noise reduction effect decreases. It is.

[Experiment example]

Fig. 6 shows a tire of the present invention (marked with a mark) in which a block pattern is formed on the tire tread by a sub-a20 having a bent part 21 in the middle, and a straight sub-groove 2 shown in Fig. 2(a).
FIG. 2 is a diagram showing the test results of examining the relationship between the groove direction angle θ of the sub-groove 20 and pattern noise for a conventional tire (marked with ◯) in which a block pattern was formed on the tire tread surface by using the tire tread.

(8) The specifications of the tires used in the test and the test conditions are as follows.

Tire size...195/60 R15 tire internal pressure...2. Okg/crf+load...
...300 kg/piece The ratio a/A of the projected length A of the minor groove 20 in the tire circumferential direction and the projected length a of the bent portion 21 in the tire circumferential direction of the tire of the present invention is 0.13 to 0.3
The range is 3.

As is clear from FIG. 6, if the groove direction angle θ of the sub-groove 20 with respect to the tire circumferential direction is the same, the groove direction angle θ is 3.
Within the range of 0° to 60°, compared to the conventional tire in which a block pattern was formed on the tire tread by the straight sub-groove 20 shown in FIG. It can be seen that the tire of the present invention in which a block pattern is formed on the tread surface can reduce pattern noise.

〔Effect of the invention〕

As described above, the present invention provides a block comprising: (9) a plurality of substantially linear main grooves arranged in the tire tread surface in the tire circumferential direction, and a sub-groove connecting the plurality of main grooves; In a pneumatic tire having a pattern, a bent part is provided at the intermediate part of the sub-groove, and the groove direction angle of the sub-groove is set to 30' to 60° with respect to the tire circumferential direction. Compared to a conventional tire that has a block pattern in which the minor grooves connecting the main grooves are simply sloped and formed with a pattern, the change in trend stiffness in the tire circumferential direction is as shown in FIG. 5 (bl). can be further averaged and pattern noise can be significantly reduced, while the minimum stiffness level of the tread can be increased compared to the conventional tires mentioned above, improving the wear resistance of the block. It is possible to prevent uneven wear and cassoping and improve tire durability.

[Brief explanation of drawings]

Figure 1 (al is a partially enlarged plan view explanatory diagram showing a block pattern in which the groove direction angle of the minor groove is 90° with respect to the tire circumferential direction, Figure 1 (bl is a diagram showing the rigidity change of the same pattern (10)) Figure 2 (a) is a partially enlarged plan view explanatory diagram showing a block pattern in which the groove direction angle of the minor groove is inclined with respect to the tire circumferential direction, and Figure 2 (bl shows the change in rigidity of the same pattern) FIG. 3 is an explanatory plan view showing a part of the tread of a pneumatic tire according to an embodiment of the present invention, FIG. 4 is a partially enlarged plan view explanatory view of the same, and FIG. 5 f
al is placed on the tread surface of this pneumatic tire] - Shows the basic pattern of the red pattern, Fig. 5fbl is a diagram showing changes in rigidity of the same basic pattern, and Fig. 6 shows the groove direction angle of the minor groove and noise. FIG. DESCRIPTION OF SYMBOLS 10... Main groove, 20... Minor groove, 21... Bent part of the minor groove, θ... Groove direction angle of the minor groove. Agent Patent attorney Makoto Ogawa − Patent attorney Ken Noguchi Teru Patent attorney Kazuhiko Saishita (11) Iψ Hoshi To ↓ k4 ＼U w period Ki k4 Cli %N Figure 3 JP-A-Sho GO-IG1204 (5) Figure 6

Claims (1)

[Claims] 1. A pneumatic pump having a block pattern in which a plurality of substantially linear main grooves in the tire circumferential direction are arranged on the tire tread, and sub-grooves connecting the plurality of main grooves are arranged. In the tire, a bent part is provided in the middle part of the sub-groove, and
The groove direction angle of this sub-groove is 30° to 6° with respect to the tire circumferential direction.
A pneumatic tire characterized by its 0° angle. 2. The ratio a/A of the projected length A of the minor groove in the tire circumferential direction and the projected length a of the bent portion in the tire circumferential direction is 1/10≦a.
The pneumatic tire according to claim 1, wherein /A≦4/10.