JPH06166303A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To provide a pneumatic tire wherein noise is reduced without lowering its water discharging performance and maneuvering stability in the tire with block patterns. CONSTITUTION:Many blocks 4 divided by a plurality of main grooves 2 extending in the circumferential direction and a plurality of sub-grooves 3 crossing these main grooves and extending in the cross direction of a tire are formed by providing these main grooves 2 and sub-grooves 3 on a tread 1. In a pneumatic tire with block patterns wherein the rotary direction is designated in one direction, the angle beta between the wall face of a sub-groove in the kicking- out side of a block 4 and the normal of a tread is made 10 deg. or more, and the angle alpha between the wall face of a sub-groove in the step-in side of the block 4 and the normal line of the tread is also made smaller than the angle 4 in the kicking side by 5 deg. or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire having a block pattern in which noise generated during running is reduced.

[0002]

2. Description of the Related Art Conventionally, a tire having a rib pattern has a block pattern formed by forming a block on a tire tread surface with a main groove extending in the tire circumferential direction and a sub groove extending in the tire width direction intersecting with the main groove. Sufficient drainage can be secured by the sub-groove as compared with. However, on the other hand, there is a drawback that a large amount of noise is generated. As shown in FIG. 3, this noise is compressed in the ground contact tread, and is suddenly released and vibrates immediately after kicking out of the block B that has been deformed so as to bend in the direction opposite to the tire rotation direction. This phenomenon was remarkable in flat tires.

As measures for reducing the noise due to such a block pattern, there are proposals such as reducing the sub-grooves and reducing the tire ground contact width. However, these measures reduce the original drainage property of the block pattern. However, since it causes a problem that steering stability is deteriorated, it is not an essential noise reduction measure.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a pneumatic tire having a block pattern, in which noise is reduced without deteriorating the drainage performance (wet performance) and steering stability. To do.

[0005]

The present invention for achieving the above object comprises a plurality of main grooves extending in the tire circumferential direction on a tread surface, and a plurality of sub-grooves intersecting the main grooves and extending in the tire width direction. In the pneumatic tire having a directional block pattern in which a large number of blocks divided into these main grooves and sub-grooves are formed by providing the directional block pattern, the kick side of the blocks is provided. The angle β formed by the sub-groove wall surface with the tread normal is 10 ° or more, and the angle α formed by the sub-groove wall surface on the stepping side of the block with the tread normal is 5 ° or more than the kick-side angle β. It is characterized by being made smaller.

As described above, in a tire having a directional block pattern, the kick-off side sub-groove wall surface angle β is 10 ° or more and is larger than the step-on side sub-groove wall surface angle α. Since the rigidity of the side is increased and the vibration of the block immediately after kicking out is suppressed, the generation of noise is reduced. Further, by making the sub-groove wall surface angle α on the stepping side smaller than the angle β on the kicking side by 5 ° or more, the rigidity on the stepping side is reduced, and the noise due to the impact when the block is stepped on is also reduced. Moreover, since it is not necessary to substantially reduce the number of sub-grooves and the ground contact width by the above-described action, wet performance and steering stability are not deteriorated.

The tire of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a tread pattern of a pneumatic tire according to an embodiment of the present invention. The figure shows a directional block pattern in which the tire rotation direction is designated in the arrow direction, and a plurality of main grooves 2 in the circumferential direction on the tire tread 1 and a plurality of auxiliary grooves extending in the tire width direction intersecting the main grooves 2 are provided. A groove 3 is provided, and the main groove 2 and the sub groove 3 are provided.
A large number of blocks 4 surrounded by are formed.

As shown in FIG. 2, in the block 4, the front and rear sub-grooves 3 have different groove wall surface angles. That is,
The angle β formed by the wall surface of the auxiliary groove 3 on the kicking side of the block 4 with the tread normal is larger than the angle α formed by the wall surface of the auxiliary groove 3 on the tread side with the tread normal, and the kicking side angle β is 10
The angle is not less than 0 °, preferably 10 ° to 30 °. Such a large angle β increases the rigidity of the kicking side of the block and suppresses the vibration of the block when it is suddenly released to the kicking side from the state of being compressed in the ground contact tread, which causes noise. To reduce.

Further, the stepping side angle α is 0 ° or more and 5 ° or more, preferably 5 ° or more than the kicking side angle β.
It is made small in the range of -15 °. In this way, by suppressing the depression side angle α to be small, the rigidity on the depression side can be reduced, and the impact sound when the block 4 steps on the tread surface can be reduced. In addition, the groove angle α as described above,
Since noise is reduced only by adjusting β, it is sufficient to set the number and size of the sub-groove 3 and the ground contact width of the tread that are necessary for drainage and steering stability, which leads to a reduction in wet performance and steering stability. There is no such thing.

[0010]

As described above, according to the present invention, in the tire having the directional block pattern, the auxiliary groove wall surface angle β on the kicking side of the block is made larger than the angle α on the stepping side and is 10 ° or more. Therefore, the vibration when the block is released from the grounded state to the kicking side is suppressed, and the angle α on the stepping side is made smaller than the angle β on the kicking side by 5 ° or more, so the impact when stepping on the block is reduced, Noise can be reduced by these combined actions. Also,
Noise is reduced by adjusting the groove angle, and it is not necessary to change the number of sub-grooves or the tread contact width, so that the original wet performance and steering stability of the block pattern can be maintained.

[Brief description of drawings]

FIG. 1 is a plan view showing an example of a tread pattern provided on a tire of the present invention.

FIG. 2 is a sectional view taken along the line AA in the tire circumferential direction of FIG.

FIG. 3 is an explanatory view of a tire circumferential direction cross section showing the movement of a block of a conventional tire having a block pattern.

[Explanation of symbols]

 1 Tread 2 Main groove 3 Sub groove 4 Block

Claims (1)

[Claims] 1. A tread surface is provided with a plurality of main grooves extending in the tire circumferential direction and a plurality of sub-grooves intersecting the main groove and extending in the tire width direction, whereby the tread surface is divided into these main grooves and sub-grooves. In a pneumatic tire having a directional block pattern in which a large number of blocks are formed and the rotation direction thereof is designated as one direction, an angle β formed by a sub-groove wall surface on the kicking side of the block and a tread normal is 10 °. In addition to the above, the pneumatic tire in which the angle α formed by the sub groove wall surface on the stepping side of the block with the tread surface normal is smaller than the angle β on the kicking side by 5 ° or more.