JP2889417B2 - 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, and more particularly to a pneumatic tire with reduced tire noise.

[0002]

2. Description of the Related Art In recent years, with the improvement in quietness of a vehicle, the contribution of noise generated by tires to the entire vehicle has been increased, and it is required to reduce the noise. In particular, it is desired to reduce the noise in a high frequency region of 800 or more. It is. One of the main sound sources in such a high frequency region is a sound due to air column resonance.

[0003] In the tire tread, a plurality of longitudinal grooves which are generally continuous in the tire circumferential direction are arranged to maintain a wet grip. Such tires, on the tread,
A vertical column with the ground forms a kind of air column. Due to the deformation of the tire tread during rolling, air flows in this air column,
Thereby, a sound having a specific wavelength, that is, a wavelength twice as long as the air column is generated. This phenomenon is called air column resonance, and is a main sound source of noise of a tire having a vertical groove. For example, when the vertical length of the vertical groove is 20 cm, about 900 sounds are generated. This sound has a substantially constant frequency irrespective of the speed of the tire, and increases the in-vehicle sound and the outside sound.

[0004]

As means for preventing this columnar resonance, Japanese Patent Application Laid-Open No. 61-113504 discloses
A technique is disclosed in which shielding is provided in a vertical groove at a circumferential pitch corresponding to 0.3 to 0.4 times the ground contact length to prevent air column resonance. Although the shield in such a flute prevents air column resonance, it impedes water flow and lowers the wet grip performance, which is the purpose of the flute. Has also proposed.

However, in the above proposal, the depth of the groove is, for example, 8 mm, while the thickness of the shield is, for example, 7 mm, the width of the slit is about 1.25 mm, and the depth is about 4 mm. Since the slit is small compared to the object, the reduction in wet grip cannot be sufficiently prevented, and it is difficult to apply it to tires, especially in conjunction with the desire for high wet grip performance due to recent high performance of vehicles. Seem.

An object of the present invention is to provide a pneumatic tire that can prevent air column resonance and reduce tire noise while maintaining wet grip performance.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a tire having a plurality of longitudinal grooves extending continuously in the tire circumferential direction in a tread portion, the longitudinal grooves intersecting the longitudinal grooves and interrupting the circumferential continuity. And at least one film having a thickness measured in the tire circumferential direction of 0.5 mm or more and less than 2.0 mm,
Together be present in a ground plane in a state obtained by adding a normal load to fill the normal internal pressure Shi assembled rim in a normal rim, this membrane member, one another without have a substantial width against
The pneumatic tire is provided with a cutout for drainage formed of a split surface, and the membrane is displaced in a circumferential direction in each longitudinal groove.

[0008]

[Function] The vertical grooved film prevents air column resonance, reduces tire noise, and reduces the thickness of the film by 0.2.
By setting the cutout to a value of from 2.0 mm to 2.0 mm, drainage can be maintained and a decrease in wet grip performance can be prevented.

An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a cross-sectional view in a standard state where the pneumatic tire 1 is mounted on a regular rim and filled with a regular internal pressure, and FIG. 2 shows a contact surface of a tire tread when a regular load is further applied. Comprises a carcass 6 that is folded from the tread portion 2 to the bead portion 4 through the sidewall portion 3 at the bead core 5 and a belt layer 7 disposed inside the tread portion 2 and outside the carcass 6, The pneumatic tire 1 is formed as a radial tire for passenger cars formed by using an organic fiber cord as the carcass 6 and the belt layer 7. In addition, it can be used for other vehicles such as buses and trucks using a steel cord.

In the present embodiment, the tread portion 2 has a rib pattern having three longitudinal grooves 10 extending continuously in the tire circumferential direction. The number of the vertical grooves 10 may be less than three or four or more. Further, the vertical groove 10 may be a zigzag shape or a so-called straight groove having a linear shape.
The drainage effect is increasing.

The vertical grooves 10 have a groove width of 4 times the tread width.
It is a so-called main groove having a groove depth of about 5% to about 12%, and other fine grooves, sipes, and the like can be provided.
Further, it may be a block type pattern.

Preferably, the film body 12 is arranged in all the vertical grooves 2. The film body 12 has a thickness T measured in the tire circumferential direction.
It forms a thin film having a thickness of 0.5 mm or more and smaller than 2 mm, crosses the vertical groove 10, and can interrupt the circumferential continuity of the vertical groove 10.

The film body 12 is provided with a ground contact length L of each vertical groove 10.
1, L2 (generically referred to as grounding length L), approximately twice (2
The generation of the sound of the wavelength L) due to the air column resonance is caused by the flute 1
0, the pitch length P at which at least one film body 12 is always present in the vertical groove 10 on the ground plane S moving with the rolling, and thus the ground length L A shorter circumference is provided at a distance. It is to be noted that two film bodies 12 may be present on the ground plane S, but when three film bodies 12 exist on the ground plane S, the drainage performance is reduced.

Therefore, the tread surface always has one or two
It is preferable that the peripheral length of the film body 12 be larger than 0.5 times and smaller than 1 time of the ground contact length L so that there are three pieces and three pieces do not exist.

Further, the film bodies 12 are displaced and displaced from each other by a circumferential distance K in each groove 10 so as not to be aligned in the tire axial direction. Thereby, the film body 1
2 can prevent and disperse the cycle of the impact sound and the resonance sound of the air column caused by hitting the road surface.

The film body 12 is provided with a notch 14.
The cut portion 14 is formed by, for example, cutting with a blade.
As a result, as shown in FIG.
It consists of split surfaces that touch each other without any problems.

In addition, as shown in FIG. 3, the cut portion 14 is formed at the center of the film body 12 to a depth reaching the groove bottom in this example.

Thus, as shown in FIG. 4, when the tire rotates on the wet road surface in the direction of D, the vertical groove 10
The water inside flows in the direction of W. Due to this water pressure, the membrane 1
Numeral 2 is easily opened at the cutout 14, drains the water without obstructing the water flow, and maintains the wet grip performance. If the thickness T of the film is less than 0.5 mm, it is opened even by the flow of air and cannot prevent air column resonance. If the thickness T exceeds 2.0 mm, the water flow is obstructed and the wet grip performance is reduced. Has been found to be.

The notch 14 is provided up to the groove bottom to maintain drainage after abrasion. However, as shown in FIG. 5, the notch 14 does not exceed 0.3 times the groove depth H from the groove bottom. Even if terminated at a position P distant from the groove bottom, drainage can be maintained along with rotation of the tire by substantially not abrasion to the groove bottom. At that time, as shown by a dashed line in FIG.
By forming a notch 15 having a circular end and a circular notch 15, the film body can be prevented from being broken and the opening can be facilitated. Also, when reaching the groove bottom, the same notch can be used. A part can be formed.

[0020]

EXAMPLES A tire having a tread pattern shown in FIG. 1 was experimentally produced with a tire having a tire size of 185 / 60R14, and the effect of the present invention was evaluated. Table 1 shows the results. The contact length L of the contact surface S was about 120 mm.

[0021]

[Table 1]

Each of the tires of the example and the comparative example had three straight grooves, and the groove width, groove depth, and groove position were the same.

The noise was evaluated in an anechoic vehicle laboratory.
Noise at a speed of 60 km / h was measured according to the standard of JASOc606. The wet grip performance is an index when the reciprocal of the stopping distance when each tire is mounted on a 1800 cc displacement domestic car and the vehicle is fully braked at a speed of 50 km / h on a wet road of a test course is defined as a comparative example 100. displayed. The larger the value, the better the wet grip performance.

[0024]

Effects of the Invention] According to the present invention, it is possible to reduce the noise caused by the air column resonance of the longitudinal groove, and Ru can be used to ensure the necessary wet grip performance. Also, put the membrane on each flute
Position in the circumferential direction at
The impact sound generated by striking can be dispersed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a tire of the present invention.

FIG. 2 is a plan view illustrating a tread contact surface;

FIG. 3 is a perspective view showing a film body in detail.

FIG. 4 is a perspective view illustrating the operation of the membrane.

FIG. 5 is a front view showing another example of the film body.

[Explanation of symbols]

 2 Tread part 10 Vertical groove 12 Membrane 14 Notch

Claims (1)

(57) [Claims] 1. A tire having a plurality of longitudinal grooves extending continuously in the tire circumferential direction in a tread portion. The longitudinal grooves cut across the longitudinal grooves to interrupt the circumferential continuity and were measured in the tire circumferential direction. At least one film body having a thickness of 0.5 mm or more and less than 2.0 mm is rim-assembled into a regular rim, filled with a regular internal pressure, and present on a ground contact surface with a regular load applied thereto. Have a substantial width
A pneumatic tire characterized in that cut-off portions for drainage, which are formed of split surfaces that are in contact with each other, are provided, and the membrane is displaced in the circumferential direction in each longitudinal groove.