JPH06106916A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To provide a pneumatic tire wherein generation of a hydroplaning phenomenon is suppressed to concurrently reduce also generation of a noise. CONSTITUTION:In a tire 1, a pair of side walls and a tread part 2 astride between both the side walls are toroidally connected. The tread part 2 is formed by providing s main peripheral groove 5 and a subperipheral groove 6 substantially parallel relating to a plane, containing respective tread circumference in a tread part central region 3 and its both side directional regions 4 over the total periphery of the tread part, further by providing directivity pattern respectively extended into a herringbone pattern from both side walls of the main peripheral groove 5 to arrange a plurality of oblique grooves 7, and the main peripheral groove 5 is formed by connecting broad and narrow width parts W1, W2 through a width gradually reduced part with a circumferential space in accordance with an arranging pitch of the oblique groove 7 and by connecting one end of the oblique groove 7 to this broad width part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a directional pattern that enhances drainage when running on a wet road surface, suppresses the occurrence of hydroplaning phenomenon, and at the same time reduces noise generation on a dry road surface. It relates to a pneumatic tire.

[0002]

2. Description of the Related Art Pneumatic tires for general use are required to have stable performance under various road surface conditions used, for example, dry road surfaces as well as wet road surfaces. When running on a wet road surface with this pneumatic tire,
Depending on driving conditions, a large amount of water may enter between the road surface and the tire contact surface. If the water film existing between them is thin, the water film on the road surface can be destroyed by the action of the arrangement angle of the tread groove formed in the tread of the tire and the action of the rotational force of the tire. The water in the membrane is in front of the tire,
Since it can be discharged laterally and backward smoothly, the contact area between the tire and the road surface can be maintained without being disturbed by the water film, and the force can be normally transmitted between the tire contact surface and the road surface. .

However, as the water film on the road surface becomes thicker,
The water film on the road surface cannot be completely destroyed by the tread groove or the like, and in this case, water is forced to enter the tire ground contact surface. Even if water enters the contact surface like this, there is no problem if it drains quickly to the side or rear of the tire and the tire can normally contact the road surface, but it is better than the amount of drainage to the side or rear of the tire. When the amount of water that has entered the ground contact surface is larger, the water will stop in the ground contact surface, so the area where the tire is in direct contact with the road surface decreases, and when this area becomes zero the tire The surface of the water slides, causing a so-called hydroplaning phenomenon. When this phenomenon occurs, the tires completely ride on the water without making direct contact with the ground and lose its maneuverability. As a result, it often leads to an accident.

Therefore, various studies have been made on a method of suppressing the occurrence of the hydroplaning phenomenon. In order to suppress the occurrence of this phenomenon, it is important how smoothly the water film on the road surface where the tire touches the ground can be removed.

A typical example of the one having improved drainage is a tire having a directional pattern. This tire has a plurality of lateral grooves in the tread, which are arranged so as to incline from the central area of the tread toward both side areas so as to enter the contact areas in sequence (Fig. 4). The existing water can be effectively pushed out to the outside of the front of the tire, and as a result, the water can be prevented from entering the tire contact surface, so that the hydroplaning phenomenon is less likely to occur.

[0006]

However, even in a tire having this directional pattern, as the water film on the road surface becomes thicker, more water will come into the tire ground contact surface. Due to the groove shape peculiar to this tire, this invaded water tends to collect water in the central area of the tread portion, so the central area of the tread portion easily floats above the water surface, and subsequently the lateral area floats up, The hydroplaning phenomenon occurs when the entire ground contact surface gets on the water.

From the above, in the case of a tire having a directional pattern, water that has entered between the tire contact surface and the road surface, especially water that has entered the central region of the tread portion, can be promptly removed rearward without stagnation. Whether or not drainage is good depends on whether or not the drainage is good.

Therefore, the present invention improves drainage performance in a pneumatic tire having a directional pattern, specifically, in the case where the water film present on the road surface is considerably thick,
The problem is to suppress the occurrence of the hydroplaning phenomenon by promptly removing the water that has entered the tire contact surface to the rear of the tire. The present invention was also able to reduce the noise generated by the tire itself when running on a dry road surface, and will be described later.

[0009]

SUMMARY OF THE INVENTION According to the present invention, a pair of sidewalls and a tread portion extending between the sidewalls are connected in a toroidal shape, and the tread portion has a tread portion central region and both side regions thereof over the entire circumference thereof. A directional pattern having a main circumferential groove and a sub circumferential groove that are substantially parallel to a plane including the tread circumference, and further having a plurality of diagonal grooves extending from both side walls of the main circumferential groove and forming an arrow shape. In a pneumatic tire that has a main circumferential groove, a wide width portion and a narrow width portion having circumferential intervals according to the pitch of the diagonal groove are connected through a gradually decreasing width portion, and one end of the diagonal groove is communicated with this wide width portion. It is a pneumatic tire characterized by being. Further, the ratio of the groove width of the narrow portion W _{1 to} the wide portion W ₂ is 0.4 to
It is more preferably 0.9.

An example of a pneumatic tire according to the present invention is shown in FIG.
In the figure, 1 is a pneumatic tire, 2 is a tread portion, 3 is
Is a central region of the tread portion, 4 is a lateral region of the tread portion, 5 is a main circumferential groove, 6 is a sub circumferential groove, and 7 is an oblique groove.

In the pneumatic tire 1 of the present invention, a pair of sidewalls and a tread portion 2 extending between the sidewalls are connected in a toroidal shape. The tread portion 2 has a tread central area 3 and side areas 4 along the entire circumference.
Is provided with a main circumferential groove 5 and a sub circumferential groove 6 which are substantially parallel to a plane including the tread circumference, and a plurality of diagonal grooves 7 extending from both side walls of the main circumferential groove 5 and having an arrow shape. It has a directional pattern.

According to the present invention, the main circumferential groove 5 is provided with the oblique groove 7 by a pitch.
Wide part W with a circumferential interval according to ₂And narrow part W₂And
The wide width portion W of the main circumferential groove 5 is connected through the gradually decreasing width portion.₂No slope
It is characterized in that one end of the female groove 7 is communicated.

Further, the wide portion W ₂ of the narrow portion W ₁ of the main circumferential groove 5
It is more preferable that the ratio to the ratio is 0.4 to 0.9. If this ratio is less than 0.4, the water that has entered the main circumferential groove 5 is excessively squeezed in the narrow portion, so that backward discharge cannot be performed quickly, and if it exceeds 0.9, the function as a squeeze is no longer fulfilled. This is because the rearward discharge cannot be performed quickly also in this case.

[0014]

[Function] Since the hydroplaning phenomenon is caused by the intrusion of water into the ground contact surface of the pneumatic tire, the quality of the drainage has a great influence. Specifically, the water film on the road surface is relatively small. When the tire is thick (about 10 mm), for example, as the rotational speed of the tire increases, even if water is pushed out to the front of the tire, a large amount of water will be present in the tire ground contact surface, so that the amount of water behind the tire at this time will increase. It has already been mentioned above that the quality of the water removal ability greatly affects the occurrence of the hydroplaning phenomenon. Here, the operation of the inventive tire will be described in comparison with a conventional tire having a directional pattern. The inventive tire is characterized by the tread pattern, and other structures can be followed because a general pneumatic tire does not need to be modified.

The conventional tire having a directional pattern is more excellent in the ability to push water out of the front of the tire (drainability) than the tire having a non-directional pattern. However, even if the ability to push the water forward of the tire is excellent, as the amount of water on the road surface increases, more water will exist in the tire ground contact surface.In this case, due to the groove arrangement specific to the directional pattern, It is easy for water to be drawn into the ground contact surface, and it is particularly easy for water to collect in the central area of the tread portion rather than in the lateral area.
As a result, as the amount of water that penetrates into the tire contact surface increases, the central area of the tread portion first rides on the water, and then the side area of the tread portion begins to ride on the surface area where the tire directly contacts the road surface. When becomes zero, the hydroplaning phenomenon occurs.

Therefore, the inventor of the present invention promptly removes water invading the central region of the tread portion in the tire contact surface, particularly water invading the main circumferential groove and water invading oblique grooves communicating with the main circumferential groove, from the rear side of the tire. It was thought that the discharge to the water would suppress the occurrence of the hydroplaning phenomenon.

Therefore, in the tire of the present invention, in order to promptly drain the water that has entered the tread portion central region 3, the main circumferential groove 5 which has been arranged with the same width over the entire circumference of the conventional tread portion 2 is used.
Has a structure in which a wide width portion and a narrow width portion having a circumferential interval according to the arrangement pitch of the oblique groove 7 are connected via a gradually decreasing width portion, so that water that has entered the main circumferential groove 5 in the tire ground contact surface is The drainage speed to the rear of the tire is increased and removed by the strength of the water pressure in the main circumferential groove, or the action of a pump, so to speak, and by connecting one end of the diagonal groove 7 to this wide portion, The water that has entered also easily flows into the main circumferential groove 5 due to the water pressure relationship with the main circumferential groove 5, and this water is also removed to the rear of the tire together with the water in the main circumferential groove 5.

From the above, in the tire of the present invention, even if water enters the central region 3 of the tread portion, the water can be quickly discharged to the rear of the tire, so that the occurrence of the hydroplaning phenomenon can be suppressed. It was

Further, when running on a dry road surface, when air flows into the tread groove in the tire ground contact surface, and this air is rapidly discharged to the outside, noise called blow-off noise is generated, which is a problem. . However, since the main circumferential groove 5 has a structure in which the width of the groove is periodically repeated as described above, a so-called silencer effect can be obtained, and thus an effect of reducing noise can also be obtained.

[0020]

EXAMPLE A tire of 205 / 55R16 having a carcass of polyester cord and three belt layers (two steel layers and one nylon cap layer) having a known structure was used for drainage and A noise test was conducted. -Test tire The test tire is the invention tire shown in FIG. 1 and the conventional tire shown in FIG. The invention tire has the main circumferential groove 5 of the tread portion 2.
Has a structure in which a wide width portion W ₂ and a narrow width portion W ₁ having a circumferential interval according to the arrangement pitch of the diagonal groove 7 are connected via a gradually decreasing width portion, and the diagonal groove 7 is communicated with the wide width portion. Have.

The widths of the narrow width portion W ₁ and the wide width portion W ₂ of the main circumferential groove 5 are set to 8.5 mm and 14.5 mm, respectively. In this case, the W ₁ / W ₂ ratio is 0.59. In addition, W ₁ / W
The ratio of ₂ is more preferably in the range of 0.4 to 0.9.

Although the width of the main circumferential groove 5 is varied, the side walls of the groove are periodically changed in the width direction of the tread portion. However, the present invention changes the cross-sectional area of the main circumferential groove 5 periodically. Since the purpose can be achieved by this, only one side wall of the main circumferential groove 5 may be changed, and in that case, it is preferable to form the side wall on the outer side in the width direction of the tread portion (FIG. 2). The shape of the side wall of the main circumferential groove 5 is preferably curved, but may be linear. In the representative examples of the invention tires (FIGS. 1 to 3), the directional patterns that are symmetrical with respect to the equatorial plane are shown, but the invention can also be applied to the case of the asymmetrical directional pattern.

The conventional tire has the same structure as the invented tire except that the tread portion 2 has a general directional pattern and the main circumferential groove 5 has the same width over the entire circumference.

Test method: The drainage property is measured by measuring the speed at which a hydroplaning phenomenon occurs when the tire is mounted on an actual vehicle and the vehicle is run on a road surface covered with water at a water depth of 10 mm while gradually increasing the speed. It was evaluated by The noise is measured by running on a rotating drum with a smooth surface and using the tire noise test method (JASOC606).
Was evaluated by measuring the band power value near the 1.8 kHz peak. Table 1 shows the test results.

[0025]

[Table 1]

From these test results, the tire of the present invention is suppressed in the occurrence of the hydroplaning phenomenon as compared with the conventional tire. Furthermore, the effect of reducing the noise generated by the tire itself is also recognized.

[0027]

According to the present invention, in a tire having a directional pattern, the tread portion 2 is large even when there is a large amount of water on the road surface which diminishes the effect of extruding water to the front of the tire, which is a characteristic of the tire. the main circumferential groove 5 of the wide portion W ₂ and the narrow portion W ₁ for placing the circumferential spacing chosen through a gradually decreasing width portion responsive to arrangement pitch of the oblique grooves 7 and communicates the oblique groove 7 in the wide portion structure As a result, the water that has entered can be promptly removed to the rear of the tire, and as a result, the occurrence of the hydroplaning phenomenon can be suppressed. Further, since the main circumferential groove 5 has a shape exhibiting a sound deadening effect on a dry road surface, it is also effective in reducing noise.

[Brief description of drawings]

FIG. 1 is a front view of a main portion of a developed tread portion of an inventive tire used in an example.

FIG. 2 is a front view of a main portion of a tread portion of another invention tire developed.

FIG. 3 is a front view of a main portion of a tread portion of another invention tire developed.

FIG. 4 is a front view of a main portion of a tread portion of a conventional tire developed.

[Explanation of symbols]

 1 Pneumatic tire 2 Tread area 3 Central area of tread area 4 Lateral area of tread area 5 Main circumferential groove 6 Secondary circumferential groove 7 Diagonal groove 8 Center circumferential line 9 Tire rotation direction W1 Narrow width portion W2 Wide width portion

Claims (2)

[Claims] 1. A pair of sidewalls and a tread portion extending between the sidewalls are connected in a toroidal shape, and the tread portion has a plane including a tread circumference in the central region of the tread and both side regions thereof over the entire circumference thereof. In the pneumatic tire having a directional pattern having a main circumferential groove and a sub circumferential groove that are substantially parallel to each other, and further arranging a plurality of oblique grooves extending from both side walls of the main circumferential groove and forming an arrow shape, Pneumatic, characterized in that a wide width portion and a narrow width portion having a circumferential interval corresponding to the pitch of the diagonal groove are connected to each other through a gradually decreasing width portion, and one end of the diagonal groove is connected to this wide width portion tire. 2. The pneumatic tire according to claim 1, wherein the ratio of the groove width of the narrow width portion (W ₁ ) to the wide width portion (W ₂ ) is 0.4 to 0.9.