JPH05254312A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To provide a pneumatic tire which has such a tread pattern as allowing both reduction of tire noise and the wet hydroplaining property to coexist. CONSTITUTION:A pneumatic tire is so constructed that a pair of side walls 2 and a crown part 3 extending over both side walls 2 are connected to each other like a toroid, the crown part 3 includes a tread 1 engaged with the road surface, and the tread 1 includes a circumferential groove 6 extended substantially in a straight line toward the circumferential direction in the side area thereof, plural lug grooves 9 extended from the tread side end 8 to the circumferential groove 6 and land parts 10 divided by a group of grooves. Further, a means 11 for at least obstructing a smooth flow of a fluid flowing in the lug grooves 9 at the time of running is provided comparatively close to the circumferential groove 6.

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 tire tread pattern which achieves both low tire noise and wet hydroplaning.

[0002]

2. Description of the Related Art Conventionally, in a tire whose rotation direction is specified, for example, a pair of circumferential straight grooves sandwiching the equatorial plane of the tire in the center of the tread, and these circumferential grooves and both ends of the tread. Each of them is provided with an intermediate circumferential straight groove, and a large number of inclined lug grooves are arranged in a direction converging toward the center of the tread between both ends of the tread to the central circumferential groove. An arrow-shaped tread made by dividing the is known. In this case, the circumferential groove located on the axially outer side of the tread and the inclined lug groove connecting the both ends of the tread were formed to have substantially the same width and depth at any position in the longitudinal direction.

[0003]

In the above-mentioned conventionally known treads, the noise level contributing to the shoulder lug groove is sometimes deteriorated. This can be called a shoulder lug blowout sound, and is due to the flow action of the air that has entered the shoulder lug groove from the shoulder circumferential groove, that is, the pump action. A method of reducing the volume as a whole, that is, a method of making the lug groove thin or shallow, or a combination of both was adopted. However, it was generally accepted that such a method would hinder drainage during wet in the shoulder lug groove, making it difficult to achieve both low noise performance and wet performance.

The present invention was devised in order to solve the problems of the prior art as described above, and its purpose is to make the outermost lug groove structure of the tread the outermost circumferential groove. By adopting a special structure that prevents air flowing from the direction from flowing smoothly, we aim to reduce tire noise while also making it possible to avoid deterioration of hydroplaning performance, noise reduction and wet hydroplaning. It is to provide a pneumatic tire having a tread pattern that achieves both properties.

[0005]

In order to achieve the above object, in a pneumatic tire of the present invention, a pair of sidewalls and a crown portion extending over both sidewalls are connected in a toroidal shape, and a road surface is connected to the crown portion. A circumferential groove having an engaging tread, the tread extending substantially linearly in a circumferential direction in a side area thereof, a plurality of lug grooves extending from the tread side end toward the circumferential groove, and the groove group. In a tire including a land portion divided by, there is provided a means including at least a means for hindering a smooth flow of fluid flowing in the lug groove at a position relatively close to the circumferential groove during traveling. To be done.

[0006]

The operation of the pneumatic tire constructed as described above will be described as follows: 1) In the area near the inlet of the shoulder lug groove from the main circumferential groove of the shoulder portion, the shoulder in the ground contact surface during ground contact rolling The flow of air that has entered from the circumferential main groove into the shoulder lug groove is blocked in the flow direction of the shoulder lug groove by the crossing direction of the shoulder lug groove from the main circumferential groove of the shoulder lug, bending, or resistance such as restriction. By holding and attenuating it, it is linked to the reduction of noise. 2) Therefore, the cross-sectional volume of the shoulder lug groove should be kept within a range necessary for wet drainage, and the shoulder lug groove should act independently on wet drainage and then be emitted from the shoulder lug groove. It has such an action to suppress the generated noise. 3) As a result, the wet hydroplaning property and the reduction of tire noise can both be achieved.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a tread pattern of a pneumatic tire according to an embodiment of the present invention, and FIGS. 2 (a) and 2 (b) show shoulder lug grooves in the tread pattern of the pneumatic tire of FIG. FIG. 3 is an enlarged plan view of a constricted portion provided as a means for hindering a smooth flow of flowing fluid, and FIG. FIG. 3 is a cross-sectional view of the shoulder lug groove in the tread pattern of the pneumatic tire of FIG. 1 in which a ridge is provided in the lug groove as a means for hindering a smooth flow of fluid flowing in the shoulder lug groove. FIG. 4 is a diagram showing a tread pattern of a pneumatic tire of a comparative example.

In FIG. 1, reference numeral 1 is a tread, which is formed so that a pair of (a part of) the sidewalls 2 and a crown portion 3 extending over both sidewalls 2 are connected in a toroidal shape, and the crown portion 3 engages with a road surface. Has been done. The tread 1 has a center rib 4 at the center, and a center circumferential groove 5 and a shoulder circumferential groove 6 are arranged on the outer side of the tread 1 symmetrically with respect to the equatorial plane C. In the meantime, the inclined lug groove 7 is bored in the circumferential direction. There is a shoulder lug groove 9 between the shoulder circumferential groove 6 and the tread end 8, and the shoulder lug groove 9 is close to the shoulder circumferential groove 6 as a means for preventing the air entering from the shoulder circumferential groove from flowing smoothly. Letter 1
It is bent in a shape of 1, and is arranged at an appropriate pitch on the circumference of the tire in the circumferential direction, and between these shoulder lug grooves 9 is a shoulder land portion 10. The bending of the shoulder lug groove 9 hinders the flow of fluid to reduce tire noise.

FIGS. 2 (a) and 2 (b) show a shoulder circumferential groove 6 and a shoulder lug groove 9 having a shape narrowed in the direction of the shoulder circumferential groove 6 as means for giving resistance to the fluid flowing in the lug groove. The constricted part 12 is formed in the shoulder lug groove 9 near the connection part. The shoulder lug groove 9 has a shape that narrows in the direction of the shoulder circumferential groove 6, but since the drainage property itself when running on a wet road surface is not much different from the conventional one, the presence of this constricted portion is present. By cooperating with the above, while maintaining the wet hydroplaning property, it is possible to provide resistance to the flow of the air entering from the shoulder circumferential groove 6 to attenuate the noise and promote the reduction of the tire noise. .. In FIG. 2, only one groove wall is used for squeezing,
Needless to say, the groove walls may be narrowed or a constricted portion may be provided in the opening to the shoulder circumferential groove 6. FIG. 3 also shows the bottom 9 of the shoulder lug groove near the shoulder circumferential groove 6 as a means for giving resistance to the fluid flowing in the lug groove.
This is a modified embodiment in which the ridge 13 is formed on B, but this is only provided with a constricted portion in the cross-sectional direction, and the function and effect are substantially the same as those of the modified embodiment of FIG. In each of the above examples, resistance is given to the air flowing in the lug groove,
While aiming to reduce the noise of the tire, it is configured to prevent the deterioration of the wet hydroplaning property, and it is intended to achieve both the reduction of the tire noise and the wet hydroplaning property. Of course, the shoulder circumferential groove and the lug groove may be completely blocked as long as they are not damaged. Further, it is of course possible to form a constricted portion on both the groove bottom and the groove side wall of the shoulder lug groove 9, for example, a combination of the embodiments shown in FIGS. 2B and 3. But it is okay. Further, the constricted position is preferably axially inward of the outer wall of the shoulder circumferential groove and the center of the tread ground contact end, and is preferably located near the shoulder circumferential groove. When the present invention as shown in the above embodiment is applied to the tread of the pneumatic tire, it is limited to the arrow-shaped tread (unidirectional tread) as shown in FIG. 1, and the rotation direction of the tire is as shown in FIG. The lower side must be the step-in side and the upper side must be the kick-out side. That is, the pneumatic tire of the present invention is not hurt even if there is a means for resisting the fluid flowing in the lug groove as the water drainage in the shoulder lug groove as described above for the first time under such conditions. As a result, both reduction of tire noise and wet hydroplaning can be achieved.

The basic examples of the tread pattern of the pneumatic tire of the present invention have been described above. Next, the tread patterns of the examples and comparative examples of the present invention were applied to the pneumatic tires for test, and the tread patterns were tested on an indoor unit stand. A test (automobile standard tire noise test method JASOC 606) was carried out and will be described. At that time, the tire size of the pneumatic tire was 205 / 55R16, the carcass had two polyester cord layers, and the belt layer had steel cord layers 2.
It is a tire having a common structure, and the tread patterns of the comparative example and the example are as shown in FIGS. 1, 2 and 4.

Results of indoor unit bench test (automobile standard tire noise test method JASOC606): Peak value of 1.8 KHz at a speed of 50 km / h

From the results of the above test, the reduction in the sound pressure level at the peak value of 1.8 kHz at the speed of 50 km / h shows that the shoulder lug groove has a constriction, a bend,
It is clear that this is due to the result of the provision of a means such as a throttle to prevent the smooth flow of fluid. Regarding wet hydroplaning, the discharge itself in the shoulder lug groove is reduced even if the above flow resistance means is provided. It turned out not to do.

[0013]

As described in detail above, in the pneumatic tire of the present invention, the means for hindering the smooth flow of the fluid flowing in the shoulder lug groove at the time of traveling in the arrow tread is located relatively close to the circumferential groove. In preparation for
While ensuring the cross-sectional volume of the shoulder lug groove as much as necessary for wet drainage, noise generated from the shoulder lug groove can be suppressed, and as a result both low tire noise and wet hydroplaning can be achieved. It has the effect of being able to do so.

[Brief description of drawings]

FIG. 1 is a diagram showing a tread pattern according to an embodiment of the present invention.

FIG. 2A is a diagram showing a tread pattern of another embodiment of the present invention. (B) is an enlarged view of the lug groove structure of (a).

FIG. 3 is an enlarged view showing a lug groove structure of still another embodiment of the present invention.

FIG. 4 is a tread pattern showing a comparative example showing a conventional technique.

[Explanation of symbols]

 1 tread 2 sidewall 3 crown part 4 center rib 5 center part circumferential groove 6 shoulder circumferential groove 7 lug groove 8 tread end 9 shoulder lug groove 10 shoulder land part 11 letter 12 constricted part 13 ridge

Claims (1)

[Claims] 1. A pair of sidewalls and a crown portion that straddles both sidewalls are connected in a toroidal shape, and a tread that engages with a road surface is provided on the crown portion, and the tread is substantially circumferentially provided in a side area thereof. In a tire including a linear groove extending in a straight line, a plurality of lug grooves extending from the tread side end toward the circumferential groove and a land portion divided by the groove group, a fluid flowing in the lug groove during traveling. A pneumatic tire comprising means for at least preventing smooth flow at a position relatively close to the circumferential groove.