JPH04221207A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To provide a pneumatic tire in which the noise suppressing performance is improved without sacrificing the drainage performance. CONSTITUTION:As for a tire having a plurality of straight line shaped circumferential direction grooves 20 which extend in parallel in substantially endless form in the circumferential direction of the tire on a tread surface part, a plurality of weirs 40 made of polyvinyl alcohol which possesses the property of being softened after water absorption and being hardened when dried are fixing-arranged on the periphery of the tread so as to extend from at least one side wall of the circumferential direction groove to the other side wall. In the traveling on a wet road surface, the weir is softened, and the water flow in the circumferential direction groove is not obstructed, and the superior drainage performance can be secured. In the traveling on a dry road surface, the weir is hardened, and the resonance of air column in the circumferential direction groove is obstructed, and noise can be effectively reduced. Accordingly, the noise can be suppressed advantageously, and the superior traveling feeling as a tire for high speed traveling can be realized.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvements in pneumatic tires, and more particularly to pneumatic tires with improved noise performance without sacrificing drainage performance.

0002

2. Description of the Related Art In recent years, vehicles capable of traveling at high speeds of 200 to 300 km/h have been developed, especially due to the improvement of the road network, and further improvements in tire performance have been desired.

[0003] For pneumatic tires used for high-speed driving, one of the particularly required properties is drainage performance in rainy weather, that is, hydroplaning property (the tire floats up on a water film on the road surface as the tire runs at high speed). , a phenomenon in which the coefficient of friction between the road surface and the tread suddenly decreases), it is desirable to widen the width of the circumferential grooves in the tread pattern and arrange them substantially straight in the circumferential direction of the tire. In fact, most high-speed tires in recent years have been equipped with wide and straight circumferential grooves.

On the other hand, high-speed tires are required to have the above-mentioned drainage performance as well as vehicle comfort, especially low noise, but conventional high-performance tires have wide and straight circumferential grooves. Due to this, there is a drawback that tire noise is significantly generated and the noise property is poor.

[0005] In other words, the noise generated in the tread of a tire mainly includes the impact sound of the pattern and the pumping sound, as well as air column resonance within the circumferential groove (when the land part of the tread hits the road surface on the ground contact surface during running). (When stepping in) and dragging (when kicking off), the phenomenon in which land vibration resonates within the linear circumferential groove) is said to have a large effect, but as mentioned above, in order to improve drainage performance, When the groove width of the circumferential groove is increased, noise generation due to air column resonance in particular becomes significant.

[0006]

[Problems to be Solved by the Invention] Therefore, in conventional pneumatic tires, noise performance must be sacrificed to improve drainage performance, and drainage performance must be sacrificed to improve noise performance. There was a trade-off between drainage and noise.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the conventional pneumatic tires.

[0008] Accordingly, an object of the present invention is to provide a pneumatic tire with improved noise performance without sacrificing drainage performance.

[0009]

[Means for Solving the Problems] That is, the pneumatic tire of the present invention has a plurality of linear circumferential grooves extending substantially endlessly in parallel in the circumferential direction of the tire in the tread surface, and has water absorption. A plurality of weirs made of polyvinyl alcohol having the property of softening when dry and hardening when dry are arranged on the circumference of the tread so as to extend from at least one side wall of the circumferential groove toward the other side wall. It is characterized by being arranged in a fixed manner.

0010

[Function] The pneumatic tire of the present invention has a weir made of polyvinyl alcohol that softens when it absorbs water and hardens when it dries, from at least one side wall of the circumferential groove to the other side wall. As if extending,
In addition, since a plurality of them are fixedly arranged on the circumference of the tread, noise can be improved without sacrificing drainage performance.

That is, when driving on a wet road surface, the weir softens and does not impede the flow of water in the circumferential groove, so excellent drainage performance can be ensured, and when driving on a dry road surface, the weir hardens and forms a partition wall. Since the air column resonance within the circumferential groove is hindered, noise can be effectively reduced.

Therefore, according to the pneumatic tire of the present invention, noise can be advantageously suppressed without sacrificing drainage performance due to the large groove width of the circumferential groove, and the tire is suitable for high-speed running. It is possible to achieve an excellent driving feeling.

[0013]

[Embodiments] Hereinafter, embodiments of the pneumatic tire of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a developed view of a tread surface showing an example of the pneumatic tire of the present invention, FIG. 2 is an enlarged perspective view of portion A in FIG. 1, and FIG. 3 is a diagram showing another example of the pneumatic tire of the present invention. An enlarged perspective explanatory view of the weir portion shown in FIGS. 4(a) and (
b) is an explanatory diagram showing the action of the weir portion during running.

In the drawings, parts other than the tread surface T are not shown, but the parts other than those shown, such as the crown, sidewalls, carcass, and belt layer, have a well-known structure.

Thus, in this embodiment, the tread surface T of the pneumatic tire of the present invention shown in FIG.
The circumferential grooves 20 and 30 of the book are arranged in a straight line and endlessly parallel to the circumferential direction at predetermined intervals in the radial direction.

Although not shown, a plurality of lateral grooves are arranged in the tread surface T in a direction intersecting the circumferential grooves 10, 20, and 30, that is, substantially parallel to the radial direction. Multiple blocks can be formed.

Here, the circumferential grooves 20 and 30 are usually set to have a groove width of 5 to 15 mm and a depth of 7.0 to 10.0 mm, and may have a straight shape as shown in the figure. Although it can be formed into a modified clamp shape, the effect of the present invention is most remarkable when it is a straight shape.

In the pneumatic tire of the present invention constructed as described above, weirs 40 made of polyvinyl alcohol, which has the property of softening when water is absorbed and hardening when dry, are installed in the circumferential grooves 20, 30. It is important that a plurality of them are fixedly arranged around the circumference of the tread so as to extend from at least one side wall to the other side wall, thereby improving noise performance without sacrificing drainage performance. can be achieved.

That is, as shown in FIGS. 1 and 2 (section A in FIG. 1), for example, both side walls 2 of the circumferential groove 20
1 and 22, weirs 40 and 40 are made to face each other and are fixed to each other with a gap 41 maintained therebetween.

The weir 40 is made of polyvinyl alcohol, which has the property of softening when it absorbs water and hardening when it dries.

That is, the weir 40 used here is preferably one made of laminated polyvinyl alcohol (Poval) films cross-linked by electron beams, X-rays, heat, or sulfur, and has a thickness of about 5 to 15 mm. The physical properties of the film are: stress required for 10% elongation: 2,000 to 10
,000Kg/cm2, tensile strength: 200-500K
g/cm2 and elongation: 90 to 200%.

The weir 40 is fixed in a cantilever manner to the side walls of the circumferential grooves 20 and 30 with adhesive or the like.
A plurality of pieces, preferably about 2 to 7 pieces, are arranged around the circumference.

The arrangement of the weir 40 is based on the circumferential grooves 20, 30.
It is preferable that the grooves are arranged on the circumference at equal or irregular intervals, and in a staggered manner as shown between the left and right circumferential grooves 20 and 30.

Furthermore, it is more desirable that one weir 40 be arranged in each circumferential groove 20, 30 in the ground contact surface of the tread.

It is preferable that one weir 40 occupies at least 5% of the groove cross-sectional area of the circumferential grooves 20, 30, and if it is less than 5%, the noise prevention effect is undesirably small.

FIGS. 4(a) and 4(b) illustrate the action of the weir portion during running in the first embodiment described above.

That is, as shown in FIG. 4(a), when the vehicle is running on a dry road surface, the weir 40 hardens and becomes a partition wall, which prevents air column resonance within the circumferential groove 20, thereby effectively reducing noise. be able to.

Furthermore, as shown in FIG. 4(b), when running on a wet road surface, the weir 40 softens and the gap 41 opens wide in the running direction (arrow) of the tire, so that the circumferential groove 2
The flow of water inside the tank is not obstructed, and excellent drainage performance can be ensured.

Next, in the second embodiment shown in FIG.
This embodiment differs from the first embodiment in that it is fixed in a cantilever manner to only one side wall 21 of the circumferential groove 20.

In this case, the area of the weir 40' is increased so that the other side wall 22 becomes a water passage.

In the case of the second embodiment, for example, the weirs 40' can be arranged in a staggered manner within the circumferential groove 20, thereby further improving noise.

Next, the structure and effects of the pneumatic tire of the present invention will be explained in more detail using test examples.

(Test example) Tire size 225/45ZR
17, Rim used: 17 x 8J, Air pressure: 2.5Kg/c
m2, the block pattern shown in Figures 1 and 2 above is applied to the tread of a passenger car tire with a load of 400 kg.
This tire was then evaluated.

[0035] Other structures such as the radial carcass and belt layer of the tire and manufacturing conditions were similar to those of conventional tires, so details will be omitted.

That is, in FIGS. 1 and 2, the depth of each circumferential groove 20, 30 is 8.0 mm, and the groove width is 10.0 m.
m, height of polyvinyl alcohol weir 40: 8.0 mm
, Thickness: 5.0mm, Width of center gap 41: 1.0mm,
The tire of the present invention was obtained by arranging the number of weirs: 5 at irregular intervals on the circumference and staggered in the radial direction.

On the other hand, for comparison, each circumferential groove 20, 30
A conventional tire was obtained in the same manner except that the arrangement of the weir 40 inside the tire was omitted.

Regarding these two types of tires, noise performance (indoor noise measurement during actual vehicle running...all speed average) and drainage performance (
The following table shows the results of an evaluation of the rate at which hydroplaning occurs when an actual vehicle drives on a wet road with a water depth of 6.0 mm.

[0039]

[Table 1]

As is clear from the above results, the tire of the present invention has drainage performance equivalent to that of the conventional tire, and at the same time
Compared to conventional tires, they produce less noise and have improved comfort.

[0041]

[Effects of the Invention] As explained above in detail, the pneumatic tire of the present invention softens the weir when running on a wet road surface,
Since the flow of water in the circumferential grooves is not obstructed, excellent drainage is ensured, and when driving on dry roads, the weir hardens and prevents air column resonance in the circumferential grooves, effectively reducing noise. can be reduced.

Therefore, according to the pneumatic tire of the present invention, noise can be advantageously suppressed without sacrificing drainage performance due to the large groove width of the circumferential groove, and the tire is suitable for high-speed running. It is possible to achieve an excellent driving feeling.

[Brief explanation of the drawing]

[Fig. 1] Fig. 1 is a developed view of a tread surface showing an example of a pneumatic tire of the present invention.

[Fig. 2] Fig. 2 is an enlarged perspective explanatory view of part A in Fig. 1.

[
FIG. 3 is an enlarged perspective explanatory view of a weir portion showing another example of the pneumatic tire of the present invention

[Fig. 4] Fig. 4 (a) and (b) are explanatory diagrams showing the action of the weir part during running.

[Explanation of symbols]

T Tread surface 10 Central circumferential groove 20 Circumferential groove 21 Side wall of circumferential groove 22 Side wall of circumferential groove 30 Circumferential groove 40 Weir 40´　Weir 41 Gap

Claims (1)

[Claims] Claim 1: A tire having a plurality of linear circumferential grooves extending substantially endlessly in parallel in the circumferential direction of the tire in a tread surface, the property of softening when water is absorbed and hardening when dry. A pneumatic tire characterized in that a plurality of weirs made of polyvinyl alcohol having the following are fixedly arranged on the circumference of the tread so as to extend from at least one side wall of the circumferential groove toward the other side wall. .