JPH0450006A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve water runaway ability and prevent hydroplaining from occurring by providing curved grooves in a hyperbola shape which extends toward a shoulder part gradually in a tire anti-rotation direction with the part in vicinity of a main groove taken as a starting point respectively on both the right and left sides of the main groove in a treat surface. CONSTITUTION:A tread pattern is a directional pattern with an arrowheaded direction T taken as a tire rotational direction. With this constitution, one main groove 2 which continues over the whole periphery in a tire peripheral direction EE' is provided at the central part of a tread surface 1, and plural sub-grooves 3 which continue from the main groove 2 to both shoulder ends on both of right and left sides are provided. Besides, plural curved grooves 5 in a hyperbola shape are provided from a position in vicinity of both the sides of the main groove 2 to both side shoulder parts 4, 4. The curved grooves 5 are formed so that its tangential line in vicinity of the main groove may have an angle of 0-45 degree to the tire peripheral direction, its tangential line at the shoulder part may have an angle of 45-90 degree to the tire peripheral direction and the curved grooves may be drawn in a hyperbola shape in a top view.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pneumatic tire with improved drainage performance.

[Conventional technology]

Conventionally, wet road performance of pneumatic tires for passenger cars (
In order to improve wet performance (wet performance) and prevent hydroplaning, tires having a trend pattern called a directional pattern as shown in FIGS. 7 and 8 have been proposed. In FIG. 7, a helical (sine wave) sub-groove 3 is provided on a tread surface 1 whose rotational direction is T so as to cross a plurality of linear main grooves 2 provided in the circumferential direction of the tire. There is. In FIG. 8, a slightly curved chevron-shaped sub-groove 3 is provided on a tread surface 1 whose rotational direction is T, so as to cross a plurality of linear main grooves 2 provided in the circumferential direction of the tire.

However, with the tread pattern shown in Figure 7,
- Because there is an inflection point in the middle of the sub-groove 3, water in the ground contact surface experiences great resistance at the inflection point when water is drained out of the contact surface through the sub-groove 3 when driving on a wet road. There was a problem that drainage efficiency decreased. Although the tread pattern shown in FIG. 8 has improved drainage efficiency compared to the tread pattern shown in FIG. 7, it has not yet reached a satisfactory level in terms of drainage performance when running at high speeds exceeding 80 km/h.

[Problem to be solved by the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a pneumatic tire that improves drainage performance and prevents hydroplaning when traveling on a wet road at high speed or when the water film is thick.

[Means to solve the problem]

In the pneumatic tire of the present invention, a leading edge is provided on the tread surface that continues for one circumference in the tire circumferential direction, and shoulders are formed on both left and right sides of the leading edge starting from the vicinity of the main groove and gradually toward the anti-rotation side of the tire. A hyperbolic curved groove extending toward the end of the shoulder part is provided, and the hyperbolic curved groove has an angle of a tangent to the tire circumferential direction at the side with the main groove in a range of 0 to 45 degrees. Therefore, the angle of the tangent at the shoulder with respect to the tire circumferential direction is 45
It is characterized by being in the range of @ to 90°.

In this way, in the present invention, hyperbolic curved grooves are provided so as to extend from the main grooved side to both shoulder parts.
This hyperbolic curved groove acts like a main groove at the main grooved side and acts like a sub-groove at the shoulder portion, making it possible to improve drainage performance.

In addition, in the present invention, "hyperbolic shape" does not mean a strict hyperbola, but also includes a curve similar to a hyperbola.

Hereinafter, the above means will be explained in detail with reference to the drawings.

FIG. 1 is an explanatory plan view showing an example of a trend pattern of the pneumatic tire of the present invention. In FIG. 1, the tread pattern is a directional pattern with the direction of arrow T as the rotational direction of the tire, and in the center of the tread surface 1 there is one main line that continues for one circumference in the tire circumferential direction EE'. A groove 2 is provided, and a plurality of sub-grooves 3 are provided extending from the main groove 2 to both left and right sides to both shoulder ends. moreover,
A plurality of hyperbolic curved grooves 5 are provided in both shoulder portions 4.4 from very close positions on both the left and right sides of this main groove 2, respectively.

The curved groove 5 has a shape that starts near the main groove 2, gradually moves toward the shoulder portion in the counter-rotation direction of the tire, and finally exits to the end of the shoulder portion. In this curved groove 5, the tangent in the vicinity of the main groove 2 is at an angle of 0 to 45'', preferably 0 to 15'' with respect to the tire circumferential direction, and the tangent at the shoulder part is at an angle of 0 to 15''. The angle is in the range of 45° to 90° with respect to the circumferential direction, and the shape is hyperbolic in plan view. The starting point of this curved groove 5 does not necessarily have to be separated from the main groove 2, and may be connected to the main groove 2.Also, it is better to provide a sub-groove 3, but as shown in FIG. It does not have to be provided.

By the way, in order to prevent the occurrence of hydroplaning, it is important to prevent water from entering the ground contact surface of the tire and to secure a larger ground contact area. As a means for this purpose, grooves are provided on the trend surface, and the arrangement and direction of the grooves are optimized to improve drainage performance. Therefore, when we observed the drainage route within the ground plane, we found that
The main groove provided in the circumferential direction of the tire has the most important effect on drainage performance, and when water introduced into the main groove exceeds the capacity of the main groove, it is introduced into the sub-groove. Therefore, the effect of the sub-grooves becomes especially important when driving at high speeds or when the water film in the ground contact surface is thick. Since the hyperbolic curved groove 5 provided in the present invention is oriented in a direction substantially along the main groove 2 in the central region of the tread, it performs the same function as the main groove 2 in this portion. Further, in the present invention, since a large number of hyperbolic curved grooves 5 are provided, drainage performance is improved.

In addition, the hyperbolic curved groove 5 is close to the sub-groove 3 in the shoulder part 4, but because of its hyperbolic shape, there is no inflection point in the drainage path and it can smoothly pass through to the end of the shoulder part 4. I can do it. In this way, in the present invention, the curved groove 5 is made to have the functions of both the main groove and the sub-groove. In addition, by making the curve 5 hyperbolic in this way, water escapes in a direction perpendicular to the leading edge end when cornering, so drainage efficiency can be particularly improved during cornering.

The main groove 2 is most preferably linear, but does not necessarily have to be linear as long as it is see-through in the tire circumferential direction; for example, it may be zigzag. Moreover, although it is preferable that one main groove 2 be arranged at a part of the center in the width direction of the tire, a plurality of main grooves 2 may be arranged. This is because when there is only one main groove 2, the main groove 2 and the pinch of the rain group do not coincide with each other on a road surface provided with a rain loop, so that the wandering phenomenon does not occur.

Further, as described above, in the present invention, by arranging the sub-grooves 3, drainage performance is further improved. In addition, sub groove 3
, the starting end 5° of the curved groove 5 may either penetrate through the sub-groove 3 or remain in contact with the sub-groove 3.

The main groove 2 and the curved groove 5 may be connected via a kerf 6, as shown in FIGS. 2 and 3, and the pattern of the trend surface 1 is as shown in FIGS. 1 and 2. As shown in FIG. 3, the main groove 2 may be arranged in a left-right symmetrical pattern in a part of the center in the width direction of the tire, or as shown in FIG. It may be a left-right asymmetric pattern.

Since the pneumatic tire of the present invention thus constructed has a directional pattern, when it is mounted on a vehicle,
As shown in FIG. 4, the direction of the starting end 5'' of the curved groove 5 is aligned with the tire rotation direction T when viewed from above. In the case of a tire with an asymmetric pattern shown in FIG. 3, the shoulder portion side where the distance from the main groove 2 to the shoulder portion 4 is smaller is the inner side of the vehicle. This is to improve steering stability during cornering.

Examples are shown below.

Example The following four types of pneumatic tires with tire size 225150 R16 (invention tire 1.II, conventional tire I, I
Regarding I), the rate of hydroplaning occurrence was evaluated. The results are shown in FIG. Note that the tire structures and materials of these tires were all the same.

(11 Tire of the present invention I.

It has a tread pattern shown in FIG. In Figure 5,
Only the main groove 2 and the hyperbolic curved groove 5 are arranged on the tread surface 1.

(2) Inventive tire ■.

It has a tread pattern shown in FIG. In Figure 6,
In addition to the main groove 2 and the hyperbolically curved groove 5, sub-grooves 3 are arranged on the tread surface 1.

(3) Conventional tires■.

It has a tread pattern shown in FIG. In Figure 7,
A tread surface 1 is provided with a main groove 2 and a helical sub-groove 3.

(4) Conventional tires■.

It has a tread pattern shown in FIG. In Figure 8,
The tread surface 1 is provided with a main groove 2 and a mountain-shaped sub-groove 3.

Each tire capable of hydroplaning was mounted on a vehicle, and the vehicle was run on a wet paved road surface with a water depth of #10III11 while gradually increasing the speed, and the speed at which hydroplaning occurred was measured.

As can be seen from Figure 9, the conventional tires ■ and ■ have a
Hydroplaning occurs before the tire reaches a speed of km/h, but in the tires I and II of the present invention, the hydroplaning occurred at a speed of 801 v/h for the former and 92 km/h for the latter, both of which were faster than the conventional tires. The speed at which hydroplaning occurs is higher than that of tires ■ and ■. Therefore, the tires 1 and 2 of the present invention have better drainage performance than the conventional tires 1 and 2.

〔Effect of the invention〕

As explained above, according to the present invention, a main groove is provided on the trend surface that continues all around the tire in the circumferential direction, and grooves are formed on both left and right sides of the main groove, starting from the vicinity of the main groove. A hyperbolic curved groove is provided on the anti-rotation side of the tire that gradually goes to the shoulder and exits at the end of the shoulder, making it possible to improve drainage performance, which makes it possible to drive at high speeds on wet roads. Hydroplaning can be prevented even when the water belly is thick.

[Brief explanation of drawings]

1 to 3 are plan view explanatory diagrams showing an example of the tread pattern of the pneumatic tire of the present invention, FIG. 4 is a perspective explanatory diagram of an example of the pneumatic tire of the present invention, and FIGS. 5 and 6 are respectively 7 and 8 are plan view explanatory views showing an example of the tread pattern of a conventional pneumatic tire, and FIG. The figure is an explanatory diagram showing the hydroplaning occurrence speed of each tire. DESCRIPTION OF SYMBOLS 1... Tread surface, 2... Main groove, 3... Sub groove, 4... Shoulder part, 5... Curved groove, 6... Kerf. Tada

Claims (1)

[Claims] A leading part is provided on the tread surface that continues all around the tire in the circumferential direction, and on both the left and right sides of the leading part, starting from the vicinity of the main groove, the leading part gradually moves toward the anti-rotation side of the tire toward the shoulder part. A hyperbolic curved groove is provided at the end, and the angle of the tangent to the main grooved side with respect to the tire circumferential direction is 0 to 45.
A pneumatic tire in which the angle of the tangent at the shoulder portion with respect to the tire circumferential direction is in the range of 45° to 90°.