JPH02299910A - Pneumatic tire excellent in wet performance - Google Patents

Abstract

PURPOSE:To improve durability and wet performance by forming on a tread surface a plurality of sipe regions consisting of closed curve-like thin grooves having a specified width and specifying a ratio of the total surface area of each sipe region to the total surface area of the tread surface. CONSTITUTION:Each half section of a tread 10 halved by the equator surface S of a tire is formed with a plurality of lug grooves 14 connected respectively to slant grooves 16 slantly crossing the equator surface S of the tire. An end of a connecting groove 18 is opened to the crossing portion O of said respective grooves 14, 16. A tread surface 20 is defined by said respective grooves 14, 16, 18. Thus, the tread surface 20 is provided with a plurality of sipe regions 22 defined by closed curve-like thin grooves having 2mm or less width a. The rate R of the total surface area throughout the whole periphery of the tire in each sipe region 22 to the total surface area throughout the whole periphery of the tire on the tread surface 20 is set to 30-70%.

Description

Detailed Description of the Invention (Field of Industrial Application) This invention provides a pneumatic tire that has excellent uneven wear resistance and cyptear resistance, and also has excellent maneuverability under wet road surfaces, especially for heavy-duty tires. It concerns pneumatic tires.

(Prior Art) Heavy-duty pneumatic tires used for trucks, buses, construction vehicles, etc. that require high driving performance and braking performance are designed with wide lateral grooves extending substantially in the width direction of the tire. Those with a lug pattern consisting of such lateral grooves and wide circumferential grooves extending in the circumferential direction of the tire; A block pattern consisting of a plurality of blocks is preferably used.

Normally, the tread surface defined by the wide grooves that define these patterns, that is, the rubber surface that comes into direct contact with the road surface, has narrow grooves with a predetermined depth in the tire width direction. The sipes are formed to reduce the shearing force that acts on the kick-off side of the rubber block when the tire is transferred, suppressing the occurrence of uneven wear on the part, and the edges of the sipes to reduce the shearing force that acts on the kick-out side of the rubber block. Improvements in uneven wear resistance and wet performance have been attempted through the so-called edge effect, which cuts the formed water film and brings the tread into direct contact with the road surface.

(Problem to be solved by the invention) However, as shown in FIG. As a result, the rigidity of the rubber block in the tire width direction and longitudinal direction decreases,
There was also the problem that uneven wear resistance and maneuverability deteriorated, and sufficient drainage and wet performance could not be ensured.

On the other hand, as shown in Figures (b) and (C), if at least one end of the narrow groove forming the sipe terminates inside the edge of the rubber block without opening at the edge,
There was a problem in that cyputia occurred at the terminal end.

The present invention was made in view of such problems,
The object of the present invention is to provide a pneumatic tire, particularly a heavy-duty pneumatic tire, which has excellent uneven wear resistance and cyptear resistance and excellent maneuverability under wet conditions.

(Means for Solving the Problem) In order to achieve this object, in the pneumatic tire of the present invention, the tread portion of the tire tread is defined by narrow grooves in the shape of a closed curve with a groove width of 2 mm or less. A plurality of sipe regions are formed, and the ratio of the total surface area of these sipe regions to the surface area of the tread portion is 30% to 70%.

(Function) Since the plurality of sipe regions formed by narrow grooves in the shape of closed curves in the rubber block of the tire tread are closed curves, the rigidity of the rubber block does not decrease significantly, and therefore, This will not cause any deterioration in uneven wear resistance or handling performance. Furthermore, since the closed curved narrow groove always has a component in the circumferential direction of the tire, the drainage performance of the tire and, by extension, the wet performance of the tire are not impaired.

On the other hand, the edge portion of the sipe region defined by the narrow groove has an edge effect of cutting the water film formed on the road surface, so that sufficient wet performance is ensured.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a trev pattern of a pneumatic tire according to the present invention, which is substantially divided by the tire equatorial plane S]. A plurality of wide lug grooves 14 are formed at predetermined intervals in the tire circumferential direction, and each half of the tire is extended in relation to the tire equatorial plane S. They are arranged so as to be shifted by a predetermined pitch in the circumferential direction. The internal structure has a general radial structure, but since it is not directly related to the present invention, a detailed explanation thereof will be omitted here.

The lug grooves 14 extending in the tire width direction in each half of the tread 10 are bent in one direction parallel to each other in the middle part, and are bent in one direction in parallel to the tire equatorial plane S to the center part of the tread IO. They are respectively connected to the formed diagonal grooves 16 and take a substantially symmetrical arrangement with respect to the tire equatorial plane S.

Furthermore, connecting grooves 18 are formed in each half of the tread 10, and one end of these connecting grooves 18 connects to the lug groove 14 and the diagonal groove 6.
It opens at the intersection O, and the other end opens into another lug groove located adjacently in the tire circumferential direction.

The edge portion of the tread portion 20 defined by the lug grooves 14, the diagonal grooves 16, and the connecting grooves 18 has a portion obliquely intersecting with the tire equatorial plane, which improves the driving performance and braking performance of the tire. In addition to the above, since it is possible to resist movement in the width direction of the tire, it is possible to suppress skidding of the tire and improve maneuverability and stability. Moreover, on a wet road surface, the water film formed there is cut and the tread portion 20 is brought into contact with the road surface, resulting in a so-called edge effect, which makes it possible to improve wet performance. can.

Further, in the pneumatic tire of the present invention, the tread portions 20 are provided with a plurality of sipe regions 22 defined by narrow grooves in the shape of closed curves.

In this embodiment, these sipe regions 22 are narrow grooves 2 formed by annular closed curves, as shown in FIG. 1(b).
4, and an edge that stands up against the ridge 20 is formed at the peripheral edge of the sipe region.

The total surface area of the plurality of sipe regions 22 defined in the tread portion 20 by the narrow grooves 24 over the entire circumference of the tire Ss
The ratio R (S s/'I' s) to the total surface area 1's of the tread portion 20 around the entire circumference of the tire is 30% to 70%.
, preferably from 40% to 60%, and the groove width d is preferably 211II11 or less.

Here, the total area Ts of the tread portion of the total area Ss of the sipe area
The reason for setting the ratio I to 30% to 70% is that, as shown in Figure 2 (a), when the ratio I is smaller than 30%, the wet performance of the tire is reduced by the narrow grooves forming the sipe area. On the other hand, when the ratio becomes larger than 70%, as shown in Figure (b), the uneven wear resistance of the tire becomes worse than the rubber blocks of the tread in the width direction of the tire. This is because it is comparable to that of a tire having a sipe region defined by penetrating narrow grooves.

Therefore, the ratio R of the total area Ss of the sipe region 22 to the total area Ts of the tread portion is in the range of 30% to 70%, preferably 30% to 70%, where the wet performance and uneven wear resistance performance are significantly improved. shall be selected so that it falls within the range of .

Furthermore, the reason why the groove width d of the narrow groove 24 is set to 211II1 to F is that, as shown in FIG. This is because the edge effect due to the edges of these sipe regions cannot be exhibited, and therefore the desired wet performance cannot be achieved.

In addition, in the same figure, the ratio R (・S s / T s) is 5
Although the case where it is 0% is illustrated, the ratio r is 30% to 70%.
The same applies to the case where the sipe region 22 is within the range of 100%, and for comparison, the wet performance of a tire in which the sipe region 22 is not formed in the tread portion 20 is shown as an index of 100.
Further, a medium sipe region 22 defined by the narrow groove 24
When the wet performance and uneven wear resistance performance of the tire were examined by changing the area of the tire, the results shown in FIG. 4 were obtained.

That is, when the surface area of the single sipe region 22 defined by the annular narrow groove 24 is less than 9 ms', no improvement in wet performance can be expected; - In the case of
Conventional tire with sipes shown in Figure (a) (Comparative Example 1
) has almost the same level of uneven wear resistance.

In addition, the groove depth is 45% to 55% of the groove depth of the diagonal groove 16 or the lug groove 14, considering the drainage performance in the narrow groove.
% is preferable.

Therefore, it is preferable that the surface area of each sipe region 22 be between 9mo+'' and 42,65W!.
In Figure 4(a), the index 100 refers to a tire with no sipes formed, and in Figure 4(b), the index 100 refers to a tire with no sipes formed.
and respectively indicate tires having the sipes shown in Comparative Example 1.

Furthermore, in order to investigate the cyptear resistance characteristics of the sipe region defined by such an annular narrow groove 24, the sipe tear resistance characteristics shown in FIG. 10 (
As shown in c), a conventional tire (Comparative Example 2) in which both ends of the narrow groove forming the sipe do not open to the edge of the rubber block of the tire tread is installed on the same vehicle, and while being rotated. When the tires were actually driven and the occurrence of cyptear was compared at 50% wear, the results shown in Figure 5 were obtained.

As is clear from this figure, by making the narrow grooves 24 defining the sipe region into closed curves, the sipe tear resistance can be improved compared to the conventional one.

Further, a tire according to the present invention in which the sipe region is formed of narrow grooves in the shape of a closed curve, a tire as Comparative Example 1 shown in FIG. Tires as Comparative Example 2 having the sipes shown in Figure 1O (c) where both ends of the narrow groove terminate within the rubber block were installed alternately on the same vehicle, and their handling characteristics were investigated through a feeling test. As a result, the results shown in FIG. 6 were obtained.

As is clear from this figure, the tire of the present invention, which has a sipe region defined by narrow grooves in the form of a closed curve, has a steering performance that is approximately 20% lower than that of the conventional tire.
- It was found that Here, the handling characteristics 100 are:
2 shows the results of a feeling test in Comparative Example 1.

Further, in the embodiment shown in FIG. 1, a total of eight sipe regions 22 are formed in the tread portions of the tread that are defined by the lug grooves, diagonal grooves, and connecting grooves and are paired in the tire width direction. However, as is clear from the above,
The area of each sipe region is made smaller than the area of each sipe region of the embodiment shown in FIG. 1, and the number of sipe regions is larger than that of the embodiment shown in FIG. 1. FIG. 7(a) It was found that similar results were obtained in other examples shown in . Incidentally, the surface area of the middle sipe region in the embodiment shown in FIG. 7(a) is 12
m'', which satisfies the conditions specified in FIG.

Furthermore, as shown in FIG. 7(b), 9, the sipe region 2
2 may be defined by two annular narrow grooves disposed coaxially. In this case, the edge components of the sipes can be efficiently removed onto the tire surface.

In the above-described embodiments, by forming the closed curve defining the sipe region into an annular narrow groove, it is possible to provide a tire having the advantage that the influence of the rolling direction of the tire is extremely small. However, the invention is not limited thereto, and for example, as shown in FIGS. 8(a) to (c), the sipe region may be triangular, square, or approximately star-shaped. You can also do that.

Further, as shown in FIG. 9, the narrow grooves 24 defining the sipe region 22 extend inward in the tire radial direction so as to be oblique to the surface of the tread portion 20 of the tire tread. It is also possible to adopt a configuration that increases the rigidity of the rubber block during braking.

Although the above-mentioned embodiments have been described in relation to tires having a lug pattern, the present invention is not limited to these embodiments (for example, tires having a rib-lug pattern, and can also be applied to tires having a block pattern, and various modifications are possible within the scope of the claims.

(Effects of the Invention) Thus, according to the present invention, it is possible to provide a pneumatic tire that has excellent uneven wear resistance and cyptear resistance, and does not impair handling performance under wet conditions.

[Brief explanation of the drawing]

FIG. 1(a) is a diagram showing a preferred embodiment of the present invention.
Figure (b) is an enlarged view of one of the sipe areas shown in Figure 1 (a), and Figures 2 (a) and (b) are tread steps in the sipe area of the tire shown in Figure 1. Figure 3 is a diagram showing the ratio to the surface area, wet performance and uneven wear resistance performance, respectively.
Figures 4(a) and 4(b) are diagrams showing the relationship between the groove width of the narrow grooves defining the sipe area of the tire shown in the figure and the wet performance.
Figure 5 is a diagram showing a comparison of the sipe tear resistance between the tire shown in Figure 1 and a conventional tire, Figure 6 is a diagram showing the relationship between the sipe area area and wet performance and uneven wear resistance performance. FIG. 7(a) and (b) are diagrams showing other preferred embodiments of the present invention, respectively. (a) to (c) are diagrams respectively showing other sipe region shapes applicable to the present invention; FIG. 9 is a cross-sectional diagram illustrating the sipe region of yet another embodiment of the tire of the present invention; FIGS. 1O (a) to (c) are diagrams each schematically showing the conventional sipe shapes formed on the rubber blocks of the tire tread surface. 10... Tread part 12... Shorter part 14...
-Lug groove 16...Diagonal groove 18...Connection groove 20...Tread portion 22...Sipe area
24... Narrow groove ◇ 4 Beni Hayasaki Arrival/Mawari = Kata-kema Figure 3 Figure 4 (a) (b) Figure 5 Figure 6 Ratio 14Fll f Hisoftii! 12 Figure 7 (a) of the present invention

Claims (1)

[Claims] 1. A plurality of sipe regions each defined by closed curved narrow grooves with a groove width of 2 mm or less are formed on the tread portion of the tire tread, and the ratio of the total surface area of these sipe regions to the surface area of the tread portion is 30%. A pneumatic tire with excellent wet performance characterized by ~70%.