JPH06156015A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To provide a pneumatic tire which realizes high wet drainage performance and noise reduction, maintains high-speed durability and improves maneuvering stability. CONSTITUTION:A belt layer 1 constituted of a plurality of plies 11, 12 and 13 so that they overlap crossing each other in which crown parts continue in the toroidal state between a pair of right and left side walls and a non-extending cord is arranged inclined by angles theta1, and theta2 against an equatorial face C across the width of a tread T inside in the radial direction, is arranged. The belt layer 11 is in the herringbone state including a large number of inclined grooves 2 and land parts 51 and 52 inclinedly extending from the center part in the direction of both ends of the tread includes a ply 13 and a pair of separated plies 11 and 13, and a separating position of the separated plies 11 and 12 is located at a converging part almost close to the center of the inclined groove 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is based on a combination of an arrowhead-shaped or C-shaped directional pattern aiming at steering stability in dry and wet road running and a divided and C-shaped inclined angle belt structure. And a flat tire for a high-performance vehicle.

[0002]

2. Description of the Related Art In recent years, the tread pattern of high-performance flat tires has a low angle with respect to the equatorial plane C in the central area of the tread in order to achieve both wet drainage performance and noise reduction. The directional pattern, which is composed of lug grooves bent at a high angle and has no circumferential groove, is becoming popular in the area. However, this tread pattern can improve both wet drainage performance and passing noise performance when combined with the conventional steel belt structure, but no performance advantage can be found for steering stability on dry road surfaces and wet road surfaces. The current situation.

[0003]

[Problems to be Solved by the Invention] Low Angle Non-straight G
The characteristics of roove tires are high drainage performance and 1,000 to 1,300 generated due to the straight group (Straight Groove).
Although it is to reduce the air column resonance of Hertz, there is a problem as described below regarding the steering stability on a dry road surface when the tread pattern and the conventional two steel belt structure are combined.

(1) Since the conventional tread pattern is a block pattern composed of a combination of straight grooves and diagonal lug grooves, the tread surface is divided relatively evenly, and as a result, the tread surface is divided in the circumferential direction and the cross-sectional direction. The tread portion can be easily deformed, and the grounding characteristics do not change much when cornering, while the low-angle non-straight groove pattern has no circumferential straight groove.It has a rib-based overall shape. Due to the large difference in the angle of inclination of the lugs, the tread rigidity in the central area of the road surface becomes too strong, and the contact characteristics are particularly poor in the cross-sectional direction at the time of contact, and there is a change in the contact characteristics on the OUT side and IN side during cornering. It turned out to be big, and there was a problem in that respect.

(2) In the structure in which the low angle groove (the inclination angle with respect to the equatorial plane is 30 ° or less) and the directional pattern and the conventional two steel belts are combined, the belt angle of the outermost layer of the belt and the center The angle becomes almost parallel to the inclination angle of either the left or right lug groove (see FIG. 4A), and the following problems occur. When inflated, the width of the groove in the left side of the drawing is large and the buckling at the time of contact with the ground is large, which lowers the steering stability and deteriorates pattern noise. Generation of cracks There was a large difference in the tread rigidity between the right side and the left side in Fig. 4,
The present invention, in which the change in the cornering characteristics on the left and right is large, was devised in order to solve the above-mentioned problems, and achieves both high wet drainage performance and noise reduction, maintaining high-speed durability and maneuvering stability. The purpose of the present invention is to provide a pneumatic tire with improved durability.

[0006]

In order to achieve the above object, in the pneumatic tire of the present invention, a pair of left and right sidewalls and a crown portion extending between both sidewalls are connected in a toroidal shape. , A crown is provided with a tread that engages with a road surface, and a plurality of plies in which the non-extensible cords are arranged at a shallow angle with respect to the equatorial plane of the tire on the inner side in the radial direction of the tread over the full width of the tread, A belt layer is formed by stacking the cords so that the cords cross each other, and the tread is extended from the center of the tread to both ends of the tread. In a tire that is in the shape of an arrow, the belt layer includes one full ply and a pair of left and right split plies, and the cord of the ply adjacent to the tread is a tread. Provided is that one or the other of the dividing plies is overlapped above or below the full ply so as to intersect the right inclined groove, respectively, and the dividing position of the dividing ply is in the convergent portion of the inclined groove near the center of the tread. To be done.

[0007]

As described above, one of the belt layers is a full ply,
The other one is a pair of left and right dividing plies, so that the cords of the plies close to the tread intersect the left and right inclined grooves of the tread, respectively, so that the dividing ply dividing position is located at the convergent portion of the inclined groove near the center of the tread. In this case, unlike the combination of the conventional directional pattern having a low-angle inclined groove and the conventional belt structure composed of two steel belts, the phenomenon of landing between the low-angle inclined grooves of the tread is reduced. As the contact length increases, the difference between the left and right rigidity of the tread decreases, so that the change in the contact characteristics between the outside and the inside during cornering is reduced, and the steering stability is improved. In addition, the groove width when inflating does not change significantly, there is less buckling at the time of contact with the ground, and steering stability is improved, while the tread rigidity between the equatorial and left and right sides of the tread is uniform, and the vehicle is turning to the right. The cornering characteristics when turning and turning left are at the same level. In this case,
When the belt cord has a larger inclination angle than the low-angle inclination groove, the rigidity of the tread surface can be easily balanced. For the asymmetrical pattern (FIG. 3) in which the apex of the low-angle inclined groove is displaced from the equatorial plane (FIG. 3), the dividing edge of the belt layer close to the tread surface should be substantially coincident with the center line of this pattern. .

[0008]

Embodiments will be described below with reference to the drawings. FIG. 1 (a) is a view showing an embodiment in which the embodiment A of the tread pattern of the pneumatic tire of the present invention and the embodiment A'of the belt structure are combined. 1 (b) to 1 (d) are views showing cross sections of Examples B'to D'of the belt structure. FIG. 2 is a view showing an embodiment B of the tread pattern of the pneumatic tire of the present invention (the tread pattern itself is the same as the embodiment A of FIG.
Example in which Example C ′ shown in (c) is combined). Figure 3
FIG. 8 is a diagram showing Example C of the tread pattern of the pneumatic tire of the present invention. FIG. 4 is a view in which a tread pattern and a belt structure of a conventional example are combined.

In the pneumatic tire of the present invention, a pair of left and right sidewalls (not shown) and a crown portion (no reference numeral) straddling both sidewalls are connected in a toroidal shape. The portion is provided with a tread T that engages with the road surface. A belt layer 1 (1 ₁ , 1 ₁ in which steel cords are arranged at 15 ° to 30 ° with respect to the equatorial plane C of the tire on the inner side of the tread T in the radial direction across the width of the tread T.
1 ₂ , 1 ₃ ) are provided. In the center area of the tread T, the left and right sides of the tread T are inclined at acute angles of θ ₁ and θ ₂ , respectively, and are gently bent in the middle to form a gentle angle θ ₁ ′ with the equatorial plane C. By the way, the inclined groove 2 that rises toward the tread end and the inclined auxiliary groove 3 that makes an angle of θ ₂ ′ with the equatorial plane C are circumferentially provided in the tread end side area alternately with the inclined groove 2. There is. Both grooves are discontinuous on the left and right of the equatorial plane C and are displaced in the circumferential direction by a half pitch.

The inclined auxiliary groove 3 intersects the inclined groove 2 on the upper side thereof, and the sipe 4 extends from the tip thereof toward the equatorial plane C at the same angle and intersects another inclined groove 2 as a whole. It forms a directional pattern. The angle θ ₁ or θ ₂ formed with the equatorial plane C of the inclined groove 2 is a low angle lug groove of 30 ° or less, and θ ₁ or θ ₂ is preferably in the range of 15 ° to 20 °. Further, the angle θ ₁ ′ or θ ₂ ′ formed by the inclined groove 2 or the auxiliary auxiliary groove 3 and the equatorial plane C is 60 ° to 80 °.
It is preferably in the range of. Further, the angles θ ₁ of the inclined grooves 2 of the left and right treads T between the half pitches with respect to the equatorial plane C,
The difference between the two angles of θ ₂ is 25 ° or less, preferably 15
It should be below °. Further, the upper and lower portions, which are divided by the groove with the inclined auxiliary groove 3 as a boundary, form land portions 5 ₁ and 5 ₂ , respectively. Further, the center of the pattern of the tread T may be displaced to the left or right from the equatorial plane C of the tire. Of the belt layers 1 (1 ₁ , 1 ₂ , 1 ₃ ) having steel cords provided over the entire width on the radially inner side of the tread T, the right belt layer 1 ₁ and the left belt layer 1 ₂ are are each divided belt layer, the orientation of the code or the opposite direction, both of the belt layer 1 _1, 1 ₂ in the belt layer 1
₃ is sandwiched from the upper side and the lower side, is bent and reinforced on the equatorial plane C, and the cord of the belt layer 1 ₃ intersects these two belt layers 1 ₁ and 1 ₂ . At the center of the equatorial plane C, a central auxiliary ply 6 whose cord direction is 0.1 times the belt width T _W or more and whose cord direction is substantially parallel to the equatorial plane C is provided. This auxiliary ply 6 may have at least one sheet. Further, the cords of the belt layer 1 (1 ₁ , 1 ₂ , 1 ₃ ) are arranged so as to intersect the lug grooves forming the inclined groove 2 and the inclined auxiliary groove ₃ of the tread pattern. Further, the material of the cords constituting the belt layer may be either steel or Kevlar, and the material of the cords of the center and end auxiliary plies and the cap layers 6, 7 and 8 is nylon.

1 (b) to 1 (d) show a belt structure in which an auxiliary ply is further added to the basic belt structure in FIG. 1 (a), and FIG. 1 (b) is shown in FIG. 1 (a). The belt layer 1 (1 ₁ , 1 ₂ , 1 ₃ ) of FIG. 1 is further provided with end auxiliary plies 7 on the left and right ends, and FIG.
In (b), the cap layer 8 is disposed between the central auxiliary ply 6 and the belt layers 1 ₁ and 1 ₂ so as to cover the belt layers 1 ₁ and 1 ₂ . Figure 1 (d) is
Instead of the belt layers 1 ₁ and 1 ₂ in (a), the belt structure has a two-layer structure in which the left and right end sides of the belt layer 1 ₃ are respectively folded downward and upward. In short, the above FIG. 1 (a)
1 (a) to 1 (c) show a divided belt, and FIG. 1 (d) shows a folded belt.

Further, although separated position of the belt layer 1 _1, 1 ₂ in the above convergence position of the inclined groove 2 is desired, it may in some misalignment. FIG. 2 shows an angle θ ₁ = θ ₂ = 18 ° formed with the equatorial plane C in the central area of the inclined groove 2 in the embodiment A of the tread pattern explained in FIG. 1, and the inclined groove 2 and the inclined auxiliary groove 3 in the shoulder portion. Angle θ with the equatorial plane C of
Size 22 used for actual vehicle tests with ₁ '= θ ₂ ′ = 62 °
This is a tread pattern of a 5/50 R16 tire. On the other hand, the belt structure adopted for this tire is shown in Fig. 1-
The structure of Example C'of (c) is adopted, and the dimensions and arrangement are as shown in FIG. 2 and as follows.

[0013] On the other hand, the dimensions and the like in which the conventional tire structure (FIG. 4) in which the conventional tread and the conventional belt are combined are similarly applied to the tire size 225/50 R16 are as follows. (I) Tread pattern Same as the tread pattern shown in FIG. 2, and has a structure without cuts (sipe). (II) Belt structure Belt layer 1 consists of two steel belts 1 on the underside of the tread.
_1, 1 ₂ are arranged, the code angle of the belt 24 °
And Tire size by determining dimensions and angles as above
We designed a 225/50 R16 tire and tested the internal pressure as
When the actual vehicle test was carried out under a load equivalent to 2 passengers with a load of 2.0 kg / cm ² , the following results were obtained.

[0014] (1) The above numerical values are 100 for the index of the conventional example,
In comparison therewith, the value of the present invention is shown by an evaluation index. (2) Wet straight running drainage is evaluated by the remaining area at a water depth of 6 mm and a speed of 100 km / h, and other characteristics are based on sensory evaluation by the driver on the test course.

FIG. 3 shows another embodiment of the tread pattern in which the pattern of the tread T with respect to the equatorial plane C is asymmetric, and the angle θ ₁ of the inclined groove 2 is 20 on the left side.
On the right side, the angle θ ₂ of the slant groove 2 is 32 °, and on the right side, between the slant groove 2 provided in the circumferential direction similarly to the tread pattern of FIG.
Are arranged so as to intersect with the inclined grooves 2 and be gently inclined, and are arranged without intersecting between the inclined grooves 2 on the right side. Therefore, in consideration of steering stability during cornering, it is preferable to mount the tire having such a tread pattern with the right side in FIG.

[0016]

Since the present invention is configured as described in detail above, the belt layer includes one full ply and a pair of left and right dividing plies, and the cord of the ply adjacent to the tread is the inclined groove of the tread. By arranging one or the other of the dividing plies above or below the full ply so as to respectively intersect with each other, and arranging the dividing position of the dividing ply at the convergent portion near the center of the tread of the inclined groove, the equatorial plane C
On the other hand, unlike a combination of a directional pattern having a low-angle inclined groove and a conventional belt structure composed of two scale belts, the groove width does not change much when expanded and the buckling becomes large when touching the ground. As a result, it contributes to steering stability, reduces pattern noise, eliminates the occurrence of groove bottom cracks, and the tread surface rigidity is uniform on the left and right of the equatorial surface, resulting in both left and right turning of the vehicle. Since the cornering characteristics are at the same level and the change in the grounding characteristics on the out side and the in side during cornering is also small, it is possible to achieve both high wet drainage performance and noise reduction as a whole while improving steering stability. It is possible to expect effects such as.

[Brief description of drawings]

FIG. 1 (a) is a diagram showing an example in which Example A of a tread pattern of a pneumatic tire of the present invention and Example A ′ of a belt structure are combined. (B)-(d) is the figure which showed the cross section of Examples B'-D 'of a belt structure.

FIG. 2 is a view showing an embodiment in which the embodiment B of the tread pattern of the pneumatic tire of the present invention and the embodiment C ′ of the belt structure are combined.

FIG. 3 is a diagram showing Example C of the tread pattern of the pneumatic tire of the present invention.

FIG. 4 is a plan structural view of a pneumatic tire in which a conventional tread pattern is combined with a belt structure of a conventional two-steel belt.

[Explanation of symbols]

1 the belt layer 1 ₁ belt layer 1 ₂ belt layer 1 ₃ belt layer 2 inclined grooves 3 inclined Homizo 4 cuts 5 ₁ land portion 5 ₂ land portion 6 central auxiliary ply 7 end auxiliary ply 8 capping layer W ground contact width T _W belt Width T tread

Claims (1)

[Claims] 1. A pair of left and right sidewalls, and a crown portion that straddles between the sidewalls are connected in a toroidal shape, and a tread that engages with a road surface is provided on the crown portion.
A belt layer formed by stacking a plurality of plies in which non-stretchable cords are arranged inclining at a shallow angle with respect to the equatorial plane of the tire over the width of the tread in the radial direction of the tread so that the cords cross each other. In the tire which is arranged and reinforced, and in which the tread is in the shape of an arrowhead including a large number of inclined grooves extending obliquely from the central portion toward both ends of the tread and a land portion divided by these groove groups, the belt layer is 1 Includes one full ply and a pair of left and right split plies, and one or the other of the split plies is placed above or below the full ply so that the cords of the plies close to the tread intersect the left and right inclined grooves of the tread, respectively. A pneumatic tire characterized in that the ply cutting position is located in the convergent portion of the inclined groove near the center of the tread.