JP2799115B2 - Pneumatic tire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire capable of improving running performance on snow and running on ice without impairing tire noise.

[0002]

2. Description of the Related Art In recent years, studless tires from which spikes and the like have been removed have been frequently used for running on icy roads and snowy roads. Generally, in order to enhance running performance on snow, a block pattern with a high groove area ratio is adopted on the tread surface, and a snow column for biting is formed firmly in the groove by increasing the contact pressure of the block. doing. In addition, by forming siping on the block surface to enhance ice running performance, and generating a scratching effect on the icy road surface,
The road surface friction coefficient is increased.

[0003]

However, the increase in the groove area ratio conversely reduces the ground contact area, and also impairs the road surface frictional force such as a decrease in the number of sipes formed or a decrease in block rigidity. As described above, there is a conflicting relationship between the running performance on snow and the running performance on ice, and it has been extremely difficult to sufficiently satisfy the conventional requirements. Moreover, the increase in the groove area ratio, for example, the increase in the groove area of the vertical groove extending in the circumferential direction of the tire causes the increase of 800 to 12 due to the air column resonance.
A high frequency of about 00 Hz is generated, which degrades noise performance.

According to the present invention, the running performance on snow can be effectively improved without increasing the groove area by employing a vertical groove having a straight groove bottom and a twisted surface provided on a groove wall surface facing the vertical groove. Another object of the present invention is to provide a pneumatic tire capable of improving running performance on ice while improving noise performance.

[0005]

In order to achieve the above object, a pneumatic tire according to the present invention comprises at least two longitudinal grooves extending in a circumferential direction of a tire on a tread surface and a lateral groove extending in a direction intersecting the longitudinal grooves. And a block pattern tire in which the tread surface is divided into blocks by providing
At least one of the groove-side groove wall surfaces facing the vertical groove of the blocks on both sides of the vertical groove intersects a groove bottom line formed of a straight line extending in the tire circumferential direction at both side edges of the groove bottom, and the groove-side groove wall surface intersects the tread surface. And a torsion surface connecting an upper edge line inclined in a direction away from the groove bottom line to the block side with respect to the tire circumferential direction.

[0006]

A twisted surface is formed on at least one of the groove side wall surfaces on both sides of the longitudinal groove, and the twisted surface has a groove bottom line formed of a straight line extending in the tire circumferential direction. That is, since the groove bottom of the longitudinal groove forming the straight, air in said longitudinal groove, leading to end-stage discharge effect from the initial wear, such as water, may increase by a large margin compared with the conventional zigzag groove. This is because, in addition to the improvement of wet grip performance, pumping noise, such as being able to discharge smoothly before the air pressure in the groove at the time of touchdown becomes excessively high,
The occurrence of air column resonance or the like can be reduced, and tire noise can be reduced.
In addition, the twisted surface streaks the flutes as wear progresses.
Wet grip performance, tie
In addition to improving noise performance, it can also exhibit an uneven wear suppression effect
You.

The upper edge line of the twisted surface is inclined away from the groove bottom line toward the block. In other words, since the width of the vertical groove changes according to the rolling direction of the tire, especially the twisted surface
The upper edge line is twisted between adjacent blocks in the tire circumferential direction.
If the upper edge line of the surface and the inclination direction are alternately changed,
Regardless of the direction of rotation of the shaft , a strong snow column for biting can be effectively formed in the vertical groove, and the solidified snow column can be efficiently discharged. Therefore, grip performance on snowy roads, especially braking,
Snow road performance during cornering can be greatly improved. In addition, since the above-mentioned effects can be exhibited without increasing the groove area, the ground contact area is not reduced unnecessarily, and furthermore, it is possible to maintain the block rigidity required for forming the siping and to contribute to the improvement of the traveling performance on ice. .

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a pneumatic tire 1 has a tread surface S provided with a longitudinal groove G extending in a tire circumferential direction and a lateral groove g extending in a direction intersecting the longitudinal groove G in the tire circumferential direction.
To form a block pattern.

In the present embodiment, the vertical groove G includes a vertical groove G1 extending on the tire equator and a vertical groove G2 disposed outside the vertical groove G1.
G2, and outer longitudinal grooves G3, G3 further disposed outside thereof.
Consists of Also, an inner block row R1 in which blocks B1 partitioned by a horizontal groove g1 are arranged between the vertical grooves G1 and G2.
However, a middle block row R2 in which blocks B2, which are separated by a horizontal groove g2, are arranged between the vertical grooves G2, G3, and a horizontal groove g3 is provided between the vertical groove G3 and a tread edge e. An outer block row R3 in which outer blocks B3 are arranged is formed.

At least two of the five vertical grooves G are provided.
In this example, four of the middle and outer vertical grooves G2 and G3 each have a straight groove bottom whose groove bottom K extends linearly in the tire circumferential direction, and therefore, both side edges E of this groove bottom are Are formed by straight lines parallel to each other.

In the blocks B on both sides of the vertical groove G forming the straight groove bottom, at least one of the groove-side groove wall faces F facing the vertical groove G includes the twisted surface 2.

In this embodiment, as shown in FIGS. 2, 3, and 4, in the blocks B2 and B3 on both sides of the vertical groove G3, the shoulders of the groove-side groove wall surfaces FA2 and FA3 facing the vertical groove G3. A twisted surface 2A is formed on the entire groove-side groove wall surface FA3. Since the vertical groove G3 has a straight groove bottom K, the groove-side groove wall face FA3 of the outer block B3 forms a groove bottom line X3, which is a lower edge x, of a straight line extending in the tire circumferential direction. ing. The upper edge y where the groove-side groove wall surface FA3 intersects the tread surface S is composed of a linear upper edge line Y3 inclined in a direction away from the groove bottom line X3 toward the block side with respect to the tire circumferential direction. Accordingly, the groove-side groove wall surface FA3 is formed as a twisted surface 2A that connects the groove bottom line X3 and the upper edge line Y3. The other groove-side groove wall face FA2 on the tire equator side has straight upper and lower edges y and x extending parallel to each other in the tire circumferential direction,
The groove side groove wall surface FA2 is formed by a plane 3A2 along the circumferential direction of the tire connecting the upper and lower edges y and x.

Therefore, in this embodiment, the twisted surface 2A and the plane 3A2 face each other, and the upper edge lines Y3 of the circumferentially adjacent blocks B3 are alternately inclined in different directions.

As shown in FIGS. 2, 5, and 6, the vertical groove G
In the blocks B1 and B2 on both sides sandwiching 2, the twisted surfaces 2B1 and 2B2 are formed on both of the groove-side groove wall surfaces FB1 and FB2 facing the vertical groove G2.

That is, the groove side groove wall surfaces FB1 and FB2 are formed by forming groove bottom lines X1 and X2, which are lower edges thereof, as straight lines extending in the tire circumferential direction. Each upper edge y where the groove-side groove wall surfaces FB1 and FB2 intersects the tread surface S is defined by the groove bottom lines X1 and X
2, a base line Y0 extending in the tire circumferential direction.
And upper edge lines Y1 and Y2 inclined in a direction away from the groove bottom lines X1 and X2 to the block side with respect to the circumferential direction of the tire, respectively. Therefore, the groove side groove wall surface FB
1, FB2 is a part of the groove bottom lines X1, X2 and a base line YO.
And flat surfaces 3B1 and 3B2 along the circumferential direction of the tire and torsion surfaces 2B1 and 2B2 connecting the remaining portions of the groove bottom lines X1 and X2 and the upper edge lines Y1 and Y2. The groove side groove wall surfaces FB1 and FB2 are, for example, as shown in FIG. 6 representing the groove side groove wall surface FB2, a bending point Q where the base line YO intersects with the upper edge line Y2, and a point P on the groove bottom line X2 below it. Are separated into a rectangular plane 3B2 and a twisted surface 2B2. Also, as shown in FIGS. 7A and 7B, points P1 and P deviated forward or rearward from the point P.
The deformed flat surface 3B2 and the twisted surface 2B2 may be distinguished by lines L1 and L2 connecting the bending point Q and the bending point Q. However, in order to maximize the effect of forming and discharging the snow column in the groove, it is preferable that the twisted surface and the flat surface be formed on the groove-side groove wall surfaces FB1 and FB2. In the above, the boundary line L is formed on a perpendicular bisector of the groove bottom line X, and the twisted surface and the plane are divided into approximately two equal parts so as to face each other.

As described above, since the groove bottoms K of the vertical grooves G2 and G3 are formed straight, the effect of discharging air, water and the like in the vertical grooves can be enhanced, and the wear from the beginning to the end of wear can be achieved. In addition, both wet grip performance and tire noise performance can be improved. The twisted surfaces 2A, 2B1, 2B2 are shown in FIG.
(A) and (b), as representatively showing the cross section of the longitudinal groove G3 in the meridional section of the tire, the groove width W of the longitudinal groove and the wall surface inclination angle α are changed according to each position in the tire rolling direction. . For this reason, when rolling a tire, a strong
Snow pillar effectively be formed, yet can be easily discharged out of the groove. Therefore, a large reaction force (resistance) is obtained from the snowy road surface, and the running performance on snow can be greatly improved. In addition, since the twisted surfaces 2A, 2B1, and 2B2 bring the vertical grooves closer to the straight grooves as the wear progresses, in addition to the improvement of the wet grip performance and the tire noise performance, the uneven wear can be suppressed.

In this embodiment, a zigzag groove is employed as the inner vertical groove G1, and the upper edge and the lower edge of the vertical groove G1 are formed by parallel zigzag lines. Therefore, in this example, each groove side wall surface FC1 of the block B1 on both sides sandwiching the vertical groove G1.
Each form a plane. Further, in each of the blocks B1, B2, B3 of such a block pattern, a siping T extending substantially in parallel with the lateral groove g is provided as necessary to improve the performance on ice due to the effect of scratching the road surface.

(Specific Example) A tire having the block pattern shown in FIG.
Example tires 1, 2, and 3 were prototyped with different groove area ratios, and the prototype tires were mounted on a 2-D / 4-type vehicle, and the actual tires were run on a constant volume condition on snow and The braking performance on ice was indicated by an index. The index value is 100 for a general snow tire, and the larger the index, the better. The comparative example tire 1 having the same groove area ratio, tread rubber compound and block pattern as the prototype tire and having a flat surface along the tire circumferential direction instead of the twisted surface,
Two and three prototypes were manufactured, and the braking performance on snow and on ice were compared with those tires. The results are shown in FIG. It can be seen that the braking on snow has been greatly improved in each case. It should be noted that the comparative example tires 1, 2, and 3 differ from the example tires 1, 2, and 3 respectively in only the twisted surface.

[0019]

As described above, the pneumatic tire of the present invention uses a vertical groove having a straight groove bottom and a twisted surface provided on a groove-side groove wall surface facing the vertical groove, so that noise performance is reduced. In addition, the performance on snow and the performance on ice can be improved while improving the wet performance.

[Brief description of the drawings]

FIG. 1 is a development view of a block pattern showing an embodiment of the present invention.

FIG. 2 is a partially enlarged view showing a part thereof in an enlarged manner.

FIG. 3 is a sectional view showing an outer vertical groove.

FIG. 4 is a perspective view showing a twisted surface of an outer block.

FIG. 5 is a sectional view showing a vertical groove in the middle.

FIG. 6 is a perspective view showing a twisted surface of a middle block.

FIG. 7A is a perspective view showing another example of the twisted surface.

FIG. 7B is a perspective view showing another example of the twisted surface.

8 (a), I, I of FIG. 2 illustrating the features of the outer flutes.
It is a line sectional view.

FIG. 8 (b) illustrates the features of the outer flutes, II and II in FIG.
It is a line sectional view.

FIG. 9 is a diagram showing test results of running tires on icy and snowy roads according to the example.

[Explanation of symbols]

 2, 2A, 2B1, 2B2 Helix surface E Groove bottom side edge F, FA2, FA3, FB1, FB2 Groove side groove wall surface G, G1, G2, G3 Vertical groove g, g1, g2, g3 Horizontal groove S Tread surface X, X1, X2, X3 Groove bottom line Y, Y1, Y2, Y3 Upper edge line

Claims (2)

(57) [Claims] 1. A tire having a block pattern in which a tread surface is divided into blocks by providing at least two longitudinal grooves extending in a tire circumferential direction and a lateral groove extending in a direction intersecting the longitudinal grooves on a tread surface. At least one of the groove-side groove wall surfaces facing the vertical groove of the blocks on both sides of the vertical groove intersects a groove bottom line formed of a straight line extending in the tire circumferential direction at both side edges of the groove bottom, and the groove-side groove wall surface intersects the tread surface. A pneumatic tire further comprising a twisted surface connecting an upper edge line inclined in a direction away from the groove bottom line to the block side with respect to the tire circumferential direction. (2) One of the groove-side groove wall faces facing the vertical groove is
In addition to the twisted surface, the other
直線 A straight groove bottom line extending parallel to the circumferential direction
Including a plane that joins the edge, And the upper edge line of the twisted surface is adjacent to the tire circumferential direction.
Alternate the upper edge line of the twisted surface of the block and the inclination direction
The pneumatic tire according to claim 1, wherein: