JP2000264018A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire having a tread pattern so as to improve traction performance and well-balanced traveling performance on ice and snow. SOLUTION: This pneumatic tire is provided with a pair of circumferential main grooves 2 on a tread surface part, divides the tread surface part into three areas of the central area and both side areas, and has a plurality of overall approximately W-shaped transverse grooves 3 arranged to extend in the tire circumferential direction from one end to the other end on the tread surface part. In the central area, the transverse grooves 3 extending from the opposite directions have open ends 5 which open to terminate in the transverse grooves 3 approximately midway the axial width each other, two sub land part rows 6 are divided by forming zigzag-shaped circumferential sub grooves extending in the circumferential direction in the central area, and the transverse grooves 3 in each adjacent land part have different inclining directions relative to the tire circumferential direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly, to a pneumatic winter tire (so-called snow tire) having a tread pattern capable of improving performance on ice and snow in a well-balanced manner.

[0002]

2. Description of the Related Art As a tread pattern conventionally known in a snow tire capable of exhibiting performance on ice and snow, a tread pattern shown in FIG. 7 is representative. As can be seen in FIG.
Such a snow tire is defined by a circumferential main groove formed by combining a zigzag main groove 12 and a straight main groove 11 continuous in the tire circumferential direction, and a transverse groove 13 intersecting with the circumferential main groove and extending in the tire width direction. It is common to have blocks formed.

[0003] The blocks thus defined have been arranged almost evenly from the tread center area to the tread end area, and the radial sipes have been almost evenly arranged.

[0004]

However, in snow tires having the above-described block pattern which have been conventionally known, the performance on ice and snow cannot be said to be exhibited in a well-balanced manner. There were many issues to be solved.

That is, since the angle of the transverse groove in the conventional block is approximately 90 ° with respect to the circumferential direction of the tire, the edges of the block enter the snow almost simultaneously when the tire rotates, so that the block penetrates when entering the snow. It was difficult to increase the pressure, and as a result, it was difficult to improve traction performance on snow. Also, when traction was applied to the snow tire and spinning (slip state) occurred on snow, a situation could occur in which spinning was further promoted.

It is an object of the present invention to provide a pneumatic tire having a tread pattern that improves traction performance and improves performance on ice and snow in a well-balanced manner.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies focusing on the groove configuration of the tread for improving the traction on snow, and as a result, have found that the block of the part that first penetrates the snow is obtained. The sharpening angle increases the penetration pressure, making it easier for the block to enter the snow, and this causes the edge of the transverse groove with a smaller angle to the circumferential direction to work intermittently, causing strong snow traction, Further, by arranging the block so as to form a substantially W-shaped transverse groove as a whole, the block functions as described above at four locations in the width direction, and as a result, the above object can be achieved.
The present invention has been completed. That is, the present invention is as shown in the following (1) to (7).

(1) A pair of circumferential main grooves are provided on the tread surface of the tread, and the tread portion is divided into three regions of a center region and both side regions, and a tire is provided from one end to the other end of the tread surface. In the pneumatic tire, in which a plurality of transverse grooves extending in the circumferential direction and forming a substantially W-shape as a whole are arranged in the central area, the transverse grooves extending in opposite directions in the central area have substantially the same axial width as each other. An intermediate end having an open end terminating in the middle transverse groove and defining a circumferentially extending zig-zag circumferential sub-groove in the central area to define two sub-land rows; The pneumatic tire is characterized in that the transverse direction of the transverse groove is different from that in the tire circumferential direction.

(2) In the pneumatic tire, the transverse groove in the central area is 30 ° to 70 ° measured from the acute angle side with respect to the tire circumferential direction. The groove width (Wc) of the opening end that opens and terminates in a substantially middle transverse groove and the groove width (Wa) of the opening end to the circumferential main groove are the groove widths between these opening ends (Wa). Wb) A narrower pneumatic tire.

(3) In the pneumatic tire, a groove width (Wc) of the open end that terminates in the transverse groove in the central area and ends in a transverse groove that is substantially intermediate in the axial width of each other;
The groove width (Wa) at the opening end to the circumferential main groove and the groove width (Wb) between these opening ends satisfy the relationship expressed by the following equation: Wc <Wa ≦ Wb, The maximum value is W
c appears closer to the opening end side of Wa than the opening end side of c, and when Wc is 100, Wb is 200 to 400;
The pneumatic tire in which a is in the range of 110 to 350.

(4) The pneumatic tire according to the present invention, wherein the pair of circumferential main grooves have a flared element composed of an enlarged portion and a reduced portion of the groove width connected in the circumferential direction.

(5) In the pneumatic tire, the surface shape of each block of the sub-land portion row in the central area gradually decreases in width toward the outside in the axial direction.

(6) In the pneumatic tire, the transverse groove is formed substantially in a straight line in the axial direction.

(7) The pneumatic tire according to the present invention, wherein the outermost transverse groove in each of the both side sections has an acute angle of 55 ° to 90 ° with respect to the tire circumferential direction.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to embodiments. In one embodiment of the tire of the present invention shown in FIG. 1, a tread 1 has a pair of circumferential main grooves 2 on a tread portion, and the tread portion is divided into a central section B and three sections A and B on both sides. Have been. Thus, by providing a pair of thick circumferential grooves in the tread tread, drainage during running on a wet road surface can be ensured.

The transverse grooves 3 arranged in plural form extend from one end of the tread portion to the other end in an inclined manner in the tire circumferential direction,
A substantially W-shape is formed as a whole. By adopting a W-shaped configuration as a whole, it is possible to set four blocks having acute angles according to the present invention in the tread surface. In the case of a V-shaped configuration such as a normal directional pattern, there are only two places, and the vicinity of the center of both side area blocks and the center area block has only a zigzag structure.

In the central section B, the transverse grooves 3 extending from opposite directions have an open end 5 which opens and terminates in a transverse groove substantially intermediate in the axial direction of each other, and has a zigzag periphery extending circumferentially in the central section. The direction sub groove 2a is formed. This gives 2
There are two sub-land rows. In addition, the inclination direction of the transverse groove 3 with respect to the tire circumferential direction in each adjacent land portion is different.

In the portions 5 and 7 where the transverse grooves 3 are opened in the circumferential main groove 2, since the edges of the blocks are at an acute angle, the blocks penetrate into the snow on the icy and snowy roads from these portions. Since the edge of the block is sharp, the edge pressure when penetrating into the snow is increased, and the block easily enters the snow.

The acute angle α of the edge of the block 6 with respect to the circumferential direction is preferably set to 30 to 70 °. Thus, the edge can be always stably entered into the ground contact surface while the tire is rotating, instead of entering the edge at one time into the ground contact surface on snow. That is, a block edge component can be continuously generated in the tread surface during rotation.

FIG. 3 conceptually shows how the edge always enters the ground contact surface during tire rotation. In the block according to the present invention shown in FIG. 3B, the amount of edges entering the snow at one time is small, but a new edge always enters the ground contact surface during tire rotation. On the other hand, in the conventional block shown in FIG. 3A, an edge is formed at once, and thereafter the edge does not work at all. FIG. 4 is a graph showing the amount of the edge entering the snow with the rotation of the tire in comparison between the two.

If the angle α is less than 30 °, the rigidity of the block is weakened, the wear resistance is deteriorated, and the block is close to the circumferential direction, so that traction hardly occurs.
On the other hand, if it exceeds 70 °, it becomes difficult to form an acute angle portion in the block, and it becomes impossible to continuously insert an edge into the tread surface.

In the present invention, particularly when traction is applied and spinning is performed on snow, effective traction is obtained. On the other hand, in the conventional block, when spinning, there is a time when the edge does not work at all, and it is considered that spinning is further promoted. In addition, as shown in FIG. 5, when the groove in the central area B is set in a zigzag manner, when snow moves from the vicinity of the circumferential groove to the central area due to the rotation of the tire, it can be firmly pressed down, A high snow column shear force is generated, and traction can be improved.

As shown, the pair of circumferential main grooves 2
It is preferable that a trumpet-shaped element consisting of an enlarged portion and a reduced portion of the groove width is connected in the circumferential direction, and more preferably, the surface shape of each block of the sub-land portion row in the central area is set to the width toward the outside in the axial direction. Is gradually reduced. Thereby, block 6
Make it easier to penetrate the snow.

In both side sections A and C, the acute angle β of the transverse groove 3 with respect to the tire circumferential direction is preferably from 55 ° to 55 °.
90 °. By making the outermost groove angle of the outer transverse groove substantially parallel to the ground shape, the edge can be effectively used at the time of drilling, and traction can be improved. At this time, in consideration of wear resistance and hydroplaning resistance, more preferably 70 to 8
5 °. In FIG. 1, reference numeral 8 denotes a sipe.

Next, FIG. 2 shows a tread portion of a tread 1 of a snow tire according to another embodiment of the present invention. The basic structure of the tread pattern shown in FIG. 2 is the same as that shown in FIG. 1, and this embodiment is different from the previous embodiment in that the width of the transverse groove 3 in the central section B is changed.

FIG. 6 is an enlarged view of the transverse groove 3 in the central area B of the tread pattern shown in FIG. In the figure, an open end 5 that opens and terminates in a transverse groove 3 that is substantially intermediate in the axial direction of each other.
, The groove width at the opening end 4 to the circumferential main groove at Wa, and the groove width between these opening ends as Wb. In this embodiment, Wc and Wa are narrower than Wb, and preferably satisfy the relationship represented by the following expression: Wc <Wa ≦ Wb, and more preferably, the maximum value of Wb is closer to the Wa side than the Wc side. And Wc is 100, Wb is 200 to 400, and Wa is 110 to 350.
Within the range. Further, it is preferable that the transverse groove 3 is formed substantially in a straight line side in the axial direction. The width and the like of the transverse groove 3 are respectively defined as described above by adopting the transverse groove shown in FIG. 6 so that the block penetrated by snow packs the transverse groove 3 with snow. By rotating more snow into the lateral grooves 3, the snow is sent to the narrow width Wc side of the central area and is strongly compressed, so that a stronger and harder snow column is formed and the snow important for traction is formed. This is because a column shear force is generated. At this time, it is the above-mentioned preferable relationship and each range that the traction can be effectively generated without impairing the wear resistance, the kinetic performance on a dry road surface, and the like.

The structure other than the tread pattern of the pneumatic tire of the present invention can be determined according to a conventional manner, and is not particularly limited.

[0028]

The present invention will be described below with reference to examples and comparative examples. Example 1 according to the tread pattern shown in FIG.
, The pneumatic tire of Example 2 according to the tread pattern shown in FIG. 2, and the pneumatic tire of the comparative example (all sizes 195 / 65R15) according to the tread pattern shown in FIG. 7 under the following conditions, respectively. Prototype made.

Example 1 Negative rate: 40% Central section transverse groove width: 6.8 mm Side section transverse groove width: 6-7 mm Circumferential main groove width: average 10.5 mm Central section transverse groove angle α: 50 ° (circumferential) Acute angle from the direction) Angle of the cross groove on both sides β: 75 ° (the acute angle side in the circumferential direction)

Example 2 Negative ratio: 40% Central section transverse groove width Wa, Wb, Wc: 6.5 mm, 9.
5 mm, 3 mm Side section transverse groove width: 6 to 7 mm Circumferential main groove width: average 10.5 mm Central section transverse groove angle α, γ: (from the circumferential groove side) 40
°, 62 ° Both-side area crossing groove angle β: 75 ° (sharp circumferential side)

Comparative Example Negative ratio: 40%

The following pneumatic tires were tested for the following performance on ice and snow. Feeling on snow: Comprehensive evaluation of braking performance, starting performance, straightness, and cornering performance on test roads on snow-covered roads Snow braking: Measurement of braking distance when fully braking from 40 km / h on snow-covered traction on snow: Snow-covering Acceleration time from starting at a distance of 50 m above Feeling on ice: Comprehensive evaluation of braking, starting, straightness, and cornering on a test track on an ice surface Brake on ice: 20 km / h on an ice plate Measurement of braking distance when full braking was performed from the results. The higher the value, the better the result. The results obtained are shown in Table 1 below.

[0033]

[Table 1]

[0034]

As described above, in the pneumatic tire of the present invention, the traction performance is improved by adopting the specific tread pattern, and the performance on ice and snow can be improved in a well-balanced manner.

[Brief description of the drawings]

FIG. 1 is a developed view of a tread pattern according to the present invention.

FIG. 2 is a development view of another tread pattern according to the present invention.

FIG. 3 is a conceptual diagram illustrating a state in which an edge enters a ground contact surface during rotation of a tire.

FIG. 4 is a graph showing the amount of edges entering the snow as the tire rotates.

FIG. 5 is an explanatory diagram showing a moving direction of snow in a zigzag groove in a central area B.

FIG. 6 is a partially enlarged perspective view showing a transverse groove in a central area B of the tread pattern shown in FIG. 2;

FIG. 7 is a development view of a conventional tread pattern.

[Explanation of symbols]

 Reference Signs List 1 tread 2 circumferential main groove 2a circumferential sub groove 3 transverse groove 4 open end 5 open end 6 block 7 open end 8 sipe

Claims (7)

[Claims] 1. A tread having a pair of circumferential main grooves in a tread portion, the tread portion being divided into three regions, a central region and both side regions, and a tire circumferential surface extending from one end to the other end of the tread portion. In a pneumatic tire having a plurality of transverse grooves extending in an inclined direction and having a substantially W-shape as a whole, the transverse grooves extending in opposite directions in the central area are substantially intermediate in their axial widths. And has an open end that opens and terminates in the transverse groove, and defines two zigzag circumferential sub-grooves extending in the circumferential direction in the central area to define two sub-land rows, A pneumatic tire characterized in that the transverse grooves have different inclination directions with respect to the tire circumferential direction. 2. The traverse groove in the central section comprises 30 ° to 70 ° measured from the acute angle side with respect to the tire circumferential direction. The groove width (Wc) of the opening end that terminates in the groove and the groove width (Wa) at the opening end to the circumferential main groove are smaller than the groove width (Wb) between these opening ends. The pneumatic tire as described. 3. The groove width (Wc) of the open end which terminates in the transverse groove in the central area, which is open to a transverse groove substantially intermediate in the axial direction, and the width of the open end to the circumferential main groove. The groove width (Wa) and the groove width (Wb) between these open ends satisfy the relationship expressed by the following equation: Wc <Wa ≦ Wb, and the maximum value of Wb is W
c appears closer to the opening end side of Wa than the opening end side of c, and when Wc is 100, Wb is 200 to 400;
The pneumatic tire according to claim 2, wherein a is in the range of 110 to 350. 4. The pneumatic pneumatic pump according to claim 1, wherein the pair of circumferential main grooves has a flared element formed of an enlarged portion and a reduced portion of the groove width connected in the circumferential direction. tire. 5. The pneumatic tire according to claim 1, wherein each block surface shape of the sub-land portion row in the central area gradually decreases in width toward the outside in the axial direction. 6. The traverse groove is substantially axially
The pneumatic tire according to any one of claims 1 to 5, wherein the pneumatic tire is formed by straight sides. 7. The pneumatic tire according to claim 1, wherein an acute side angle of the outermost transverse groove in each of the both side sections with respect to the tire circumferential direction is 55 ° to 90 °.