JPH07132710A - Pneumatic tire for winter - Google Patents

Abstract

PURPOSE:To improve on-ice performance while maintaining on-snow performance by forming lateral grooves in a groove width gradually increased during a tread leading to its both ends from its central part, and forming right/left tilt grooves inserted through a plurality of the lateral grooves, successively arranged in the peripheral direction from the tread central part start end crossed with the lateral groove, to have the end of ending in a land part. CONSTITUTION:In a tread l, many lateral grooves 21, 22, averaged to be tilted loosely upward in the peripheral direction while leading to an equatorial surface o-o part in a tread central position by extending over from one end (e) to the other end (e), are arranged with a prescribed space provided in the peripheral direction, to divide a land part 3. A linear tilt groove 4, extended toward the tread end (e) in the same direction to a tilt direction of the lateral grooves 23, 22 every other right/left alternately relating thereto, with a spot, crossing with the lateral grooves 21, 22 in the equatorial surface o-o position almost in the center of the tread 1, serving as the start end, is arranged to divide the land part 3 into a block 9 in the lateral direction. The tilt groove 4 has the start end 6 crossing with the lateral grooves 21, 22 and a tread end side terminal end 7 stopped in the lard part 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tread for winter, and more particularly to a tread structure which exhibits particularly excellent on-ice performance of a radial pneumatic winter tire.

[0002]

2. Description of the Related Art As a conventionally known tread of a pneumatic tire capable of exhibiting both performances on ice and snow, a tread shown in FIG. 2 as a plan view is typical. This tread has a pair of straight groove 22 extending continuously in the circumferential direction at a position where the ends e are substantially equally divided into three, and both straight grooves, and between the straight groove and the straight groove and the tread end. A plurality of block rows by arranging crank-shaped grooves 23 that continuously extend in the same direction, and at the same time connecting a plurality of lateral grooves 24 extending in a substantially axial direction between these circumferential grooves and between the circumferential grooves and the tread end. Where, in each block,
Again, this is provided with a plurality of notches or sipes extending substantially axially. A tire provided with such a tread can exhibit excellent driving, braking and cornering characteristics on both ice and snow, which cannot be obtained by a summer tire.

[0003]

Under the recent tendency toward warm winter, however, the friction coefficient of the frozen road surface decreases, so that driving, braking and cornering characteristics on ice superior to those of conventional tires can be obtained. There is a strong demand for the appearance of tires that can perform.

However, basically, in order to improve the performance on ice, it is effective to increase the ground contact surface area of the tread to reduce the negative ratio (the ratio of the ground contact surface area to the total area of the ground contact surface including the groove). On the other hand, in order to improve the snow performance, it is effective to increase the groove area to increase the negative rate.Since these two performances are in a trade-off relationship with each other, the ice performance can be improved without deteriorating the snow performance. It was difficult to improve.

In view of the above, it is an object of the present invention to provide a winter pneumatic tire in which the performance on ice is effectively improved while maintaining the performance on snow.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a cylindrical tread extends from one end to the other end of the tread and has a lateral groove that is gently inclined in one direction in the circumferential direction while extending to almost the center of the tread in the circumferential direction. While the land part is divided by arranging many in
A tire having a plurality of linear inclined grooves inclined in the same direction as the lateral groove from substantially the center of the tread and extending leftward and rightward toward both ends of the tread, and having a plurality of cuts extending along the lateral groove in the land portion, The lateral groove has a groove width that gradually increases from the central portion of the tread to both ends of the tread, and the left and right inclined grooves penetrate a plurality of lateral grooves sequentially arranged in the circumferential direction from the tread central portion starting end intersecting with the lateral groove. A pneumatic tire for winter, which has an end that ends in the land.

[0007]

According to the present invention, in the flow of the lateral groove when the tire is running, when the side projecting in the circumferential direction is grounded first, the grounding contour on the kicking side of the grounding portion and the arrangement shape of the lateral groove are substantially the same. Due to the edge effect of the land portion divided by the lateral groove, the driving characteristics are significantly improved especially on snow and ice.

On the other hand, since it has a groove greatly inclined with respect to the axial direction so as to extend through a plurality of lateral grooves, the edge effect of the land portion divided by the inclined groove causes slippage when a lateral force is applied during cornering. It can be advantageously suppressed.

Then, the width of the lateral groove that divides the land portion in the circumferential direction is gradually increased from the central portion of the tread toward the tread end, so that the circumferential length of the block at the central portion of the tread can be made equal to the circumferential length of the block at both ends of the tread. Since the length can be set longer than the length in the direction, it is advantageous in suppressing block deformation when a circumferential external force is applied to the block on the ice board. When the groove width is changed so that the former is small and the latter is large in relation to the negative ratio between the center of the tread and the ends of the remaining tread, the ground contact of the center of the tread that mainly acts on a hard icy road is made. The pressure can be kept low, which advantageously increases the coefficient of friction of the land surface against icing roads, and on relatively soft snowy roads, due to the higher negative ratio tread flanks, the required load hold. You can secure ruding. By providing the tread end side end portion of the inclined groove in the land portion, the rigidity of the land portion divided by the widened portion will not be lowered more than necessary.

[0010]

FIG. 1 is a tread plan view of a tire showing an embodiment of the present invention. In the figure, tread 1 is at one end
equatorial plane in the middle of the tread, extending from e to the other end e
The land portion is divided by arranging a large number of lateral grooves 2 which are gently inclined upward in the drawing on one side in the circumferential direction up to the oo portion at predetermined intervals in the circumferential direction. Further, approximately one in the middle of the tread, in this embodiment, the starting point is the point where it intersects with the lateral groove 2 at the equatorial plane oo, and every other lateral groove 2 is placed alternately to the tread end e in the same direction as the inclination direction of the lateral groove. A linear slant groove 4 extending in the horizontal direction is arranged, and the land portion divided by the lateral groove is further laterally divided into blocks 9. The sloping groove 4 has, in this embodiment, a tread end side end 7 which extends through three lateral grooves from the beginning 6 which intersects with the lateral groove at the center of the tread and which remains in the land portion 3.

Since the tread 1 has a radius of curvature centered on the inner side in the radial direction on the cross section, the tread 1 is formed so as to be loosely projected in one circumferential direction of the lateral groove 2 in such a tread. When the vehicle is mounted so that the protruding portion precedes both ends of the lateral groove 2 on the tread end e side and comes into contact with the ground, it has a shape that substantially matches the grounding contour on the kicking side. Transverse grooves 2 ₁ In this example, the alternating component y extending obliquely with a component x extending generally axially from the tread edge e, contiguous upwardly inclined in FIG,
In the middle of the course, it intersects with the inclined groove 4 and reaches the center of the tread. In the position intersecting with the lateral groove 2 ₁ of the inclined groove 4, and the inclined component y of lateral grooves and the inclined groove 4 overlap to form a common portion. The transverse grooves 2 ₂ extends toward the tread center in the same manner from the tread edge e and the transverse grooves 2 _1, crosses the axially outer portion of the inclined groove 4, another inclined grooves adjacent further axial or circumferential direction, Intersects with the relatively inner part of the
And transverse grooves 2 _1, which has extended from the other end e of the tread continuous through the connecting portion z. In the intersection of also the inclined groove 4 when the transverse grooves 2 _2, it overlaps the inclined component y. And the connecting part z
Is almost as wide as the width of a particular portion of the lateral grooves to be described later, the front end of the inclined groove 2 ₂ are included in this connection portion.

The angle α formed by the straight line m showing the average inclination of the lateral groove with respect to the axial reference line or the meridian line is 5 ^. ~ 30
^. Is the range. This angle range was set on the basis of the above-mentioned contour of the tread contact surface on the kicking side. Next is a slanted groove
4 centerline (or its mean if it extends a little in a curved line)
The angle of n with respect to the axial reference line l is 55 ^. ~ 75 ^. Is. Lower limit of angle β 55 ^. If it exceeds, the shape of the block is excessively flattened and the rigidity is lowered, which is not preferable. On the other hand, the upper limit is 75 ^. If it exceeds, the tip of the block 9 becomes too sharp and the rigidity decreases, which is also not preferable. In addition, in this embodiment, a pair of linear circumferential grooves 8 is provided at a position substantially intermediate between the axially outer end 7 of the inclined groove 4 and the tread end e, and the land portion 3 is divided between the tread end e and the linear circumferential groove 8. However, this circumferential groove can be omitted. However, in this case, the end 7 of the inclined groove is extended in the direction of the flow of the inclined groove to penetrate the lateral groove 2 adjacent to that direction, and the terminal is provided in the land portion adjacent to this lateral groove, whereby the axial direction is The rigidity of the independent blocks arranged along the line is made almost uniform.

Regarding the groove width, the lateral groove 2 is assumed to increase gradually or stepwise from the tread center side toward the tread end e direction. In this embodiment, the width v of the axial component x of the lateral groove 2 at the tread center part _1, interrelationship of width v ₃ of width v ₂ and axial components x tread edge portion in the axial direction component x of approximately the midpoint of the equatorial plane oo and the tread edge e, when indicated by v ₁ / v ₂ 0. _{2 to} 0.9 and v _{2 to} v ₃ are preferably in the range of 0.5 to 1.0. On the other hand, the width of the inclined groove component y can be aligned with any of the axial direction components x adjacent to it. In this embodiment, the groove widths of the inclined groove 4 and the circumferential groove 8 are substantially equal to the groove width v ₁ and the connecting portion z
The width of is set almost equal to the width of v ₃ .

The lateral groove 2 may be provided in a step shape as shown in FIG. 1, or may be provided in a single arc shape or in combination with a plurality of arcs extending straight or inclined in the circumferential direction. However, as shown in the example
It is preferable to combine the component components and arrange them in a polygonal line shape in order to form a sharp edge in the land portion divided by the component.

Each block 9 is provided with a plurality of zigzag cuts 5 in the direction in which the lateral groove extends. These notches 5
With some exceptions, starts from a groove (sloping groove 4 and circumferential groove 8) arranged in a direction intersecting with the cut and terminates in the block substance.

In order to investigate the effect of the tire of the present invention thus formed, the tread of the embodiment shown in FIG. 1 and the tread of the comparative example shown in FIG. 2 were run on snow using an 185 / 70R14 size, and on ice. Nail running and ice braking tests were conducted.

Regarding the structure of the tire, the internal skeleton has a radial structure composed of two plies in which polyester cords are arranged in the meridian direction of the tire, and a steel cord is provided on the outer periphery of the crown portion of the carcass in the meridian direction. Against 70 ^. A commonly known structure in which a belt layer formed by stacking two sheets of plies tilted at an angle of 1 to each other so that the cords intersect each other is arranged and reinforced by arranging the belt layer in the full width of the tread is commonly used.

The details of the tread of the present invention are as follows. (1) transverse groove 2 average angle alpha: ^12. Groove width v ₁ : 2.5 mm v ₂ : 5.5 mm v ₃ : 6.5
mm (2) Inclined groove 4 angle β: 71 ^. Groove width: 5.5 mm (3) Width of connecting part z: 6.5 mm

As test conditions, four tires of the present invention and four comparative tires were prepared as test tires, and the internal pressure was 2K.
It was filled with gf / cm ² and mounted in a passenger car, and two passengers boarded. As a test method, the snow running performance was evaluated by a feeling on the snow running total performance including starting, braking, straight running and cornering on a snowy road of a test course. Next, during cornering on ice, a circle was turned on an ice plate with a radius of 20 m, and the time required at that time was measured and evaluated. The on-ice braking test measured the braking distance when full braking was performed at a speed of 20 Km / H on an ice board. As a result, when the value of the comparative tire was shown as an index with 100, the running performance on snow was 95, which was a low evaluation, but both the cornering on ice and the braking performance on ice obtained a value of 120, which was remarkably excellent. Got an evaluation.

[0020]

As described above in detail, the tire of the present invention can exhibit excellent performance against running on ice, which is particularly demanded as a studless type winter tire.

[Brief description of drawings]

FIG. 1 is a plan view of a tread of a tire according to the present invention.

FIG. 2 is a plan view of a conventional tire tread.

[Explanation of symbols]

 1 Tread 2 Lateral groove 3 Land portion 4 Inclined groove 5 Notch α Average lateral angle of lateral groove β Average average angle of oblique groove

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B60C 11/12 C 8408-3D

Claims (1)

[Claims] 1. A land portion is formed by arranging a large number of lateral grooves extending in the circumferential direction from one end to the other end of the cylindrical tread, and gently sloping in one direction in the circumferential direction while extending to almost the center of the tread. On the other hand, it includes a plurality of linear slanted grooves which are inclined in the same direction as the lateral groove from substantially the center of the tread and which extend leftward and rightward toward both ends of the tread, and are provided with a plurality of notches extending along the lateral groove in the land portion. In the tire, the lateral groove has a groove width that gradually increases from the central portion of the tread to both ends of the tread, and the left and right inclined grooves are sequentially arranged in the circumferential direction from the starting end of the tread central portion that intersects with the lateral groove. A winter pneumatic tire having a terminal end that penetrates a plurality of lateral grooves and ends in a land portion.