JPH062443B2 - Tread pattern tires with crossed sipes - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a tire having a block pattern defined by a plurality of circumferential main grooves and branch grooves connecting adjacent main grooves, and in particular, The present invention relates to improvement of sipes formed in block portions.

[Prior Art] In a tire having a block pattern, it has been well known that a braking force and a traction force are ensured in a wet state and in a snowy state by forming sipes in a block portion.

Various types of sipe are offered,
When focusing on braking force and traction force, for example, Japanese Patent Laid-Open No. 61-
As shown in No. 261109, in a tire used on a snowy road, a plurality of tires extending in the lateral direction with respect to the tire rotation direction are provided in a block portion in order to increase the frictional resistance by scratching the snowy surface with the edge of the sipe. It is common that the sipe is formed.

[Problems to be Solved by the Invention] However, when a plurality of sipes extending in the lateral direction with respect to the tire rotation direction are formed in this manner, it is effective against a vertical acting force intersecting with the sipes. However, it does not work effectively as a frictional resistance against the lateral force generated when changing the traveling direction such as when changing the lane, and the total braking and traction performance of front, rear, left and right is insufficient. I was seen.

Therefore, an object of the present invention is to provide a tread having a sipe that enables the block to work effectively even when a force is applied to the block from any of the front, rear, left, and right directions, and can improve braking / traction performance during ice and snow. It is in the area of providing tires with patterns.

[Means for Solving the Problems] As a result of intensive studies and investigations for achieving the above-mentioned object, the present inventor has found that as a sipe for carving a block, a cross type of a sipe including a parallel component and a tilt component with respect to the tire rotation axis direction. It's about sipe.

That is, in the present invention, in a tire having a block pattern defined by a plurality of main grooves in the circumferential direction and branch grooves connecting adjacent main grooves, as a result of examining the arrangement and shape of sipes carved in blocks , A tire having a tread pattern having crossed sipes in which at least four sipes are arranged which are arranged and shaped to extend radially from substantially the central portion of the block and then extend substantially parallel to the tire rotation axis direction toward the end portion of the block. did.

[Operation] That is, when a cross sipe that radially extends from the central portion of the block and then extends in parallel with the tire axial direction is formed, the component parallel to the tire rotation direction of the sipe is generated by the scratching action of the edge of the sipe. , The slip resistance to the tire traveling direction is increased, the tilt component increases the slip resistance to the lateral force acting on the tire, and the blocks are arranged from the longitudinal direction or the lateral direction (front / rear / left / right). It also responds to the acting force in multiple directions and exhibits a twist that expands the ground contact surface, so that the grip force on snow and frozen roads is improved, and braking / traction performance can be improved.

Embodiments Embodiments shown in the accompanying drawings will be described below. FIG. 1 is a development view showing an embodiment of a tread pattern according to the present invention, which has one linear main groove 1a extending in the circumferential direction on the tire center line, and which is also symmetrical in the circumferential direction at its left-right symmetrical position. Each has one zigzag-shaped main groove 1b extending to the. Reference numerals 2a and 2b are branch grooves branched from the respective main grooves 1a and 1b. The branch groove 2a connects adjacent main grooves to form a plurality of blocks 3a, and the branch groove 2b is located near the shoulder portion. A plurality of blocks 3b are formed by partitioning with the side grooves 4.

In each block, reference numeral 5 is a cross sipe according to the present invention, which is an inclined sipe 5a extending radially from a substantially central portion of the block and a tire rotation axis direction which is continuous with the inclined sipe 5a and which extends toward the block end portion. The horizontal sipe 5b extends in parallel. 6 is a tire axial sipe similar to the conventional one.

It is preferable that the crossing sipes are formed in 50% or more of all blocks, and if it is 50% or less, the desired effect cannot be sufficiently obtained.

In addition, the depth of the cross sipe is 50% to 10% of the depth of the main groove.
0% The same depth as the main groove is preferable, but when increasing the number of sipes to improve maneuverability on ice, etc., to prevent the rigidity of the block from decreasing and the wear resistance etc. to decrease. , The depth of the sipe may be shallow. But,
Since it is necessary to maintain tire performance until 50% wear, it must be deeper than 50% of the main groove.

2 (A) and 2 (B) are explanatory views that schematically show the responsive state of the block when an acting force is applied from the vertical direction and the horizontal direction, respectively, and the block is multidirectional due to the presence of the cross sipe. It is possible to respond to.

FIG. 3 shows a responsive state when a vertical acting force is applied to the block pattern of FIG.
It shows a twist that expands the ground plane in response to multiple directions. In the figure, the alternate long and short dash line shows the block state before grounding, and the solid line shows the block state after grounding and when a vertical acting force is applied during braking.

In FIGS. 1 and 3, reference numeral 7 denotes a recess provided in the center of the cross sipe, which has a depth substantially equal to that of the cross sipe. Providing such a recess makes the movement of the block smoother when an acting force is applied, and is effective for enlarging the ground contact surface and improving braking force / traction force.
As shown in FIG. 4, this recess can be formed by attaching the central end of a plurality of blades 8 to be attached to the vulcanization mold body to the column 9 when forming the cross sipe. Attaching the blade to the column can accurately position the blade,
It also has an effect of preventing the formed sipes from not intersecting at one point in the central portion due to wobbling or bending of the blade ends. However, if they do not intersect at a single point, a small block surrounded by sipes will be formed in the center,
When the tire is taken out of the mold, it will be cut off and will remain in the mold, which will become foreign matter during the next vulcanization.

Next, the results of a trial production of a radial tire having a tire size of 165 / 80R13 and an actual running test on snow and an icy road will be shown.

In the table, tire numbers 1, 2, and 3 are examples of the present invention having the tread pattern of FIG. 1, tire number 4 is a comparative example in which the number of sipes is reduced, and tire number 5 is shown in FIG. As described above, the main groove, the branch groove, the block pattern, etc. are the same as those in the embodiment of FIG. 1, but the conventional type comparative example having the sipes S arranged in parallel with the tire rotation axis direction.

The test methods in the table are as follows.

"Ice braking" It is the reciprocal of the distance to stop the vehicle by running the test vehicle with test tires on the icy road at a speed of 40km / hr and fully locking the brake.

“Ice turning” The reciprocal of the lap time when turning around a circle with a radius of 15 m on an ice road.

"Tracting on snow" Two test vehicles equipped with test tires are connected by a rope with a load cell in the middle and pulled together, and the force at that time is measured and shown as a peak value.

The numerical values in the table are indexed with tire number 5 being 100.

In the table, the number of sipes is the number of sipes in one block, and the depth of the sipes is a percentage display with respect to the main groove.

As is clear from the above table, the tire of the example having four or more crossing sipes in one block is improved in all of the ice braking, the ice turning, the snow traction and the feeling as compared with the comparative example tire. Showing the effect.

[Advantages of the Invention] As described above, the present invention provides a tire having a tread pattern having crossed sipes, so that the block is suitable for expanding the ground contact area against the acting force from any of vertical and horizontal directions at the time of ground contact. It is possible to provide a tire that exhibits a responsive state, has an increased gripping force, and has improved braking / traction performance when traveling on an icy road or snow.

[Brief description of drawings]

FIG. 1 is a development view showing an embodiment of a tire having a tread pattern having crossed sipes according to the present invention, and FIGS. 2 (A) and 2 (B) are applied with acting force from the longitudinal direction and the lateral direction, respectively. 3 is an explanatory view schematically showing the responsive state of the block in the case, FIG. 3 is an explanatory view showing the responsive state when a vertical acting force acts on the block pattern of FIG. 1, and FIG. FIG. 5 is a perspective view showing an embodiment of a blade forming a sipe, and FIG. 5 is a development view of a conventional type tread pattern having sipes arranged in parallel with the tire rotation axis direction. 1a, 1b ... main groove 2a, 2b ... branch groove 3a, 3b ... block 5 ... cross sipe 7 ... hollow

Claims (3)

[Claims] 1. In a tire having a block pattern defined by a plurality of circumferential main grooves and a branch groove connecting adjacent main grooves, the block ends after radially extending from a substantially central portion of the block. At least four sipes extending substantially parallel to the tire rotation axis direction are provided toward the portion, and a depth substantially equal to that of the sipes formed by the columns of the sipes forming blade is provided at the radial center of the radially extending sipes. A tread pattern tire having crossed sipes, characterized by having a dent. 2. A tread pattern tire having crossed sipes according to claim 1, wherein the block having crossed sipes occupies 50% or more of the front block. 3. The umbrella of the cross sipe is 50% to 10% of the main groove.
A tread pattern tire having crossed sipes according to claim 1 which is 0%.