JP2006168501A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of making drain effect, edge effect and surface friction effect compatible with excellent performance on ice. <P>SOLUTION: When this pneumatic tire 10 rolls on an ice road surface and any block 18 grounds, small blocks 18A divided by sipings 20 fall down and are deformed. At this time, a plurality of projections 22 formed up to 2mm from a stepping surface side of one wall surface 20A of the siping 20 are in contact with the vicinity of an edge of the other wall surface 20B of the siping 20. As a result, an edge part of the siping 20 on a side that the projections 22 contact is slightly swollen by pressing force of the projections 22, and grounding pressure (edge pressure) of the edge part of the siping 20 is increased. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire, and particularly to a pneumatic tire excellent in performance on ice.

  Conventionally, in winter pneumatic tires, in order to improve acceleration and braking performance when starting on ice, lateral sipes have been added to the block portion of the tire tread pattern. However, as the number of sipe increases, the force that the edge part scratches the road surface (hereinafter referred to as the edge effect) and the effect that the sipe part sucks up the water film on the ice surface (hereinafter referred to as the drainage effect) increase, but the block rigidity decreases. As the contact area on ice decreases, the frictional force between the tire and the icy road surface (hereinafter referred to as surface frictional force) decreases. If the decrease in surface friction force exceeds the increase in edge effect and drainage effect, the performance on ice is not improved, so there is a limit to improving the performance on ice by adding sipes.

  In contrast, tread rubber has been improved to improve drainage, and pneumatic tires and the like having a foam rubber layer in the tread have been developed (see Patent Documents 1 to 3).

  In recent years, a three-dimensional sipe shape and the like have been developed so as to suppress a decrease in the contact area and ensure a surface frictional force even if the number of sipes is increased (see Patent Document 4).

  However, foam rubber is a technique that mainly improves drainage, so that the performance on ice is remarkably improved at a temperature around 0 ° C where a water film is likely to be generated. It was relatively difficult to improve.

Even if the number of sipes is increased while securing a contact area using a three-dimensional sipe, it is inevitable that the block rigidity is lowered with the increase in the number of sipes, and the small blocks are easily collapsed during tire traveling. As a result, the handling performance and wear performance on the dry road surface deteriorate, and there is a limit to the method of increasing the number of sipes in order to balance with other various performances.
Japanese Patent No. 2510533 Patent No. 002518870 Patent No. 002564760 Japanese Patent Application No. 11-113321

  In view of the above problems, an object of the present invention is to provide a pneumatic tire excellent in performance on ice that can achieve both a drainage effect, an edge effect, and a surface friction effect.

  The invention according to claim 1 is a pneumatic tire provided with a plurality of blocks defined by a plurality of grooves intersecting each other in a tread, wherein the blocks are formed with sipes extending along the tire axial direction. At least one groove wall surface of the sipe is characterized in that a plurality of protrusions that are in contact with the other groove wall surface at the time of ground contact are formed between 2 mm from the tread surface.

  Next, the operation of the pneumatic tire according to claim 1 will be described.

  In the pneumatic tire according to claim 1, a plurality of protrusions formed between the tread surface side of one groove wall surface of the sipe and 2 mm are in contact with the other groove wall surface when the block is grounded. .

  That is, when the tire rolls on the icy road surface, when the small block divided by the sipe collapses and deforms, the multiple protrusions contact the edge of the other groove wall (position up to 2mm from the sipe tread side). To do. As a result, the edge portion of the sipe on the side in contact with the protrusion is slightly raised by the pressing force of the protrusion, and the contact pressure (edge pressure) at the edge portion of the sipe increases. Therefore, the edge effect is improved, and the braking performance on ice, the traction performance on ice, the braking performance on snow, and the traction performance on snow can be improved.

  According to a second aspect of the present invention, in the pneumatic tire according to the first aspect, the height of the protrusion is 40% or more of the distance between the groove walls of the sipe.

  Next, the operation of the pneumatic tire according to claim 2 will be described.

  In the pneumatic tire according to claim 2, when the height of the protrusion is less than 40% of the distance between the groove walls of the sipe, the protrusion is formed on the other groove wall surface when the small block collapses and deforms. The vicinity of the edge cannot be pressed. Therefore, by setting the height of the protrusion to 40% or more of the distance between the groove walls of the sipe, when the small block collapses and deforms, the protrusion surely presses near the edge of the other groove wall surface, and the edge The edge effect can be improved by increasing the pressure.

  According to a third aspect of the present invention, in the pneumatic tire according to the first or second aspect, a total sum of width dimensions in the tire axial direction of the plurality of protrusions in one sipe is 25 of the length of the sipe. % Or more.

  Next, the operation of the pneumatic tire according to claim 3 will be described.

  In the pneumatic tire according to claim 3, when the total width dimension of the plurality of protrusions in the tire axial direction is less than 25% of the length of the sipe, the small block collapses and the protrusions of the other groove wall surface When the vicinity of the edge is pressed, the length (range) of the rise in the length direction of the sipe formed on the tread near the edge is reduced. Therefore, when the total width dimension of the plurality of protrusions in the tire axial direction is 25% or more of the width dimension of the sipe in the tire axial direction, when the small block collapses and deforms, By pressing the vicinity of the edge of the groove wall surface, the edge pressure can be reliably increased to improve the edge effect.

  The invention according to claim 4 is characterized in that a dimension of the protrusion in the tire radial direction is 0.5 mm or more.

  In the pneumatic tire according to claim 4, when the dimension of the protrusion in the tire radial direction is less than 0.5 mm, the rigidity of the protrusion becomes small, and when the small block collapses and deforms, the protrusion becomes the other groove. The vicinity of the edge of the wall cannot be pressed strongly. Therefore, when the size of the protrusion in the tire radial direction is 0.5 mm or more, when the small block collapses and deforms, the protrusion presses near the edge of the other groove wall surface, and the edge pressure is surely increased. The edge effect can be improved.

  As described above, since the pneumatic tire of the present invention has the above-described configuration, the pneumatic tire has an excellent effect on ice that can achieve both the drainage effect, the edge effect, and the surface friction effect.

  A pneumatic tire 10 according to a first embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the tread 12 of the pneumatic tire 10 of the present embodiment includes a plurality of circumferential grooves 14 extending along the tire circumferential direction (arrow S direction) and the tire axial direction (arrow W direction). A plurality of rectangular blocks 18 are provided in a tread plan view that is partitioned by a plurality of lateral grooves 16 extending along the horizontal axis.

  In addition, since the internal structure of this pneumatic tire 10 is the same structure as a general pneumatic tire, description of an internal structure is abbreviate | omitted.

  As shown in FIG. 2, linear sipes 20 extending in the tire axial direction and crossing are formed in the block 18 at equal intervals in the circumferential direction (S), thereby defining a plurality of small blocks 18A. .

  On one wall surface 20A of the sipe 20 of the small block 18A, a plurality of columnar protrusions 22 are provided in a straight line along the tire width direction (W). In the present embodiment, these protrusions 22 have the same diameter, and are formed between 2 mm from the tread surface side toward the bottom surface of the sipe 20.

  As shown in FIG. 3, the height of these protrusions 22 is the distance between one wall surface 20A of the sipe 20 of the small block 18A and the wall surface 20B of the sipe 20 facing this wall surface 20A, that is, the sipe. It is set to occupy 40% or more of the distance between the 20 groove walls. The height of the protrusion 22 may be 40% or more of the distance between the groove walls of the sipe 20, and may be formed so as to contact the wall surface 20B, for example.

  Further, the dimensions of the protrusions 22 in the tire width direction are set so that the total dimension of the plurality of protrusions 22 in the tire width direction is 25% or more of the length of the sipe 20 in one sipe 20. . The total dimension of the plurality of protrusions 22 in the tire width direction may be 25% or more of the dimension of the sipe 20 in the tire width direction. For example, as shown in FIG. The wall surface 20 </ b> A may be formed to fill the tire width direction, that is, close to 100% of the dimension of the sipe 20 in the tire width direction. The dimension of the protrusion 22 in the tire radial direction is 0.5 mm or more.

  Next, the operation of the pneumatic tire 10 according to the embodiment of the present invention will be described.

  A plurality of protrusions 22 formed between 2 mm from the tread surface side of one wall surface 20A of the sipe 20 are in contact with the other wall surface 20B of the sipe 20 during deformation. That is, when the pneumatic tire 10 rolls on the icy road surface and any one of the blocks 18 comes into contact with the ground, the small block 18A divided by the sipe 20 falls down and deforms. At this time, the plurality of protrusions 22 formed on one wall surface 20A of the sipe 20 come into contact with the vicinity of the edge of the other wall surface 20B of the sipe 20 (position from the tread surface side of the sipe 20 to 2 mm). As a result, the edge portion of the sipe 20 on the side where the protrusion 22 contacts is slightly raised by the pressing force of the protrusion 22, and the ground pressure (edge pressure) at the edge portion of the sipe 20 increases.

  As shown in FIG. 5, braking force or driving is applied to a block in which the protrusion 22 is not formed on the wall surface 20A of the sipe 20, and to a block 18 in which the protrusion 22 is formed on the wall surface 20A of the sipe 20, as shown in FIG. Comparing the contact pressure when the force is applied, it can be seen that the contact pressure at the edge portion of the small block 18A is higher in the block in which the protrusion 22 is formed on the wall surface 20A of the sipe 20.

  Therefore, the edge effect is improved, and the braking performance on ice, the traction performance on ice, the braking performance on snow, and the traction performance on snow can be improved.

  When the height of the protrusion 22 is less than 40% of the distance between the groove walls of the sipe 20, the protrusion 22 presses near the edge of the other wall surface 20B when the small block 18A collapses and deforms. Can not do it. Therefore, by setting the height of the protrusion 22 to be 40% or more of the distance between the groove walls of the sipe 20, when the small block 18A falls down and deforms, the protrusion 22 presses the vicinity of the edge of the other wall surface 20B. The edge effect can be improved by reliably increasing the edge pressure.

  Further, in a single sipe 20, when the total width dimension of the plurality of protrusions 22 in the tire axial direction is less than 25% of the length of the sipe 20, the small block 18 </ b> A falls down and the protrusion 22 becomes the other wall surface. When the vicinity of the edge of 20B is pressed, the length (range) of the rising in the length direction of the sipe 20 formed on the tread near the edge becomes small. Therefore, in one sipe 20, the small block 18A does not collapse by making the total width dimension of the plurality of protrusions 22 in the tire axial direction be 25% or more of the width dimension of the sipe 20 in the tire axial direction. At the time of deformation, the protrusion 22 presses the vicinity of the edge of the other wall surface 20B, and the edge pressure can be reliably increased to improve the edge effect.

Further, when the thickness of the protrusion 22 in the direction orthogonal to the tire axis is less than 0.5 mm, the rigidity of the protrusion becomes small, and when the small block 18A falls down and deforms, the protrusion 22 becomes the edge of the other wall surface 20B. The neighborhood cannot be pressed strongly. Therefore, by setting the width dimension of the protrusion 22 perpendicular to the tire axial direction to 0.5 mm or more, when the small block 18A collapses and deforms, the protrusion 22 reliably presses the vicinity of the edge of the other wall surface 20B. The edge effect can be improved by increasing the edge pressure.
(Test example)
In order to confirm the effect of the present invention, three types of tires of the examples to which the present invention was applied, three types of tires of comparative examples, and one type of conventional tires were prepared, and the performance on ice was evaluated by running the actual vehicle. went.

  The tire size was 195 / 65R15, and the vehicle was driven with an internal pressure of 200 kPa.

  As shown in FIG. 7, the dimensions of the block of the conventional example are 40 mm in the tire circumferential direction, 30 mm in the tire width direction, 9 mm in height, 7 mm in depth, and 0.4 mm in dimension between the groove walls. Thus, sipes are formed.

  In Comparative Examples 1 to 3, as shown in FIG. 8, the columnar protrusions 22 are arranged at equal intervals from the center of the block width in the block of the conventional example. Then, the evaluation was performed by changing the height of the protrusion 22, the position where the protrusion 22 is formed (distance from the tread surface side), and the number of the protrusions 22.

  In Examples 1 to 3, the height of the protrusion 22 and the position of the protrusion 22 are fixed, and the protrusion width, that is, the ratio of the total dimension of the protrusion in the tire width direction to the dimension of the sipe 20 in the tire width direction is changed. And evaluated.

  In addition, as shown in FIG. 9, three types of protrusion shape, cylindrical shape (A), square columnar shape (B), and oval shape (C), were used. Further, as shown in FIG. 10, the distance from the tread surface to the end of the protrusion 22 on the sipe bottom side is set to c.

  The evaluation results are as shown in Table 1. In the evaluation, the vehicle was mounted on a passenger car, and a start test and a braking test were performed on an icy road surface. The braking test measures the braking distance from the speed of 40 km / h until full braking is applied, and the average deceleration calculated from the time from the speed of 40 km / h until braking is applied and the stationary distance. Was evaluated. The results are expressed as an average deceleration index with the conventional example being 100, and the larger the average deceleration index, the better the braking performance.

試験の結果、比較例１より、踏面側から２ｍｍの範囲に突起２２が形成されていない場合には、従来例のタイヤに対して氷上性能がほとんど向上していないのが分かる。また、比較例２より、突起高さｂが０．１５ｍｍの場合、すなわち、ブロック壁面間距離０．４ｍｍに対して４０％未満の場合には、従来例のタイヤに対して氷上性能が向上していないのが分かる。さらに、比較例３より、突起２２のタイヤ幅方向の寸法の総計の割合が、小ブロック１８Ａの長さ３０ｍｍに対して２５％未満の場合にも、従来例のタイヤに対して氷上性能がほとんど向上していないのが分かる。つまり、本発明が適用された実施例のタイヤは、従来例に対して氷上減速度、すなわち氷上ブレーキ性能に優れていることが分かった。

As a result of the test, it can be seen from Comparative Example 1 that when the protrusions 22 are not formed in a range of 2 mm from the tread side, the performance on ice is hardly improved as compared with the conventional tire. Further, from Comparative Example 2, when the protrusion height b is 0.15 mm, that is, when it is less than 40% with respect to the block wall distance of 0.4 mm, the performance on ice is improved with respect to the conventional tire. I understand that it is not. Furthermore, from Comparative Example 3, even when the ratio of the total dimension of the protrusions 22 in the tire width direction is less than 25% with respect to the length of the small block 18A of 30 mm, the performance on ice is almost the same as that of the conventional tire. You can see that it has not improved. That is, it was found that the tire of the example to which the present invention was applied was superior in the deceleration on ice, that is, the braking performance on ice, compared to the conventional example.

  In the present embodiment, the shape of the protrusion 22 is a cylindrical shape, but the shape of the protrusion 22 may be other shapes such as an ellipse, an ellipse, a rectangle, and a polygon as shown in FIG. . Further, the plurality of protrusions are not necessarily formed so as to have the same diameter in the case of a cylinder and the length of one side in the case of a polygonal shape.

  Furthermore, in this embodiment, although the circumferential groove 14 extended along the tire circumferential direction, the circumferential groove may be inclined with respect to the tire circumferential direction. In this case, the inclination angle is preferably within 40 degrees, and more preferably within 20 degrees.

  In addition, the shape of the block 18 when the tread 12 is viewed in plan is rectangular, but the shape of the block is not limited to a rectangle, and by adding the direction of the circumferential groove 14 and the lateral groove 16, chamfering, notches, etc., It may be a polygon such as a hexagon or an octagon, a substantially U-shape, a circle or an ellipse.

  Furthermore, in the present embodiment, the sipe 20 is a straight sipe extending linearly, but may be a zigzag sipe or three-dimensional sipe extending in a zigzag shape.

It is a top view of the tread of the pneumatic tire concerning the embodiment of the present invention. It is a perspective view of the small block in which the protrusion was formed. (A) is a top view of the small block in which the protrusion was formed, and (B) is a side view. It is a perspective view which shows the other form of the small block in which the protrusion was formed. It is explanatory drawing explaining distribution of the ground pressure which acts on a conventional block. It is explanatory drawing explaining distribution of the ground pressure which acts on the block of this invention. It is the upper side figure and side view of a conventional block. It is the upper side figure and side view of the block of this invention. It is a perspective view which shows the shape of the processus | protrusion formed in the block of this invention. It is explanatory drawing explaining distance c from a tread surface to the edge part of the sipe bottom side of a processus | protrusion.

Explanation of symbols

10 Pneumatic tire 12 Tread 18 Block 20 Sipe 22 Protrusion

Claims (4)

A pneumatic tire in which a tread is provided with a plurality of blocks defined by a plurality of grooves intersecting each other, and a sipe extending along the tire axial direction is formed on the block,
A pneumatic tire characterized in that at least one groove wall surface of the sipe is formed with a plurality of protrusions that are in contact with the other groove wall surface at the time of contact between the tread surface and 2 mm.   The pneumatic tire according to claim 1, wherein a height of the protrusion is 40% or more of a distance between groove walls of the sipe.   3. The pneumatic tire according to claim 1, wherein the total width dimension in the tire axial direction of the plurality of protrusions in one sipe is 25% or more of the length of the sipe.   The pneumatic tire according to any one of claims 1 to 3, wherein a dimension of the protrusion in a tire radial direction is 0.5 mm or more.

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