JP2009214697A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving a friction characteristic on an icy road surface by making compatible all of a drain effect, an edge effect and a grounding effect. <P>SOLUTION: The pneumatic tire has a block 5 partitioned by a plurality of tread grooves 3 formed on a tread, and sipes 7 formed in a plurality in the block 5, positioning both ends in the tread width direction in the block 5 and thinner than the tread grooves 3, and is characterized in that the sipes 7 have width directional parts 7A substantially orthogonally arranged with respect to the tire peripheral direction, and a peripheral directional part 7B continuing from the width directional part 7A and arranged at an angle different from the width directional part 7A with respect to the tire peripheral direction, and a length RL in the peripheral direction being a length in the titre peripheral direction of a small block 5A partitioned by the width directional part 7A and the peripheral directional part 7B is changed in the tread width direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire in which sipes are formed in blocks partitioned by a plurality of grooves.

  Conventionally, a pneumatic tire for a snowy and snowy road surface (a so-called studless tire) has a block partitioned by a plurality of grooves formed on a tread surface in order to secure friction characteristics on a road surface on ice. A thin sipe is formed.

For example, a pneumatic tire is disclosed in which both ends of the sipe in the tread width direction are opened to the outside of the block, thereby removing a water film generated on ice and improving an edge effect of scratching ice (for example, , See Patent Document 1).
JP-A-1-101204 (pages 2 to 3)

  By the way, it is said that as a constituent factor governing the frictional characteristics on the road surface on ice, in addition to the drainage effect and the edge effect described above, there is a grounding effect for securing a ground contact area on ice.

  However, in the conventional pneumatic tire described above, since both ends of the sipe in the tread width direction are opened to the outside of the block, the block collapses and the grounding effect is reduced. The characteristics may be reduced.

  That is, when both ends of the sipe in the tread width direction are opened to the outside of the block (end opening structure), it is advantageous for the drainage effect and the edge effect, but is disadvantageous for the grounding effect. On the other hand, if both ends of the sipe in the tread width direction are positioned in the block (end closing structure), it is disadvantageous for the drainage effect and the edge effect, but it is advantageous for the grounding effect.

  The drainage effect / edge effect and the ground contact effect have a contradictory relationship, and there is a demand for the development of a technique for solving these problems and improving the friction characteristics on the road surface on ice.

  Accordingly, the present invention has been made in view of such a situation, and it is possible to improve the drainage effect and the edge effect without impairing the ground contact effect, and to improve the friction characteristics on the road surface on ice. The object is to provide a tire.

  In order to solve the above-described problems, the present invention has the following features. First, the first feature of the present invention is that a block defined by a plurality of grooves formed on the tread surface, a plurality of blocks are formed, and both ends in the tread width direction are located in the block and are narrower than the grooves. A sipe, and a sipe that is arranged substantially orthogonal to the tire circumferential direction, and that is continuous from the width direction part and arranged at an angle different from the width direction part with respect to the tire circumferential direction. The circumferential length which is the length to the tire circumferential direction of the small block which has a circumferential direction part and is divided by the width direction part and the circumferential direction part changes in a tread width direction.

  According to such a feature, the both ends of the sipe in the tread width direction are located in the block (so-called end closing structure), so that collapse deformation can be suppressed and a sufficient grounding effect can be obtained. .

  Moreover, when the block slides on the ice surface due to the change in the circumferential length in the tread width direction, minute vibrations are generated in the small block, and this minute vibration is repeated, so that a water film generated on the ice is formed. Since it becomes easy to discharge | emit and the force which scratches (digs up) ice increases, the drainage effect and the edge effect can be improved.

  In this way, the drainage effect and the edge effect can be improved without impairing the ground contact effect, and the friction characteristics on the road surface on ice can be dramatically improved.

  Another feature is summarized in that the circumferential portion is arranged to be inclined with respect to the tire circumferential direction.

  According to such a feature, since the circumferential portion is arranged to be inclined with respect to the tire circumferential direction, the water film generated on the ice can be easily discharged, and the drainage effect does not occur. Can be further improved.

  Another feature is that the shortest circumferential length, which is the shortest distance in the circumferential length, is 1.0 to 2.5 mm, and the longest circumferential direction length, which is the longest distance in the circumferential length, is 3.5 to 5. The gist is 0 mm.

  Another feature is that the end closing length, which is the length in the tread width direction from the groove defining the block to both ends of the sipe in the tread width direction, is 1.0 to 3.0 mm.

  ADVANTAGE OF THE INVENTION According to this invention, the pneumatic tire which can improve the drainage effect and the edge effect, and can improve the friction characteristic on an ice surface can be provided, without impairing a ground contact effect.

  Next, an example of a pneumatic tire according to the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions are different from actual ones. Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(Composition of pneumatic tire)
1 is a development view showing a tread pattern of the pneumatic tire according to the present embodiment, and FIG. 2 is a perspective view showing blocks provided in the pneumatic tire according to the present embodiment. These are top views (plan views) showing blocks provided in the pneumatic tire according to the present embodiment.

  Here, the pneumatic tire 1 which concerns on this Embodiment shall be a general radial tire provided with a bead part, a carcass layer, and a belt layer (not shown).

  As shown in FIG. 1, the pneumatic tire 1 includes a block 5 defined by a plurality of grooves (hereinafter, tread grooves 3) formed on a tread surface. The tread groove 3 includes a plurality of circumferential grooves 3A extending in the tire circumferential direction and a plurality of width direction grooves 3B extending in the tread width direction on the tread surface.

  As shown in FIGS. 1 to 3, in the block 5, both ends 7 e in the tread width direction are located in the block 5 (so-called end closing structure), and a sipe 7 thinner than the tread groove 3 is formed. ing. A plurality of sipes 7 are formed in each block 5 (four in the drawing).

  The sipe 7 is arranged at an angle different from the width direction portion 7A with respect to the tire circumferential direction, and the width direction portion 7A arranged substantially orthogonal to the tire circumferential direction and the width direction portion 7A. And a circumferential portion 7B.

  The circumferential portion 7B is disposed to be inclined with respect to the tire circumferential direction. The circumferential portion 7B is disposed so as to be inclined in the opposite direction to the circumferential portion 7B adjacent to the tire circumferential direction. In particular, the inclination angle (α) of the circumferential portion 7B with respect to the tire circumferential direction is preferably 5 to 40 degrees (see FIG. 3B).

  If the inclination angle (α) of the circumferential portion 7B is smaller than 5 degrees, it is difficult to discharge the water film generated on the ice, and the sipe 7 may accumulate in the sipe 7. On the other hand, when the inclination angle (α) of the circumferential portion 7B is larger than 40 degrees, the root portion of the expanding portion 9B described later becomes wide, and vibration or the like may not easily occur.

  Here, the circumferential length RL that is the length in the tire circumferential direction of the small block 5A defined by the width direction portion 7A and the circumferential direction portion 7B changes in the tread width direction. That is, as shown in FIG. 4, the small block 5A has a constricted portion 9A that is constricted when the block is viewed from above. In the small block 5A, the width is reduced from the constricted portion 9A toward the widened portion 9B that is wider than the constricted portion 9A.

  Specifically, the shortest circumferential direction length RL1 that is the shortest distance in the circumferential direction length RL is preferably 1.0 to 2.5 mm. When the shortest circumferential direction length RL1 is smaller than 1.0 mm, the adjacent width direction portion 7A becomes too close, and the grounding effect may be lowered. On the other hand, if the shortest circumferential direction length RL1 is larger than 2.5 mm, it may be difficult for fine vibrations to occur.

  Moreover, it is preferable that longest circumferential direction length RL2 which is the longest distance in circumferential direction length RL is 3.5-5.0 mm. If the longest circumferential direction length RL2 is smaller than 3.5 mm, the adjacent width direction portion 7A becomes too close, and the grounding effect may be lowered. On the other hand, when longest circumferential direction length RL2 is larger than 5.0 mm, it may become difficult to generate a fine vibration.

  The end closing length EL, which is the length in the tread width direction from the tread groove 3 (circumferential groove 3A) defining the block 5 to the tread width direction both ends 7e of the sipe 7, is 1.0 to 3.0 mm. Preferably there is. If the end closing length EL is smaller than 1.0 mm, the tread groove 3 is too close to the tread width direction both ends 7e of the sipe 7, and the grounding effect may be lowered. On the other hand, when the end closing length EL is larger than 3.0 mm, the tread groove 3 is too far from the both ends 7e in the tread width direction of the sipe 7, and the drainage performance may be deteriorated.

(Action / Effect)
According to the pneumatic tire 1 according to the present embodiment described above, the both ends of the sipe 7 in the tread width direction are positioned in the block 5 (so-called end closing structure), as shown in FIG. In addition, collapse deformation can be suppressed, and a sufficient grounding effect can be obtained.

  That is, the block 5 shown in FIG. 5 has a linear shape in the tread width direction as compared to the block 50 (see FIG. 8C) in which a straight sipe 70 is formed in an end opening structure in the tread width direction. As with the block 50 (see FIG. 9C) in which the sipe 70 is formed with a closed end structure, the collapse deformation can be suppressed and a sufficient ground contact area (a) can be secured.

  Further, when the circumferential length RL is changed in the tread width direction, when the block 5 slides on the ice surface, a minute vibration is generated in the small block 5A, and this minute vibration is repeated to be generated on the ice. Since the water film can be easily discharged and the force to scratch (dig up) the ice is increased, the drainage effect and the edge effect can be improved.

  In this way, the drainage effect and the edge effect can be improved without impairing the ground contact effect, and the friction characteristics on the road surface on ice can be dramatically improved.

  Further, since the circumferential portion 7B is arranged to be inclined with respect to the tire circumferential direction, the water film generated on the ice can be easily discharged, and the sipe 7 does not accumulate. Can be improved.

[Other embodiments]
As described above, the contents of the present invention have been disclosed through the embodiments of the present invention. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention.

  Specifically, the pneumatic tire 1 has been described as a general radial tire including a bead portion, a carcass layer, and a belt layer (not shown). However, the pneumatic tire 1 is not limited to this and is not a radial tire. Tires (for example, bias tires).

  Moreover, although the circumferential direction part 7B demonstrated as what was arrange | positioned inclined with respect to the tire circumferential direction, it is not limited to this, For example, as shown in FIG. Of course, they may be arranged in parallel.

  Further, the small block 5A has been described as being reduced from the constricted portion 9A toward the widened portion 9B. However, the present invention is not limited to this. For example, as shown in FIG. You may amplify toward the spreading | diffusion part 9B.

  From this disclosure, various alternative embodiments, examples, and operational techniques will be apparent to those skilled in the art. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

  Next, in order to further clarify the effects of the present invention, test results performed using the pneumatic tires according to the following Comparative Examples 1 and 2 and Examples 1 to 4 will be described. In addition, this invention is not limited at all by these examples.

  Data regarding each pneumatic tire is measured under the following conditions.

・ Tire size: 195 / 65R15
・ Wheel size: 15 × 6J
・ Internal pressure condition: 200 kpa
・ Vehicle type: General passenger car (displacement 1.500cc)
In the pneumatic tire according to Comparative Example 1, as shown in FIG. 8, both end portions 70e of the sipe 70 in the tread width direction are opened to the outside of the block 50 (having an end opening structure). In the pneumatic tire according to Comparative Example 1, the circumferential length RL (the shortest circumferential direction length and the longest circumferential direction length) of the small block 50A is 4.0 mm.

  In the pneumatic tire according to Comparative Example 2, as shown in FIG. 9, both ends 70e of the sipe 70 in the tread width direction are positioned in the block 50 (having an end closed structure). In the pneumatic tire according to the comparative example 2, the circumferential length RL (the shortest circumferential direction length and the longest circumferential direction length) of the small block 50A is 4.0 mm.

  In the pneumatic tire 1 according to the first embodiment, as shown in FIGS. 1 to 5, both ends 7 e of the sipe 7 in the tread width direction are located in the block 5 (the end closed structure). In the pneumatic tire 1 according to Example 1, the shortest circumferential direction length RL1 of the small block 5A is 0.5 mm, and the longest circumferential direction length RL2 of the small block 5A is 4.0 mm.

  In the pneumatic tire 1 according to the second embodiment, as shown in FIGS. 1 to 5, both ends of the sipe 7 in the tread width direction are positioned in the block 5 (having an end closing structure). In the pneumatic tire 1 according to Example 2, the shortest circumferential direction length RL1 of the small block 5A is 2.0 mm, and the longest circumferential direction length RL2 of the small block 5A is 4.0 mm.

  In the pneumatic tire 1 according to the third embodiment, as illustrated in FIGS. 1 to 5, both ends of the sipe 7 in the tread width direction are positioned in the block 5 (having a closed end structure). In the pneumatic tire 1 according to Example 3, the shortest circumferential direction length RL1 of the small block 5A is 2.0 mm, and the longest circumferential direction length RL2 of the small block 5A is 6.0 mm.

  In the pneumatic tire 1 according to the fourth embodiment, as shown in FIGS. 1 to 5, both ends of the sipe 7 in the tread width direction are located in the block 5 (the end closed structure). In the pneumatic tire 1 according to Example 3, the shortest circumferential direction length RL1 of the small block 5A is 1.0 mm, and the longest circumferential direction length RL2 of the small block 5A is 5.0 mm.

＜摩擦特性＞
各空気入りタイヤが装着された車両で氷上路面を走行し、初速度４０ｋｍ／ｈからフルブレーキをかけて静止状態となるまでの制動距離を計測し、初速度と制動距離から平均減速度を算出した。なお、比較例に係る空気入りタイヤの氷上路面での摩擦特性を“１００”とし、実施例に係る空気入りタイヤの氷上路面での摩擦特性を指数表示した。指数が大きいほど、氷上路面での摩擦特性に優れている。 The friction characteristics of the pneumatic tires according to Comparative Examples 1 and 2 and Examples 1 to 4 will be described with reference to Table 1.

<Friction characteristics>
Run on the surface of the road with a vehicle equipped with pneumatic tires, measure the braking distance from the initial speed of 40 km / h until full braking is applied, and calculate the average deceleration from the initial speed and braking distance. did. In addition, the friction characteristic on the road surface on ice of the pneumatic tire according to the comparative example was “100”, and the friction characteristic on the road surface on ice of the pneumatic tire according to the example was displayed as an index. The larger the index, the better the friction characteristics on the road surface on ice.

  As a result, as shown in Table 1, the pneumatic tires according to Examples 2 and 4 have the shortest circumferential length of 1.0 to 2.5 mm and the longest circumferential length of 3.5 to 5.0 mm. Therefore, it was found that the friction characteristics on the road surface on ice are excellent.

It is an expanded view which shows the tread pattern of the pneumatic tire which concerns on this Embodiment. It is a perspective view which shows the block provided in the pneumatic tire which concerns on this Embodiment. It is a top view (plan view) showing a block provided in the pneumatic tire according to the present embodiment. It is a perspective view which shows the small block provided in the pneumatic tire which concerns on this Embodiment. It is side surface sectional drawing (AA sectional drawing of Fig.3 (a)) which shows the block provided in the pneumatic tire which concerns on this Embodiment. It is a top view which shows the block provided in the pneumatic tire which concerns on other embodiment (the 1). It is a top view which shows the block provided in the pneumatic tire which concerns on other embodiment (the 2). It is a perspective view, an upper surface, and a side view showing a pneumatic tire according to Comparative Example 1. It is a perspective view, an upper surface, and a side view showing a pneumatic tire according to Comparative Example 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Pneumatic tire, 3 ... Tread groove, 3A ... Circumferential groove, 3B ... Width direction groove, 5 ... Block, 5A ... Small block, 7 ... Sipe, 7A ... Width direction part, 7B ... Circumferential direction part, 7e ... Sipe tread width direction end, 9A ... constriction, 9B ... expansion, RL ... circumferential length, RL1 ... shortest circumferential length, RL2 ... longest circumferential length, EL ... end closing length

Claims (4)

A block defined by a plurality of grooves formed on the tread surface;
A plurality of the blocks are formed, both ends in the tread width direction are located in the block, and a sipe narrower than the groove is provided.
The sipe has a width direction portion arranged substantially orthogonal to the tire circumferential direction, and a circumference continuous from the width direction portion and arranged at an angle different from the width direction portion with respect to the tire circumferential direction. A direction part,
The pneumatic tire is characterized in that a circumferential length, which is a length in the tire circumferential direction, of a small block defined by the width direction portion and the circumferential direction portion varies in the tread width direction.   The pneumatic tire according to claim 1, wherein the circumferential portion is disposed to be inclined with respect to the tire circumferential direction. The shortest circumferential length, which is the shortest distance in the circumferential length, is 1.0 to 2.5 mm,
2. The pneumatic tire according to claim 1, wherein a longest circumferential direction length that is a longest distance in the circumferential direction length is 3.5 to 5.0 mm.   The end closing length, which is the length in the tread width direction from the groove defining the block to both ends of the sipe in the tread width direction, is 1.0 to 3.0 mm. The pneumatic tire according to any one of claims 3 to 3.

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