JP2008221955A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of reducing dispersion of on-ice performance depending on weather by improving a snow sticking characteristics on a tread face of the pneumatic tire for an icy/snowy road represented by a brand new studless tire. <P>SOLUTION: In the pneumatic tire, a tread part has a tread pattern provided with blocks separated by tire circumferential direction grooves and inclining lag grooves having an inclining angle α equal to or larger than 40° and equal to or smaller than 70° to the tire circumferential direction and sipes are provided at the tread part and shallow surface processed grooves are arranged with a crossing angle β in a range within substantial right angle ±10° to the inclining angle α of the inclining lag grooves. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pneumatic tire for icy and snowy roads.

  Conventionally, pneumatic tires for icy and snowy roads typified by studless tires are designed to strengthen the drainage and snow drainage performance of new tires, to ensure icy and snow performance, and to wear the tread surface early to make the rubber itself In order to obtain the above characteristics, it has been proposed to improve the surface processing (riblet processing) by putting it in a certain direction.

  For example, in a pneumatic tire for snowy and snowy roads provided with sipes, a plurality of shallow grooves shallower than sipes are formed on the tread surface of the block, and the angle of these shallow grooves with respect to the tire circumferential direction is 42 degrees to 60 degrees. Has been proposed (Patent Document 1).

  Also, in a pneumatic tire for ice and snowy roads in which a plurality of land portions made up of blocks or ribs are defined in the tread portion and a plurality of sipes are provided on the land portions, a plurality of shallower than the sipes are formed on the tread surface of the land portion. There has been proposed a pneumatic tire for icy and snowy roads in which narrow grooves are formed and the edges of the narrow grooves are curved, or the width at the opening of these narrow grooves is larger than the width at the bottom ( Patent Document 2).

However, all of these Patent Documents 1 and 2 are cases where the snow has adhered to the tread surface, especially in a situation where snow has accumulated slightly on flat ice or a snowy road, and the original grip performance of rubber cannot be exhibited. There was a problem that there was.
JP 2004-34903 A JP 2004-34902 A

  In view of the above-mentioned points, the present invention can improve the snowy characteristics of the tread surface of a pneumatic tire for icy and snowy roads typified by a new studless tire, and can reduce variations in performance on ice due to weather. An object is to provide a pneumatic tire.

The pneumatic tire of the present invention that achieves the above object has the following configuration (1).
(1) The tread portion has a tread pattern having a block divided by a tire circumferential direction groove and an inclined lug groove having an inclination angle α of not less than 40 degrees and not more than 70 degrees with respect to the tire circumferential direction; A pneumatic tire characterized by having a sipe and surface-finished shallow grooves arranged with a crossing angle β within a range of approximately ± 10 degrees within a range substantially perpendicular to the inclination angle α direction of the inclined lug grooves .

In the pneumatic tire of the present invention, preferably, the pneumatic tire has a more specific configuration of any one of the following (2) to (10).
(2) The above-mentioned (1), wherein the surface-processed shallow grooves are arranged with a crossing angle β in a range substantially within ± 5 degrees with respect to the inclination angle α of the inclined lug groove. Pneumatic tires.
(3) The surface processed shallow groove has a groove depth of 0.1 mm to 1.5 mm, a groove width of 0.1 mm to 0.8 mm, and a distance between adjacent surface processed shallow grooves of 0.5 mm to 2 mm. The pneumatic tire according to the above (1) or (2), characterized in that:
(4) The pneumatic tire according to any one of claims 1 to 3, wherein the sipe is provided so that a sipe center line is substantially parallel to an inclination direction of the inclined lug groove.
(5) The pneumatic tire according to any one of claims 1 to 4, wherein the tire center portion has a row of ribs.
(6) On the inner layer side of the rubber layer constituting the tread portion, a belt layer having fiber cords arranged with a bias angle in the tire circumferential direction is directly adjacent to the rubber layer constituting the tread portion. The pneumatic tire according to claim 1, wherein the pneumatic tire is arranged.
(7) On the inner layer side of the rubber layer constituting the tread portion, at least two belt layers made of steel cords arranged with a bias angle of 25 degrees or more and 33 degrees or less with respect to the tire circumferential direction are arranged. The pneumatic tire according to claim 1, wherein the pneumatic tire is a tire.
(8) The depth of the surface processed shallow groove is configured to gradually increase in a direction from the stepping side to the kicking side of the block surface divided by the inclined lug groove. The pneumatic tire according to any one of claims 1 to 7.
(9) The groove width of the surface processed shallow groove is configured to gradually increase in the direction from the stepping side to the kicking side of the block surface divided by the inclined lug groove. The pneumatic tire according to any one of claims 1 to 8.
(10) The surface processed shallow groove is configured such that the existence density gradually increases in a direction from the stepping side to the kicking side of the block surface divided by the inclined lug groove. The pneumatic tire according to any one of claims 1 to 9.

  ADVANTAGE OF THE INVENTION According to this invention, the pneumatic tire which can improve the characteristic with snow with respect to the tread surface of the pneumatic tire for icy and snowy roads represented by the studless tire at the time of a new article, and can reduce the variation in on-ice performance by the weather is provided. The

  Hereinafter, the pneumatic tire of the present invention will be described in more detail with reference to the drawings.

  The pneumatic tire of the present invention has a tread pattern having a block divided by a tire circumferential direction groove and an inclined lug groove having an inclination angle α of 40 degrees or more and 70 degrees or less with respect to the tire circumferential direction in the tread portion, In addition, the tread portion has a sipe and has a surface processed shallow groove arranged with a crossing angle β in a range of approximately ± 10 degrees within a range substantially perpendicular to the inclination angle α of the inclined lug groove. Is.

  FIG. 1 shows an example of an embodiment of a pneumatic tire according to the present invention, and is an appearance model diagram schematically showing a groove pattern on a tire tread surface.

  The pneumatic tire 1 is an icy and snowy road tire having a tire circumferential groove 3 and an inclined lug groove 4 in a tread 2, and blocks 5 are divided by these grooves and arranged around the tire. As shown in the enlarged portion of FIG. 6 and FIG. 1, the tread block tread surface has a range within approximately ± 10 degrees perpendicular to the inclination angle α direction of the sipe 6 and the inclined lug groove, that is, A large number of surface-treated shallow grooves 7 arranged with an intersecting angle β of 80 to 100 degrees with respect to the direction of the inclination angle α are arranged in parallel.

  The surface processed shallow groove 7 is generally a groove that is shallower than the sipe 6, and is preferably provided in a continuous straight line so that a large number of the grooves extend in parallel. The surface processing is also called riblet processing. . The shallow groove does not necessarily have to be on a continuous straight line, may be interrupted in the middle, or may have a broken line shape, or may have a slightly curved shape.

  In the pneumatic tire of the present invention, in the conventional pneumatic tire of the same type, the surface-finished shallow groove as described above is provided so as to be parallel to the tire circumferential direction. In the case where shallow grooves are provided in the conventional circumferential direction, if water is braked on a flat ice path during snowfall, moisture floating on the ice surface When snow with a lot of snow sticks to the tread, the tread rubber cannot directly contact the icy road, and the distance required for braking may be greatly extended. This is because the road surface rigidity in the longitudinal direction is on the icy road. This is probably because the movement of the road surface is too small because it is too large for the braking force.

  On the other hand, according to the present invention, by setting the angle of the surface processed shallow groove to be within a range of about ± 10 degrees perpendicular to the inclined lug groove as described above, normal on-ice performance at the initial stage of wear can be obtained. Not only can it be ensured, but it also improves the performance on ice during snowfall by improving the characteristics with snow (snow tension). When the crossing angle β is less than 80 degrees (right angle −10 degrees), the rigidity of the tread is too large and the effect of improving the snowy characteristics is not preferable, and more than 100 degrees (right angle +10 degrees). In this case, snow is easily clogged in the shallow groove, and the effect of the present invention is reduced.

  2 to 5 show other embodiments of the pneumatic tire according to the present invention, and the present invention can be adopted even in a groove pattern having a rib groove in the center portion. .

  According to the various findings of the present inventors, the surface-treated shallow grooves are arranged with a crossing angle β in a range (85 degrees to 95 degrees) within a range substantially within ± 5 degrees with respect to the inclination angle α of the inclined lug grooves. It is preferable that higher effects can be obtained.

  In addition, the surface processed shallow groove has a groove depth of 0.1 mm to 1.5 mm, a groove width of 0.1 mm to 0.8 mm, and a distance between adjacent surface processed shallow grooves of 0.5 mm to 2 mm. It is preferable that there is a large effect of providing the shallow groove. When the depth of the surface processed shallow groove is smaller than 0.1 mm, the effect on the ice performance is small, and when it is larger than 1.5 mm, the tread rigidity is lowered and the steering stability is lowered. There is not preferable.

  Further, when the surface processed shallow groove width is smaller than 0.1 mm, the effect on the performance on ice is small, and when it is larger than 0.8 mm, the tread rigidity is lowered and the steering stability is lowered. This is not preferable.

  Further, when the distance between the surface processed shallow groove widths is smaller than 0.5 mm, the tread rigidity is lowered and the steering stability is lowered, and when larger than 2 mm, the effect on the performance on ice is reduced. Small and not preferred.

  Further, it is important that the inclination angle α of the inclined lug groove is not less than 40 degrees and not more than 70 degrees. When the inclination angle α is smaller than 40 degrees, the tread rigidity is lowered and the steering stability is lowered. If it is larger than that, the drainage and snow drainage properties will be reduced, and the wet performance of the tire will be lowered.

  It is preferable that the sipe is provided so that the sipe center line is substantially parallel to the inclination direction of the inclined lug groove in order to exhibit the effect satisfactorily.

  In addition, the tire center portion is preferably a pattern having rib rows, and particularly in the range of travel of 80 km / h or less, such as traveling on a snowy road or on an icy road, the movement of the surface of the SH portion (shoulder portion) block Therefore, the SH portion (shoulder portion) block is likely to be covered with snow, whereas the tire center portion is less likely to be covered with snow because of the large tread movement. Therefore, in order to increase the tire ground contact area, it is preferable that the center portion is a rib, and the braking performance on ice can be further improved by using the rib.

  At that time, it is important that the surface processed shallow groove of the SH portion (shoulder portion) block is substantially perpendicular to the lug groove (80 to 100 degrees) as in the present invention. For the surface processed shallow grooves, the crossing angle β may not be substantially right angle and may be parallel to the tire circumferential direction.

  In the present invention, the tire center portion refers to a portion within a contact width of 15% or less from the tire equatorial plane, and it is preferable that the center rib exists within the range. In addition, the term “rib” as used herein refers to a rib that exists in the circumferential direction in a ground contact shape at a standard air pressure of JATMA standard, a standard rim width, and a maximum load of 60%.

  Further, in the pneumatic tire of the present invention, a belt layer having steel cords arranged with a bias angle in the tire circumferential direction on the inner layer side of the rubber layer constituting the tread portion serves as a rubber layer constituting the tread portion. It is preferable that they are arranged directly adjacent to each other. This means that the belt reinforcement layer using the fiber cord extending in the circumferential direction is not reinforced, and the belt layer having the steel cord arranged with the bias angle described above suppresses the movement. This is preferable because it is structurally easy to move and snow is less likely to occur at that point.

  In the pneumatic tire of the present invention, at least two layers of steel cords arranged on the inner layer side of the rubber layer constituting the tread portion with a bias angle of 25 degrees or more and 33 degrees or less with respect to the tire circumferential direction. The belt layer is preferably disposed, and the belt cord angle is increased in this way to promote the movement of the tread surface, which is less likely to cause snow.

  Furthermore, in the pneumatic tire of the present invention, in order to make drainage and snow drainage performance more effective, the depth of the surface processed shallow groove is changed from the stepping side of the block surface divided by the inclined lug groove to the kicking side. It is preferable to be configured so that it gradually becomes deeper in the direction of heading.

  Furthermore, for the same reason, the groove width of the surface processed shallow groove is configured to gradually increase in the direction from the stepping side to the kicking side of the block surface divided by the inclined lug groove. preferable.

  For the same reason, the surface processed shallow groove may be configured such that its existence density gradually increases in the direction from the stepping side to the kicking side of the block surface divided by the inclined lug groove. It is preferable.

  The pneumatic tire of the present invention is suitably used as a studless tire for an RV vehicle by taking advantage of the above-described features.

  A pneumatic tire having a tread pattern (lug groove, circumferential groove), sipe, and surface processed shallow groove as described above of the present invention can be manufactured using a vulcanization mold in which the groove or the like is cut. .

  Hereinafter, based on an Example, the structure and effect of the pneumatic tire of this invention are demonstrated concretely.

Examples 1 to 4, Conventional Example 1
A pneumatic tire having an inclined lug groove (inclination angle α = 65 degrees) and having a tire size of 265 / 70R16 112Q has a cross-section angle of 65 degrees with respect to the inclined lug groove (conventional example 1). A pneumatic tire for icy and snowy roads having five specifications of an intersection angle of 80 degrees (Example 1), an intersection angle of 90 degrees (Examples 2 and 4), and an intersection angle of 100 degrees (Example 3) was manufactured. . The difference between the second embodiment and the fourth embodiment is that the tire center shape is a block in the second embodiment but is a rib in the fourth embodiment.

  The test conditions were 200 kPa for air pressure, 4 liters of 4-wheel drive gasoline vehicle, and a test vehicle with an ABS braking device. ABS braking of 10 mm and an initial speed of 40 km / h was performed, and braking performance and snowiness were evaluated.

Regarding the determination of snowiness, the exposure amount of the block tread was visually determined. The larger the exposure amount, the better the snowiness, and the following four-level evaluation was performed.
◎: 90% or more ○: 70% or more and less than 90% △: 50% or more and less than 70% ×: less than 50%

  The results of evaluating the braking performance on ice and the ability to snow with and without snow on the pneumatic tires of the examples and the conventional examples are as shown in Table 1, and the pneumatic tire of the present invention is very excellent. I understand that.

FIG. 1 shows an example of an embodiment of a pneumatic tire according to the present invention, and is an appearance model diagram schematically showing a groove pattern on a tire tread surface. Are omitted). FIG. 2 shows another embodiment of the pneumatic tire according to the present invention, and is an external model diagram schematically showing the groove pattern on the tire tread surface (the surface processed shallow grooves are not shown). ing). FIG. 3 shows another example of a pneumatic tire according to the present invention, and is an external model diagram schematically showing a groove pattern on a tire tread surface (illustration of the surface processed shallow groove is omitted). ing). FIG. 4 shows another embodiment of the pneumatic tire of the present invention, and is an appearance model diagram schematically showing the groove pattern on the tire tread surface (the surface processed shallow grooves are not shown). ing). FIG. 5 shows another embodiment of the pneumatic tire of the present invention, and is an appearance model diagram schematically showing the groove pattern on the tire tread surface (illustration of the surface processed shallow groove is omitted). ing). FIG. 6 is a model diagram showing the relationship between the inclination angle α of the inclined lug groove and the angle β at which the surface processed shallow groove intersects the inclination angle α direction of the inclined lug groove in the pneumatic tire of the present invention. (The illustration of sipe is omitted).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Tire circumferential direction groove 4 Inclined lug groove 5 Block 6 Sipe 7 Surface processing shallow groove 8 Rib row α Inclination angle of inclined lug groove β Surface processing shallow with respect to inclination angle α direction of inclined lug groove Angle β at which the grooves intersect

Claims (10)

  The tread portion has a tread pattern having a tire groove in the tire circumferential direction and a block divided by an inclined lug groove having an inclination angle α of 40 degrees or more and 70 degrees or less with respect to the tire circumferential direction, and a sipe is formed in the tread portion. And a surface-treated shallow groove arranged with a crossing angle β within a range substantially within ± 10 ° with respect to the inclination angle α direction of the inclined lug groove.   2. The pneumatic tire according to claim 1, wherein the surface-treated shallow grooves are arranged with a crossing angle β within a range of approximately ± 5 degrees perpendicular to the inclination angle α of the inclined lug grooves. .   The surface processed shallow groove has a groove depth of 0.1 mm to 1.5 mm, a groove width of 0.1 mm to 0.8 mm, and a distance between adjacent surface processed shallow grooves of 0.5 mm to 2 mm. The pneumatic tire according to claim 1 or 2, characterized by the above.   The pneumatic tire according to any one of claims 1 to 3, wherein the sipe is provided such that a sipe center line is substantially parallel to an inclination direction of the inclined lug groove.   The pneumatic tire according to any one of claims 1 to 4, wherein the tire center portion has a rib row.   On the inner layer side of the rubber layer constituting the tread portion, a belt layer having fiber cords arranged with a bias angle in the tire circumferential direction is disposed directly adjacent to the rubber layer constituting the tread portion. The pneumatic tire according to any one of claims 1 to 5, wherein   At least two belt layers made of steel cords arranged with a bias angle of 25 degrees or more and 33 degrees or less with respect to the tire circumferential direction are arranged on the inner layer side of the rubber layer constituting the tread portion. The pneumatic tire according to any one of claims 1 to 6.   The depth of the surface processed shallow groove is configured to gradually increase in a direction from the stepping side to the kicking side of the block surface divided by the inclined lug groove. The pneumatic tire according to any one of 1 to 7.   The groove width of the surface processed shallow groove is configured to gradually increase in a direction from the stepping side to the kicking side of the block surface divided by the inclined lug groove. The pneumatic tire according to any one of 1 to 8.   2. The surface processed shallow groove is configured such that the existence density gradually increases in a direction from the stepping side to the kicking side of the block surface divided by the inclined lug groove. The pneumatic tire in any one of -9.

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