JP2009023505A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire suitable as the so-called year-round tire making dry road traveling performance and snow road traveling performance compatible with good balance. <P>SOLUTION: This pneumatic tire has a main groove provided in at least a peripheral direction, a sub groove provided in a direction except the peripheral direction and a block provided to be surrounded by the main groove and the sub groove on a tread surface. In the sub groove, a planar projection having a distal end on a tread surface side which is not linked with the block and is a free end is provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire.

  More specifically, for example, a so-called all-season tire, a pneumatic tire used for dry road driving and snow road driving, dry road driving performance (hereinafter sometimes referred to as “dry performance”) and snow road driving performance. (Hereinafter, sometimes referred to as “snow performance”).

  Conventionally, there is a so-called all-season pneumatic tire that is used for both dry road running and snowy road running.

  This all-season tire is originally made to satisfy both dry road performance and snow road performance, but the dry road performance and snow road performance are originally in conflicting conditions. Therefore, it is difficult to achieve both, and in particular, it is difficult to satisfy both performances in a highly balanced manner.

  In particular, it is required to solve all-season tires when driving on snowy roads, because the groove width is narrower than that of the thick main groove in the tread surface, especially in the circumferential direction. There is a problem that the sub-groove existing at an angle is clogged with snow, and the running performance on the snow is deteriorated.

  One such measure is to increase the groove volume by increasing the entire groove width of the sub-groove or increasing the groove wall angle, making it difficult to clog snow. In this method, the groove area is increased simultaneously and the ground contact area is reduced, which leads to a problem that dry performance, particularly steering stability on a dry road, is deteriorated.

It has been proposed to improve the snow column shear force and snow removal performance on the road surface on snow, and to provide protrusions and grooves on the lug groove wall surface. The actual situation was not solved.
JP-A-2005-324685

  An object of the present invention is to balance dry road running performance (hereinafter sometimes referred to as “dry performance”) and snowy road running performance (hereinafter sometimes referred to as “snow performance”) in view of the above-described points. The object is to provide a pneumatic tire suitable as a so-called all-season tire that is well balanced.

The pneumatic tire of the present invention that achieves the above-described object has the following configuration (1).
(1) Air having at least a main groove provided in the circumferential direction, a sub groove provided in a direction other than the circumferential direction, and a block provided surrounded by the main groove and the sub groove on the tread surface. 2. A pneumatic tire according to claim 1, wherein a plate-like projection having a free end without being connected to an adjacent block at the tread surface side is provided in the sub-groove.

In the pneumatic tire of the present invention, the specific configuration is more preferably one of the following configurations (2) to (4).
(2) The pneumatic tire according to (1), wherein the plate-like protrusion is provided so that a tip of the plate-like protrusion is higher than a block height position of an adjacent block.
(3) One of the plate-like protrusions is connected to an adjacent block in a height range of 80% or less of the height of the plate-like protrusion, and the other one side is not connected. The pneumatic tire according to (1) or (2).
(4) The thickness of the plate-like protrusion is 0.5 to 2 mm, and the maximum width of the plate-like protrusion is 10 to 90% of the maximum width of the groove in which the plate-like protrusion is installed. The pneumatic tire according to any one of (1) to (3) above, wherein

  According to the pneumatic tire of the present invention, there is provided a pneumatic tire suitable as a so-called all-season tire in which dry road running performance and snowy road running performance are balanced.

  Hereinafter, the present invention will be described in more detail.

  The pneumatic tire of the present invention has a main groove 4 provided at least in the circumferential direction and a sub-groove provided in a direction other than the circumferential direction on the tread surface, as schematically shown in FIG. 2 and a block 1 provided surrounded by the main groove and the sub-groove, the free end is not connected to the block 1 in which the tip on the tread surface side is connected to the inside of the sub-groove 2. It is characterized in that the plate-like protrusion 3 is provided.

  In the pneumatic tire according to the present invention, the plate-like protrusions are provided in the sub-grooves as described above, and the tread surface side is also a free end. The plate-like projection is pushed to the opposite side of the rotation direction by the snow entering the groove, but the elasticity of the plate-like projection generates a force to return to the original, moving the entered snow, so the snow is clogged in the groove It becomes difficult, and it becomes possible to ensure on-snow performance without increasing the groove volume.

  In the present invention, the “sub-groove” refers to a groove extending in a direction other than the circumferential direction, and generally refers to a groove having a narrower groove width (a smaller groove width) than a thick main groove extending in the circumferential direction. .

  In the pneumatic tire of the present invention, as a preferred embodiment, as shown in FIG. 2 (a), the plate-like projection 3 has its tip so that the tip end is higher than the block height position of the adjacent block 1. With this configuration, the plate-like projection 3 becomes easier to move when it rolls on a snowy road (because it is forcibly moved). It is preferable because the snow that enters is less likely to clog. According to the various findings of the present inventors, the degree of the increase is preferably about 0.3 to 0.7 mm, more specifically about 0.4 to 0.6 mm.

  Further, the plate-like protrusion 3 is effective even if its tip is lower than the block height position of the adjacent block 1, and in such a case, the height is 40% or more of the adjacent block height. It is good to make it. If it is lower than that, the effect of providing the plate-like protrusions 3 is particularly poor.

  Preferably, as shown in FIG. 2B, one side of the plate-like protrusion 3 is connected to an adjacent block in a height range of 80% or less of the height of the plate-like protrusion. The other one side may be configured not to be connected, and this configuration can prevent the plate-like protrusion 3 itself from being pushed down by the snow that has entered the sub-groove and falling down. .

  The thickness of the plate-like protrusion 3 is preferably 0.5 to 2 mm, and the maximum width of the plate-like protrusion 3 is the maximum of the sub-groove 2 in which the plate-like protrusion 3 is installed. It is good to make it 10 to 90% of large. By setting the thickness of the plate-like protrusion 3 within the above-described range, the bending rigidity of the plate-like protrusion 3 becomes appropriate, and the effects of the present invention can be exhibited better and for a long time. That is, if the thickness is too thin and the bending rigidity is too low, the plate-like protrusion 3 loses snow, or conversely if the bending rigidity is too high, the plate-like protrusion 3 becomes difficult to move. Therefore, it is difficult to fully exhibit the expected effect of the present invention, which is to remove snow from the sub-groove.

  Providing the plate-like protrusions 3 in the sub-grooves is a mold design having a recess corresponding to the plate-like protrusions at the time of designing the tire mold, and the others can be manufactured in the same manner as normal tire manufacturing. .

  The plate-like protrusions are preferably made of a rubber material excellent in repeated bending resistance, but generally may be made of a rubber material that forms a tire tread surface.

  It is important to provide the plate-like projections in sub-grooves extending in a direction other than the circumferential direction other than the main groove extending in the circumferential direction. In the example of the tread groove pattern shown in FIG. 3, it is possible to provide about 1 to 2 places in the sub-groove for each of the intersections where the three sub-grooves intersect each other. The number of installations, installation positions, and the like are not limited, and may be provided at effective positions corresponding to individual groove patterns.

  Based on the all-season tire having the tread pattern shown in FIG. 3, the all-season tire itself (conventional product), three sub-grooves (2A, 2B) surrounded by circles in FIGS. 2B, 2C) in the vicinity of the intersection 5 where the sub-grooves 2A, 2C intersect, and the sub-grooves 2A, 2C are provided with plate-like protrusions (Examples 1 to 4). A total of six types of tires (comparative example 1) were produced in which each width of (2A, 2B, 2C) was increased by 1 mm.

  In Example 1, as shown in FIG. 2A, both sides of the plate-like protrusion are not connected to the adjacent block, and the height is 1 mm lower than the adjacent block height.

  In Example 2, as shown in FIG. 2A, both sides of the plate-like protrusion are not connected to the adjacent block, and the height is 0.5 mm higher than the adjacent block height.

  In Example 3, as shown in FIG. 2B, one side of the plate-like protrusion is connected to the adjacent block to a height position of 75%, and the height is 1 mm lower than the adjacent block height. It is.

  In Example 4, as shown in FIG. 2B, one side of the plate-like protrusion is connected to the adjacent block to a height position of 75%, and the height is 0.5 mm higher than the adjacent block height. It is expensive.

  Each tire was mounted on an actual vehicle (tire size: 215/60 R16, test vehicle: 2000 cc, 4WD), and evaluation was made on snowy road running performance and dry road running performance. The evaluation results are as shown in Table 1.

In addition, the evaluation method of each performance was performed by the method described below.
(1) Snow performance (braking performance):
Evaluation was based on the braking distance from 40 km / h. The index evaluation is based on the reciprocal number, where the braking distance of the conventional product is 100, and the shorter the braking distance, the higher the index value.
(2) Snow performance (turning performance):
The evaluation was based on the lap time required when turning a circle with a radius of 30 m. The index evaluation is performed by taking the reciprocal number with the lap time of the conventional product as 100, and the lap time is short, and the larger the index value, the better.
(3) Dry performance (steering stability):
The evaluation was carried out in a feeling evaluation on the handling road, and was evaluated as a 5-point perfect score with the conventional product as 3 points.

FIG. 1 is a schematic perspective view schematically showing the structure of a pneumatic tire according to the present invention. FIGS. 2 (a) and 2 (b) show examples of plate-like projections installed in the pneumatic tire according to the present invention. FIG. 3 shows the installation positions of the plate-like protrusions on the tread surface in the embodiment of the pneumatic tire according to the present invention.

Explanation of symbols

1 Block 2 Sub-groove 3 Plate-like projection 4 Main groove 5 Near the intersection where the sub-groove intersects with the plate-like projection in the embodiment

Claims (4)

  In a pneumatic tire having, on a tread surface, at least a main groove provided in the circumferential direction, a sub groove provided in a direction other than the circumferential direction, and a block provided surrounded by the main groove and the sub groove. The pneumatic tire is characterized in that a plate-like protrusion serving as a free end is provided in the sub-groove without being connected to an adjacent block on the tread surface side.   2. The pneumatic tire according to claim 1, wherein the plate-like protrusion is provided such that a tip of the plate-like protrusion is higher than a block height position of an adjacent block.   The one side of the plate-like protrusion is connected to an adjacent block in a height range of 80% or less of the height of the plate-like protrusion, and the other side is not connected. 2. The pneumatic tire according to 2.   The thickness of the plate-like protrusion is 0.5 to 2 mm, and the maximum width of the plate-like protrusion is 10 to 90% of the maximum width of the groove in which the plate-like protrusion is installed. The pneumatic tire according to any one of claims 1 to 3.

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