JP4577455B1 - Pneumatic tire - Google Patents

Abstract

In a pneumatic tire having a tire tread pattern different from the conventional one, wet performance and uneven wear are improved.
A tread pattern has a land portion sandwiched between two circumferential grooves, an open end with one end opened to one of the circumferential grooves, and a terminal end closed with the land portion. And a plurality of inclined lug grooves extending in the first direction of the tire circumferential direction from the opening end, and a second direction having a start end in the middle of each of the inclined lug grooves and opposite to the first direction And a narrow groove narrower than the groove width of the inclined lug groove at the start end position and closed at a land portion. Each of the inclined lug grooves has a curved portion curved between the open end and the end, and a straight portion including the end extending substantially parallel to the tire circumferential direction, and the closed end of the narrow groove is The tire circumferential direction is on the side of the second direction with respect to the end of the inclined lug groove adjacent to the second direction with respect to each of the inclined lug grooves.
[Selection] Figure 1

Description

  The present invention relates to a pneumatic tire having a tread pattern.

  The tread pattern of a passenger car pneumatic tire generally includes a plurality of main grooves extending in the tire circumferential direction and a plurality of lug grooves extending in the tire width direction in the tread portion. In such a pneumatic tire, a large number of lug grooves are provided in order to improve wet performance including drainage performance and wet steering stability (steering stability on a wet road surface). As a result, the groove area ratio on the ground contact surface of the tread portion is increased, and the edge component of the tread portion is also increased, so that drainage performance and wet steering stability are improved. However, on the other hand, the tread rigidity in the tread portion varies in the tire circumferential direction, and because the fluctuation component is large, uneven wear often occurs, and the tread rigidity is reduced by providing a large number of lug grooves. In many cases, dry steering stability (steering stability on a dry road surface) is lowered.

Under such circumstances, a pneumatic tire having a tread pattern shown in FIG. 7 is known (Patent Document 1). This pneumatic tire can improve the skid resistance in wet and other snow conditions. As shown in FIG. 7, three ribs 103 are provided in the center region 100 </ b> A of the tread surface 100. Only one end of each rib 103 communicates with the main groove 102 and extends in the tire width direction. First lug grooves 104 are arranged in the tire circumferential direction T at predetermined intervals. At least one extending in the tire circumferential direction T at a position where only one end communicates with the first lug groove 104 between the first lug grooves 104 of each rib 103 and substantially divides the rib widths W ₁ and W _2. The sipe 105 is provided. The tire circumferential direction length L ₁ of the sipe 105 is in the range of 40 to 60% of the distance L ₂ between the first lug grooves 104. In both shoulder regions 100B and 101B, ribs 107 are divided and formed between the auxiliary groove 106 extending in the tire circumferential direction T and the outer main grooves 102 and 102.

JP 2006-224770 A

  However, although the pneumatic tire can improve the skid resistance in wet and snow conditions, it is difficult to improve wet performance including drainage and wet handling stability and uneven wear at the same time.

  Accordingly, an object of the present invention is to provide a tread pattern having excellent wet performance and uneven wear characteristics in a pneumatic tire having a tire tread pattern different from the conventional one.

An aspect of the present invention is a pneumatic tire having a tread pattern.
In the tire tread part of this pneumatic tire,
Two circumferential grooves continuous in the tire circumferential direction;
The land portion sandwiched between the circumferential grooves and continuing in the tire circumferential direction has an open end opened to one of the circumferential grooves as one end and a terminal end closed by the land portion as the other end. And a plurality of inclined lug grooves provided on the tire circumference that are inclined with respect to the tire width direction so as to extend from the opening end in the first direction of the tire circumferential direction,
The land portion has a start end in the middle of each of the inclined lug grooves, extends in a second direction opposite to the first direction, and is narrower than a groove width of the inclined lug groove at the start end position. And a narrow groove or sipe having a closed end which is closed with a.
Each of the inclined lug grooves has a curved portion that is curved between the open end and the end, or a bent portion that is bent, and a straight portion including the end that extends substantially parallel to the tire circumferential direction. .
The closed end of each narrow groove or sipe of each of the inclined lug grooves has the second end in the tire circumferential direction with reference to the end of the inclined lug groove adjacent to each of the inclined lug grooves in the second direction. Located on the direction side.

  The pneumatic tire having the tread pattern of the above form can simultaneously improve wet performance and uneven wear.

It is a figure explaining one Embodiment of the tread pattern used for the pneumatic tire of the present invention. (A), (b) is a figure explaining the principal part of the tread pattern shown in FIG. (A), (b) is a figure explaining the relationship between the inclination lug groove of one Embodiment, the obstruction | occlusion groove | channel, and a land part. It is a figure of the tread pattern produced as another Example of this invention. It is a figure of the tread pattern produced as a comparative example with respect to this invention. It is a figure of the tread pattern produced as a prior art example. It is a figure explaining an example of the conventional tread pattern.

Hereinafter, the pneumatic tire of the present invention will be described. A pneumatic tire (hereinafter referred to as a tire) that is an embodiment of the present invention is a tire for a passenger car. Passenger car tires are the tires specified in Chapter A of JATMA YEAR BOOK 2009, TRA YEARBOOK (THE TIRE and RIM Association, INC.)
Tires specified in SECTION 1 of the tire, tires specified in the ETRTO STANDARD MANUAL PASSENGER CAR TYRES chapter.

As shown in FIG. 1, the tire of this embodiment has a tread pattern 10 formed in the tread portion. FIG. 1 is a diagram in which the tread pattern 10 is easily understood and is viewed in a plane.
As the structure and rubber member of the tire according to the present embodiment, known ones may be used or new ones may be used, and there is no particular limitation.
The tire circumferential direction used in the following description refers to the direction in which the tread portion moves when the tire is rotated about the tire rotation axis, and the tire width direction refers to the direction parallel to the tire rotation axis. In FIG. 1, the tire circumferential direction is the X direction (upward direction (X ₁ ) and lower direction (X ₂ ) in the figure), and the tire width direction is represented in the Y direction (left direction and right direction in the figure). ing.

As shown in FIG. 1, the tread pattern 10 includes three circumferential grooves 12 (12c, 12l, 12r), a plurality of inclined lug grooves 16 (16l, 16r), and a plurality of sipes 18 (18l, 18r). And a plurality of shoulder lug grooves 22 and a plurality of shoulder sipes 24. The shoulder lug 22 groove and the shoulder sipe 24 are provided in the shoulder region of the tire. The shoulder region refers to a region further away from the circumferential groove farthest from the center line CL among the three circumferential grooves 12 in each of the left and right half tread portions.
The circumferential groove 12 includes a circumferential groove 12c, a circumferential groove 121, and a circumferential groove 12r, and is a groove that extends continuously in the tire circumferential direction. A treadwear indicator as defined in JIS D4230 is provided at each groove bottom of the circumferential grooves 12c, 12l, and 12r. Each groove width of the circumferential groove 12 is, for example, 5 mm to 15 mm, and the groove depth is, for example, 4 mm to 8 mm.
In the tread pattern 10, a circumferential groove 12 c is provided on the tire center line CL, and two circumferential grooves 12 l and 12 r are provided at the same distance on both sides. The circumferential groove 12l is provided in the left half tread portion of the tire center line CL in FIG. 1, and the circumferential groove 12r is provided in the right half tread portion of the tire center line CL in FIG.

  Although the tread pattern 10 shown in FIG. 1 has three circumferential grooves, there may be four, five, etc. circumferential grooves. For example, in the case of four circumferential grooves, two circumferential grooves are provided on both sides of the tire center line CL, and will be described later in a land portion between the two circumferential grooves located on the same side. An inclined lug groove is provided. Further, the circumferential grooves 121 and 12r do not need to be arranged at positions symmetrical with respect to the tire center line CL, and may be arranged asymmetrically.

  In the tread pattern 10, two land portions 14l and 14r continuous in the tire circumferential direction are formed between the circumferential groove 12c on the tire center line CL and the two circumferential grooves 12l and 12r. ing. That is, one of the two circumferential grooves defining each of the two land portions 141 and 14r is a circumferential groove 12c on the tire center line CL. The two land portions 14l and 14r are provided with inclined lug grooves 16l and 16r.

FIG. 2A is a diagram illustrating the inclined lug groove 16r, and FIG. 2B is a diagram illustrating the inclined lug groove 16l.
The opening ends 16a of the inclined lug grooves 16l and 16r are, in each of the land portions 12l and 12r, the circumferential grooves 12r and 12l farther from the tire center line CL of the two circumferential grooves 12l and 12c or 12r and 12c. It is provided on the side.
In the present invention, the opening ends of the inclined lug grooves 16l and 16r may be provided in the circumferential groove 12c closer to the tire center line CL of the two circumferential grooves. The opening end 16a of 16r is preferably provided in a circumferential groove far from the tire center line CL from the viewpoint of uneven wear. In the present embodiment, it is preferable that no lug groove is opened in the circumferential groove 12 closer to the tire center line CL. However, for example, a sipe may be opened.

As shown in FIGS. 2 (a) and 2 (b), the inclined lug grooves 16l and 16r have an opening end 16a with one end opening in the circumferential grooves 12l and 12r, and the other end with the land portions 14l and 14r. And is inclined with respect to the tire width direction so as to extend from the opening end 16a in the first direction of the tire circumferential direction. Wherein the first direction of the inclined lug grooves 16r is X ₂ (downward). First direction inclined lug grooves 16l is X ₁ direction (upward). Thus, in the tread pattern 10, the inclined directions of the inclined lug grooves 16l and 16r extending from the opening end are different.
The inclined lug grooves 16l and 16r have a curved portion 16c that is curved between the open end 16a and the end 16b, and a straight portion 16d that includes the end 16b and extends substantially parallel to the tire circumferential direction. Instead of the bending portion 16c, a bent portion that is partially bent may be used. Further, the term “substantially parallel to the tire circumferential direction in the straight portion 16d” refers to a range of an inclination angle of 0 to 5 degrees with respect to the tire circumferential direction.

  The groove depth of the inclined lug grooves 16l and 16r is, for example, 30% to 80% of the groove depth of the circumferential grooves 12l and 12r, and the groove width is, for example, 1.5 to 5 mm. The inclined lug grooves 16l and 16r increase in groove depth and width as they proceed from the end 16b to the opening end 16a. Such groove depth and groove width are included in the above numerical range.

The land portions 14l and 14r are provided with sipes 18l and 18r extending from the inclined lug grooves 16l and 16r, respectively, and being narrower than the groove width of the inclined lug grooves. The sipes 18l and 18r each have a start end 18a in the middle of each of the inclined lug grooves 16l and 16r, and extend in a second direction opposite to the first direction. The sipes 18l and 18r are formed at the land portions 14l and 14r. The closed end 18b is closed. The direction of the straight line connecting the start end 18a and the closed end 18b of the sipes 18l and 18r is inclined by 10 to 80 degrees with respect to the tire circumferential direction. As described above, since the first direction of the inclined lug groove 16l and the first direction of the inclined lug groove 16r are different, the second direction in which the sipe 18l extends and the second direction in which the sipe 18r extends are different. Second direction sipe 18r is X ₁ direction (upward direction), the second direction of the sipe 18l is X ₂ (downward). Thus, the inclined lug grooves 16l and 16r and the sipes 18l and 18r of the land portions 14l and 14r have a point-symmetric shape.
The widths of the sipes 18l and 18r are 0.1 mm to 2 mm or less, but thin grooves of 2 mm to 3 mm may be used instead of the sipes 18l and 18r.

The characteristics of the sipes 18l and 18r will be described in detail. The closed ends 18b of the sipes 18l and 18r are the ends 16b ′ of the inclined lug grooves 16l ′ and 16r ′ adjacent to the inclined lug grooves 16l and 16r in the second direction (FIG. 2 ( It is located on the second direction side with reference to a) and (b). As shown in FIG. 2 (a), the position of the closed end 18b of the sipe 18r, to the 'end 16b' of the adjacent inclined lug grooves 16r, the side of the X ₁ direction. Further, as shown in FIG. 2 (b), the position of the closed end 18b of the sipe 18l, to the 'end 16b' of the adjacent inclined lug grooves 16l, the side of the X ₂ direction. In other words, when the inclined lug grooves 16l ′ and 16r ′ and the sipes 18l and 18r are viewed from the tire width direction, that is, from the lateral direction of FIGS. 2A and 2B, the inclined lug grooves 16l ′ and 16r ′. And sipes 18l and 18r partially overlap in the tire circumferential direction. The reason for this configuration is to improve wet performance and uneven wear at the same time. This point will be described later.

  Furthermore, shallow grooves 20 having a shallower depth than the sipes 18l and 18r are provided in the land portions 14l and 14r. The shallow groove 20 is between the position in the tire circumferential direction of the closed end 18b of the sipes 18l and 18r and the position in the tire circumferential direction of the end 16b of the inclined lug groove, and is a start end extending from the inclined lug groove of the sipe 18 Of the land portion 14 between the position in the tire width direction of 18a and the position in the tire width direction of the circumferential groove (circumferential groove on the tire center line CL) 12c on the side without the opening end of the inclined lug groove 16 It is preferable to be provided in the region. Thereby, initial wear can be improved. Since the form of the initial wear has a great influence on the uneven wear performance after the middle stage of wear, the uneven wear performance can be improved by improving the initial wear. The shallow groove 20 does not open to the circumferential grooves 12l, 12r, 12c, the inclined lug grooves 16l, 16r, and the sipes 18l, 18r.

A plurality of shoulder lug grooves 22 and a plurality of narrow shoulder grooves are formed in the shoulder region of the tread portion on the outer side in the tire width direction of the circumferential grooves 12l and 12r as viewed from the tire center line CL (the side away from the tire center line CL). 24 is provided.
The shoulder lug groove 22 opens at the ground contact end of the shoulder region and is provided on the tire circumference. The grounding end is located on the grounding line E shown in FIG. This ground line E is determined by the limit position where the shoulder region comes into contact when the tire is assembled to the applicable rim and the tire is grounded on a flat surface under the conditions of normal internal pressure and specified load.
“Applied rim” means “applied rim” defined in JATMA, “Design Rim” defined in TRA, or “Measuring Rim” defined in ETRTO. In addition, the normal internal pressure means “maximum air pressure” defined in JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined in TRA, or “INFLATION PRESSURES” defined in ETRTO. The specified load means “maximum load capacity” defined in JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined in TRA, or “LOAD CAPACITY” defined in ETRTO. However, in the case of a tire for a passenger car, the specified internal pressure is an air pressure of 180 [kPa], and the specified load is 80 [%] of the maximum load capacity.

The shoulder narrow groove 24 is provided between the shoulder lug grooves 22 adjacent to each other in the tire circumferential direction.
The shoulder lug groove 22 does not open to any of the circumferential grooves 12l and 12r, and the shoulder narrow groove 24 opens to the circumferential grooves 12l and 12r. That is, the circumferential grooves 12l and 12r are provided with shoulder opening ends of the shoulder narrow grooves 24 in addition to the opening ends 16a of the inclined lug grooves 16l and 16r. Since the shoulder lug groove 22 does not open to any of the circumferential grooves 12l and 12r, the pattern noise generated by the tread pattern is reduced while ensuring drainage, and the block rigidity in the shoulder region is increased. Steering stability on a dry road surface can be improved. Furthermore, uneven wear can be improved by providing the shoulder narrow groove 24.
The shoulder narrow groove 24 has a groove width of 2 mm to 3 mm, but a shoulder sipe of 0.1 mm to 2 mm can be used instead of the shoulder narrow groove 24.

  In the tread pattern 10, the curved inclined lug grooves 16l and 16r are provided in the land portions 14l and 14r, whereby the groove volume can be increased and drainage performance can be improved. Moreover, since the opening end 16a is provided in the circumferential grooves 12l and 12r, the drainage performance is further improved. Furthermore, by providing the inclined lug grooves 16l and 16r with the terminal ends 16b closed by the land portions 12l and 12r, the block rigidity can be increased and the steering stability on the dry road surface can be improved. Since the inclined lug grooves 16l and 16r are inclined with respect to the tire width direction and the tire circumferential direction, the degree of freedom of movement of the block when the land portions 14l and 14r are viewed as blocks is suppressed. Thereby, uneven wear is suppressed, and pattern noise generated by vibration of several KHz of the block can be reduced.

Further, as described above, the closed ends 18b of the sipes 18l and 18r are in the second direction with reference to the end 16b 'of the inclined lug grooves 16l' and 16r 'adjacent to the second direction in the inclined lug grooves 16l and 16r. Located on the side. Thus, by determining the positions of the closed end 18b and the end 16b ′, wet performance and uneven wear can be improved at the same time.
FIG. 3A is a diagram for explaining a main part of the tread pattern 10. In FIG. 3A, the shallow groove 20 is not shown.
As shown in FIG. 3A, when the land portion between the inclined lug grooves is divided into regions S ₁ , S ₂ and S ₃ along the tire circumferential direction, the position of the inclined lug groove 16 and the sipe 18 by position and partially overlap in the tire circumferential direction, it is possible to determine the block rigidity against displacement in the tire width direction of the area S ₂ to a predetermined range, the block in the tire width direction in a region S ₁ to S ₃ Changes in the tire circumferential direction of rigidity can be suppressed.
However, as shown in FIG. 3 (b), when the position of the position and sipes 18 of the swash lug grooves 16 do not overlap partially in the tire circumferential direction, the block rigidity is increased in the area S _5, the area S ₄ ~ change in block rigidity in the tire width direction of S ₆ is increased. At this time, uneven wear tends to occur at a position where the block rigidity greatly changes.

On the ground contact surface of the tire, wear of the tread portion is fast in the center region across the tire center line CL. In the tread pattern 10, the opening ends 16 a of the inclined lug grooves 16 l and 16 r are not provided in the circumferential groove 12 c, so that portions in the vicinity of the circumferential grooves 12 c of the land portions 14 l and 14 r (region R in FIG. 3A). ₁ ) The rigidity reduction can be suppressed, and uneven wear (center wear) can be suppressed.
Further, by providing a straight portion 16d parallel to the tire circumferential direction in the vicinity of the end 16b of the inclined lug groove 16, the tire width direction component of the inclined lug groove 16 is reduced, and the straightness and wet performance of the tire are simultaneously improved. be able to. Straightness refers to the stability with which a traveling vehicle can run straight even if minute vibrations or the like occur when the tire has no slip angle.
As the depth of the groove increases from the end 16b of the inclined lug grooves 16l and 16r to the open end 16a, the inclined lugs correspond to the amount of water that gradually flows from the land portions 14l and 14r in terms of drainage. The amount of drainage of the grooves 16l and 16r can be secured. Moreover, the end portion 16b is a portion closest to the circumferential groove 16c in the inclined lug grooves 16l and 16r (region R ₁ in FIG. 3A), but the inclined lug grooves 16l and 16r in this portion are the same. Since the groove depth is shallow, the block rigidity in the tire width direction of the land portions 14l and 14r in the vicinity of the circumferential groove 12c of the land portions 14l and 14r can be increased.
Further, in each of the land portions 14l and 14r, the plurality of shallow grooves 20 are arranged so as not to overlap when viewed from the tire width direction. By providing the shallow groove 20 in this manner, the block rigidity of the land portions 14l and 14r (region R ₁ in FIG. 3A) in the vicinity of the circumferential groove 12c of the land portions 14l and 14r is maintained high. The rigidity can be smoothly changed toward the other portions of the land portions 14l and 14r, and uneven wear can be suppressed.

In such a tread pattern 10, the length L ₁ (see FIG. 3A) of the straight portions 16d of the inclined lug grooves 16l and 16r is the length L ₂ of the inclined lug grooves 16l and 16r along the tire circumferential direction. It is preferably 3 to 75% of that (see FIG. 3A). The ratio of the length L ₁ to the length L ₂ is decreased to improve the linearity of the case of tires of less than 3% margin, reduced improvement allowance when drainage of greater than 75%.

Further, the distance (width) W ₁ in the tire width direction between the end 16b of the inclined lug grooves 16l and 16r and the opening end 16a is preferably 50 to 90% of the width W ₂ of the land portions 14l and 14r. . When the ratio of the width W _{1 to} the width W ₂ is less than 50%, the groove performance is insufficient and the wet performance including drainage is reduced. When the ratio exceeds 90%, the margin for improving the driving stability on the dry road surface is increased. Get smaller.

Furthermore, sipes 18l, a starting end 18a of 18r, tilt lug grooves 16l, distance (width) W ₃ in the tire width direction between the opening end 16a of 16r are land portions 12l,. 5 to the width W ₂ of 12r It is preferably 40%. If the ratio of the width W ₃ to the width W ₂ is less than 5%, the circumferential grooves 12l, 12r and sipes 18l, distance a portion held between 18r is shortened, the block rigidity in this portion is reduced wear The speed increases, and it tends to become the core of uneven wear. When the ratio of the width W _{3 to} the width W ₂ exceeds 40%, the block rigidity of the portion sandwiched between the circumferential groove 12c and the sipes 18l and 18r is reduced, the wear rate is increased, and this becomes the core of uneven wear. easy. The ratio of the width W _{3 to} the width W ₂ is preferably 15 to 30%.

Furthermore, sipes 18l, a closed end 18b of 18r, tilt lug grooves 16l, distance (width) W ₄ in the tire width direction between the opening end 16a of 16r are 20 of the land portion 12l, the width of 12r W ₂ 60% is preferable. When the ratio of the width W _{4 to} the width W ₂ is less than 20%, the distance between the circumferential grooves 12l and 12r and the sipe 18l and 18r is shortened, and the block rigidity of this portion is reduced and wear is caused. The speed increases, and it tends to become the core of uneven wear. When the ratio of the width W _{4 to} the width W ₂ exceeds 60%, the block rigidity of the portion sandwiched between the circumferential groove 12c and the sipes 18l and 18r is lowered, the wear speed is increased, and it is easy to become a core of uneven wear. . The ratio of the width W _{4 to} the width W ₂ is preferably 30 to 50%.

  The sipes 18l and 18r preferably have a depth of 50% to 100% with respect to the groove depth of the inclined lug grooves 16l and 16r at the position of the start end 18a of the sipes 18l and 18r. When the depth of the sipes 18l and 18r becomes deeper than the depth of the inclined lug grooves 16l and 16r, the block rigidity of the portion sandwiched between the sipes 18l and 18r and the circumferential grooves 12l and 12r is reduced and the wear rate is increased. It becomes faster and tends to become the core of uneven wear. On the other hand, when the depths of the sipes 18l and 18r with respect to the groove depths of the inclined lug grooves 16l and 16r are less than 50%, wet performance including drainage is deteriorated.

The separation distance in the tire width direction between one end of the shallow groove 20 and the closed ends of the sipes 18l and 18r is preferably 2 mm or less. In addition, the separation distance in the tire width direction between the other end of the shallow groove 20 and the end of the inclined lug grooves 16l and 16r is preferably 2 mm or less.
The groove depth in the shallow groove 20 is preferably 2 to 10% of the groove depth of the circumferential grooves 12l and 12r. The shallow groove 20 is provided in a portion where the block rigidity is increased in each of the land portions 14l and 14r, thereby improving uneven wear. Since the shallow groove 20 is shallow, the shallow groove 20 itself disappears and does not function in a state in which wear has progressed. However, in the initial stage of wear that has the greatest influence on uneven wear, tires with block rigidity in the land portions 14l and 14r. Changes in the circumferential direction can be suppressed, and uneven wear can be suppressed.
The width of the shallow groove 20 is preferably 0.2 to 2 mm. If the width is narrower than the width of 0.2 mm, the partial wear is not sufficiently improved. When the width exceeds 2 mm, on the contrary, the change in the block rigidity of each part in the tire circumferential direction increases, and uneven wear tends to occur. The width of the shallow groove 20 is preferably 0.5 to 1 mm.

The position of the shoulder opening end of the shoulder sipe 24 in the tire circumferential direction is a distance between the opening end 16a of the inclined lug grooves 16l and 16r adjacent to each other from the position of the opening end 16a of the inclined lug grooves 16l and 16r in the tire circumferential direction. It is preferable that the distance is 10% or more and 90% or less. When this distance is less than 10% and more than 90% of the distance between the open ends 16a, the block rigidity in the tire width direction of the land portion on both sides of each of the circumferential grooves 16l and 16r in the tire circumferential direction is changed. Can not be dispersed with respect to the change in the block rigidity of the land portions 14l and 14r, the sound pressure level of the pattern noise increases.
The shoulder lug groove 22 does not open to the circumferential grooves 121 and 12r. Thereby, pattern noise can be reduced, and steering stability on a dry road surface can be improved while ensuring drainage.

Like the tread pattern 10, by providing the circumferential groove 12c on the tire center line with the longest contact length, drainage can be efficiently performed on a wet road surface having a water film, and wet performance is improved. Can do.
Although the tread pattern 10 has three circumferential grooves, the three circumferential grooves can improve drainage on a wet road surface.

(Examples, comparative examples, and conventional examples)
In order to examine the effect of the tread pattern 10, a tire was prototyped. The size of the prototyped tire is 195 / 65R15 91H. The patterns 1 to 31 manufactured as examples, comparative examples 1 and 2, and the conventional example all employ a tread pattern having three circumferential grooves. The prototype tire was assembled on a 15x6JJ rim, mounted on a 1.8 liter class passenger car under the condition of 210kPa internal pressure, wet performance including drainage and wet handling stability under the condition of two passengers, and uneven wear In addition to the characteristics, the steering stability on dry road surfaces (dry steering stability) and pattern noise (sensory evaluation) were investigated.
For uneven wear, the wear form after traveling 10,000 km in a predetermined traveling mode (flat road, average traveling speed 80 km / hour) was quantified by visual observation. Wet performance, dry handling stability, and pattern noise were evaluated by a sensory test with a driver. The evaluation results of wet performance and dry handling stability indicate that the higher the value, the better. Also, the numerical value of the pattern noise evaluation result indicates that the higher the value, the more the pattern noise is reduced. Regarding the evaluation value of each performance, the value 5 is a permissible limit level of the performance, and a value of 5 or more is required as a tire.

(About patterns)
The above performance evaluation was performed on each pattern including the tread pattern 10 shown in FIG.
Pattern 1 is the pattern of the embodiment shown in FIG. Pattern 2 is the pattern of the embodiment shown in FIG. 4 in which the opening end of the inclined lug groove is located on the side of the circumferential main groove on the tire center line CL. Comparative Example 1 has a pattern shown in FIG. In Comparative Example 1, the position of the closed end of the narrow groove extending from the inclined lug groove is on the lower side with respect to the end of the inclined lug groove adjacent to the upper direction in FIG. 5 in the right half tread portion. The pattern is not on the upper side. Further, in the left half tread portion, the position of the closed end of the narrow groove is on the upper side with reference to the end of the inclined lug groove adjacent to the lower direction in FIG. 5 and is not on the lower side. It is. The conventional example is the pattern shown in FIG. Information on the dimensions of each pattern and evaluation results of performance are shown in Table 1 below.

  From Table 1, it can be seen that Patterns 1 and 2 are superior in wet performance and uneven wear compared to Comparative Example 1 and the conventional example. That is, by disposing the closed end 18b of the narrow groove 18 on the second direction side with respect to the end 16b of the inclined lug groove 16 adjacent to each of the inclined lug grooves 16 in the second direction, In addition, wet performance including wet steering stability and uneven wear can be improved at the same time.

(About the straight part of the inclined lug groove)
Next, as shown in Table 2 below, Patterns 3 to 9 in which only the length of the linear portion was changed and tires of Comparative Example 2 were produced, and various performance evaluations were performed. In Table 2, the length of the straight line portion is represented by the ratio of the length L ₁ to the length L ₂ shown in FIG.

  From Table 2, in patterns 3-9, wet performance and uneven wear are superior to Comparative Example 2 (length of straight portion 0%). When the ratio of the straight line portion is less than 3%, the straightness of the tire in dry steering stability is lowered, and when it exceeds 75%, the drainage performance is lowered and the wet performance is lowered. Thus, the straight portion is preferably 3 to 75% of the length of the inclined lug groove along the tire circumferential direction.

(About the length of the inclined lug groove in the tire width direction)
Next, as shown in Table 3 below, patterns 10 to 14 in which only the length of the inclined lug groove in the tire width direction was changed were produced, and various performance evaluations were performed. In Table 3, the length of the inclined lug groove in the tire width direction is represented by the ratio of the width W _{1 to} the width W ₂ shown in FIG.

  From Table 3, the patterns 11 to 14 are superior in wet performance to the pattern 10. On the other hand, the patterns 10 to 13 have better DRY steering stability than the pattern 14. Accordingly, the length of the inclined lug groove in the tire width direction is preferably 50 to 90% of the width of the land portion.

(About the position of the start end of the narrow groove extending from the inclined lug groove)
Next, as shown in Table 4 below, patterns 15 to 19 in which only the position of the start end of the narrow groove extending from the inclined lug groove was changed, and various performance evaluations were performed. In Table 4, the position of the start end of the narrow groove extending from the inclined lug groove is represented by the ratio of the width W _{3 to} the width W ₂ shown in FIG.

  From Table 4, in patterns 15 to 19, the wet performance and DRY steering stability of patterns 16, 1, 17, and 18 are superior to patterns 15 and 19. Accordingly, the distance in the tire width direction between the start end of the narrow groove and the opening end of the inclined lug groove is preferably 5 to 40% of the width of the land portion.

(About the position of the closed end of the narrow groove extending from the inclined lug groove)
Next, as shown in Table 5 below, patterns 20 to 25 in which only the position of the closed end of the narrow groove extending from the inclined lug groove were changed, and various performance evaluations were performed. In Table 5, the closed end position of the narrow groove is represented by the ratio of the width W _{4 to} the width W ₂ shown in FIG.

  From Table 5, in the patterns 20 to 25, the uneven wear of the patterns 21, 22, 1, 23, 24 is superior to the patterns 20, 25. Accordingly, the distance in the tire width direction between the closed end of the narrow groove and the open end of the inclined lug groove is preferably 20 to 60% of the width of the land portion. Furthermore, since the partial wear property of the pattern 22, the pattern 1, and the pattern 23 is high, More preferably, it is 30 to 50%.

(Narrow groove depth)
Next, as shown in Table 6 below, patterns 26, 27, and 1 in which only the groove depth of the narrow groove extending from the inclined lug groove was changed, and various performance evaluations were performed.

  According to Table 6, the pattern 27 is inferior in wet performance among the patterns 26, 27, and 1. On the other hand, the pattern 26 is inferior in uneven wear. The pattern 1 in which the fine groove has a depth of 50% to 100% with respect to the groove depth of the inclined lug groove at the position of the start end of the fine groove is excellent in both wet performance and uneven wear.

(Shallow groove depth)
Next, as shown in Table 7 below, patterns 28, 29, and 1 in which only the groove depth of the shallow groove (the portion denoted by reference numeral 20 in FIGS. Evaluation was performed.

  From Table 7, the pattern 28 is inferior in uneven wear among the patterns 28, 29 and 1. On the other hand, the pattern 29 is inferior in DRY steering stability. The pattern 1 in which the groove depth of the narrow groove is 2 to 10% of the depth of the circumferential groove is excellent in DRY steering stability in addition to wet performance and uneven wear.

(About the position of the shoulder sipe)
Next, as shown in Table 8 below, patterns 30, 31, and 1 in which only the position of the shoulder sipe was changed were produced, and various performance evaluations were performed. The position of the shoulder sipe is the position in the tire circumferential direction of the opening end of the shoulder sipe. This position is expressed in terms of how much the opening position of the shoulder sipe is away from the position of the opening end of the inclined lug groove when the distance between the opening ends of the inclined lug groove adjacent to each other is 100%. Has been.

  From Table 8, among patterns 30, 31, and 1, patterns 30, 31 have the same wet performance, uneven wear, and DRY steering stability as pattern 1, but pattern noise is inferior to pattern 1. ing. The pattern 1 in which the position of the opening end of the shoulder sipe in the tire circumferential direction is 10% or more and 90% or less of the distance between the opening ends of the adjacent inclined lug grooves and is separated from the opening end of the inclined lug groove is wet. In addition to excellent performance and uneven wear, pattern noise is also low.

  As mentioned above, although the pneumatic tire of this invention was demonstrated in detail, this invention is not limited to the said embodiment, Of course, in the range which does not deviate from the main point of this invention, you may make a various improvement and change. is there.

10 tread pattern 12, 12c, 12r, 12l circumferential groove 14, 14r, 14l land portion 16, 16r, 16l inclined lug groove 16a opening end 16b terminal end 16c bent portion 16d linear portion 18, 18r, 18l sipes 18a start end 18b blockage Edge 20 Shallow groove 22 Shoulder lug groove 24 Shoulder narrow groove 100 Tread surface 100A Center region 100B, 101B Shoulder region 102 Main groove 103 Rib 104 First lug groove 105 Sipe 106 Auxiliary groove 107 Rib

Claims (18)

A pneumatic tire having a tread pattern,
In the tire tread part,
Two circumferential grooves continuous in the tire circumferential direction;
The land portion sandwiched between the circumferential grooves and continuing in the tire circumferential direction has an open end opened to one of the circumferential grooves as one end and a terminal end closed by the land portion as the other end. And a plurality of inclined lug grooves provided on the tire circumference that are inclined with respect to the tire width direction so as to extend from the opening end in the first direction of the tire circumferential direction,
The land portion has a start end in the middle of each of the inclined lug grooves, extends in a second direction opposite to the first direction, and is narrower than a groove width of the inclined lug groove at the start end position. A narrow groove or sipe having a closed end closed with
Each of the inclined lug grooves has a curved portion that is curved between the open end and the end, or a bent portion that is bent, and a linear portion that includes the end and extends substantially parallel to the tire circumferential direction. And
The closed end of each narrow groove or sipe of each of the inclined lug grooves has the second end in the tire circumferential direction with reference to the end of the inclined lug groove adjacent to each of the inclined lug grooves in the second direction. A pneumatic tire characterized by being located on the direction side. Each of the two half tread portions sandwiching the tire center line in the tread portion has the inclined lug groove and the narrow groove or sipe,
When the first direction of the inclined lug groove of one of the two half-tread portions is referred to as a third direction, and the first direction of the other inclined lug groove of the two half-tread portions is referred to as a fourth direction, The third direction and the fourth direction are opposite directions;
The second direction of one narrow groove or sipe of the two half tread portions is referred to as a fifth direction, and the second direction of the other narrow groove or sipe of the two half tread portions is referred to as a sixth direction. The pneumatic tire according to claim 1, wherein the fifth direction and the sixth direction are opposite directions.   The pneumatic tire according to claim 1 or 2, wherein the opening end of the inclined lug groove is provided in a circumferential groove far from a tire center line of the tread portion among the two circumferential grooves. .   The pneumatic tire according to claim 3, wherein a lug groove does not open in a circumferential groove closer to a tire center line of the tread portion among the two circumferential grooves.   The pneumatic tire according to any one of claims 1 to 4, wherein a depth of the inclined lug groove becomes shallower from the opening end toward the terminal end.   The pneumatic tire according to any one of claims 1 to 5, wherein a length of the straight portion of the inclined lug groove is 3 to 75% of a length of the inclined lug groove along a tire circumferential direction. .   The pneumatic according to any one of claims 1 to 6, wherein a distance in the tire width direction between the terminal end of the inclined lug groove and the opening end is 50 to 90% of a width of the land portion. tire.   The distance in the tire width direction between the start end of the narrow groove or sipe and the opening end of the inclined lug groove is 5 to 40% of the width of the land portion. The pneumatic tire according to claim 1.   The distance in the tire width direction between the closed end of the narrow groove or sipe and the open end of the inclined lug groove is 20 to 60% of the width of the land portion. The pneumatic tire according to claim 1.   The narrow groove or sipe has a depth of 50% to 100% with respect to a groove depth of the inclined lug groove at the position of the start end of the narrow groove or sipe. The pneumatic tire according to item. Furthermore, the land portion has a shallow groove whose depth is shallower than the narrow groove or sipe,
The shallow groove is between the position of the closed end in the tire circumferential direction and the position of the end of the inclined lug groove in the tire circumferential direction, and the starting end extends from the inclined lug groove of the narrow groove or sipe. The region of the land portion between the position in the tire width direction of the tire and the position in the tire width direction of the circumferential groove on the side without the opening end of the inclined lug groove is any one of claims 1 to 10. The pneumatic tire according to claim 1.   The pneumatic tire according to claim 11, wherein a separation distance in a tire width direction between one end portion of the shallow groove and a closed end of the narrow groove or sipe is 2 mm or less.   The pneumatic tire according to claim 11 or 12, wherein a separation distance in the tire width direction between the other end portion of the shallow groove and a terminal end of the inclined lug groove is 2 mm or less.   The pneumatic tire according to any one of claims 11 to 13, wherein a depth of the shallow groove is 2 to 10% of a depth of the circumferential groove. In the shoulder region of the tread portion, a plurality of shoulder lug grooves which are opened at the ground contact edge of the shoulder region and are provided along the tire circumferential direction and a plurality of shoulder narrow grooves provided between the shoulder lug grooves adjacent to each other are provided. A groove or shoulder sipe,
15. The shoulder lug groove does not open to any of the circumferential grooves, and the shoulder narrow groove or shoulder sipe opens to one of the circumferential grooves. Pneumatic tires. One of the circumferential grooves is provided with the opening end of the inclined lug groove and the opening end of the shoulder narrow groove or shoulder sipe,
The position of the shoulder opening end of the shoulder narrow groove or shoulder sipe in the tire circumferential direction is determined by the position of the inclined lug groove adjacent to the opening end of the inclined lug groove from the position of the opening end of the inclined lug groove in the tire circumferential direction. The pneumatic tire according to claim 15, which is separated by a distance of 10% or more and 90% or less of a distance between the open ends.   The land portion where the inclined lug groove and the narrow groove or sipe are provided is provided in each of the half tread portions on both sides across the tire center line of the tread portion, and the tire among the two circumferential grooves. The pneumatic tire according to any one of claims 1 to 16, wherein one or more circumferential grooves are provided between a circumferential groove close to a center line and a tire center line of the tread portion. . The land portion where the inclined lug groove and the narrow groove or sipe are provided is provided in each of the half tread portions on both sides across the tire center line of the tread portion,
The pneumatic tire according to any one of claims 1 to 16, wherein one of the two circumferential grooves is provided on the tire center line.