JP2013139241A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve draining performance while maintaining at least steering stability and snow traction performance, in a pneumatic tire.SOLUTION: A tread pattern includes outer main grooves and inner main grooves extending in a tire circumferential direction, and first inclined lug grooves and second inclined lug grooves provided in regions held between the outer main grooves and the inner main grooves. The first inclined lug grooves and the second inclined lug grooves extend in a first direction of the tire circumferential direction on the outside in the tire width direction from internal positions in an intermediate region without being opened to the inner main grooves. The first inclined lug grooves are opened to one of the outer main grooves, and the second inclined lug grooves are blocked without being opened to the outer main grooves. Each of the second inclined lug grooves has an inclined portion with a small inclination angle in the tire circumferential direction compared with the first inclined lug grooves, and the inclined portion of each second inclined lug groove crosses at least two of the first inclined lug grooves.

Description

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

  Pneumatic tires for passenger cars for all seasons are tires developed as intermediate tires between normal tires used during non-snow periods and snow tires called winter tires, and are particularly widely used in North America and Europe. Yes. This all-season pneumatic tire has sufficient handling stability on dry roads, snow traction on snowy roads when snowing, and drainage on wet roads when it rains. Is required.

  Conventionally, in order to improve drainage performance, in the tire tread pattern, the inclination with respect to the tire circumferential direction is small in the tire center region including the tire center line (the inclination with respect to the tire width direction is large), and the inclination with respect to the tire circumferential direction in the shoulder region is A plurality of large inclined lug grooves (small inclination with respect to the tire width direction) have been provided in the tire circumferential direction. However, if the groove width (groove area ratio) of the inclined lug groove is increased in order to improve drainage performance, the interval between adjacent inclined lug grooves in the tire center region becomes narrower, so that the tread rigidity in the land portion decreases. In some cases, the steering stability performance is degraded.

  In a pneumatic tire in which such an inclined lug groove is provided in a tread pattern, for example, the following pneumatic tire capable of achieving both a drainage performance and a steering stability performance at a high level is known (Patent Document 1). .

Specifically, in the pneumatic tire, a pair of central main grooves extending along the tire circumferential direction are disposed in the central region of the tread portion. Rib-shaped central land portions are defined between the central main grooves, and side main grooves extending along the tire circumferential direction are disposed between the central main grooves and the tread ends located on the corresponding sides. Is done. An intermediate land portion is defined between each central main groove and the side main groove adjacent thereto, and a side land portion is defined between the tread end and the side main groove adjacent thereto. Furthermore, a plurality of first inclined grooves extending at a relatively small angle with respect to the tire circumferential direction from the side main grooves toward the central main groove side and terminating in the intermediate land portion, and the tire circumferential direction from the tread end And a second inclined groove extending at a relatively large angle and opening to the side main groove.
The intermediate land portion is located adjacent to the central main groove and extends continuously in the tire circumferential direction. The intermediate land portion is located between the rib-like land portion and the first inclined groove. A bottom surface facing the land portion, and a vertex that faces the bottom surface and is located at the bottom of the groove on the terminal end of the first inclined groove, and has a substantially inclined shape from the bottom to the top. A pseudo land portion having a flat top surface chamfered by Thereby, it is supposed that both drainage performance and steering stability performance can be achieved at a high level. However, the above publication does not mention snow traction performance.

JP 2005-35334 A

  An object of the present invention is to provide a pneumatic tire that can improve drainage performance while maintaining at least steering stability performance and snow traction performance in a pneumatic tire using a method different from the above-described conventional technology. And

One aspect of the present invention is a pneumatic tire. In the pneumatic tire, a tread pattern is provided in a tread portion of the pneumatic tire.
The tread pattern is
Compared to the tire center line, a pair of outer main grooves extending in the tire circumferential direction, provided at positions close to the ground contact ends of the tread portion located on both sides in the tire width direction,
A pair of inner main grooves extending in the tire circumferential direction, provided at a position closer to the tire center line than each of the ground contact ends;
In the respective regions on both sides of the tread portion in the tire width direction with respect to the tire center line, an intermediate portion in contact with the ground provided in an intermediate region sandwiched between one of the outer main grooves and one of the inner main grooves The land,
Lug grooves provided in each of the intermediate regions, outside the tire center line so as to be away from the tire center line from positions inside the intermediate regions without opening in the inner main groove, and A plurality of first inclined lug grooves extending toward a first direction of the tire circumferential direction and opening into one of the outer main grooves;
Lug grooves provided in each of the intermediate regions, outside the tire center line so as to be away from the tire center line from positions inside the intermediate regions without opening in the inner main groove, and A plurality of second inclined lug grooves that extend toward the first direction in the tire circumferential direction and that are closed without opening in the outer main groove.
Each of the second inclined lug grooves has a groove width that increases with distance from the tire center line, and each of the second inclined lug grooves is in the tire circumferential direction as compared with the first inclined lug groove. The inclined portion has a small inclination angle, and the inclined portion of the second inclined lug groove crosses at least two of the first inclined lug grooves.
The pair of inner main grooves are provided on both sides of the tread portion across the tire center line, but as another aspect of the present invention, one inner main groove is used instead of the pair of inner main grooves. It can also be provided on the tire center line.

  According to the pneumatic tire, drainage performance can be improved while maintaining at least steering stability performance and snow traction performance in the tire.

It is a tire sectional view showing the section of the pneumatic tire of this embodiment. FIG. 2 is a development view of a part of a tread pattern in which a tread pattern provided in a tread portion of the pneumatic tire shown in FIG. 1 is developed on a plane. It is a figure which shows the definition of the various dimensions of the pattern element provided in the intermediate area of the tread pattern shown in FIG. 2 is a development view of a part of a tread pattern used in Example 1. FIG. 6 is a development view of a part of a tread pattern used in Example 2. FIG. 6 is a development view of a part of a tread pattern used in Comparative Example 1. FIG. 6 is a development view of a part of a tread pattern used in Comparative Example 2. FIG. FIG. 4 is a development view of a part of a tread pattern of another embodiment different from the tread pattern of the present embodiment shown in FIG. 2.

Hereinafter, the pneumatic tire of the present invention will be described. FIG. 1 is a tire cross-sectional view showing a cross section of a pneumatic tire (hereinafter referred to as a tire) 10 of the present embodiment.
The pneumatic tire 10 is, for example, a passenger car tire. Passenger car tires are tires defined in Chapter A of JATMA YEAR BOOK 2010 (Japan Automobile Tire Association Standard). In addition, the present invention can also be applied to small truck tires defined in Chapter B and truck and bus tires defined in Chapter C.
The numerical value of the dimension of each pattern element specifically explained below is a numerical example in the tire for passenger cars, and the pneumatic retirement according to the present invention is not limited to these numerical examples.

  The tire circumferential direction described below refers to the direction of rotation of the tread surface when the tire 10 is rotated about the tire rotation axis, and the tire radial direction is a radiation extending perpendicular to the tire rotation axis. The direction in the tire radial direction means the side away from the tire rotation axis in the tire radial direction. The tire width direction means a direction parallel to the tire rotation axis direction, and the tire width direction outside means both sides of the tire 10 away from the tire center line CL.

(Tire structure)
The tire 10 includes a carcass ply layer 12, a belt layer 14, and a bead core 16 as a skeleton material. Around these skeleton materials, a tread rubber member 18, a side rubber member 20, and a bead filler rubber member 22. And a rim cushion rubber member 24 and an inner liner rubber member 26.

  The carcass ply layer 12 includes carcass ply materials 12a and 12b in which organic fibers are covered with rubber, which are wound between a pair of annular bead cores 16 to form a toroidal shape. In the tire 10 shown in FIG. 1, the carcass ply layer 12 is composed of carcass ply materials 12a and 12b, but may be composed of one carcass ply material. A belt layer 14 composed of two belt members 14a and 14b is provided outside the carcass ply layer 12 in the tire radial direction. The belt layer 14 is a member in which a rubber is coated on a steel cord disposed at a predetermined angle, for example, 20 to 30 degrees with respect to the tire circumferential direction, and the lower belt material 14a is replaced with the upper belt material 14b. The width in the tire width direction is longer than that. The inclination directions of the steel cords of the two-layer belt materials 14a and 14b are opposite to each other. For this reason, belt material 14a, 14b is a crossing layer, and controls expansion of carcass ply layer 12 by the filled air pressure.

A tread rubber member 18 is provided outside the belt layer 14 in the tire radial direction, and side rubber members 20 are connected to both ends of the tread rubber member 18 to form side portions. A rim cushion rubber member 24 is provided at the inner end in the tire radial direction of the side rubber member 20 and is in contact with a rim on which the tire 10 is mounted. The bead core 16 is sandwiched between the portion of the carcass ply layer 12 before being wound around the bead core 16 and the portion of the carcass ply layer 12 that is wound around the bead core 16 on the outer side in the tire radial direction. Thus, a bead filler rubber member 22 is provided. An inner liner rubber member 26 is provided on the inner surface of the tire 10 facing the tire cavity region filled with air surrounded by the tire 10 and the rim.
In addition, the tire 10 includes a belt cover layer 28 that covers the belt layer 14 from the outer side in the tire radial direction of the belt layer 14 and that covers the organic fiber with rubber, and a sheet material 29 that covers the organic fiber that covers the bead portion with rubber. Is provided.

  Although the tire 10 has such a tire structure, the tire structure of the pneumatic tire of the present invention is not limited to the tire structure shown in FIG.

(Tread pattern)
FIG. 2 is an example of a development view of a part of the tread pattern in which the tread pattern 30 provided in the tread portion of the tire 10 shown in FIG. 1 is developed on a plane.
The tread pattern 30 includes, as pattern elements, a pair of outer main grooves 32a and 32b, a pair of inner main grooves 34a and 34b, a pair of intermediate land portions 36a and 36b, first inclined lug grooves 38a and 38b, 2 inclined lug grooves 40a and 40b. In addition, the tread pattern 30 includes, as pattern elements, third inclined lug grooves 42a and 42b, connecting grooves 44a and 44b, shoulder land portions 46a and 46b, shoulder lug grooves 48a and 48b, and a shoulder closing groove 50a. , 50b, notches 52a, 52b, and a center land portion 54.
Hereinafter, in the tread pattern 30, when describing pattern elements provided on both sides in the tire width direction across the tire center line CL, only numbers excluding “a” and “b” attached as pattern element codes are described. For example, the outer main groove 32, the inner main groove 34, and the like will be described.

The outer main grooves 32 are provided in positions closer to the ground contact ends E located on both sides of the tread portion in the tire width direction (left and right direction in FIG. 2) than the tire center line CL, and extend in the tire circumferential direction. It is a circumferential main groove. The outer main groove 32 shown in FIG. 2 has a zigzag shape extending in the tire circumferential direction while being bent in the tire width direction, and is a groove extending linearly in the tire circumferential direction (vertical direction in FIG. 2). There may be. The outer main groove 32 has a see-through portion in which the entire circumference of the tread pattern 30 is developed on a plane, and when the outer main groove 32 is viewed from one end to the other end, the other end can be seen. Any groove may be used.
The groove width of the outer main groove 32 is, for example, 5 to 20 mm, and the groove depth is, for example, 5 to 15 mm. The outer main groove 32 may be included in a region separated from the tire center line CL by a distance in the range of 25 to 45% with respect to the ground contact width W that is a distance between the ground contact ends E on both sides of the tread portion. The ground contact width W is the distance between the ground contact ends E on both sides of the tire portion in the tire width direction.

The inner main groove 34 is a circumferential main groove that is provided at a position closer to the tire center line CL than the ground contact ends E and extends in the tire circumferential direction. The inner main groove 34 shown in FIG. 2 is a groove extending linearly in the tire circumferential direction, but may have a zigzag shape extending in the tire circumferential direction while being bent in the tire width direction. The inner main groove 34 may be a groove in which a see-through portion exists. The groove width of the inner main groove 34 is, for example, 5 to 20 mm, and the groove depth is, for example, 5 to 15 mm. The inner main groove 34 may be included in a region spaced from the tire center line CL by a distance in the range of 5 to 25% with respect to the ground contact width W.
A center land portion 54 is formed between the pair of inner main grooves 34 (34a, 34b).

  In addition, the grounding end E assembles the tire 10 on a rim prescribed in JATMA YEAR BOOK 2010, and fills the tire 10 with air pressure corresponding to the maximum load capacity shown in the air pressure-load capacity correspondence table in JATMA YEAR BOOK 2010. These are end portions in the tire width direction in the ground contact surface of the tire 10 obtained when a load of 80% of the maximum load capacity is applied and grounded on a plane.

  The intermediate land portion 36 is provided in an intermediate region R sandwiched between one of the outer main grooves 32 and one of the inner main grooves 34 in each of the regions on both sides of the tread portion in the tire width direction with respect to the tire center line CL. Land. In the intermediate region R, a first inclined lug groove 38, a second inclined lug groove 40, a third inclined lug groove 42, and a connecting groove 44 are provided.

The first inclined lug groove 38 is not opened in the inner main groove 34, and the outer side in the tire width direction so as to be away from the tire center line CL from the position inside each intermediate region R and the first in the tire circumferential direction. 1 is a lug groove extending in the direction 1 (upward in the drawing of FIG. 2). A plurality of first inclined lug grooves 38 are provided in the tire circumferential direction. The first inclined lug groove 38 opens into the outer main groove 32. The groove width of the first inclined lug groove 38 is an end region where one edge of the groove is bent and the groove width is gradually narrowed, such as the end on the inner main groove 34 side, or the opening of the first inclined lug groove 38. Except for the end region where the edge of the intermediate land portion 38 corresponding to the portion is rounded in an arc shape and the groove width gradually increases, the groove depth is, for example, 2 to 15 mm, and the groove depth is, for example, 3 to 12 mm. is there.
The first inclined lug groove 38 is provided with a notch 52 protruding in the direction opposite to the first direction in the middle of extending toward the outer main groove 32. The notch 52 is provided at a position substantially opposed in the tire circumferential direction across one end of the second inclined lug groove 40 and a land portion, which will be described later.

  The second inclined lug groove 40 is a substantially intermediate position in the tire circumferential direction of the adjacent first inclined lug groove 38 and does not open to the inner main groove 34 from the position inside the intermediate region R to the tire center line CL. The lug groove extends outward in the tire width direction and away from the tire and toward the first direction in the tire circumferential direction. Further, the second inclined lug groove 40 is closed without opening to the outer main groove 32. A plurality of second inclined lug grooves 40 are provided in the tire circumferential direction. As the second inclined lug groove 40 moves away from the tire center line CL, the groove width increases. The drainage performance is improved by increasing the width of the second inclined lug groove 40 as the distance from the tire center line CL increases. The second inclined lug groove 40 starts to extend in parallel with the first inclined lug groove 38 from the end portion on the inner main groove 34 side, and smoothly bends in the first direction along the first inclined lug groove 40. Compared to 38, the inclination angle with respect to the tire circumferential direction becomes smaller. This part is an inclined part. The inclined portion extends substantially linearly. The second inclined lug groove 40 crosses the two first inclined lug grooves 38 adjacent to each other in the tire circumferential direction at the inclined portion. That is, the second inclined lug groove 40 has an inclined portion having a smaller inclination angle with respect to the tire circumferential direction than the first inclined lug groove 38, and the inclined portion of the second inclined lug groove 40 has two first inclined lugs. Crosses the groove 38. The second inclined lug grooves 40 are provided in the tire circumferential direction every other plurality of first inclined lug grooves 38 provided in the tire circumferential direction. The groove width of the second inclined lug groove 40 is, for example, 2.0 mm to 6.0 mm, and the groove depth is, for example, 3.0 mm to 8.0 mm. In the present embodiment, the inclined portion of the second inclined lug groove 40 crosses two first inclined lug grooves 38 adjacent in the tire circumferential direction, but may cross three or more first inclined lug grooves 38. However, it is preferable to cross the two first inclined lug grooves 38 from the viewpoint of preventing a decrease in steering stability performance.

  The third inclined lug groove 42 is an intermediate region R between two first inclined lug grooves adjacent in the tire circumferential direction and extends along the inclined direction of the first inclined lug groove 38. The third inclined lug groove 42 is a substantially intermediate position in the tire circumferential direction between two adjacent first inclined lug grooves in the intermediate region R, and has a position close to the inner main groove 34 as a start end, and the first inclined lug groove 38. Without being connected to the outer main groove 32, and is closed at a position close to the outer main groove 32 in the intermediate region R and ends. A connecting groove 44 is connected to the start end of the third inclined lug groove 42. The groove width of the third inclined lug groove 42 is, for example, 2.0 mm to 5.0 mm, excluding the end region, and the groove depth is, for example, 3.0 mm to 6.0 mm.

  The connecting groove 44 traverses the first inclined lug groove 38 and the end (the start end) of the third inclined lug groove 42 located on the inner main groove 34 side, and the first inclined lug groove 38 located on the inner main groove 34 side. The end portion of the two inclined lug grooves 40 is connected. The connecting groove 44 extends substantially in the tire circumferential direction. The groove width of the connecting groove 44 is, for example, 2.0 mm to 5.0 mm, and the groove depth is, for example, 3.0 mm to 6.0 mm.

A shoulder land portion 46 and a shoulder lug groove 48 are mainly provided in the shoulder region between the ground contact edge E on the outer side in the tire width direction of the outer main groove 32.
The shoulder land portion 46 is a portion in contact with the ground between the outer main groove 32 and the ground contact end E.
The shoulder lug groove 48 communicates between the outer main groove 32 and each of the ground contact ends E and opens to the outer main groove 32.
The opening that opens in the outer main groove 32 of the shoulder lug groove 48 is provided at the same position as the position in the tire circumferential direction of the opening in which the first inclined lug groove 38 opens in the outer main groove 32. The opening of the shoulder lug groove 48 is located at a bent portion where the outer main groove 32 bends in a zigzag shape.
Further, the shoulder lug groove 48 is configured such that the groove width becomes narrower as it approaches the ground contact end E. The corners of the opening located in the direction opposite to the first direction in the tire circumferential direction of the shoulder lug groove 48 are rounded in an arc shape.
The groove width of the shoulder lug groove 48 is, for example, 2.0 mm to 6.0 mm, excluding the opening, and the groove depth is, for example, 3.0 mm to 7.0 mm.
The shoulder land portion 46 is provided with an acutely bent shoulder closing groove 50 extending from the shoulder lug groove 48 into the shoulder land portion 46. The groove width of the shoulder closing groove 50 is, for example, 2.0 mm to 5.0 mm, excluding the end portion, and the groove depth is, for example, 1.0 mm to 4.0 mm.

  In the present embodiment, the pattern elements provided in the shoulder region on the outer side in the tire width direction of the outer main groove 32 include the shoulder land portion 46, the shoulder lug groove 48, and the shoulder closing groove 50 described above. It is not limited.

Thus, in the present embodiment, the first inclined lug groove 38 does not open to the inner main groove 34. This is because when the first inclined lug groove 38 opens into the inner main groove 34, a plurality of large and small blocks surrounded by the groove are formed around the area where the first inclined lug groove 38 opens into the intermediate land portion 36. Therefore, the tread rigidity varies at each position in the tire circumferential direction, and the steering stability performance deteriorates.
The first inclined lug groove 38 is inclined in the tire circumferential direction and the tire width direction in order to improve snow traction performance and drainage performance, but the inclination angle of the first inclined lug groove 38 with respect to the tire width direction is changed. One of the snow traction performance and the drainage performance is improved, and the other is lowered. For this reason, in the present embodiment, the second inclined lug grooves 40 are formed so that the second inclined lug grooves 40 cross at least two first inclined lug grooves 38. With this configuration, as can be seen from the examples described later, drainage performance can be improved while maintaining steering stability performance and snow traction performance.

FIG. 3 is a diagram showing definitions of various dimensions of the pattern elements provided in the intermediate region R.
In FIG. 3, A indicates the width of the intermediate land portion in the tire width direction. The width A represents the distance in the tire width direction between the edge where the intermediate land portion 34 contacts the inner main groove 34 and the edge positioned at the outermost side in the tire width direction where the intermediate land portion 34 contacts the outer main groove 32. . In FIG. 3, B indicates a separation distance in the tire width direction at both ends of the first inclined lug groove 38. In FIG. 3, C indicates a separation distance in the tire circumferential direction between both end portions of the second inclined lug groove 40. In FIG. 3, D indicates a separation distance in the tire width direction at both ends of the third inclined lug groove 42. In addition, since the end (start end) on the inner main groove 34 side of the third inclined lug groove 42 is connected to the connecting groove 44, it is difficult to determine the end (start end) on the inner main groove 34 side. Stipulated as follows. That is, when the edge of the third inclined lug groove 42 is traced from the end on the outer main groove 32 side toward the end (starting end) on the inner main groove 34 side, The position where the inclination angle with respect to the tire width direction increases by 10% with respect to the average inclination angle of the edge traced so far is determined as the position of the end (starting end) on the inner main groove 34 side.
In FIG. 3, θ is an inclination angle of the first inclined lug groove 38 with respect to the tire width direction.
The inclination angle θ indicates an angle at which a straight line connecting the groove width center points at both ends of the first inclined lug groove 38 is inclined with respect to the tire width direction. When the edges of both ends of the first inclined lug groove 38 are rounded and it is difficult to determine the groove width at both ends, the positions of both ends are determined by approximating the rounded edges with two straight lines to form corners. Then, the groove width at the end is specified.

In the present embodiment, the ratio B / A is preferably 0.7 or more and 0.9 or less from the viewpoint of improving drainage performance while maintaining at least steering stability performance and snow traction performance. When the ratio B / A is less than 0.7, in the intermediate region R, the distance between the inner main groove 34 and the end of the first inclined lug groove 38 is increased, and the tread of the land portion that is continuous in the tire circumferential direction Stiffness is enhanced and steering stability is improved, but the groove area ratio is reduced and drainage performance is lowered, and the first inclined lug groove 38 is shortened and the edge component of the first inclined lug groove 38 is reduced. Snow traction performance is reduced. On the other hand, when the ratio B / A exceeds 0.9, the distance between the inner main groove 34 and the end of the first inclined lug groove 38 is shortened, and the land portion continuous in the tire circumferential direction is reduced, and the tread rigidity is reduced. As a result, the steering stability performance decreases.
The ratio A / W, which is the ratio of the width A to the ground width W, is preferably 0.2 to 0.3 or less, and the ratio B / W, which is the ratio of the separation distance B to the ground width W, is 0. It is preferable that it is 3 or more and 0.4 or less. The width A is, for example, 50 to 60 mm, and the separation distance B is, for example, 35 to 55 mm. The inclination angle θ of the first inclined lug groove 38 is, for example, 35 to 60 degrees.

  Further, the ratio C / A is preferably 1.4 or more and 2.2 or less from the viewpoint of improving the drainage performance while maintaining at least the steering stability performance and the snow traction performance. When the ratio C / A is less than 1.4, the length of the second inclined lug groove 38 in the tire circumferential direction is shortened, and the drainage performance is degraded. When the ratio C / A exceeds 2.2, a large and small block surrounded by the groove is further formed across the first inclined lug groove 38, and the tread rigidity varies at each position, so that the steering stability is lowered. The ratio C / W of the separation distance C to the ground contact width W is preferably 0.4 to 0.6. The separation distance C of the second inclined lug groove 40 is, for example, 80 to 110 mm.

  The ratio D / A is preferably 0.5 or more and 0.7 or less from the viewpoint of improving the drainage performance while maintaining at least the steering stability performance and the snow traction performance. When the ratio D / A is less than 0.5, the length of the third inclined lug groove 42 is not sufficient, so that the snow traction performance is deteriorated, and the two adjacent first inclined lug grooves 38 and the second inclined lug groove Uneven wear easily occurs in the block surrounded by the lug groove 40 and the outer main groove 32. When the ratio D / A exceeds 0.7, the end of the third inclined lug groove 42 approaches the outer main groove 32 so that the two adjacent first inclined lug grooves 38, the second inclined lug groove 40, The tread rigidity of the block surrounded by the outer main groove 32 is lowered, and the steering stability performance is deteriorated. The separation distance D of the third inclined lug groove 42 is, for example, 30 to 45 mm.

Moreover, in this embodiment, although the connection groove 44 is provided, the connection groove 44 does not need to be provided. However, it is preferable to provide the connecting groove 44 in order to avoid a side slip on the road surface on snow and to improve drainage performance.
Further, since the outer main groove 32 is a zigzag groove extending in the tire circumferential direction while being bent in the tire width direction, the tire 10 has improved snow traction performance.
In addition, since the groove width of the shoulder lug groove 48 becomes narrower as it approaches the ground contact edge E, the snow is pressed by the shoulder lug groove 48 to increase the snow shearing force of the snow, improving the snow traction performance and passing the snow. Noise is additionally reduced.

(Example)
In order to confirm the effect of the tire according to the present embodiment, the tread pattern was variously changed to produce a tire. The tire size of the produced tire is a tire for passenger cars and is 245 / 45R18 97Y. Tires are mounted on 2-liter class front-wheel drive passenger cars, assembled on rims specified in JATMA YEAR BOOK 2010, and air pressure corresponding to the maximum load capacity shown in the air pressure-load capacity correspondence table in JATMA YEAR BOOK 2010. The tire was filled and a load of 80% of the maximum load capacity was determined as a load.

For the evaluation, the above passenger car was run on the dry road surface on the test course, and the sensory evaluation of the steering stability performance by the driver was performed. Furthermore, the hydroplaning generation | occurrence | production speed | velocity was measured by making it drive | work the road surface which provided the water film of the water depth of 10 mm on a test course. Furthermore, the above-mentioned passenger car was run on a snowy road surface on a test course, and the sensory evaluation of the snow traction performance by the driver was performed.
The sensory evaluation was evaluated based on 100 points, and the evaluation results of each example and comparative example were indexed with the sensory evaluation result of Comparative Example 1 below as the index 100 (reference). The higher the index, the better the steering stability performance and snow traction performance. The drainage performance was obtained by indexing the measurement results of each of the examples and the comparative examples with the measurement result of the hydroplaning generation rate of the following Comparative Example 1 as the index 100 (reference). The higher the index, the better the drainage performance.

Table 1 below shows the specifications and evaluation results of Examples 1 to 3 and Comparative Examples 1 and 2.
Example 1 has a tread pattern as shown in FIG. 4 in which the third inclined lug groove 42 and the connecting groove 44 are not provided in the tread pattern as shown in FIG. 2.
The second embodiment has a tread pattern as shown in FIG. 5 in which the connecting groove 44 is not provided among the tread patterns as shown in FIG.
Example 3 has a tread pattern as shown in FIG.
In the tread pattern shown in FIG. 2, the third inclined lug groove 42 and the connecting groove 44 are not provided in the tread pattern as shown in FIG. 2, and the second inclined lug groove 40 crosses the three first inclined lug grooves 38. Have.
The comparative example 1 has a tread pattern as shown in FIG. 6 in which the second inclined lug groove 40, the third inclined lug groove 42, and the connecting groove 44 are not provided among the tread patterns as shown in FIG.
In the comparative example 2, in the tread pattern as shown in FIG. 2, the third inclined lug groove 42 and the connecting groove 44 are not provided, and the second inclined lug groove 40 crosses only one first inclined lug groove. It has a tread pattern as shown in FIG.

Examples 1 and 4 in Table 1 can improve drainage performance while maintaining at least steering stability performance and snow traction performance as compared with Comparative Examples 1 and 2.
By forming the second inclined lug groove 40 so that the second inclined lug groove 40 crosses at least two first inclined lug grooves 38 that are not opened in the inner main groove 34, the steering stability performance and the snow traction performance are at least achieved. It can be seen that drainage performance can be improved while maintaining.
Further, it can be seen from the comparison between Examples 1 and 2 that the snow traction performance is further improved by providing the third inclined lug groove 42.
Furthermore, it can be seen from the comparison between Examples 2 and 3 that by providing the connecting groove 44, the skid on the road surface on the snow is lowered and the snow traction performance is further improved.

Table 2 below shows the specifications and evaluation results of Examples 5 to 8 and Comparative Example 3.
Examples 5 to 8 and Comparative Example 3 have a tread pattern as shown in FIG. 2, but various values of the ratio B / A were varied by varying the separation distance B. In all of Examples 5 to 8 and Comparative Example 3, the connecting groove 44 is provided. The eighth embodiment has the same specifications as the third embodiment. The second inclined lug grooves 40 of Examples 5 to 8 and Comparative Example 3 cross the two first inclined lug grooves 38.

  From comparison of Examples 5 to 8 and Comparative Example 3 in Table 2, the ratio B / A is 0.7 to 0.9, while maintaining at least steering stability performance and snow traction performance, more drainage performance. It turns out that it is preferable at the point which improves.

Table 3 below shows the specifications and evaluation results of Examples 9 to 13.
Examples 9 to 13 have a tread pattern as shown in FIG. 1, but various values of the ratio C / A were varied by varying the separation distance C. In all of Examples 9 to 13, the connecting groove 44 is provided, and the second inclined lug groove 40 crosses the two first inclined lug grooves 38.

  From comparison of Examples 9 to 13 in Table 3, that the ratio C / A is 1.4 to 2.2 is that the drainage performance is further improved while maintaining at least the steering stability performance and the snow traction performance. It turns out that it is preferable. In Example 13, the improvement of the steering stability performance cannot be expected as compared with Comparative Example 1.

Table 4 below shows the specifications and evaluation results of Examples 14 to 18.
Examples 14-18 have a tread pattern as shown in FIG. 1, but various values of the ratio D / A were varied by varying the separation distance D. In each of Examples 14 to 18, the connecting groove 44 is provided, and the second inclined lug groove 40 crosses the two first inclined lug grooves 38.

  From the comparison of Examples 14 to 18 in Table 4, the ratio D / A is 0.5 to 0.7, while maintaining the steering stability performance and the snow traction performance with at least a margin, while further improving the drainage performance. It turns out that it is preferable at the point which improves. In Example 14, the improvement in snow traction performance cannot be expected as compared with Comparative Example 1. In Example 18, the improvement of the steering stability performance cannot be expected as compared with Comparative Example 1.

  Although the tread pattern 30 of the present embodiment is configured to provide the pair of inner main grooves 34 with the tire center line CL interposed therebetween, as shown in FIG. 8, the inner main grooves 34 are provided on the tire center line CL. It may be a configuration. The tire structure in this case may be the same as the tire structure shown in FIG. 1 or may be another tire structure. The tire pattern shown in FIG. 8 also exhibits the same effect as the tread pattern 30 shown in FIG.

  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.

DESCRIPTION OF SYMBOLS 10 Pneumatic tire 12 Carcass ply layer 12a, 12b Carcass ply material 14 Belt layer 14a, 14b Belt material 16 Bead core 18 Tread rubber member 20 Side rubber member 22 Bead filler rubber member 24 Rim cushion rubber member 26 Inner liner rubber member 28 Belt cover layer 29 sheet material 30 tread patterns 32, 32a, 32b outer main grooves 34, 34a, 34b inner main grooves 36, 36a, 36b intermediate land portions 38, 38a, 38b first inclined lug grooves 40, 40a, 40b second inclined lug grooves 42, 42a, 42b Third inclined lug grooves 44, 44a, 44b Connection grooves 46, 46a, 46b Shoulder land portions 48, 48a, 48b Shoulder lug grooves 50, 50a, 50b Shoulder closing grooves 52, 52a, 52b Notch 54 Center Land

Claims (9)

A pneumatic tire,
A tread pattern is provided on the tread portion of the pneumatic tire,
The tread pattern is
Compared to the tire center line, a pair of outer main grooves extending in the tire circumferential direction, provided at positions close to the ground contact ends of the tread portion located on both sides in the tire width direction,
A pair of inner main grooves extending in the tire circumferential direction, provided at a position closer to the tire center line than each of the ground contact ends;
In the respective regions on both sides of the tread portion in the tire width direction with respect to the tire center line, an intermediate portion in contact with the ground provided in an intermediate region sandwiched between one of the outer main grooves and one of the inner main grooves The land,
Lug grooves provided in each of the intermediate regions, outside the tire center line so as to be away from the tire center line from positions inside the intermediate regions without opening in the inner main groove, and A plurality of first inclined lug grooves extending toward a first direction of the tire circumferential direction and opening into one of the outer main grooves;
Lug grooves provided in each of the intermediate regions, outside the tire center line so as to be away from the tire center line from positions inside the intermediate regions without opening in the inner main groove, and A plurality of second inclined lug grooves extending in a first direction of the tire circumferential direction and further closing without opening in the outer main groove,
Each of the second inclined lug grooves has a groove width that increases with distance from the tire center line, and each of the second inclined lug grooves is in the tire circumferential direction as compared with the first inclined lug groove. A pneumatic tire having an inclined portion with a small inclination angle, wherein the inclined portion of the second inclined lug groove crosses at least two of the first inclined lug grooves. A pneumatic tire,
A tread pattern is provided on the tread portion of the pneumatic tire,
The tread pattern is
Compared to the tire center line, a pair of outer main grooves extending in the tire circumferential direction, provided at positions close to the ground contact ends of the tread portion located on both sides in the tire width direction,
One inner main groove provided on the tire center line and extending in the tire circumferential direction;
A pair of intermediate land portions in contact with the ground, provided in an intermediate region sandwiched between one of the pair of outer main grooves and the inner main groove in regions on both sides in the tire width direction with respect to the tire center line;
Lug grooves provided in each of the intermediate regions, outside the tire center line so as to be away from the tire center line from positions inside the intermediate regions without opening in the inner main groove, and A plurality of first inclined lug grooves extending toward a first direction of the tire circumferential direction and opening into one of the outer main grooves;
Lug grooves provided in each of the intermediate regions, outside the tire center line so as to be away from the tire center line from positions inside the intermediate regions without opening in the inner main groove, and A plurality of second inclined lug grooves extending in a first direction of the tire circumferential direction and further closing without opening in the outer main groove,
Each of the second inclined lug grooves has a groove width that increases with distance from the tire center line, and each of the second inclined lug grooves is in the tire circumferential direction as compared with the first inclined lug groove. A pneumatic tire having an inclined portion with a small inclination angle, wherein the inclined portion of the second inclined lug groove crosses at least two of the first inclined lug grooves.   When the width of each of the intermediate land portions in the tire width direction is A and the separation distance in the tire width direction of both ends of each of the first inclined lug grooves is B, the ratio B / A is 0.7 or more and 0.00. The pneumatic tire according to claim 1 or 2, which is 9 or less.   The ratio C / A is 1.4 or more, where A is the width of each of the intermediate land portions in the tire width direction and C is the separation distance in the tire circumferential direction of both ends of each of the second inclined lug grooves. The pneumatic tire according to any one of claims 1 to 3, which is 2 or less.   Further, in each of the intermediate regions of the tread portion, between the two first inclined lug grooves adjacent to each other in the tire circumferential direction among the first inclined lug grooves, along the inclination direction of the first inclined lug groove. A third inclined lug groove extending is provided, where a distance D in the tire width direction of both ends of the third inclined lug groove is D, and a width in the tire width direction of the intermediate land portion is A, a ratio D / A The pneumatic tire according to any one of claims 1 to 4, wherein is 0.5 or more and 0.7 or less. Further, in each of the intermediate regions of the tread portion, between the two first inclined lug grooves adjacent to each other in the tire circumferential direction among the first inclined lug grooves, along the inclination direction of the first inclined lug groove. A third inclined lug groove extending is provided;
Furthermore, in each of the intermediate regions of the tread portion, an end located on the tire center line side of the third inclined lug groove across one of the first inclined lug grooves, and the second inclined lug The pneumatic tire according to any one of claims 1 to 5, wherein a connecting groove that connects an end portion of the groove located on the tire center line side is provided.   The pneumatic tire according to any one of claims 1 to 6, wherein the outer main groove has a zigzag shape extending in the tire circumferential direction while being bent in the tire width direction.   The tread pattern further includes a shoulder land portion in contact with the ground provided in a shoulder region between each of the outer main grooves and each of the grounding ends, and the shoulder regions include the pair of outer main grooves. A shoulder lug groove communicating with each of the grounding ends, and an opening in which the shoulder lug groove opens in each of the outer main grooves is provided in each of the first inclined lug grooves. Provided at the same position as the position in the tire circumferential direction of the opening that opens to each of the main grooves, the opening of the shoulder lug groove is located at a bent portion where each of the pair of outer main grooves bends in a zigzag shape The pneumatic tire according to claim 7. The tread pattern further includes a shoulder land portion in contact with the ground provided in a shoulder region between each of the outer main grooves and each of the grounding ends, and the shoulder regions include the pair of outer main grooves. A shoulder lug groove communicating with each of the grounding ends, and an opening in which the shoulder lug groove opens in each of the outer main grooves is provided in each of the first inclined lug grooves. The width of the shoulder lug groove is narrowed as the shoulder lug groove approaches the grounding end, and the shoulder lug groove is provided at the same position as the position in the tire circumferential direction of the opening that opens in each of the main grooves. The pneumatic tire according to item 1.

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