JP5233787B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire having quietness and drainage.

  In general, the drainage performance of a pneumatic tire is improved by increasing the groove area. However, simply widening the groove width causes a decrease in the rigidity of the block and an increase in the air volume in the groove, so that pattern noise occurs and quietness deteriorates. Thus, quietness and drainage are contradictory performances.

  Conventionally, a pneumatic tire aimed at improving quietness and drainage is known. The pneumatic tire has at least one pair of circumferential main grooves extending in the tire circumferential direction in the pattern center area, and extends from the circumferential main groove to the putter end side, and is inclined in the same direction with respect to the tire circumferential direction. And a plurality of inclined grooves opened at the end of the ground width. And in this conventional pneumatic tire, it is going to improve drainage, ensuring block rigidity and reducing pattern noise by the inclined groove provided inclining with respect to the tire peripheral direction (for example, patent documents) 1 or 2).

JP-A-9-2025 Japanese Patent Laid-Open No. 9-164813

  However, in recent years, further improvement in quietness and drainage has been desired in order to cope with higher performance of vehicles.

  This invention is made | formed in view of the above, Comprising: It aims at providing the pneumatic tire which can improve silence and drainage.

  In order to achieve the above object, the pneumatic tire according to the present invention includes at least two circumferential main grooves provided along the tire circumferential direction within the tire contact width of the tread portion, and the circumferential main groove. In a pneumatic tire provided with a land portion formed in a compartment, the tire is provided in the outermost land portion in the tire width direction having a tire contact width end, and communicates with the circumferential main groove on the outermost side in the tire width direction. An inclined groove extending obliquely with respect to the circumferential direction, an intermediate groove extending at an obtuse angle from the extended end of the inclined groove, and an acute angle outward in the tire width direction at the extended end of the intermediate groove The first sub-groove disposed at the inner side in the tire width direction of the tire ground contact width end, and the tire width direction outermost portion having the tire contact width end. At the outer land part, Characterized in that a second sub-groove formed opened to the tire contact width end without communicating with the direction main groove and the first sub-groove.

  According to the pneumatic tire, the inclined groove portion, the intermediate groove portion, and the folded groove portion that extend in different directions are configured to communicate with each other, and the first sub-groove disposed on the inner side in the tire width direction of the tire ground contact width end, A second sub-groove that is opened to the tire ground contact width end without being connected to the direction main groove and the first sub-groove is provided in the land portion on the shoulder side. For this reason, each of the first sub-groove and the second sub-groove supplements each other so as to suppress deformation of the land portion on the shoulder side, so that the rigidity of the land portion is increased and the braking performance is improved, and a sufficient groove area is provided. Will be secured. As a result, drainage can be improved. Moreover, since the first sub-groove and the second sub-groove do not divide the land portion into blocks along the tire width direction, air pumping or the like can be used to contain air in the grooves when each groove contacts the ground. Since the situation in which the blocks come into contact with the road surface at a constant pitch is prevented, the pattern noise is suppressed and the quietness can be improved.

  In the pneumatic tire according to the present invention, the tire width direction dimension from the opening edge on the tire width direction outer side to the tire ground contact width end in the circumferential main groove on the outermost side in the tire width direction is La, and the first sub The tire width direction dimension between the intermediate groove part of the groove and the circumferential main groove at the outermost side in the tire width direction is L1, and the tire from the closed end of the folded groove part of the first sub groove to the tire ground contact width end When the width direction dimension is L2, and the tire width direction dimension from the inner end in the tire width direction of the second sub groove to the outer circumferential main groove on the outermost side in the tire width direction is L3, 0.1 ≦ L1 / La ≦ It is set to the range of 0.4, 0.1 <= L2 / La <= 0.4, and 0.3 <= L3 / La <= 0.7.

  According to this pneumatic tire, if L1 / La is less than 0.1, the rigidity of the land portion on the shoulder side is insufficient and there is a concern about uneven wear. On the other hand, if L1 / La exceeds 0.4, the rigidity of the land portion on the shoulder side is too high, leading to deterioration of silence and drainage. And by optimizing L2 / La and L3 / La, both quietness and drainage can be achieved.

  In the pneumatic tire according to the present invention, the inclined groove portion has an inclination angle θ with respect to a tire circumferential direction set in a range of 20 [degrees] ≦ θ ≦ 80 [degrees].

  According to this pneumatic tire, by optimizing the inclination angle θ of the inclined groove portion, when the inclined groove portion comes into contact with the air, the air pumping in which air is confined in the groove, or the block contacts the road surface at a constant pitch Therefore, pattern noise is suppressed and quietness can be improved. Moreover, since the rigidity of the land portion is increased by supplementing so as to suppress the deformation of the land portion on the shoulder side, occurrence of uneven wear can be suppressed.

  Further, in the pneumatic tire according to the present invention, the tire circumferential direction of the inclined groove portion and the intermediate groove portion with respect to a tire contact area dimension Ta passing through a bending point between the inclined groove portion and the intermediate groove portion in the tire circumferential direction. The dimension T1 is set in the range of 0.2 ≦ T1 / Ta ≦ 0.8.

  According to this pneumatic tire, if T1 / Ta is less than 0.2, the groove area cannot be secured and the drainage performance is deteriorated. On the other hand, if T1 / Ta exceeds 0.8, pattern noise cannot be suppressed and quietness deteriorates. Therefore, it is preferably set in the range of 0.2 ≦ T1 / Ta ≦ 0.8.

  In the pneumatic tire according to the present invention, the tire circumferential direction dimension T2 of the folded groove part is 0.3 ≦ T2 / T1 ≦ 0.8 with respect to the tire circumferential direction dimension T1 of the inclined groove part and the intermediate groove part. It is set to a range.

  According to this pneumatic tire, if T2 / T1 is less than 0.3, the rigidity of the land portion on the shoulder side cannot be increased, so that the pattern noise cannot be suppressed and the silence is deteriorated. On the other hand, when T2 / T1 exceeds 0.8, the rigidity of the land portion on the shoulder side decreases, resulting in deterioration of braking performance and uneven wear resistance. Therefore, it is preferable that the range is set to 0.3 ≦ T2 / T1 ≦ 0.8.

  In the pneumatic tire according to the present invention, the tire width direction dimension L4 from the tire width direction outer opening edge of the circumferential main groove on the outermost side in the tire width direction to the tire equatorial plane is 0 with respect to the tire ground contact width Lw. .3 × (Lw / 2) ≦ L4 ≦ 0.6 × (Lw / 2).

  According to this pneumatic tire, the outermost circumferential main groove in the tire width direction is disposed closer to the center of the tire ground contact width, so that medium frequency road noise (200 Hz to 300 Hz) can be reduced.

  In the pneumatic tire according to the present invention, the groove width L5 of the circumferential main groove on the outermost side in the tire width direction is set in a range of 5 [mm] ≦ L5 ≦ 20 [mm], and the first sub-groove The groove width L6 is set in the range of 1.5 [mm] ≦ L6 ≦ 6 [mm], and the groove width L7 of the second sub-groove is in the range of 1.5 [mm] ≦ L7 ≦ 6 [mm]. It is characterized by being set.

  According to this pneumatic tire, by optimizing the groove width L5 of the circumferential main groove on the outermost side in the tire width direction, the groove width L6 of the first sub groove, and the groove width L7 of the second sub groove, Both quietness and drainage can be achieved.

  The pneumatic tire according to the present invention includes a first sub-groove that is configured by communicating an inclined groove portion, an intermediate groove portion, and a folded groove portion that extend in different directions, and that is disposed on the inner side in the tire width direction of the tire ground contact width end; A second sub-groove that is opened at the tire ground contact width end without being connected to the circumferential main groove and the first sub-groove is provided in the land portion on the shoulder side. For this reason, sufficient groove area is ensured, raising the rigidity of the land part by the side of a shoulder and improving braking performance. As a result, drainage can be improved. Moreover, since the first sub-groove and the second sub-groove do not divide the land portion into blocks along the tire width direction, pattern noise is suppressed and silence can be improved.

  Embodiments of a pneumatic tire according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. The constituent elements of this embodiment include those that can be easily replaced by those skilled in the art or those that are substantially the same. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

  1 is a plan view showing a tread portion of a pneumatic tire according to an embodiment of the present invention, FIG. 2 is a meridional sectional view of the pneumatic tire shown in FIG. 1, and FIG. 3 is an embodiment of the present invention. It is a graph which shows the result of the performance test of this pneumatic tire.

  In the following description, the tire width direction means a direction parallel to the rotation axis (not shown) of the pneumatic tire 1, and the inner side in the tire width direction means the side toward the tire equatorial plane C in the tire width direction, the tire width The direction outer side means a side away from the tire equatorial plane C in the tire width direction. Further, the tire radial direction refers to a direction orthogonal to the rotation axis, the tire radial inner side is the side toward the rotation axis in the tire radial direction, and the tire radial direction outer side is the side away from the rotation axis in the tire radial direction. Say. The tire circumferential direction is a circumferential direction with the rotation axis as a central axis.

  The pneumatic tire 1 described below is configured to be substantially symmetric with respect to the tire equatorial plane C. The tire equatorial plane C is a plane that is orthogonal to the rotational axis of the pneumatic tire 1 and passes through the center of the tire width of the pneumatic tire 1. The tire width is the width in the tire width direction between the portions located outside in the tire width direction, that is, the distance between the portions farthest from the tire equatorial plane C in the tire width direction. The tire equator line is a line on the tire equator plane C along the circumferential direction of the pneumatic tire. And the pneumatic tire 1 demonstrated below is comprised so that it may become substantially symmetrical centering on the tire equatorial plane C. FIG.

  As shown in FIGS. 1 and 2, the pneumatic tire 1 has a tread portion 2. The tread portion 2 is made of a rubber material and is exposed at the outermost side in the tire radial direction of the pneumatic tire 1, and the surface thereof is the contour of the pneumatic tire 1. The surface of the tread portion 2 is formed as a tread surface 21 that is a surface that comes into contact with the road surface when a vehicle (not shown) on which the pneumatic tire 1 is mounted travels. The tread surface 21 of the tread portion 2 has at least two circumferential main grooves 22 extending in the tire circumferential direction within the tire contact width Lw and at least three land portions defined by the circumferential main grooves 22. 23. For example, in the present embodiment, four circumferential main grooves 22 are formed, and five land portions 23 are defined by the circumferential main grooves 22.

  Here, the tire ground contact width Lw means that when the pneumatic tire 1 is assembled to a regular rim and filled with a regular internal pressure and a regular load is applied, the tread surface 21 of the pneumatic tire 1 is grounded to the road surface. This is the maximum width in the tire width direction of the tire contact area G, which is an area. Further, both outermost ends in the tire width direction of the tire contact area G are referred to as tire contact width ends Ga, and in FIG. 1, the tire contact width ends Ga are continuously illustrated in the tire circumferential direction.

  The regular rim is a “standard rim” defined by JATMA. The normal internal pressure is a “test air pressure” defined by JATMA. The normal load is a “test load” defined by JATMA.

  In this pneumatic tire 1, a first sub-groove 24 and a second sub-groove 25 are provided on the tread surface 21 of the land portion 23 on the outermost side (shoulder side) in the tire width direction having the tire contact width end Ga. .

  The first sub-groove 24 is disposed on the inner side in the tire width direction of the tire ground contact width end Ga, and includes an inclined groove portion 241, an intermediate groove portion 242, and a turn-back groove portion 243.

  The inclined groove portion 241 is connected to the circumferential main groove 22 at the outermost side in the tire width direction with the base end opened and communicated with the tire circumferential direction (circumferential main groove 22) so as to be separated from the circumferential main groove 22. It extends at an acute angle.

  Further, the intermediate groove portion 242 extends from the extending end (bending point A) of the inclined groove portion 241 so as to be substantially along the tire circumferential direction while being bent at an obtuse angle. The intermediate groove portion 242 may be provided with an angle of 0 [deg.] Or more and 20 [deg.] Or less with respect to the tire circumferential direction.

  Further, the folded groove 243 is folded and extended at an acute angle on the outer side in the tire width direction at the extending end of the intermediate groove 242. The extending end of the folded groove portion 243 is closed at the inner side in the tire width direction of the tire ground contact width end Ga without opening to the tire ground contact width end Ga. Further, the folding groove 243 is curved and provided so as to be separated from the intermediate groove 242.

  A plurality of first sub-grooves 24 configured in this way are provided along the tire circumferential direction.

  The second sub-groove 25 extends inside and outside in the tire width direction of the tire ground contact width end Ga so as to open to the tire ground contact width end Ga without communicating with the circumferential main groove 22 and the first sub groove 24. Has been. One end of the second sub-groove 25 extends toward the bending point A between the inclined groove portion 241 and the intermediate groove portion 242 in the first sub-groove 24, and on the inner side in the tire width direction of the tire ground contact width end Ga. It is closed. The other end of the second sub-groove 25 extends toward the shoulder portion 3 of the pneumatic tire 1 on the outer side in the tire width direction of the tire ground contact width end Ga. Further, the second sub-groove 25 is provided in a curved manner similarly to the folded groove portion 243 of the first sub-groove 24. A plurality of second sub-grooves 25 configured as described above are provided along the tire circumferential direction.

  A plurality of first sub-grooves 24 provided along the tire circumferential direction are formed such that the extending end of the intermediate groove part 242 and the inclined groove part 241 are formed by a narrow groove-shaped sipe 27 between adjacent ones in the tire circumferential direction. It is communicated. Further, the vicinity of the bending point A between the inclined groove portion 241 and the intermediate groove portion 242 in the first sub groove 24 and one end of the second sub groove 25 are communicated with each other by a narrow groove-shaped sipe 27.

  Further, on the tread surface 21 of the land portion 23 on the inner side in the tire width direction of the circumferential main groove 22 on the outermost side in the tire width direction, a protruding groove portion 26 is formed that has a base end opened and communicated with the circumferential main groove 22. Has been. The protruding groove portion 26 is inclined and extended with respect to the tire circumferential direction (circumferential main groove 22) so as to be separated from the connected circumferential main groove 22, and the extended end is closed. A plurality of the protruding groove portions 26 are provided along the tire circumferential direction. The protruding groove portion 26 is provided with a narrow groove-shaped sipe 27 that extends along the tire circumferential direction at the central portion on the opposite side to the inclination direction. The sipe 27 that opens to the protruding groove portion 26 is closed at the extending end and is not communicated with another adjacent protruding groove portion 26.

  In the pneumatic tire 1 configured as described above, the inclined groove portion 241, the intermediate groove portion 242, and the folded groove portion 243 that extend in different directions rather than at right angles to the tire circumferential direction are configured to communicate with each other, and the tire ground contact width end The tire ground contact width end Ga is opened to the tire ground contact width end Ga without communicating with the first sub groove 24 arranged on the inner side in the tire width direction of Ga, the circumferential main groove 22 and the first sub groove 24. The second sub-groove 25 extending inward and outward in the tire width direction is provided in the land portion 23 on the shoulder side. For this reason, since each groove part 241,242,243 of the different direction of the 1st subgroove 24, and the 2nd subgroove 25 are supplemented so that each may suppress the deformation | transformation of the land part 23 by the side of the shoulder, A sufficient groove area is ensured while increasing the rigidity and improving the braking performance. As a result, it becomes possible to improve drainage. Moreover, since the land portions 23 are not divided into blocks along the tire width direction by the groove portions 241, 242, 243 and the second sub grooves 25 in different directions of the first sub grooves 24, each groove This prevents air pumping in which air is confined in the groove when it contacts the ground, and a situation where the block abuts on the road surface at a constant pitch, so that pattern noise can be suppressed and quietness can be improved.

  In the pneumatic tire 1, the inclined groove portion 241, the intermediate groove portion 242, the turning groove portion 243 of the first sub groove 24, and the second sub groove 25 are provided in the tire width direction at each outermost land portion 23 in the tire width direction. It is preferable to shift the positions so that they do not match. According to such a configuration, in each land portion 23 at the outermost side in the tire width direction, air pumping in which air is confined in the groove when each groove is grounded, and a situation where the block contacts the road surface at a constant pitch are further prevented. Therefore, pattern noise can be further suppressed and silence can be further improved.

In the pneumatic tire 1 according to the present embodiment, the tire width direction dimension from the tire width direction outer opening edge to the tire ground contact width end Ga in the tire width direction outermost circumferential main groove 22 is La, The tire width direction dimension between the intermediate groove portion 242 of the first sub groove 24 and the outer circumferential main groove 22 on the outermost side in the tire width direction is L1, and from the closed end of the folded groove portion 243 of the first sub groove 24 to the tire ground contact width end. When the tire width direction dimension up to Ga is L2, and the tire width direction dimension from the tire width direction inner end of the second sub-groove 25 to the outermost circumferential main groove 22 in the tire width direction is L3, the range is as follows. Is set.
0.1 ≦ L1 / La ≦ 0.4
0.1 ≦ L2 / La ≦ 0.4
0.3 ≦ L3 / La ≦ 0.7

  That is, the tire width direction dimension L1 applied to the intermediate groove portion 242 of the first sub-groove 24 is 10% or more and 40% or less of the tire width direction dimension La applied to the outermost circumferential main groove 22 in the tire width direction. Set to range. Furthermore, the tire width direction dimension L2 applied to the folded groove portion 243 of the first sub groove 24 is 10% to 40% of the tire width direction dimension La applied to the circumferential main groove 22 on the outermost side in the tire width direction. Set to range. Further, the tire width direction dimension L3 applied to the second sub-groove 25 is set in a range of 30 [%] to 70 [%] of the tire width direction dimension La applied to the outer circumferential main groove 22 on the outermost side in the tire width direction. ing.

  If the tire width direction dimension L1 applied to the intermediate groove part 242 is less than 10% of the tire width direction dimension La applied to the circumferential main groove 22, the rigidity of the land part 23 is insufficient and there is a concern about uneven wear. On the other hand, when L1 exceeds 40 [%] of La, the rigidity of the land portion 23 is too high, and the quietness and drainage are deteriorated. Then, by optimizing the tire width direction dimension L2 applied to the folded groove portion 243 and the tire width direction dimension L3 applied to the second sub groove 25, both silence and drainage can be achieved.

  It is quiet that the tire width direction dimension L1 applied to the intermediate groove portion 242 is set in a range of 0.15 ≦ L1 / La ≦ 0.3 with respect to the tire width direction dimension La applied to the circumferential main groove 22. It is preferable for improving the property and drainage. Further, the tire width direction dimension L2 applied to the folded groove portion 243 and the tire width direction dimension L3 applied to the second sub groove 25 are 0.2 ≦ L2 / La with respect to the tire width direction dimension La applied to the circumferential main groove 22. It is preferable to set the ranges of ≦ 0.4 and 0.4 ≦ L3 / La ≦ 0.6 in order to achieve both quietness and drainage.

  In the pneumatic tire 1 according to the present embodiment, the inclined groove portion 241 of the first sub-groove 24 has an inclination angle θ with respect to the tire circumferential direction on the side where the intermediate groove portion 242 extends has an angle of 20 [degrees] ≦ θ ≦. The range is set to 80 [degrees].

  According to such a configuration, by optimizing the inclination angle θ of the inclined groove portion 241, when the inclined groove portion 241 comes into contact with the air, pumping is performed so that air is contained in the groove, or the block contacts the road surface at a constant pitch. As a result, pattern noise is suppressed and quietness can be improved. In addition, since the rigidity of the land portion 23 is increased by compensating for the deformation of the land portion 23 on the shoulder side, the occurrence of uneven wear can be suppressed.

  The inclination angle θ of the inclined groove 241 is preferably set in a range of 35 [degrees] ≦ θ ≦ 60 [degrees] in order to improve quietness and suppress uneven wear.

  In the pneumatic tire 1 according to the present embodiment, the inclined groove portion 241 and the intermediate groove portion 242 with respect to the tire contact area dimension Ta passing through the bending point A between the inclined groove portion 241 and the intermediate groove portion 242 in the tire circumferential direction. Is set in a range of 0.2 ≦ T1 / Ta ≦ 0.8. That is, the tire circumferential direction dimension T1 applied to the inclined groove part 241 and the intermediate groove part 242 is set in a range of 20% to 80% of the tire contact area dimension Ta. The tire contact area dimension Ta includes a reference line (not shown) passing through the bending point A in the tire circumferential direction (parallel to the tire equatorial plane C), and an outline line of the tire contact area G (a two-dot difference line in FIG. 1). Is a dimension between point B1 and point B2 where

  When the tire circumferential direction dimension T1 of the inclined groove part 241 and the intermediate groove part 242 is less than 20 [%] of the tire contact area dimension Ta, the groove area cannot be secured and the drainage performance deteriorates. On the other hand, if the tire circumferential direction dimension T1 of the inclined groove part 241 and the intermediate groove part 242 exceeds 80 [%] of the tire contact area dimension Ta, the pattern noise cannot be suppressed and the quietness deteriorates. Therefore, the tire circumferential direction dimension T1 of the inclined groove part 241 and the intermediate groove part 242 is preferably set in a range of 0.2 ≦ T1 / Ta ≦ 0.8 with respect to the tire contact area dimension Ta.

  Note that the tire circumferential direction dimension T1 of the inclined groove part 241 and the intermediate groove part 242 is set in a range of 0.4 ≦ T1 / Ta ≦ 0.7 with respect to the tire contact area dimension Ta. It is preferable for improving the property.

  In the pneumatic tire 1 according to the present embodiment, the tire circumferential direction dimension T2 of the turning groove part 243 is 0.3 ≦ T2 / T1 ≦ 0 with respect to the tire circumferential direction dimension T1 of the inclined groove part 241 and the intermediate groove part 242. .8 range. That is, the tire circumferential direction dimension T2 of the folded groove part 243 is set in a range of 30% to 80% of the tire circumferential direction dimension T1 of the inclined groove part 241 and the intermediate groove part 242.

  When the tire circumferential direction dimension T2 of the turning groove part 243 is less than 30% of the tire circumferential direction dimension T1 of the inclined groove part 241 and the intermediate groove part 242, the rigidity of the land part 23 cannot be increased, so pattern noise is suppressed. Can not be quiet. On the other hand, if the tire circumferential direction dimension T2 of the turn-back groove part 243 exceeds 80 [%] of the tire circumferential direction dimension T1 of the inclined groove part 241 and the intermediate groove part 242, the rigidity of the land part 23 is lowered. Abrasion deteriorates. Therefore, it is preferable that the tire circumferential direction dimension T2 of the turning groove part 243 is set in a range of 0.3 ≦ T2 / T1 ≦ 0.8 with respect to the tire circumferential direction dimension T1 of the inclined groove part 241 and the intermediate groove part 242. .

  It should be noted that the tire circumferential direction dimension T2 of the folded groove part 243 is set in the range of 0.4 ≦ T2 / T1 ≦ 0.6 with respect to the tire circumferential direction dimension T1 of the inclined groove part 241 and the intermediate groove part 242. It is preferable for improving quietness and ensuring braking performance and uneven wear resistance.

  In the pneumatic tire 1 according to the present embodiment, the tire width direction dimension from the tire width direction outer opening edge of the circumferential main groove 22 on the outermost side in the tire width direction to the tire equatorial plane C with respect to the tire contact width Lw. L4 is set in a range of 0.3 × (Lw / 2) ≦ L4 ≦ 0.6 × (Lw / 2). That is, the tire width direction dimension L4 applied to the outermost circumferential main groove 22 in the tire width direction is within a range of 0.3 ≦ 2 × L4 / Lw ≦ 0.6 with respect to the tire ground contact width Lw. The tire width direction dimension L4 applied to the outermost circumferential main groove 22 in the direction is set in a range of 30 [%] to 60 [%], which is half of the tire ground contact width Lw.

  According to such a configuration, the outermost circumferential main groove 22 in the tire width direction is disposed closer to the center of the tire ground contact width Lw, so that it is possible to reduce medium frequency road noise (200 Hz to 300 Hz). .

  In addition, the tire width direction dimension L4 from the tire width direction outer side opening edge of the circumferential main groove 22 on the outermost side in the tire width direction to the tire equatorial plane C with respect to the tire contact width Lw is 0.33 × (Lw / 2). ≦ L4 ≦ 0.55 × (Lw / 2) is preferably set in order to reduce medium frequency road noise (200 Hz to 300 Hz).

  Further, in the pneumatic tire 1 according to the present embodiment, the groove width L5 in the circumferential main groove 22 on the outermost side in the tire width direction is set in a range of 5 [mm] ≦ L5 ≦ 20 [mm], and the first sub The groove width L6 of the groove 24 is set in a range of 1.5 [mm] ≦ L6 ≦ 6 [mm], and the groove width L7 of the second sub groove 25 is 1.5 [mm] ≦ L7 ≦ 6 [mm]. Is set in the range. The relationship between the groove width L5 and the groove width L6, and the groove width L5 and the groove width L7 is set to L6 <L5 and L7 <L5. Furthermore, the groove depth in the circumferential main groove 22 on the outermost side in the tire width direction is set to be deeper than the groove depth of the first sub groove 24 and the groove depth of the second sub groove 25.

  According to this configuration, by optimizing the groove width L5 in the circumferential main groove 22 on the outermost side in the tire width direction, the groove width L6 of the first sub groove 24, and the groove width L7 of the second sub groove 25. It is possible to achieve both quietness and drainage.

  In addition, if the groove width L6 of the first sub-groove 24 is set in a range of 1.5 [mm] ≦ L6 ≦ 6 [mm], the inclined groove portion 241, the intermediate groove portion 242, and the folded groove portion 243 are the same. May be different. Furthermore, if the groove width L6 is set in a range of 1.5 [mm] ≦ L6 ≦ 6 [mm], even if the groove width L6 is constant in the length direction of the inclined groove portion 241, the intermediate groove portion 242, and the folded groove portion 243, It may change. Further, the groove width L7 of the second sub-groove 25 is constant in the length direction of the second sub-groove 25 as long as it is set in the range of 1.5 [mm] ≦ L7 ≦ 6 [mm]. , May change.

  In this example, performance tests relating to quietness and drainage were performed on a plurality of types of pneumatic tires having different conditions (see FIG. 3).

  In this performance test, a pneumatic tire having a tire size of 225 / 50R17 was assembled to a 17 × 7JJ rim, filled with an internal pressure of 210 kPa, and mounted on a test vehicle (a domestic 3.0-liter class sedan type passenger car).

  In the evaluation method, in silence (generation of pattern noise), the test vehicle runs on a smooth road surface at 60 km / h, and the sound pressure level near the center of the vehicle is measured. Then, based on this measurement result, index evaluation using the conventional example as a reference (100) is performed. This evaluation is preferable as the numerical value increases. In terms of drainage, the vehicle is run on a wet road surface with a test vehicle, and the driver evaluates the handling stability based on the conventional example by sensory evaluation. In this case, an evaluation score obtained by averaging the evaluations of five drivers is shown as an index with a standard of 100. A higher index is preferable.

  As shown in FIG. 4, the pneumatic tire of the conventional example has four main grooves so as to penetrate from the circumferential main groove 22 ′ to the ground contact end Ga ′ in the outermost land portion 23 ′ in the tire width direction. A sub-groove 24 '(groove width L6) is formed. On the other hand, the pneumatic tires of Examples 1 to 3 have four main grooves, the first sub-groove and the second sub-groove, and L1 / La, L2 / La, L3 / La, and the circumference. The groove width L5 of the direction main groove, the groove width L6 of the first sub groove, and the groove width L7 of the second sub groove are optimized. Further, in the pneumatic tire of Example 4, the inclination angle θ of the inclined groove portion is optimized in addition to the pneumatic tire of Example 3. Further, in the pneumatic tire of Example 5, T1 / Ta is optimized in addition to the pneumatic tire of Example 4. Further, in the pneumatic tire of Example 6, T2 / T1 is optimized in addition to the pneumatic tire of Example 5. Further, in the pneumatic tire of Example 7, 2 × L4 / Lw is optimized in addition to the pneumatic tire of Example 6. In addition to the pneumatic tire of Example 7, the pneumatic tire of Example 8 is optimal in the groove width L5 of the circumferential main groove, the groove width L6 of the first sub groove, and the groove width L7 of the second sub groove. It has become.

  As shown in the test results of FIG. 3, it can be seen that the pneumatic tires of Examples 1 to 8 have improved quietness and drainage.

  As described above, the pneumatic tire according to the present invention is suitable for improving quietness and drainage.

FIG. 1 is a plan view showing a tread portion of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a meridional sectional view of the pneumatic tire shown in FIG. FIG. 3 is a chart showing the results of the performance test of the pneumatic tire according to the example of the present invention. FIG. 4 is a plan view showing a tread portion of a conventional pneumatic tire.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Shoulder part 21 Tread surface 22 Circumferential main groove 23 Land part 24 1st subgroove 25 2nd subgroove 26 Projection groove part 27 Sipe 241 Inclination groove part 242 Intermediate groove part 243 Folding groove part A Bending point C Tire Equatorial plane G Tire contact area Ga Tire contact width end La Tire width direction dimension from circumferential main groove to tire contact width end L1 Tire width direction dimension between intermediate groove portion and circumferential main groove L2 From closed end of folded groove portion Tire width direction dimension to the tire contact width end L3 Tire width direction dimension from the tire width direction inner end of the second sub groove to the circumferential main groove L4 Tire equatorial plane from the opening edge of the circumferential main groove on the tire width direction outer side Width in tire width direction L5 Groove width in main circumferential groove L6 Groove width in first sub groove L7 Groove width in second sub groove Lw Tire contact width Ta Tire contact area dimension 1 inclined groove portion and the inclination angle of the tire circumferential dimension θ inclined groove portion of the tire circumferential dimension T2 fold groove of the intermediate groove

Claims (7)

In a pneumatic tire provided with at least two circumferential main grooves provided along the tire circumferential direction within the tire contact width of the tread portion, and a land portion defined by the circumferential main grooves,
An inclined groove portion provided in the land portion on the outermost side in the tire width direction having a tire ground contact width end and extending while being inclined with respect to the tire circumferential direction while communicating with the circumferential main groove on the outermost side in the tire width direction; The intermediate groove portion that is bent and extended from the extended end of the inclined groove portion at an obtuse angle, and the extended end of the intermediate groove portion is folded and extended at an acute angle outward in the tire width direction, and the extended end is closed. A first sub-groove comprising a folded groove portion and disposed on the inner side in the tire width direction of the tire ground contact width end;
A second sub-groove that is open at the tire ground contact width end without communicating with the circumferential main groove and the first sub groove at the outermost land portion in the tire width direction having the tire contact width end; A pneumatic tire characterized by comprising: The tire width direction dimension from the tire width direction outer side opening edge to the tire ground contact width end in the circumferential main groove on the outermost side in the tire width direction is La, and the intermediate groove portion of the first sub groove and the outermost side in the tire width direction L1 is a tire width direction dimension between the circumferential direction main groove and L2 is a tire width direction dimension from the closed end of the folded groove portion of the first sub groove to the tire ground contact width end, and the second sub When the tire width direction dimension from the tire width direction inner end of the groove to the circumferential main groove on the outermost side in the tire width direction is L3,
0.1 ≦ L1 / La ≦ 0.4,
0.1 ≦ L2 / La ≦ 0.4,
And 0.3 ≦ L3 / La ≦ 0.7
The pneumatic tire according to claim 1, wherein the pneumatic tire is set in a range of   3. The pneumatic tire according to claim 1, wherein the inclined groove portion has an inclination angle θ with respect to a tire circumferential direction set in a range of 20 [degrees] ≦ θ ≦ 80 [degrees].   With respect to the tire contact area size Ta passing through the bending point between the inclined groove portion and the intermediate groove portion in the tire circumferential direction, the tire circumferential direction dimension T1 of the inclined groove portion and the intermediate groove portion is 0.2 ≦ T1 / Ta. The pneumatic tire according to any one of claims 1 to 3, wherein the pneumatic tire is set in a range of ≤0.8.   The tire circumferential direction dimension T2 of the folded groove part is set in a range of 0.3 ≦ T2 / T1 ≦ 0.8 with respect to the tire circumferential direction dimension T1 of the inclined groove part and the intermediate groove part. The pneumatic tire according to any one of claims 1 to 4.   The tire width direction dimension L4 from the tire width direction outer side opening edge of the circumferential main groove on the outermost side in the tire width direction to the tire equatorial plane with respect to the tire ground contact width Lw is 0.3 × (Lw / 2) ≦ L4 ≦ The pneumatic tire according to any one of claims 1 to 5, wherein the pneumatic tire is set in a range of 0.6 x (Lw / 2).   The groove width L5 of the circumferential main groove on the outermost side in the tire width direction is set in a range of 5 [mm] ≦ L5 ≦ 20 [mm], and the groove width L6 of the first sub groove is 1.5 [mm] ≦ The range of L6 ≦ 6 [mm] is set, and the groove width L7 of the second sub-groove is set to a range of 1.5 [mm] ≦ L7 ≦ 6 [mm]. The pneumatic tire according to any one of 1 to 6.

Images