JP6019097B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire capable of improving turning performance on icy and snowy roads.

  2. Description of the Related Art Conventionally, there is known a pneumatic tire including a shoulder land portion that is divided between a shoulder main groove and a tread end by providing a shoulder main groove extending continuously in the tire circumferential direction in the tread portion.

  For example, Patent Document 1 proposes a pneumatic tire having a shoulder lug that has a shoulder lug extending from the tread end inward in the tire axial direction and a shoulder sipe extending from the shoulder main groove outward in the tire axial direction. The shoulder lug groove and the shoulder sipe are inclined in the same direction with respect to the tire circumferential direction.

JP 2013-139193 A

  However, since the shoulder lug groove and the shoulder sipe are inclined in the same direction in the pneumatic tire, the direction in which the shoulder lug groove and the shoulder sipe extend in either the right turn or the left turn May coincide with a direction perpendicular to the direction. In such a case, the edge effect in the direction perpendicular to the tire traveling direction cannot be sufficiently obtained by the shoulder lug groove and the shoulder sipe, so that the turning performance on an icy and snowy road may be deteriorated.

  The present invention has been devised in view of the above circumstances, and it is a main object of the present invention to provide a pneumatic tire capable of improving turning performance on an icy snow road in either a right turn or a left turn. It is said.

  The present invention is a pneumatic tire having a tread portion having a tread pattern in which a direction of mounting on a vehicle is specified, and the tread portion is located outside the vehicle when the tire is mounted on the vehicle. Including a tread end, an outer shoulder main groove extending continuously in the tire circumferential direction on the outermost tread end side, and an outer shoulder land portion partitioned between the outer shoulder main groove and the outer tread end, The outer shoulder land portion includes a plurality of outer shoulder inclined grooves extending outward in the tire axial direction from the outer shoulder main groove and spaced apart from each other, and an outer shoulder sipes extending inward in the tire axial direction from the outer tread end. The outer shoulder inclined groove is curved so that an angle α with respect to the tire circumferential direction gradually decreases toward the outer side in the tire axial direction. The outer shoulder sipe is characterized by communicating with the outer shoulder inclined groove inclined to the outer shoulder inclined groove opposite direction.

  In the pneumatic tire according to the present invention, each outer end in the tire axial direction of the outer shoulder inclined groove is provided close to another outer shoulder inclined groove adjacent in the tire circumferential direction, and the outer shoulder sipe is It is desirable to include a plurality of first outer shoulder sipes communicating with the other outer shoulder inclined grooves through the vicinity of the outer ends of the outer shoulder inclined grooves.

  In the pneumatic tire according to the present invention, it is preferable that the outer shoulder sipe includes a second outer shoulder sipe provided between the first outer shoulder sipes adjacent in the tire circumferential direction.

  In the pneumatic tire according to the present invention, it is preferable that a width of the outer shoulder inclined groove is 2.0 to 3.0 mm, and a width of the outer shoulder sipe is less than 2.0 mm.

  In the pneumatic tire according to the present invention, the tread portion includes an outer center main groove extending continuously between the tire equator and the outer shoulder main groove in the tire circumferential direction, the outer shoulder main groove, and the center main. A plurality of outer middle sipes that connect the outer shoulder main groove and the outer center main groove, the outer middle sipes being provided with an outer middle land portion that is divided between the outer middle land portion and the outer middle main portion. It is desirable that the outer shoulder inclined groove is inclined in the same direction and is curved so that an angle β with respect to the tire circumferential direction gradually decreases toward the outer center main groove.

  In the pneumatic tire according to the present invention, the outer middle sipe has a depth at a central portion in a longitudinal direction larger than depths at both end portions communicating with the outer shoulder main groove and the outer center main groove. desirable.

  In the pneumatic tire according to the present invention, it is preferable that a width of the outer middle sipe is less than 2.0 mm.

  The pneumatic tire of the present invention includes a plurality of outer shoulder inclined grooves extending outward from the outer shoulder main groove in the tire axial direction and spaced apart from each other on the outer shoulder land portion, and an outer shoulder extending from the outer tread end to the inner side in the tire axial direction. A sipe is provided. Since the outer shoulder inclined groove is curved so that the angle α with respect to the tire circumferential direction gradually decreases toward the outer side in the tire axial direction, the outer shoulder inclined groove is perpendicular to the tire traveling direction by the outer shoulder inclined groove according to the slip angle during turning. Edge effect in direction is obtained. Thereby, the turning performance on an icy and snowy road improves.

  On the other hand, since the outer shoulder sipe is inclined in the opposite direction to the outer shoulder inclined groove, the direction perpendicular to the tire traveling direction is determined by either the outer shoulder inclined groove or the outer shoulder sipe in either the right turn or the left turn. Edge effect can be obtained. Therefore, the turning performance on an icy and snowy road can be further enhanced.

It is an expanded view of the tread part of one embodiment of the pneumatic tire of the present invention. It is an AA line sectional view of the tread part of Drawing 1. FIG. 2 is an enlarged development view of a shoulder land portion of the tread portion of FIG. 1. FIG. 2 is an enlarged development view of a middle land portion of the tread portion of FIG. 1. It is an expanded view of the tread part of another embodiment of the pneumatic tire of the present invention. It is an expanded view of the tread part of another embodiment of the pneumatic tire of the present invention. It is an expanded view of the tread part of another embodiment of the pneumatic tire of the present invention. It is an expanded view of the tread part of another embodiment of the pneumatic tire of the present invention. It is an expanded view of the tread part of another embodiment of the pneumatic tire of the present invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a development view of a tread portion 2 of a pneumatic tire (not shown) of the present embodiment. FIG. 2 is a cross-sectional view of the tread portion 2 of FIG. As shown in FIGS. 1 and 2, the pneumatic tire of the present embodiment is suitably used as a tire for passenger cars, for example, and includes an asymmetric tread pattern in which the mounting direction of the vehicle is specified. The direction of mounting on the vehicle is displayed, for example, in characters on a sidewall (not shown).

  The tread portion 2 has an outer tread end Teo located outside the vehicle when the tire is mounted on the vehicle, and an inner tread end Tei located inside the vehicle.

  Here, the above-mentioned “tread ends” Teo and Tei are applied to a flat tire with a normal camber angle of 0 degrees by applying a normal load to an unloaded normal tire that is assembled with a normal rim and filled with a normal internal pressure. As the ground contact position on the outermost side in the tire axial direction, two locations on the vehicle outer side and the inner side are determined. The distance in the tire axial direction between the outer tread end Teo and the inner tread end Tei is determined as the tread width TW. Further, the dimensions and the like of each part of the tire are values in the normal state unless otherwise specified.

  The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, “Standard Rim” for JATMA and “Design Rim” for TRA. "If ETRTO," Measuring Rim ".

  The “regular internal pressure” is the air pressure determined by each standard for each tire in the standard system including the standard on which the tire is based, and is “maximum air pressure” for JATMA and table for “TRA”. The maximum value described in TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES is "INFLATION PRESSURE" for ETRTO, but 180 kPa for tires for passenger cars.

  Furthermore, the “regular load” is a load determined by each standard for each tire in the standard system including the standard on which the tire is based. “Maximum load capacity” for JATMA, “Table for TRA” The maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” is “LOAD CAPACITY” in the case of ETRTO.

  The tread portion 2 of the tire according to the present embodiment includes a pair of center main grooves 3A and 3B extending continuously in the tire circumferential direction on both sides of the tire equator C, and the tire axially outer sides of the center main grooves 3A and 3B. A pair of shoulder main grooves 4A, 4B extending continuously in the direction are provided. The outer center main groove 3A is located on the vehicle outer side with respect to the tire equator C, and the inner center main groove 3B is located on the vehicle inner side with respect to the tire equator C. The outer shoulder main groove 4A is positioned on the outermost tread end Teo side, and the inner shoulder main groove 4B is positioned on the innermost tread end Tei side.

  Thereby, the tread portion 2 includes a center land portion 5 sandwiched between the outer center main groove 3A and the inner center main groove 3B, and an outer middle land portion 6A sandwiched between the outer center main groove 3A and the outer shoulder main groove 4A. The inner middle land portion 6B sandwiched between the inner center main groove 3B and the inner shoulder main groove 4B, the outer shoulder land portion 7A sandwiched between the outer shoulder main groove 4A and the outer tread end Teo, and the inner shoulder main groove 4B. The inner shoulder land portion 7B is sandwiched between the inner tread end Tei.

  The center main grooves 3A and 3B and the shoulder main grooves 4A and 4B extend linearly in the tire circumferential direction. Such center main grooves 3A and 3B and shoulder main grooves 4A and 4B enhance drainage performance of the tread portion 2 and exhibit excellent turning performance on icy and snowy roads due to edge components in the tire circumferential direction.

  The width W1 of the outer center main groove 3A is preferably 4 to 7% of the tread width TW, for example. When the width W1 is less than 4% of the tread width TW, the drainage performance of the tread portion 2 may be deteriorated. Moreover, there is a possibility that the snow column shear force in the snowy road is reduced and the turning performance is affected. On the other hand, when the width W1 exceeds 7% of the tread width TW, the rigidity of the tread portion 2 is lowered and the steering stability performance may be lowered.

  Similarly, the width W2 of the outer shoulder main groove 4A is preferably 4 to 6% of the tread width TW, for example. Further, from the viewpoint of wet performance and steering stability performance, the width W1 of the outer center main groove 3A is preferably larger than the width W2 of the outer shoulder main groove 4A.

  The depth D1 of the outer center main groove 3A and the outer shoulder main groove 4A is preferably 6 to 10 mm, for example. When the depth D1 is less than 6 mm, the drainage performance of the tread portion 2 may be deteriorated. Moreover, there is a possibility that the snow column shear force on the snow road is lowered and the turning performance is affected. On the other hand, when the depth D1 exceeds 10 mm, the rigidity of the tread portion 2 is lowered, and the steering stability performance may be lowered. The depths of the inner center main groove 3B and the inner shoulder main groove 4B are the same as described above.

  The ratio W5 / W3 of the width W5 of the outer shoulder land portion 7A and the width W3 of the center land portion 5 is, for example, preferably 2.57 or more, more preferably 2.68 or more, preferably 2.89 or less, More preferably, it is 2.84 or less. When the ratio W5 / W3 is less than 2.57, the rigidity of the outer shoulder land portion 7A is insufficient, and the turning performance on the dry road surface may be deteriorated. On the other hand, when the ratio W5 / W3 exceeds 2.89, the rigidity of the center land portion 5 is insufficient, and the response performance to the steering input on the dry road surface may be deteriorated. From the same viewpoint, the ratio between the width of the inner shoulder land portion 7B and the width W3 of the center land portion 5 is, for example, preferably 2.57 or more, more preferably 2.64 or more, preferably 2.89 or less. More preferably, it is 2.80 or less.

  The ratio W4 / W3 between the width W4 of the outer middle land portion 6A and the width W3 of the center land portion 5 is preferably, for example, 1.40 to 1.72. When the ratio W4 / W3 is less than 1.40, the rigidity of the outer middle land portion 6A is insufficient, and the turning performance on the dry road surface may be deteriorated. On the other hand, when the ratio W4 / W3 exceeds 1.72, the rigidity of the center land portion 5 is insufficient, and the response performance to the steering input on the dry road surface may be deteriorated. The relationship between the width of the inner middle land portion 6B and the width W3 of the center land portion 5 is the same as described above.

  FIG. 3 is an enlarged view of the outer shoulder land portion 7A. A plurality of outer shoulder inclined grooves 31 and a plurality of outer shoulder sipes 32 are provided in the outer shoulder land portion 7A.

  The outer shoulder inclined groove 31 extends outward in the tire axial direction from the outer shoulder main groove 4A. The outer shoulder inclined groove 31 provides a snow column shearing force on the snowy road, improving the turning performance. The outer shoulder inclined grooves 31 are provided apart from each other without communicating with each other. Such outer shoulder inclined grooves 31 ensure the rigidity of the outer shoulder land portion 7A and improve the turning performance on the dry road surface.

  The outer shoulder inclined groove 31 has an outer end 31e in the tire axial direction in the outer shoulder land portion 7A without communicating with the outer tread end Teo. Each outer end 31e of each outer shoulder inclined groove 31 is provided adjacent to another outer shoulder inclined groove 31 adjacent in the tire circumferential direction.

  The angle α of the outer shoulder inclined groove 31 with respect to the tire circumferential direction is gradually decreased toward the outer side in the tire axial direction. Thus, the outer shoulder inclined groove 31 is formed to be curved, and the angle α approaches zero near the outer end 31e of the outer shoulder inclined groove 31. Such an outer shoulder inclined groove 31 provides an edge effect in a direction perpendicular to the tire traveling direction in accordance with the slip angle during turning. Thereby, the turning performance on an icy and snowy road improves. Particularly in the present embodiment, the outer shoulder inclined groove 31 is formed substantially along the tire circumferential direction in the vicinity of the outer end 31e, so that the edge component in the tire axial direction is large. Therefore, a large edge effect is obtained in the tire axial direction, and high turning performance on an icy and snowy road is obtained.

  The width W31 of the outer shoulder inclined groove 31 is preferably 2.0 to 3.0 mm, for example. When the width W31 is less than 2.0 mm, the snow column shearing force in the snowy road is lowered, which may affect the turning performance. On the other hand, when the width W31 exceeds 3.0 mm, the rigidity of the outer shoulder land portion 7A is lowered, and the turning performance on the dry road surface may be lowered.

  The depth D31 (see FIG. 2) of the outer shoulder inclined groove 31 is preferably 64 to 72% of the depth D1 of the outer shoulder main groove 4A. When the depth D31 is less than 64% of the depth D1, the snow column shearing force in the snowy road is reduced, which may affect the turning performance. On the other hand, when the depth D31 exceeds 72% of the depth D1, the rigidity of the outer shoulder land portion 7A is lowered, and the turning performance on the dry road surface may be lowered.

  The outer shoulder sipe 32 extends inward in the tire axial direction from the outer tread end Teo. Such an outer shoulder sipe 32 suppresses a decrease in tire axial rigidity of the outer shoulder land portion 7A and suppresses a decrease in turning performance on a dry road surface.

  The outer shoulder sipe 32 is inclined in the opposite direction to the outer shoulder inclined groove 31 and communicates with the outer shoulder inclined groove 31. The angle of the outer side shoulder sipe 32 with respect to the tire circumferential direction gradually decreases gradually toward the inner side in the tire axial direction. Thereby, the outer side shoulder sipe 32 is curved and formed. Such an outer shoulder sipe 32 exhibits a greater edge effect than a straight sipe.

  Since the outer shoulder sipe 32 is inclined in the opposite direction to the outer shoulder inclined groove 31, it is perpendicular to the tire traveling direction by either the outer shoulder inclined groove 31 or the outer shoulder sipe 32 in either the right turn or the left turn. Edge effect in any direction can be obtained. Therefore, the turning performance on an icy and snowy road can be further enhanced. Such a pneumatic tire excellent in turning performance on icy and snowy roads is suitably used for a non-drive wheel to which a tire chain is not attached, for example, a rear wheel of a front wheel drive vehicle.

  The width W32 of the outer shoulder sipe 32 is desirably less than 2.0 mm. Such an outer shoulder sipe 32 is closed when a large longitudinal force is applied to the outer shoulder land portion 7A at the time of sudden deceleration or sudden acceleration, and the rigidity of the outer shoulder land portion 7A is increased, and the steering stability performance on the dry road surface is improved. Contribute to improvement.

  The outer shoulder sipe 32 includes a plurality of first outer shoulder sipes 33. Each first outer shoulder sipe 33 communicates with another outer shoulder inclined groove 31 through the vicinity of the outer end 31 e of the adjacent outer shoulder inclined groove 31. By such first outer shoulder sipes 33, the adjacent outer shoulder inclined grooves 31 do not communicate with each other via the first outer shoulder sipes 33, so that it is possible to suppress a decrease in rigidity of the outer shoulder land portion 7A. Thereby, the steering stability performance on the dry road surface is improved.

  The outer shoulder sipe 32 includes a plurality of second outer shoulder sipes 34. The second outer shoulder sipe 34 is provided between the first outer shoulder sipes 33 adjacent in the tire circumferential direction. Such a second outer shoulder sipe 34 optimizes the rigidity distribution of the outer shoulder land portion 7A to suppress uneven wear and the like.

  FIG. 4 is an enlarged view of the outer middle land portion 6A. A plurality of outer middle sipes 21 are provided in the outer middle land portion 6A. The outer middle sipe 21 connects the outer shoulder main groove 4A and the outer center main groove 3A. The outer middle sipe 21 is inclined in the same direction as the outer shoulder inclined groove 31. The outer end of the outer middle sipe 21 is provided with a shift of approximately ½ pitch in the tire circumferential direction with respect to the inner end of the outer shoulder inclined groove 31 with the outer shoulder main groove 4A interposed therebetween. By such an arrangement of the outer middle sipes 21, the rigidity distribution of the outer middle land portion 6A and the outer shoulder land portion 7A is made uniform, and uneven wear is suppressed.

  The angle β of the outer middle sipe 21 with respect to the tire circumferential direction gradually decreases toward the outer center main groove 3A, that is, toward the inner side in the tire axial direction. Thereby, the outer middle sipe 21 is formed to be curved. By such an outer middle sipe 21, an edge effect is obtained in a direction perpendicular to the tire traveling direction in accordance with the slip angle during turning. Thereby, the turning performance on an icy and snowy road improves.

  The width W21 of the outer middle sipe 21 is preferably less than 2.0 mm, for example. The outer middle sipe 21 is closed when a large longitudinal force is applied to the outer middle land portion 6A during sudden deceleration or sudden acceleration, thereby increasing the rigidity of the outer middle land portion 6A and contributing to improvement in steering stability performance.

  The depth D21 of the outer middle sipe 21 is desirably 67 to 75% of the depth D1 of the outer shoulder main groove 4A. When the depth D21 is less than 67% of the depth D1, the edge effect on the snowy road may not be sufficiently obtained. On the other hand, when the depth D21 exceeds 75% of the depth D1, the rigidity of the outer middle land portion 6A is lowered, and the turning performance on the dry road surface may be lowered.

The outer middle sipe 21 has a longitudinal center portion 21a, an end portion 21b communicating with the outer center main groove 3A, and an end portion 21c communicating with the outer shoulder main groove 4A.
The outer middle sipe 21 has a depth at the central portion 21a that is greater than the depth at both end portions 21b and 21c. Such an outer middle sipe 21 exhibits a larger edge effect at the central portion 21a until it approaches the end of wear. Further, uneven wear in the vicinity of both end portions 21b and 21c can be suppressed.

  Although the pneumatic tire of the present invention has been described in detail above, the present invention is not limited to the specific embodiment described above, and can be implemented with various modifications.

  5 to 9 show another embodiment of the pneumatic tire shown in FIG.

  The pneumatic tire shown in FIG. 5 is provided at a position where the outer middle sipes 21 are connected substantially continuously from the outer shoulder inclined groove 31 with the outer shoulder main groove 4A interposed therebetween, compared to the pneumatic tire of FIG. Yes. The drainage performance is enhanced by the outer middle sipes 21 and the outer shoulder inclined grooves 31.

  In the pneumatic tire shown in FIG. 6, the tire axial direction component of the outer shoulder inclined groove 31 is set smaller than that of the pneumatic tire in FIG. 5. Such outer shoulder inclined grooves 31 enhance turning performance and drainage performance on icy and snowy roads.

  In the pneumatic tire shown in FIG. 7, the pitch in the tire circumferential direction of the outer middle sipes 21 and the outer shoulder inclined grooves 31 is set to ½ with respect to the pneumatic tire of FIG. 5. Such outer middle sipes 21 and outer shoulder inclined grooves 31 enhance the turning performance and drainage performance on icy and snowy roads.

  In the pneumatic tire shown in FIG. 8, the tire axial direction component of the outer shoulder inclined groove 31 is set smaller than that of the pneumatic tire in FIG. 7. Further, the tire circumferential direction components of the outer middle sipes 21 and the outer shoulder inclined grooves 31 are set large. Such outer middle sipes 21 and outer shoulder inclined grooves 31 enhance the turning performance and drainage performance on icy and snowy roads.

  In the pneumatic tire shown in FIG. 9, the pitch in the tire circumferential direction of the outer middle sipes 21 and the outer shoulder inclined grooves 31 is set to ½ with respect to the pneumatic tire of FIG. 6. The outer middle sipe 21 and the outer shoulder inclined groove 31 improve the turning performance and the traction performance on an icy and snowy road with a good balance.

   A pneumatic tire of size 205 / 60R16 having the tread pattern of FIG. 1 was prototyped based on the specifications of Table 1 and tested on snowy and snowy road turning performance and steering stability performance. The test method is as follows.

<Icy snow road turning performance>
The test tires mounted on the rim 16x6.0J were mounted on all wheels of a 2000cc passenger car under the condition of an internal pressure of 240 kPa. It was evaluated by the driver's sensuality. A result is a score which sets Example 1 to 100, and shows that an ice-snow road turning performance is excellent, so that a numerical value is large.

<Steering stability>
The vehicle was brought to a dry asphalt road test course, and the characteristics regarding steering response and responsiveness were evaluated by the driver's sensation in a speed range of 80 to 120 km / h. A result is a grade which sets Example 1 to 100, and shows that steering stability performance is excellent, so that a numerical value is large.

  As is clear from Table 1, it was confirmed that the pneumatic tires of the examples had significantly improved ice / snow road turning performance as compared with the comparative examples.

2 Tread portion 3A Outer center main groove 4A Outer shoulder main groove 6A Outer middle land portion 7A Outer shoulder land portion 21 Outer middle sipe 31 Outer shoulder inclined groove 32 Outer shoulder sipe 33 First outer shoulder sipe 34 Second outer shoulder sipe

Claims (7)

A pneumatic tire having a tread portion having a tread pattern in which a direction of mounting on a vehicle is specified,
The tread portion has an outer tread end positioned on the vehicle outer side when the tire is mounted on the vehicle;
An outer shoulder main groove extending continuously in the tire circumferential direction on the outermost tread end side;
An outer shoulder land section divided between the outer shoulder main groove and the outer tread end;
In the outer shoulder land portion,
A plurality of outer shoulder inclined grooves extending outward from the outer shoulder main groove in the tire axial direction and spaced apart from each other;
An outer shoulder sipe extending inward in the tire axial direction from the outer tread end; and
The outer shoulder inclined groove is curved so that an angle α with respect to the tire circumferential direction gradually decreases toward the outer side in the tire axial direction,
The pneumatic tire is characterized in that the outer shoulder sipe is inclined in a direction opposite to the outer shoulder inclined groove and communicated with the outer shoulder inclined groove. Each outer end in the tire axial direction of the outer shoulder inclined groove is provided close to another outer shoulder inclined groove adjacent in the tire circumferential direction,
2. The pneumatic tire according to claim 1, wherein the outer shoulder sipe includes a plurality of first outer shoulder sipes communicating with the other outer shoulder inclined grooves through the vicinity of the outer ends of the outer shoulder inclined grooves.   The pneumatic tire according to claim 2, wherein the outer shoulder sipe includes a second outer shoulder sipe provided between the first outer shoulder sipes adjacent in the tire circumferential direction.   The pneumatic tire according to any one of claims 1 to 3, wherein a width of the outer shoulder inclined groove is 2.0 to 3.0 mm, and a width of the outer shoulder sipe is less than 2.0 mm. The tread portion includes an outer center main groove extending continuously in the tire circumferential direction between the tire equator and the outer shoulder main groove, and an outer middle section divided between the outer shoulder main groove and the center main groove. Including the land,
In the outer middle land portion,
A plurality of outer middle sipes that connect the outer shoulder main groove and the outer center main groove are provided,
5. The outer middle sipe is inclined in the same direction as the outer shoulder inclined groove, and is curved so that an angle β with respect to a tire circumferential direction gradually decreases toward the outer center main groove. The described pneumatic tire.   6. The pneumatic tire according to claim 5, wherein the outer middle sipe has a depth at a center portion in a longitudinal direction larger than depths at both ends communicating with the outer shoulder main groove and the outer center main groove.   The pneumatic tire according to claim 5 or 6, wherein a width of the outer middle sipe is less than 2.0 mm.

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