JP2022066780A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire which achieves improvement of steering stabilizing performance and inhibits uneven wear.SOLUTION: A pneumatic tire has first to third annular grooves extending from a buttress in a tire circumferential direction and formed in an annular shape. Groove bottoms of the three annular grooves are located at the inner side relative to a ground contact end when viewed in a tire width direction. The first annular groove is the closest to the ground contact end. The second annular groove is located away from the ground contact end farther than the first annular groove. The third annular groove is located away from the ground contact end farther than the second annular groove. An innermost end, which is located at the innermost side in the tire width direction of the first annular groove, is located at the outer side relative to innermost ends of the second annular groove and the third annular groove when viewed in the tire width direction. Positions of the innermost ends of the first to third annular grooves are different from each other in the tire width direction. When each annular groove is projected onto a ground surface in parallel to a tire radial direction, the ground surface has: a first area in which the three annular grooves are overlapped; a second area in which the two annular grooves are overlapped; and a third area in which only the one annular groove is projected. The first area, the second area, and the third area are arranged in a written order from the outer side to the inner side in the tire width direction.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to pneumatic tires.

It is known that pneumatic tires used for trucks and buses have a high contact pressure at the shoulder end, which is the end of the contact patch formed by the tread, and the shoulder end is easily worn.

Patent Document 1 discloses a tire in which two annular grooves are formed in a buttress on a tire side wall surface in order to reduce the contact pressure of the shoulder end portion and suppress uneven wear.

By the way, if the buttress is provided with two annular grooves, the contact pressure in the vicinity of the contact end can be reduced by the annular grooves, but it is required to further reduce the contact pressure to suppress uneven wear. Further, in Patent Document 1, the innermost end of the annular groove closest to the ground contact end on the innermost side in the tire width direction is located on the innermost side in the tire width direction than the innermost end of the other annular grooves, and is susceptible to unevenness on the road surface. In addition, the deformation of the annular groove becomes large during running, and the wandering (wobble) that occurs when overcoming a rut becomes large, which may reduce the steering stability performance.

Japanese Unexamined Patent Publication No. 2019-99077

The present disclosure provides pneumatic tires that improve steering stability performance and suppress uneven wear.

The pneumatic tire of the present disclosure includes a ground contact surface and a tire side wall surface arranged outside the tire width direction with respect to the ground contact end outside the tire width direction on the ground contact surface, and the tire side wall surface is the ground contact end. The pneumatic tire comprises at least three annular grooves extending from the buttless in the tire circumferential direction and formed in an annular shape, including a buttless that is a region from the tire to the maximum width portion of the tire, and the at least three annular grooves. The bottoms of the grooves are located inside the tire width direction from the ground contact end, and the at least three annular grooves are from the first annular groove closest to the ground contact end and from the ground contact end rather than the first annular groove. The innermost end of the first annular groove, which includes a second annular groove separated from the second annular groove and a third annular groove farther from the ground contact end than the second annular groove, is the innermost end of the first annular groove in the tire width direction. The second annular groove and the third annular groove are located on the outer side in the tire width direction from the innermost innermost end in the tire width direction, and the first annular groove, the second annular groove and the third annular groove are respectively. When the positions of the innermost ends in the tire width direction are different from each other and each annular groove is projected onto the ground plane in parallel with the tire radial direction, the ground surface is the first region where the three annular grooves overlap. A second region in which the two annular grooves overlap and a third region in which only one annular groove is projected, and the first region from the outside in the tire width direction to the inside in the tire width direction. , The second region and the third region are arranged in this order.

The tire meridian sectional view which shows the main part of the pneumatic tire of 1st Embodiment. The side view of the pneumatic tire of 1st Embodiment. FIG. 3 is an enlarged cross-sectional view of a tire meridian showing a main part of FIG. FIG. 3 is a cross-sectional view taken along the tire meridian showing a modified example of the first embodiment. FIG. 3 is a cross-sectional view taken along the tire meridian showing a modified example of the first embodiment. The tire meridian sectional view showing the main part of the pneumatic tire of the 2nd Embodiment in an enlarged manner. A tire meridian sectional view showing an enlarged main part of a pneumatic tire according to a third embodiment. A tire meridian sectional view showing an enlarged main part of a pneumatic tire according to a fourth embodiment.

[First Embodiment]
Hereinafter, the pneumatic tire of the first embodiment of the present disclosure will be described with reference to the drawings. In the figure, "CD" means the tire circumferential direction, "WD" means the tire width direction, and "RD" means the tire radial direction. Each figure shows the shape of a new tire.

As shown in FIGS. 1 and 2, the pneumatic tire has a pair of beads (not shown), a sidewall 2 extending from each bead to the tire radial outer RD1, and a tire radial outer RD1 end of the sidewall 2. It is equipped with a tread 3 that connects each other. An annular bead core (not shown) made of a convergent body such as a steel wire coated with rubber and a bead filler made of hard rubber (not shown) are arranged on the bead. The bead is attached to the bead seat of the rim (not shown), and if the air pressure is a predetermined pressure (for example, the air pressure determined by JATTA), the bead is properly fitted to the rim flange by the tire internal pressure, and the tire is fitted to the rim. Ru.

The tire also comprises a toroid-shaped carcass 4 that extends from the tread 3 through the sidewall 2 to the bead. The carcass 4 is provided between a pair of beads, and the end portions thereof are locked in a wound state via a bead core. An inner liner rubber 5 for holding air pressure is arranged on the inner peripheral side of the carcass 4.

On the outer circumference of the carcass 4 in the tread 3, a plurality of belt plies 6a, 6b, 6c, 6d for reinforcing the carcass 4 (four in the present embodiment) and a tread rubber 30 are directed from the inside to the outside. It is provided in order. On the surface of the tread 3, a plurality of main grooves 31 extending along the tire circumferential direction CD and ribs 32 partitioned by the main grooves 31 and continuous with the tire circumferential direction CD are formed. In the present embodiment, since the tire is a rib tire, a block divided in the tire circumferential direction CD is not formed. In the present embodiment, two main grooves 31 are formed on one side of the tire, and a total of four main grooves 31 are provided, but the present invention is not limited thereto. For example, the total number may be three or five or more.

The four belt plies 6a, 6b, 6c, and 6d each include a plurality of steel cords arranged in parallel in a bamboo blind shape, and are formed by coating them with rubber. Of the four belt plies 6a, 6b, 6c, 6d, the cords of the second and third belt plies 6b, 6c from the carcass 4 toward the outer circumference are inclined in opposite directions with respect to the tire axis. Crossing. The second and third belt plies 6b and 6c are so-called main belts and sandwich the tread rubber 30.

As shown in FIG. 1, the tread 3 forms a ground plane 33. A tire side wall surface 7 formed of sidewall rubber is located on the outer WD1 in the tire width direction further than the ground contact end LE of the outer WD1 in the tire width direction on the contact patch 33. The tire side wall surface 7 includes a buttress 70 in the region from the ground contact end LE to the tire maximum width portion Wh. As in the present embodiment, the ground contact end LE corresponds to the ridge line between the ground contact surface 33 and the tire side wall surface 7 in the heavy load tire.

The contact patch 33 means a surface that is rim-assembled on a regular rim, the tire is placed vertically on a flat road surface with a regular internal pressure, and is in contact with the road surface when a regular load is applied. A regular rim is a rim defined for each tire in the standard system including the standard on which the tire is based. If it is JATMA, it will be a standard rim, TRA, or if it is ETRTO, it will be "Measuring Rim".

The regular internal pressure is the air pressure defined for each tire in the standard system including the standard on which the tire is based. Maximum air pressure for JATTA, maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and "INFRATION PRESSURE" for ETRTO, but 180 kPa if the tires are for passenger cars. However, in the case of a tire described as Extra Load or Reinforced, the value is 220 kPa.

The normal load is the load defined for each tire in the standard system including the standard on which the tire is based. If it is JATMA, it is the maximum load capacity, if it is TRA, it is the maximum value shown in the above table, and if it is ETRTO, it is "LOAD CAPACITY". And.

FIG. 3 is an enlarged view of a main part of FIG. As shown in FIGS. 1 to 3, the buttress 70 is formed with, for example, at least three annular grooves 9. At least three annular grooves 9 extend in the tire circumferential direction CD to form an annular shape and extend from the tire side wall surface 7 toward the inner WD2 in the tire width direction. The term "circular ring" does not mean only an uninterrupted ring in the tire circumferential direction, but also includes an intermittent ring that is partially interrupted. As shown in FIGS. 1 and 3, at least three annular grooves 9 have a first annular groove 9a closest to the ground contact surface 33 and a second annular groove 9b farther from the ground end LE than the first annular groove 9a. And a third annular groove 9c that is farther from the grounding end LE than the second annular groove 9b. The second annular groove 9b is located on the inner RD2 in the tire radial direction with respect to the first annular groove 9a. The third annular groove 9c is located on the inner RD2 in the tire radial direction with respect to the second annular groove 9b.

By the way, if the thickness of the groove between the two annular grooves is the same or thicker from the inside in the tire width direction to the outside in the tire width direction, the buttress becomes an annular groove when it comes into contact with the curb. Cracks are likely to occur and the groove portion is likely to be torn, and the durability of the buttress against the curb is reduced (first problem).

In order to cope with the first problem, the annular groove 9 is configured as in the first embodiment shown in FIG. At least three annular grooves 9 (first annular groove 9a, second annular groove 9b, and third annular groove 9c) have a groove bottom 90 and a groove wall surface 91 connecting the groove bottom 90 and the tire side wall surface 7, respectively. , Have. Each annular groove 9 has a first straight groove wall surface 91a as a groove wall surface 91 of the tire radial outer RD1 and a second straight groove wall surface 91b as a groove wall surface 91 of the tire radial inner RD2. The first straight groove wall surface 91a and the second straight groove wall surface 91b are straight in the tire meridian cross section. The first groove portion 71 between the second straight groove wall surface 91b of the first annular groove 9a and the first straight groove wall surface 91a of the second annular groove 9b faces from the inner WD2 in the tire width direction to the outer WD1 in the tire width direction. It is preferable that the tire is formed in a tapered shape. As a result, at least a trapezoidal cross-section portion is present in the first groove portion 71, and the rigidity of the buttress 70 can be increased.
Further, as shown in FIG. 3, the angle α1 of the first linear groove wall surface 91a of the first annular groove 9a with respect to the tire side wall surface 7 and the angle of the second annular groove 9b with respect to the tire side wall surface 7 of the first straight groove wall surface 91a. It is preferable that α1 <α2 with respect to α2 and the angle α3 with respect to the tire side wall surface 7 of the first straight groove wall surface 91a of the third annular groove 9c. This is because the first groove portion 71 between the first annular groove 9a and the second annular groove 9b is tapered.

Further, the second groove portion 72 between the second straight groove wall surface 91b of the second annular groove 9b and the first straight groove wall surface 91a of the third annular groove 9c is from the inner WD2 in the tire width direction to the outer WD1 in the tire width direction. It is preferable that the tire is formed in a tapered shape toward. As a result, at least a trapezoidal cross-section portion is present in the second groove portion 72, and the rigidity of the buttress 70 can be increased.
Further, as shown in FIG. 3, it is preferable that α1 <α2 <α3. The first groove portion 71 between the first annular groove 9a and the second annular groove 9b is tapered, and the second groove portion 72 between the second annular groove 9b and the third annular groove 9c is tapered. Because it becomes. In the example of FIG. 3, α1> 90 degrees, α2> 90 degrees, and α3> 90 degrees.

By the way, if the buttress is provided with two annular grooves, the contact pressure in the vicinity of the contact end can be reduced by the annular grooves, but it is required to further reduce the contact pressure to suppress uneven wear. Further, in Patent Document 1, the innermost end of the annular groove closest to the ground contact end on the innermost side in the tire width direction is located on the innermost side in the tire width direction than the innermost end of the other annular grooves, and the groove is longer and the road surface. It is susceptible to unevenness, the deformation of the annular groove becomes large during running, the wandering (wobble) that occurs when overcoming a rut becomes large, and the steering stability performance may deteriorate (second problem).

In order to cope with the second problem, the annular groove 9 is configured as in the first embodiment shown in FIGS. 1 and 3. As shown in FIG. 1, the innermost end 90a of the innermost tire width direction WD2 of the first annular groove 9a is from the innermost end 90a of the innermost tire width direction WD2 of the second annular groove 9b and the third annular groove 9c. Is also preferably located outside in the tire width direction. As a result, it is possible to secure the rigidity of the first annular groove, which is more susceptible to the reaction of the unevenness of the road surface as it is closer to the ground contact surface, and suppress the deformation. Further, the first annular groove 9a, the second annular groove 9b, and the third annular groove 9c have different positions in the tire width direction of the innermost end 90a of the innermost WD2 in the tire width direction. Further, as shown in FIG. 3, when each annular groove 9 is projected onto the contact patch 33 in parallel with the tire radial direction RD, the contact patch 33 has a first region Ar1, a second region Ar2, and a third. It has a region Ar3 and. In the first region Ar1, three annular grooves (9a, 9b, 9c) are projected and overlap each other. In the second region Ar2, two annular grooves 9 (9b, 9c) are projected and overlap each other. In the third region Ar3, only one annular groove 9 (9c) is projected. From the outer WD1 in the tire width direction to the inner WD2 in the tire width direction, the first region Ar1, the second region Ar2, and the third region Ar3 are arranged in this order. The shape of the annular groove 9 may be curved or linear as shown in FIG. 3 as long as it corresponds to the second problem.
The dimension L1 of the tire width direction WD of the first annular groove 9a is smaller than the dimensions L2 and L3 of the tire width direction WD of the second annular groove 9b and the third annular groove 9c, and the first annular groove 9a and the second annular groove 9a. It is more preferable that the annular groove 9b and the third annular groove 9c dimensions (L1, L2, L3) are different from each other.

The ground contact pressure tends to increase sharply from the inner WD2 in the tire width direction toward the ground contact end LE in the vicinity of the ground contact end LE like an exponential function. On the other hand, according to the above configuration, the ground pressure can be gradually lowered according to the distribution and magnitude of the ground pressure. If the dimensions of the tire width direction WD of each of the first region Ar1, the second region Ar2, and the third region Ar3 are at least 3 mm, the effect of reducing the contact pressure can be accurately exhibited.

Further, in order to appropriately correspond to the distribution and magnitude of the contact pressure, the dimension of the tire width direction WD of the first region Ar1 is equal to or larger than the dimension of the tire width direction WD of the second region Ar2, and the second region Ar2 It is preferable that the relationship that the dimension of the WD in the tire width direction of the third region Ar3 is equal to or larger than the dimension of the WD in the tire width direction of the third region Ar3 is established. Although not particularly limited, it is preferable that Ar1 ≧ Ar2 ≧ Ar3 ≧ 3 mm. As a result, it is possible to appropriately reduce the contact pressure that suddenly increases from the inside in the tire width direction toward the contact end. Of course, it is not limited to this magnitude relationship and may be changed.

As shown in FIG. 1, the innermost end 90a of the innermost tire width direction WD2 of the second annular groove 9b is outside the innermost end 90a of the innermost tire width direction WD2 of the third annular groove 9c in the tire width direction. It is preferable to be located. This is because the second annular groove 9b is more susceptible to the unevenness of the road surface than the third annular groove 9c, so that the rigidity of the second annular groove 9b can be ensured depending on the position of the innermost end 90a.
If the dimension L2 of the tire width direction WD of the second annular groove 9b is smaller than the dimension L3 of the tire width direction WD of the third annular groove 9c, it is preferable for further improving durability.

The maximum groove width of the first annular groove 9a, the second annular groove 9b, and the third annular groove 9c (the groove width between the first straight groove wall surface 91a parallel to each other and the second straight groove wall surface 91b) is 2 mm or more and It is preferably 5 mm or less. If the maximum groove width of the annular groove 9 is less than 2 mm, the effect of reducing the ground contact pressure near the ground contact end LE (shoulder) is difficult to be exhibited. Further, if the maximum groove width of the annular groove 9 is larger than 5 mm, the rigidity in the vicinity of the ground contact end LE (shoulder) becomes small, the deformation of the tire becomes large, and the steering stability performance is reduced. When the maximum groove width of the annular groove 9 is 2 mm or more and 5 mm or less, it is possible to appropriately obtain the effect of reducing the contact pressure at the shoulder end while ensuring the steering stability performance.

When the annular groove 9 is arranged in or near the tire maximum width portion Wh, the tire is greatly deformed, so that the annular groove 9 is likely to be cracked. Therefore, as shown in FIG. 1, the first annular groove 9a, the second annular groove 9b, and the third annular groove 9c are intermediate between the tire outer diameter φ1 and the tire maximum width portion Wh diameter φ2 in the tire meridian cross section. It is preferable that the tire is arranged on the outer side RD1 in the tire radial direction rather than the diameter φ3. This is because cracks can be suppressed. The above diameter is determined in a no-load state in which the tire is mounted on a regular rim and a regular internal pressure is applied. The tire maximum width portion Wh is a portion where the tire is mounted on the regular rim and the dimension of the WD in the tire width direction is the largest in a no-load state to which the regular internal pressure is applied. The specifications (dimensions, angles, etc.) of the annular groove in the present specification are determined in a no-load state in which a tire is mounted on a regular rim and a regular internal pressure is applied.

In order to maintain the effect of the annular groove 9 from the initial stage of tire wear to the final stage of wear, at least three annular grooves 9 are inside the tire radial direction from the top surface of the TWI (Tread Wear Indicator) formed in the main groove 31. It is preferably in RD2.

As shown in FIG. 3, the distance between the groove bottom 90 of the first annular groove 9a and the second annular groove 9b is shorter than the distance between the groove bottom 90 of the second annular groove 9b and the third annular groove 9c. May be good. When the groove bottom 90 of the second annular groove 9b and the third annular groove 9c is cracked, if the distance between the second annular groove 9b and the groove bottom 90 of the third annular groove 9c is short, the crack inside the tire will occur. Since it becomes large, it is preferable to satisfy the above distance relationship because it improves durability.

Further, as shown in FIG. 3, the groove bottom 90 of the second annular groove 9b and the groove bottom 90 of the third annular groove 9c are the second belt plies located on the outermost WD1 in the tire width direction among the plurality of belt plies. It is preferable that the end of 6b and the position of the tire radial RD are deviated from each other. This is to improve durability.

<Modified example of the first embodiment>
(1-1) The embodiment shown in FIG. 3 is α1 <α2 <α3, but is not limited to this if α1 <α2. For example, as shown in FIG. 4, α1 <α3 <α2 may be satisfied. If the first groove portion 71 between the second straight groove wall surface 91b of the first annular groove 9a and the first straight groove wall surface 91a of the second annular groove 9b is tapered, the second of the second annular groove 9b. The second groove portion 72 between the straight groove wall surface 91b and the first straight groove wall surface 91a of the third annular groove 9c may be tapered.

(1-2) When the first problem is not dealt with, the second straight groove wall surface 91b and the first straight groove wall surface 91a may be parallel to each other, and may be parallel to the second straight groove wall surface 91b of the first annular groove 9a. The first groove portion 71 between the second annular groove 9b and the first straight groove wall surface 91a may be formed in a tapered shape from the inner WD2 in the tire width direction toward the outer WD1 in the tire width direction. The second groove portion 72 between the second straight groove wall surface 91b of the two annular grooves 9b and the first straight groove wall surface 91a of the third annular groove 9c is directed from the inner WD2 in the tire width direction to the outer WD1 in the tire width direction. It may be formed in a thick tip.

(1-3) The positions of the innermost ends 90a of each of the first annular groove 9a, the second annular groove 9b, and the third annular groove 9c are not limited to the embodiments shown in FIGS. 1 and 3. For example, as shown in FIG. 5, the innermost end 90a of the innermost tire width direction WD2 of the second annular groove 9b is in the tire width direction with respect to the innermost innermost end 90a of the innermost tire width direction WD2 of the third annular groove 9c. Located on the inner WD2, the innermost end 90a of the innermost tire width direction WD2 of the first annular groove 9a is located on the outermost WD1 in the tire width direction than the innermost inner end 90a of the innermost tire width direction WD2 of the third annular groove 9c. It may be located. Also with this configuration, the ground pressure of the ground surface 33 can be gradually reduced.

(1-4) The groove bottom 90 of the annular groove 9 in the first embodiment is a straight line in the tire meridian cross section, but the shape of the groove bottom 90 is not limited to the straight line. For example, the groove bottom may be a partial arc. The diameter of the partial arc may be the same as the groove width. Further, the diameter of the partial arc may be made larger than the groove width to form a so-called flask bottom shape. This is because the concentration of strain can be reduced.

[Second Embodiment]
The pneumatic tire of the second embodiment will be described. The same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

By the way, when the curb comes into contact with the buttress, the curb may come into contact with the groove wall surface constituting the annular groove of the buttress and damage the groove wall surface, which may impair the durability (third problem).

In order to cope with the third problem, the shape of the annular groove 9 is made as in the second embodiment. The second embodiment shown in FIG. 6 is an embodiment in which the shape of the annular groove 9 of the first embodiment shown in FIG. 3 is changed. As shown in FIG. 6, the width W1 of the opening of each annular groove 9 (first annular groove 9a, second annular groove 9b, third annular groove 9c) is wider than at least a part of the width W2 inside the groove. narrow. The groove width W1 of the opening of the annular groove 9 means the narrowest width of the opening portion. The width W2 of at least a part of the inside of the groove may be the width of the part inside the groove rather than the narrowest opening. The shape of the groove does not matter as long as the width of the opening of the groove is narrower than the width of at least a part of the inside of the groove. Further, in order to cope with the third problem, three annular grooves 9 are not required, and the number of annular grooves 9 may be at least one.

In the second embodiment shown in FIG. 6, the annular groove 9 has a groove bottom 90 and a groove wall surface 91 connecting the groove bottom 90 and the tire side wall surface 7. The groove wall surface 91 of the tire radial outer RD1 has a first straight groove wall surface 91a. The groove wall surface 91 of the inner RD2 in the tire radial direction has a second straight groove wall surface 91b and a protruding wall 91c. The protruding wall 91c is provided between the second straight groove wall surface 91b and the tire side wall surface 7, and the opening is narrower than the inside of the groove. In the present embodiment, the protruding wall 91c is a curve having a single radius of curvature connected to the second straight groove wall surface 91b without a bending point. The "curve connected to the straight groove wall surface without bending point" may mean that the tangent line of the curve and the straight groove wall surface are parallel at the connection point connecting the straight groove wall surface and the curved surface. Further, the "curve connected to the straight groove wall surface without bending point" may mean that it is differentiable at the connection point connecting the straight groove wall surface and the curved surface. As a result, a bending point is formed between the second straight groove wall surface 91b and the protruding wall 91c, and stress is avoided from concentrating on the bending point. Of course, as long as the bending point may be formed, the protruding wall 91c is not limited to a curved line and may include a straight line.

In the example shown in FIG. 6, for all of the annular grooves 9 (first annular groove 9a, second annular groove 9b, third annular groove 9c), the first straight groove wall surface 91a and the second linear groove wall surface 91b are mutual to each other. It is parallel, and the angles α1, α2, α3 between the first straight groove wall surface 91a and the tire side wall surface 7 are larger than 90 degrees. Therefore, the first straight groove wall surface 91a and the tire side wall surface 7 directly intersect, and the angle of the intersecting rubber corners becomes an obtuse angle (greater than 90 degrees). On the other hand, the angle of the rubber corner where the second straight groove wall surface 91b and the tire side wall surface 7 intersect is an acute angle (less than 90 degrees), and the protruding wall 91c is formed between the second straight groove wall surface 91b and the tire side wall surface 7. A protruding wall 91c is provided to connect the second straight groove wall surface 91b and the tire side wall surface 7. As a result, when the rubber angle portion between the linear groove wall surfaces (91a, 91b) parallel to each other of the annular groove 9 and the tire side wall surface 7 is 90 degrees or less, the protruding wall 91c is provided. The protruding wall 91c can be softened by receiving an impact from the outside. Further, as compared with the case where the protruding wall is formed at the obtuse-angled rubber corner portion, the protruding wall 91c is more likely to be formed, and the damage prevention effect can be improved.

The second embodiment shown in FIG. 6 also corresponds to the first problem, and if the rubber between the first straight groove wall surface 91a and the second straight groove wall surface 91b is tapered, the groove wall surface 91 is formed. The same applies to the case where not only the straight groove wall surface (91b) but also the protruding wall 91c is included.

<Modified example of the second embodiment>
(2-1) The groove shape of the annular groove 9 may be any shape as long as it corresponds to the third problem. For example, the first straight groove wall surface 91a and the second straight groove wall surface 91b are not parallel to each other, and the groove width between the first straight groove wall surface 91a and the second straight groove wall surface 91b gradually increases from the groove bottom 90 toward the opening. It may be reduced to.

(2-2) In the example shown in FIG. 6, the first straight groove wall surface 91a and the second straight groove wall surface 91b are parallel to each other, but the present invention is not limited to this. Further, the second straight groove wall surface 91b and the protruding wall 91c are connected without bending points, but the present invention is not limited to this. Further, in FIG. 6, the protruding wall 91c is one curve having a single radius of curvature, but the present invention is not limited to this. Although not particularly limited, for example, the protruding wall 91c may be formed by continuously connecting one or more curves having a single radius of curvature without bending points, or may be formed by one or more straight lines. It may be formed by combining curves or straight lines without bending points.

[Third Embodiment]
The pneumatic tire of the third embodiment will be described. The same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. In the third embodiment, the directions (α1, α2, α3) of the annular groove 9 of the first embodiment are changed. As shown in FIG. 7, α1 <α2 <α3. α1 <90 degrees, α2> 90 degrees, and α3> 90 degrees. Other than that, it is the same as the embodiment shown in FIG.

[Fourth Embodiment]
The pneumatic tire of the fourth embodiment will be described. The same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. The fourth embodiment is an embodiment in which the shape of the annular groove 9 of the third embodiment is changed. As shown in FIG. 8, the width W1 of the opening of each annular groove 9 (first annular groove 9a, second annular groove 9b, third annular groove 9c) is wider than at least a part of the width W2 inside the groove. narrow. The first straight groove wall surface 91a and the second straight groove wall surface 91b are parallel to each other for all of the annular grooves 9 (first annular groove 9a, second annular groove 9b, third annular groove 9c). The angle α1 between the first straight groove wall surface 91a of the first annular groove 9a and the tire side wall surface 7 is smaller than 90 degrees. The angle α2 between the first straight groove wall surface 91a of the second annular groove 9b and the tire side wall surface 7 is larger than 90 degrees. The angle α3 between the first straight groove wall surface 91a of the third annular groove 9c and the tire side wall surface 7 is larger than 90 degrees. The annular groove 9 (first annular groove 9a, second annular groove 9b, third annular groove 9c) has a groove bottom 90 and a groove wall surface 91 connecting the groove bottom 90 and the tire side wall surface 7.

Regarding the first annular groove 9a, the angle α1 between the first straight groove wall surface 91a of the first annular groove 9a and the tire side wall surface 7 is smaller than 90 degrees, and the first straight groove wall surface 91a of the first annular groove 9a and the tire side. A protruding wall 91c connecting the two is provided between the wall surface 7 and the second straight groove wall surface 91b of the first annular groove 9a and the tire side wall surface 7 directly intersect, and the angle of the intersecting rubber corners is set. It becomes an obtuse angle (greater than 90 degrees).

With respect to the second annular groove 9b, the angle α2 between the first straight groove wall surface 91a of the second annular groove 9b and the tire side wall surface 7 is larger than 90 degrees. The first straight groove wall surface 91a of the second annular groove 9b and the tire side wall surface 7 directly intersect, and the angle α2 of the intersecting rubber corner portion becomes an obtuse angle. A protruding wall 91c connecting the second straight groove wall surface 91b of the second annular groove 9b and the tire side wall surface 7 is provided.

With respect to the third annular groove 9c, the angle α3 between the first straight groove wall surface 91a of the third annular groove 9c and the tire side wall surface 7 is larger than 90 degrees. The first straight groove wall surface 91a of the third annular groove 9c and the tire side wall surface 7 directly intersect with each other, and the angle α3 of the intersecting rubber corner portion becomes an obtuse angle. A protruding wall 91c connecting the second straight groove wall surface 91b of the third annular groove 9c and the tire side wall surface 7 is provided.

As described above, like the pneumatic tires of the embodiments shown in FIGS. 3 to 8, the ground contact surface 33 is arranged on the tire width direction outer side WD1 from the ground contact end LE of the tire width direction outer side WD1 on the ground contact surface 33. The tire side wall surface 7 includes a buttless 70 which is a region from the ground contact end LE to the tire maximum width portion Wh, and the pneumatic tire extends from the buttless 70 in the tire circumferential direction CD. It has at least three annular grooves 9 formed in an annular shape, and the groove bottom 90 of the at least three annular grooves 9 is located on the inner WD2 in the tire width direction with respect to the ground contact end LE, respectively, and the at least three annular grooves 9 are located. The first annular groove 9a closest to the ground contact end LE, the second annular groove 9b farther from the ground contact end LE than the first annular groove 9a, and the second annular groove 9b farther from the ground contact end LE than the second annular groove 9b. The first annular groove 9a, the second annular groove 9b, and the third annular groove 9c include the three annular grooves 9c, and the first annular groove 9a, the first linear groove wall surface 91a of the tire radial outer RD1 and the tire radial inner RD2, respectively. The first straight groove wall surface 91a and the second straight groove wall surface 91b are straight in the tire meridional cross section, and the pneumatic tire is the second straight line of the first annular groove 9a. A first groove portion 71 is provided between the groove wall surface 91b and the first straight groove wall surface 91a of the second annular groove 9b, and the first groove portion 71 faces from the inner WD2 in the tire width direction to the outer WD1 in the tire width direction. It may be formed in a tapered shape.

In this way, the first groove portion 71 between the second straight groove wall surface 91b of the first annular groove 9a and the first straight groove wall surface 91a of the second annular groove 9b is tapered in the tire width direction. Rigidity can be increased and the durability of the buttress against contact with the curb is improved as compared with the configuration in which the thickness of the first groove portion 71 is the same or the tip is thickened from the inner WD2 to the outer WD1 in the tire width direction. It becomes possible.

Although not particularly limited, as in the embodiments shown in FIGS. 3 and 5 to 8, there is a first position between the second straight groove wall surface 91b of the second annular groove 9b and the first straight groove wall surface 91a of the third annular groove 9c. The two grooved portions 72 may be provided, and the second grooved portion 72 may be formed in a tapered shape from the inner WD2 in the tire width direction toward the outer WD1 in the tire width direction. According to this configuration, the rigidity of the buttress can be further increased, and the durability of the buttress against contact with the curb can be improved.

Although not particularly limited, as in the embodiments shown in FIGS. 3 and 5 to 8, the angle of the first linear groove wall surface 91a of the first annular groove 9a with respect to the tire side wall surface 7 is α1 and the second annular groove 9b. The angle of the first straight groove wall surface 91a with respect to the tire side wall surface 7 is α2, and the angle of the first straight groove wall surface 91a of the third annular groove 9c with respect to the tire side wall surface 7 is α3, and α1 <α2 <α3. May be. If this angular relationship is satisfied, the first groove portion 71 between the first annular groove 9a and the second annular groove 9b is tapered to form a trapezoidal portion in the cross section, and further, the second annular groove 9b and the third annular groove 9b and the third annular groove are formed. Since the second groove portion 72 between the grooves 9c is tapered to form a trapezoidal portion in the cross section, the rigidity of the buttress can be accurately secured.

Although not particularly limited, the tires are arranged on the ground contact surface 33 and the outer WD1 in the tire width direction with respect to the ground contact end LE of the outer WD1 in the tire width direction on the ground contact surface 33, as in the pneumatic tires of the embodiments shown in FIGS. 3 to 8. The tire side wall surface 7 includes a buttless 70 which is a region from the ground contact end LE to the tire maximum width portion Wh, and the pneumatic tire extends from the buttless 70 in the tire circumferential direction CD. It has at least three annular grooves 9 formed in an annular shape, and the groove bottom 90 of the at least three annular grooves 9 is located on the inner WD2 in the tire width direction with respect to the ground contact end LE, respectively, and the at least three annular grooves 9 are located. The first annular groove 9a closest to the ground contact end LE, the second annular groove 9b farther from the ground contact end LE than the first annular groove 9a, and the second annular groove 9b farther from the ground contact end LE than the second annular groove 9b. The innermost end 90a of the innermost tire width direction WD2 of the first annular groove 9a including the three annular grooves 9c is the innermost end of the innermost tire width direction WD2 of the second annular groove 9b and the third annular groove 9c. Located on the outer WD1 in the tire width direction with respect to 90a, the first annular groove 9a, the second annular groove 9b and the third annular groove 9c have different positions of the innermost end 90a in the tire width direction WD, and each annular groove 9a, second annular groove 9b and third annular groove 9c have different positions in the tire width direction WD. When the groove 9 is projected onto the ground contact surface 33 in parallel with the tire radial direction, the ground contact surface 33 has a first region Ar1 in which the three annular grooves 9 overlap and a second region Ar2 in which the two annular grooves 9 overlap. It has a third region Ar3 on which only one annular groove 9 is projected, and the first region Ar1, the second region Ar2, and the third region Ar3 are in this order from the outer WD1 in the tire width direction to the inner WD2 in the tire width direction. It may be arranged.

According to this configuration, the innermost end 90a of the innermost WD2 in the tire width direction of the first annular groove 9a is the outermost WD1 in the tire width direction with respect to the innermost inner end 90a of each of the second annular groove 9b and the third annular groove 9c. Since it is located at, the groove length is the shortest, and the closer it is to the ground contact surface 33, the more easily the reaction of the unevenness of the road surface is secured. It is possible to improve the steering stability performance by suppressing. Nevertheless, since the first region Ar1, the second region Ar2, and the third region Ar3 are formed on the grounding surface 33, the pressure on the grounding surface, particularly the pressure near the grounding end LE, can be reduced in at least three steps, resulting in uneven wear. Can be suppressed.

Although not particularly limited, as in the embodiments shown in FIGS. 3 to 4 and 6 to 8, the innermost end 90a of the innermost WD2 in the tire width direction of the second annular groove 9b is the innermost tire width of the third annular groove 9c. It may be located on the outer WD1 in the tire width direction with respect to the innermost end 90a of the inner WD2 in the direction. According to this configuration, it is possible to secure the rigidity of the second annular groove 9b, which is more susceptible to the reaction of the unevenness of the road surface than the third annular groove 9c.

Although not particularly limited, as in the embodiment shown in FIGS. 3 to 8, the dimension of the tire width direction WD of the first region Ar1 is equal to or larger than the dimension of the tire width direction WD of the second region Ar2, and the second region Ar2 The dimension of the WD in the tire width direction may be equal to or larger than the dimension in the tire width direction of the third region Ar3. According to this configuration, the contact pressure that suddenly increases from the inside in the tire width direction toward the contact end can be appropriately reduced, and the contact pressure distribution can be optimized.

Although not particularly limited, as in the embodiment shown in FIGS. 6 and 8, the pneumatic tire is arranged on the ground contact surface 33 and the tire width direction outer side WD1 with respect to the ground contact end LE of the tire width direction outer side WD1 on the ground contact surface 33. The tire side wall surface 7 includes a buttless 70 which is a region from the ground contact end LE to the tire maximum width portion Wh, and the pneumatic tire extends from the buttless 70 to the tire circumferential CD. Moreover, it may have at least one annular groove 9 formed in an annular shape, and the width W1 of the opening of the at least one annular groove 9 may be narrower than the width W2 of at least a part inside the groove than the opening. ..

According to this configuration, the width W1 of the opening of the annular groove 9 is narrower than the width W2 of at least a part of the inside of the groove, so that when the buttress 70 comes into contact with the curb, the curb damages the groove wall surface 91 inside the groove. This can be suppressed or prevented, and the durability against curbs can be improved.

Although not particularly limited, as in the embodiment shown in FIGS. 6 and 8, at least one annular groove 9 has a first straight groove wall surface 91a of the tire radial outer RD1 and a second straight groove of the tire radial inner RD2. The wall surface 91b, the first straight groove wall surface 91a and the second straight groove wall surface 91b are straight in the tire meridional cross section and are parallel to each other, and the angle between the first straight groove wall surface 91a and the tire side wall surface 7 Is 90 degrees or less, and a protruding wall 91c is provided between the first straight groove wall surface 91a and the tire side wall surface 7 so that the opening is narrower than the inside of the groove. It may be assumed that the angles of the intersecting rubber corners are blunt.

Although not particularly limited, as in the embodiment shown in FIGS. 6 and 8, at least one annular groove 9 has a first straight groove wall surface 91a of the tire radial outer RD1 and a second straight groove of the tire radial inner RD2. The wall surface 91b, the first straight groove wall surface 91a and the second straight groove wall surface 91b are straight in the tire meridional cross section and are parallel to each other, and the angle between the first straight groove wall surface 91a and the tire side wall surface 7 Is larger than 90 degrees, and a protruding wall 91c having a narrower opening than the inside of the groove may be provided between the second straight groove wall surface 91b and the tire side wall surface 7.

As described above, when the rubber angle portion between the linear groove wall surface parallel to each other of the annular groove 9 and the tire side wall surface 7 is 90 degrees or less, the protruding wall 91c is provided, so that the protruding wall 91c is provided from the outside. It is possible to soften the impact by receiving the impact of. Further, as compared with the case where the protruding wall 91c is formed at the obtuse-angled rubber corner portion, the protruding wall 91c is more likely to be formed at the acute-angled rubber corner portion, and the damage prevention effect can be improved.

Although not particularly limited, as in the embodiment shown in FIGS. 6 and 8, the protruding wall 91c has a curved line connected to the straight groove wall surface (first straight groove wall surface 91a or second straight groove wall surface 91b) without bending points. May include. According to this configuration, since it is avoided to form a bending point between the straight groove wall surface and the protruding wall 91c, the stress acting on the groove wall surface can be dispersed and the generation of cracks can be suppressed.

Although the embodiments of the present disclosure have been described above with reference to the drawings, it should be considered that the specific configuration is not limited to these embodiments. The scope of the present disclosure is set forth not only by the description of the embodiment described above but also by the scope of claims, and further includes all modifications within the meaning and scope equivalent to the scope of claims.

It is possible to adopt the structure adopted in each of the above embodiments in any other embodiment. The specific configuration of each part is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present disclosure.

It is possible to adopt the structure adopted in each of the above embodiments in any other embodiment.

33 ... ground plane, 7 ... tire side wall surface, 70 ... buttless, 71 ... first grooved portion, 72 ... second grooved portion, 9 ... annular groove, 9a ... first annular groove, 9b ... second annular groove, 9c ... 3rd annular groove, 90 ... groove bottom, 90a ... innermost end, 91a ... first straight groove wall surface, 91b ... second straight groove wall surface, 91c ... protruding wall, Ar1 ... first region, Ar2 ... second region , Ar3 ... 3rd region, CD ... tire circumferential direction, LE ... ground contact end, WD1 ... tire width direction outside, WD2 ... tire width direction inside.

Claims (10)

It is a pneumatic tire and includes a ground contact surface and a tire side wall surface arranged on the outer side in the tire width direction with respect to the ground contact end on the outer side in the tire width direction on the ground contact surface.
The tire side wall surface includes a buttress that is a region from the ground contact end to the tire maximum width portion.
The pneumatic tire has at least three annular grooves extending from the buttress in the tire circumferential direction and formed in an annular shape.
The bottoms of the at least three annular grooves are located inside the tire width direction with respect to the ground contact end, respectively.
The at least three annular grooves are a first annular groove closest to the grounded end, a second annular groove farther from the grounded end than the first annular groove, and the grounded end from the second annular groove. Including a third annular groove away from
The innermost end of the first annular groove on the innermost side in the tire width direction is located outside the innermost end of the second annular groove and the third annular groove on the innermost side in the tire width direction, and is located on the outer side in the tire width direction. The innermost annular groove, the second annular groove, and the third annular groove have different positions in the tire width direction from each other, and each annular groove is projected onto the ground plane in parallel with the tire radial direction. In this case, the ground plane has a first region where the three annular grooves overlap, a second region where the two annular grooves overlap, and a third region where only one annular groove is projected. A pneumatic tire arranged in the order of the first region, the second region, and the third region from the outside in the tire width direction to the inside in the tire width direction. The air-filled portion according to claim 1, wherein the innermost end of the second annular groove on the innermost side in the tire width direction is located outside the innermost end of the third annular groove on the innermost side in the tire width direction in the tire width direction. tire. The dimension in the tire width direction of the first region is equal to or greater than the dimension in the tire width direction of the second region, and the dimension in the tire width direction of the second region is equal to or greater than the dimension in the tire width direction of the third region. The pneumatic tire according to claim 1 or 2. The first annular groove, the second annular groove, and the third annular groove each have a first straight groove wall surface on the outer side in the tire radial direction and a second straight groove wall surface on the inner side in the tire radial direction. The first straight groove wall surface and the second straight groove wall surface are straight lines in the tire meridional cross section.
The pneumatic tire includes a first groove portion between the second straight groove wall surface of the first annular groove and the first straight groove wall surface of the second annular groove.
The pneumatic tire according to any one of claims 1 to 3, wherein the first groove portion is formed in a tapered shape from the inside in the tire width direction to the outside in the tire width direction. A second groove gap portion is provided between the second straight groove wall surface of the second annular groove and the first straight groove wall surface of the third annular groove.
The pneumatic tire according to claim 4, wherein the second groove portion is formed in a tapered shape from the inside in the tire width direction to the outside in the tire width direction. The angle of the first linear groove wall surface of the first annular groove with respect to the tire side wall surface is α1, and the angle of the first linear groove wall surface of the second annular groove with respect to the tire side wall surface is α2. 3. The pneumatic tire according to claim 4 or 5, wherein the angle of the first straight groove wall surface of the annular groove with respect to the tire side wall surface is α3, and α1 <α2 <α3. The first annular groove, the second annular groove, and the third annular groove, respectively, have any of claims 1 to 6, wherein the width of the opening is narrower than the width of at least a part of the inside of the groove than the opening. Pneumatic tires listed in Crab. The first annular groove, the second annular groove, and the third annular groove each have a first straight groove wall surface on the outer side in the tire radial direction and a second straight groove wall surface on the inner side in the tire radial direction.
The first straight groove wall surface and the second straight groove wall surface are straight in the tire meridian cross section and are parallel to each other.
The angle between the first straight groove wall surface and the tire side wall surface is 90 degrees or less, and a protruding wall is provided between the first straight groove wall surface and the tire side wall surface to make the opening narrower than the inside of the groove. The pneumatic tire according to claim 7, wherein the angle of the rubber corner portion where the second straight groove wall surface and the tire side wall surface intersect is an obtuse angle. The first annular groove, the second annular groove, and the third annular groove each have a first straight groove wall surface on the outer side in the tire radial direction and a second straight groove wall surface on the inner side in the tire radial direction.
The first straight groove wall surface and the second straight groove wall surface are straight in the tire meridian cross section and are parallel to each other.
The angle between the first straight groove wall surface and the tire side wall surface is larger than 90 degrees, and a protruding wall is provided between the second straight groove wall surface and the tire side wall surface to make the opening narrower than the inside of the groove. The pneumatic tire according to claim 7. The pneumatic tire according to claim 8 or 9, wherein the protruding wall includes a curved line connected to the straight groove wall surface without bending points.

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