阅读说明：本技术 充气轮胎 (Pneumatic tire ) 是由 岩田康孝 于 2019-05-23 设计创作，主要内容包括：本发明提供一种充气轮胎。本发明的课题在于,在扶壁部的表面上设置有沿轮胎周向排列的多个胎侧保护部的轮胎中,在确保耐切割性的同时提高乘坐舒适性。具有从扶壁部(5)的外表面(5S)突出并且沿轮胎周向排列的多个胎侧保护部(7)。在胎侧保护部(7)内配置有相对于轮胎周向倾斜地延伸的倾斜槽(10)。倾斜槽(10)包括在槽底(Sb)排列有多根第一肋(11)的带肋倾斜槽(12)。(The invention provides a pneumatic tire. The present invention addresses the problem of improving ride comfort while ensuring cut resistance in a tire having a buttress portion surface provided with a plurality of sidewall protectors arranged in the circumferential direction of the tire. Has a plurality of sidewall protectors (7) protruding from the outer surface (5S) of the buttress portion (5) and arranged in the tire circumferential direction. An inclined groove (10) extending obliquely with respect to the tire circumferential direction is disposed in the side wall protection portion (7). The inclined groove (10) includes a ribbed inclined groove (12) in which a plurality of first ribs (11) are arranged at the bottom of the groove (Sb).)

1. A pneumatic tire comprising a pair of buttress portions extending from both ends of a tread portion in a tire axial direction toward an inner side in a tire radial direction,

at least one of the pair of buttress portions has a plurality of sidewall protectors protruding outward in the tire axial direction from the outer surface of the buttress portion and arranged in the tire circumferential direction,

an inclined groove extending obliquely with respect to the tire circumferential direction is disposed in the side wall protector,

the inclined groove includes a ribbed inclined groove in which a plurality of first ribs are arranged at the groove bottom.

2. The pneumatic tire of claim 1,

the angle theta 1 of the ribbed inclined groove relative to the tire circumferential direction is 20-40 degrees.

3. The pneumatic tire according to claim 1 or 2,

in the ribbed inclined groove, a protruding height of the first rib from the groove bottom is 0.5mm to 3.0mm, a rib width of the first rib in a direction perpendicular to a longitudinal direction is 0.5mm to 2.5mm, and an interval between the first ribs is 1.5mm to 5.5 mm.

4. The pneumatic tire according to any one of claims 1 to 3,

the first rib connects groove wall surfaces on both sides of the ribbed inclined groove.

5. The pneumatic tire according to any one of claims 1 to 4,

in a cross section of the ribbed inclined groove perpendicular to the length direction,

an angle β of groove wall surfaces on both sides of the ribbed inclined groove with respect to a normal line of an outer surface of the side wall protector is 20 ° to 60 °.

6. The pneumatic tire according to any one of claims 1 to 5,

the inclined groove has a first inclined groove and a second inclined groove whose inclination directions with respect to the tire circumferential direction are different, and at least the first inclined groove is formed as a ribbed inclined groove.

7. The pneumatic tire of claim 6,

the second inclined groove is not provided with a rib at the groove bottom.

8. The pneumatic tire according to claim 6 or 7,

the outer end of the first inclined groove in the tire radial direction intersects with the middle part of the second inclined groove in the length direction in a T shape.

9. The pneumatic tire according to any one of claims 1 to 8,

a plurality of second ribs connecting the side wall protectors adjacent in the tire circumferential direction are arranged in a row on the outer surface of the buttress portion, and the second ribs are inclined in the same direction as the first ribs with respect to the tire circumferential direction.

Technical Field

The present invention relates to a pneumatic tire having a plurality of sidewall protectors arranged in a tire circumferential direction on a surface of a buttress portion.

Background

In a pneumatic tire that is supposed to run off-road, a plurality of sidewall protectors are generally formed on the surface of a buttress portion so as to be aligned in the tire circumferential direction (see, for example, patent document 1). The side wall protection portion can prevent cutting to the side surface of the tire due to collision of sharp stones and the like with the side surface of the tire during off-road running. Further, when the vehicle travels in a muddy ground, the mud can be cut by the gap portion (concave portion) between the adjacent side wall protecting portions, and the traction performance in the muddy ground can be improved.

On the contrary, however, the sidewall protector increases the rubber thickness of the buttress portion. Therefore, the lateral rigidity (particularly, longitudinal rigidity) of the tire increases, and there is a problem that the riding comfort is lowered.

Therefore, the present inventors have proposed forming an inclined groove extending obliquely with respect to the tire circumferential direction in the side wall protector. The inclined groove deforms in a direction of decreasing the groove width in response to a load in the vertical direction, and therefore, the riding comfort can be improved. This effect is more remarkable as the angle of the inclined groove with respect to the tire circumferential direction is smaller. However, it was found that as the angle becomes smaller, stones are likely to contact and damage the groove bottom of the inclined groove during traveling, and the stones become new cutting starting points.

Therefore, in order to ensure cut resistance and improve riding comfort, it is important to suppress the occurrence of cuts at the groove bottom of the inclined groove.

Patent document 1: japanese patent laid-open publication No. 2016-55820

Disclosure of Invention

The present invention addresses the problem of providing a pneumatic tire in which a plurality of sidewall protectors are provided on the surface of a buttress portion in the circumferential direction of the tire, and in which cut resistance is ensured and riding comfort is improved.

The present invention is a pneumatic tire including a pair of buttress portions extending inward in a tire radial direction from both ends of a tread portion in a tire axial direction, wherein at least one of the pair of buttress portions has a plurality of sidewall protection portions protruding outward from an outer surface of the buttress portion in the tire axial direction and arranged in a tire circumferential direction, an inclined groove extending obliquely with respect to the tire circumferential direction is arranged in the sidewall protection portion, and the inclined groove includes a ribbed inclined groove in which a plurality of first ribs are arranged at a groove bottom.

In the pneumatic tire of the present invention, it is preferable that the angle θ 1 of the ribbed inclined groove with respect to the tire circumferential direction is 20 ° to 40 °.

In the pneumatic tire of the present invention, it is preferable that, in the ribbed inclined groove, a protruding height of the first rib from the groove bottom is 0.5mm to 3.0mm, a rib width of the first rib in a direction perpendicular to a longitudinal direction is 0.5mm to 2.5mm, and an interval between the first ribs is 1.5mm to 5.5 mm.

In the pneumatic tire according to the present invention, it is preferable that the first rib connects groove wall surfaces on both sides of the ribbed inclined groove.

In the pneumatic tire according to the present invention, it is preferable that, in a cross section perpendicular to the longitudinal direction of the ribbed inclined groove, an angle β of groove wall surfaces on both sides of the ribbed inclined groove with respect to a normal line of an outer surface of the side wall protector is 20 ° to 60 °.

In the pneumatic tire of the present invention, it is preferable that the inclined groove has a first inclined groove and a second inclined groove which are different in inclination direction with respect to the tire circumferential direction, and at least the first inclined groove is formed as a ribbed inclined groove.

In the pneumatic tire according to the present invention, it is preferable that the second inclined groove has no rib at the groove bottom.

In the pneumatic tire according to the present invention, it is preferable that the outer end of the first inclined groove in the tire radial direction and the intermediate portion of the second inclined groove in the longitudinal direction intersect in a T-shape.

In the pneumatic tire according to the present invention, it is preferable that a plurality of second ribs connecting the side wall protectors adjacent in the tire circumferential direction are arranged in line on the outer surface of the buttress portion, and the second ribs are inclined in the same direction as the first ribs with respect to the tire circumferential direction.

Effects of the invention

As described above, the present invention has the inclined groove extending obliquely with respect to the tire circumferential direction on the sidewall protector formed on the outer surface of the buttress portion. The inclined groove can be deformed in a direction of decreasing the groove width in response to a load in the vertical direction. Therefore, the vertical rigidity of the side wall protector can be reduced, and the riding comfort can be improved.

In addition, the inclined groove at least comprises a ribbed inclined groove. The groove bottom of the ribbed inclined groove is protected by a plurality of first ribs arranged in a row. Therefore, even when the inclination angle of the inclined groove is small, the occurrence of cutting at the groove bottom can be suppressed. That is, the side wall protector can achieve the following effects: the cutting resistance is ensured and the riding comfort is improved.

Drawings

Fig. 1 is a sectional view showing a pneumatic tire of one embodiment of the present invention.

Fig. 2 is a side view conceptually showing a buttress portion.

Fig. 3 is an enlarged side view of the side wall protector.

Fig. 4 is a side view showing a gap portion between adjacent side wall protectors.

Fig. 5 is a sectional view of the ribbed inclined groove in a direction perpendicular to the longitudinal direction of the ribbed inclined groove.

Fig. 6 is a sectional view of the first rib in a direction perpendicular to a longitudinal direction of the first rib.

Description of the reference symbols

1: a pneumatic tire; 2: a tread portion; 2 t: two ends; 5: a buttress portion; 5S: an outer surface; 7: a sidewall protector; 10: an inclined groove; 10A: a first inclined groove; 10B: a second inclined groove; 11: a first rib; 12: a ribbed inclined groove; 14: a second rib; bm: an intermediate portion; h1: a protrusion height; p1: spacing; sb: the bottom of the tank; sw: a groove wall surface; w1: and (4) rib width.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Fig. 1 is a tire meridian cross-sectional view of a right half portion including a tire axial center (not shown) in a standard state of a pneumatic tire 1 (hereinafter referred to as "tire 1") of the present embodiment. In the present embodiment, a tire for a four-wheel drive vehicle for all-weather use is shown as a preferable embodiment. However, the present invention can be applied to other types of tires 1 including a light truck tire and a heavy duty tire.

The "standard state" is an unloaded state in which the tire 1 is assembled to a standard rim (not shown) and is filled with a standard internal pressure. In the present specification, unless otherwise specified, the dimensions and the like of the respective portions of the tire 1 refer to values measured in this standard state.

The "standard Rim" is a Rim specified for each tire in a specification system including a specification under which the tire 1 is based, and is, for example, "standard Rim" in the case of JATMA, "Design Rim" in the case of TRA, or "Measuring Rim" in the case of ETRTO. The "standard internal PRESSURE" is an air PRESSURE determined for each TIRE in a specification system including the specification under which the TIRE 1 is based, and is "the highest air PRESSURE" in case of JATMA, the maximum value described in the table "TIRE LOAD list AT variation color INFLATION PRESSURE" in case of TRA, and the "INFLATION PRESSURE" in case of ETRTO.

A ring-shaped carcass 6 is disposed inside the tire 1 of the present embodiment, and the carcass 6 reaches a bead core 4C of a bead portion 4 from a tread portion 2 in contact with a road surface via a sidewall portion 3. The carcass 6 is formed of at least one (one in the present embodiment) carcass ply 6A, and the carcass ply 6A is formed by arranging carcass cords at an angle of, for example, 70 ° to 90 ° with respect to the tire circumferential direction. The carcass ply 6A has a main portion 6A spanning between the bead cores 4C, 4C and a pair of turn-up portions 6b connected to the main portion 6A and turned up around the bead core 4C.

The tire 1 of the present embodiment further includes a pair of buttress portions 5 extending inward in the tire radial direction from both ends 2t of the tread portion 2 in the tire axial direction. The buttress portion 5 is a region on the outer side in the tire radial direction of the sidewall portion 3, and is preferably a region on the outer side in the tire radial direction from the tire maximum width position Pm. Further, both ends 2t of the tread portion 2 are defined as the ground contact positions closest to the tire axial outer side when a standard load is applied to the tire 1 in a standard state and the tire contacts the ground at a camber angle of 0 degree. Hereinafter, in the present specification, both ends 2t of the tread portion 2 may be referred to as tread ends 2 t.

The "standard LOAD" is a LOAD determined for each TIRE in the specification, and is the maximum LOAD CAPACITY in case of JATMA, the maximum value described in the table "TIRE LOAD conditions AT variatus COLD environments in case of TRA, and the" LOAD CAPACITY "in case of ETRTO.

As shown in fig. 1 and 2, a plurality of sidewall protectors 7 protruding outward in the tire axial direction from the outer surface 5S of the buttress portion 5 are arranged in the tire circumferential direction on at least one buttress portion 5 of the pair of buttress portions 5.

The side wall protector 7 prevents a sharp stone or the like from colliding with the side surface of the tire and causing cutting during off-road running. Further, when the vehicle travels in a muddy ground, the mud can be cut by the gap 9 between the adjacent side wall protectors 7, and the traction performance in the muddy ground can be improved. Such a sidewall protector 7 is preferably provided to both the buttress portions 5.

As shown in fig. 3, an inclined groove 10 extending obliquely at an angle θ with respect to the tire circumferential direction is disposed in the side wall protector 7.

The groove depth D (shown in fig. 5) of the inclined groove 10 from the outer surface 7S of the side wall protector 7 is equal to or less than the projection height H0 (shown in fig. 1) of the side wall protector 7 from the outer surface 5S of the buttress portion 5.

In this example, the inclined groove 10 includes: a first inclined groove 10A extending from a radially inner edge Ei of the sidewall protector 7 so as to be inclined toward one side in the tire circumferential direction (the left side in fig. 3) as it goes toward the radially outer side; and a second inclined groove 10B extending obliquely to the other side in the tire circumferential direction (the right side in fig. 3). The inclined groove 10 may be inclined at a constant angle θ, or may be inclined while gradually decreasing or gradually increasing the angle θ.

Such an inclined groove 10 can be deformed in a direction of decreasing the groove width with respect to a load in the vertical direction. Therefore, the vertical rigidity of the side wall protector 7 can be reduced, and the riding comfort can be improved. This effect is more remarkable as the angle θ at which the inclined groove 10 is inclined is smaller. However, conversely, the following drawbacks are incurred: as the inclination angle θ becomes smaller, the stone easily comes into contact with the groove bottom Sb during running, causing cutting thereof.

Therefore, in the present invention, the inclined groove 10 includes the ribbed inclined groove 12, and the plurality of first ribs 11 are arranged in the groove bottom Sb in the ribbed inclined groove 12. In this example, the first inclined groove 10A is formed as a ribbed inclined groove 12.

The ribbed inclined groove 12 can protect the groove bottom Sb by the first rib 11 while exhibiting excellent riding comfort. Therefore, even when the angle θ at which the inclined groove 10 is inclined is small, the occurrence of cutting at the groove bottom Sb can be suppressed.

That is, with respect to the ribbed inclined groove 12, it is possible to improve riding comfort while suppressing a decrease in cut resistance in the tire 1 provided with the side wall protector 7. In order to effectively exhibit such capability, the angle θ 1 of the ribbed inclined groove 12 with respect to the tire circumferential direction is preferably in the range of 20 ° to 40 °. When the angle θ 1 exceeds 40 °, the ability to improve the riding comfort cannot be sufficiently exhibited. In addition, when the angle θ 1 is less than 20 °, the effect of suppressing the cutting tends to decrease. When the angle θ 1 changes, the average value of the angle θ 1 (the average of the maximum value and the minimum value) is preferably in the range of 20 ° to 40 °. In particular, the maximum value and the minimum value of the angle θ 1 are preferably in the range of 20 ° to 40 °, respectively.

As shown in fig. 5, the first rib 11 connects the groove wall surfaces Sw, Sw on both sides of the ribbed inclined groove 12. From the viewpoint of the effect of suppressing the cutting, the angle α (shown in fig. 3) of the first rib 11 with respect to the longitudinal direction of the ribbed inclined groove 12 is preferably in the range of 60 ° to 90 °.

As shown in fig. 6, in the ribbed inclined groove 12, the projection height H1 of the first rib 11 from the groove bottom Sb is preferably 0.5mm to 3.0 mm. In addition, the rib width W1 of the first ribs 11 in the direction perpendicular to the longitudinal direction of the first ribs 11 is preferably 0.5mm to 2.5mm, and the interval P1 between the first ribs 11 is preferably 1.5mm to 5.5 mm. In addition, the cross-sectional shape of the first rib 11 is preferably a trapezoidal shape or a rectangular shape from the viewpoint of cut resistance. The rib width W1 and the interval P1 are values measured at the upper end of the first rib 11.

When the projection height H1 is less than 0.5mm, the effect of suppressing cutting is insufficient, and conversely, when the projection height H1 exceeds 3.0mm, the rigidity becomes high, which is disadvantageous in terms of riding comfort. When the rib width W1 is less than 0.5mm, the effect of suppressing cutting is insufficient, and conversely, when the rib width W1 exceeds 2.5mm, the rigidity becomes high, which is disadvantageous in terms of riding comfort. In addition, when the interval P1 exceeds 5.5mm, the effect of suppressing cutting is insufficient, and when the interval P1 is less than 1.5mm, the rigidity becomes high, which is disadvantageous in terms of riding comfort.

As shown in fig. 5, the projection height H1 of the first rib 11 is preferably 50% or less of the groove depth D of the inclined groove 10. The groove depth D of the inclined groove 10 is in the range of 0.6 to 1.0 times the projection height H0 (shown in fig. 1) of the side wall protector 7 from the outer surface 5S of the buttress portion 5.

In a cross section perpendicular to the longitudinal direction of the ribbed inclined groove 12, the angle β of the groove wall surfaces Sw, Sw on both sides of the ribbed inclined groove 12 with respect to the normal to the outer surface 7S of the side wall protector 7 is preferably 20 ° to 60 °.

When the angle β is less than 20 °, the groove volume of the ribbed inclined groove 12 becomes large, and the probability of contact of stones with the groove bottom Sb increases, thus being disadvantageous in suppressing cutting. Conversely, when the angle β exceeds 60 °, the tank volume becomes small, and the rigidity becomes high, which is disadvantageous to the riding comfort. From such a viewpoint, the lower limit of the angle β is more preferably 30 ° or more, and the upper limit is more preferably 50 ° or less.

As shown in fig. 3, in this example, the inclined groove 10 includes a rib-free inclined groove 13 having no rib at the groove bottom Sb. In this example, the second inclined groove 10B is formed as a rib-less inclined groove 13.

The inclination angle θ 2 of the non-rib inclined groove 13 with respect to the tire circumferential direction is larger than the angle θ 1 of the ribbed inclined groove 12. Since θ 2 > θ 1, the chance of damage to the stone due to contact with the groove bottom Sb is reduced, ensuring cut resistance. When the angle θ 2 changes, the average value of the angle θ 2 (the average of the maximum value and the minimum value) is larger than the angle θ 1.

The directions of inclination of the first inclined groove 10A and the second inclined groove 10B with respect to the tire circumferential direction are different from each other. In this example, the tire radial direction outer end Aeo of the first inclined groove 10A intersects the longitudinal direction intermediate portion Bm of the second inclined groove 10B in a T-shape. The intermediate portion Bm is a range of a length that is 15% or more, preferably 20% or more, of the entire length of the second inclined groove 10B from the tire radial direction inner end Bei and the outer end Beo of the second inclined groove 10B, respectively.

By making the outer end Aeo of the first inclined groove 10A intersect with the second inclined groove 10B in a T-shape and interrupting it, it is possible to prevent further progress of cutting when cutting occurs in the first inclined groove 10A.

As shown in fig. 4, in this example, a plurality of second ribs 14 connecting the side wall protectors 7, 7 adjacent in the tire circumferential direction are arranged on the outer surface 5S of the buttress portion 5. In particular, the second rib 14 of this example connects the wall surfaces 7w, 7w of the side protector 7 facing each other in the tire circumferential direction. In fig. 2 and 3, the second rib 14 is omitted for clarity.

The second ribs 14 are inclined in the same direction as the first ribs 11 with respect to the tire circumferential direction. The second rib 14 can suppress the outer surface 5S from coming into contact with stones to cause cutting in the gap portion 9. For the same reason as the first ribs 11, the projecting height H2 (not shown) of the second ribs 14 from the outer surface 5S is preferably 0.5mm to 3.0mm, the upward rib width W2 (not shown) of the second ribs 14 perpendicular to the longitudinal direction of the second ribs 14 is preferably 0.5mm to 2.5mm, and the interval P2 between the second ribs 14 is preferably 1.5mm to 5.5 mm.

Particularly preferably, the second rib 14 and the first rib 11 are formed in parallel with each other at the same interval as the first rib (P1 — P2).

As shown in fig. 4, the tire radial distance L from the tire radial direction outer end Aeo of the ribbed inclined groove 12 to the tire radial direction outer edge Eo of the side protector 7 is preferably 40% or more, and more preferably 50% or more, of the tire radial direction width W7 of the side protector 7. In this way, by making the ribbed inclined groove 12 away from the outer edge Eo on the ground contact surface side, the probability of contact with stones is reduced, which is advantageous for cut resistance.

As shown in fig. 3, the side wall protector 7 of this example is provided with an auxiliary groove 16, and the auxiliary groove 16 extends from the second inclined groove 10B to the outer edge Eo of the side wall protector 7 in the tire radial direction. The auxiliary groove 16 increases the edge component in the tire radial direction, and contributes to improvement of traction performance in a muddy field. However, since the auxiliary groove 16 extends in the tire radial direction, it has little influence on the riding comfort and the cut resistance. The auxiliary groove 16 can be omitted. In addition, "extend in the tire radial direction" includes a case of being inclined by ± 10 ° or less with respect to the tire radial direction line.

In the tire 1, the first rib 11 may be provided in the second inclined groove 10B, and the second inclined groove 10B may be formed as a ribbed inclined groove 12. The inclined groove 10 may be constituted by only the first inclined groove 10A (the ribbed inclined groove 12).

While the above description has been made in detail with reference to the particularly preferred embodiments of the present invention, the present invention is not limited to the illustrated embodiments, and can be modified into various embodiments.