JP2023063646A - pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire which is excellent in resistance to external damage and durability of a side wall.SOLUTION: A raised part 7 provided in a buttress region 2B of a side wall 2 includes a maximum raised height position 7M arranged at the inner side in the tire radial direction of a mold divided position Ps. A carcass 4 has a first ply 41 laminated at the relatively inner side in the tire radial direction on a tread 3, and a second ply 42 laminated at the relatively outer side in the tire radial direction on the tread 3. One of a wind-up end 41e of the first ply and a wind-up end 42e of the second ply is arranged at a position overlapping the raised part 7 and the tire width direction and at the inner side in the tire radial direction of the maximum raised height position 7M, and the other thereof is arranged at the inner side in the tire radial direction of the inner end in the tire radial direction of the raised part 7.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a pneumatic tire having ridges in the sidewall buttress area.

BACKGROUND ART A pneumatic tire is known in which a raised portion is provided in a buttress region of a sidewall for the purpose of improving running performance on rough roads such as muddy ground and rocky terrain. With such a tire, a traction effect due to shear resistance can be obtained when traveling on rough roads, and thus rough road running performance is improved. Furthermore, since the effect (protection effect) of keeping trauma factors such as curbs and angular parts of the rock surface away from the outer surface of the sidewall is obtained, the trauma resistance of the sidewall (hereinafter simply referred to as "trauma resistance") ) will improve.

However, since the raised portion provided in the buttress region is accompanied by a local thickness change of the sidewall, it has a portion where strain tends to concentrate. Therefore, if the positional relationship with other portions of the sidewall where strain is likely to occur is not appropriate, there is a risk that cracks will occur due to the concentration of strain, resulting in reduced durability. For example, in the pneumatic tire disclosed in Patent Literature 1, the maximum height position of the raised portion substantially coincides with the mold splitting position, so there is a risk that the durability will be reduced due to strain concentration. it is conceivable that.

Japanese Patent Application Laid-Open No. 2021-95109

The present disclosure has been made in view of the above circumstances, and an object thereof is to provide a pneumatic tire having sidewalls with excellent trauma resistance and durability.

The pneumatic tire of the present disclosure is
a pair of beads;
a pair of sidewalls extending outward in the tire radial direction from each of the pair of bead portions;
a tread connected to the tire radial direction outer end of each of the pair of sidewalls;
a bead filler embedded in the bead;
a raised portion provided in the buttress region of at least one of the pair of sidewalls;
A carcass wound up from the inside to the outside in the tire width direction so as to sandwich the bead filler,
The raised portion includes a maximum raised height position arranged radially inward of the mold splitting position,
The carcass has a first ply laminated relatively inside in the tire radial direction in the tread and a second ply laminated relatively outside in the tire radial direction in the tread,
One of the rolled-up end of the first ply and the rolled-up end of the second ply is arranged at a position overlapping the raised portion in the tire width direction and radially inward of the maximum raised height position. ,
The other of the rolled-up end of the first ply and the rolled-up end of the second ply is arranged inside the tire radially inner end of the raised portion in the tire radial direction.

FIG. 1 is a meridional cross-sectional view of a tire schematically showing an example of a pneumatic tire of the present disclosure; FIG. 2 is a cross-sectional view showing an enlarged main part of the pneumatic tire in FIG. 1 ; Cross-sectional view showing the main part of the buttress region during vulcanization molding

An embodiment of a pneumatic tire of the present disclosure will be described with reference to the drawings.

The pneumatic tire T shown in FIGS. 1 and 2 is a pneumatic radial tire intended for running on bad roads including muddy ground and rocky ground. The pneumatic tire T includes a pair of bead portions 1, a pair of sidewalls 2 extending radially outward from each of the pair of bead portions 1, and a tread that continues to the tire radial direction outer ends of the pair of sidewalls 2. 3. Further, the pneumatic tire T includes a bead filler 1b embedded in the bead portion 1, a raised portion 7 provided in a buttress region 2B of at least one of the pair of sidewalls 2, and a tire width so as to sandwich the bead filler 1b. a carcass 4 rolled up from the inside to the outside of the direction.

Here, the tire radial direction is a direction along the diameter of the tire T and corresponds to the vertical direction in the drawing. 1 and 2, the upper side is the tire radial direction outer side, and the lower side is the tire radial direction inner side. The tire width direction is a direction parallel to the rotation axis of the tire T and corresponds to the left-right direction in the drawing. The side closer to the tire equatorial plane TE (the left side in FIG. 2) is the inner side in the tire width direction, and the side farther from the tire equatorial plane TE (the right side in FIG. 2) is the outer side in the tire width direction. The tire circumferential direction is the direction around the rotation axis of the tire T. As shown in FIG.

An annular bead core 1 a is embedded in the bead portion 1 . The bead core 1a is formed by coating a bundle of steel wires or the like with rubber. The bead filler 1b is arranged outside the bead core 1a in the tire radial direction. The bead filler 1b is made of rubber having a triangular cross-section and extending outward in the tire radial direction from the bead core 1a. A rim strip rubber 11 forming the outer surface of the bead portion 1 is provided outside the bead filler 1b in the tire width direction. A sidewall rubber 12 forming the outer surface of the sidewall 2 is provided outside the rim strip rubber 11 in the tire radial direction.

The carcass 4 has a toroidal shape between the pair of bead portions 1, and the ends thereof are rolled up (that is, turned up) so as to sandwich the bead core 1a and the bead filler 1b. In other words, the carcass 4 has a series of roll-up portions arranged on the outer side in the tire width direction of the bead core 1a and the bead filler 1b on the body portion extending from the tread 3 to the bead portion 1 via the sidewalls 2 . An inner liner 14 is provided on the inner peripheral side of the carcass 4 and has an excellent function of preventing gas permeation in order to maintain the air pressure.

The carcass 4 has a plurality of plies (carcass plies) laminated together. In this embodiment, the carcass 4 has a first ply 41 laminated relatively inside in the tire radial direction in the tread 3 and a second ply 42 laminated relatively outside in the tire radial direction in the tread 3. . Each of the first ply 41 and the second ply 42 is formed by coating a plurality of cords arranged in a direction substantially orthogonal to the tire circumferential direction with rubber. Metals such as steel, and organic fibers such as polyester, rayon, nylon, and aramid are preferably used as materials for the cord.

Embedded in the tread 3 are a belt layer 5 laminated on the outer side of the carcass 4 in the tire radial direction, and a belt reinforcing layer 6 laminated on the outer side of the belt layer 5 in the tire radial direction. The belt layer 5 has a plurality of plies (belt plies) laminated together. The belt ply is formed by coating a plurality of cords arranged in a direction inclined with respect to the tire circumferential direction with rubber. Steel is preferably used as the material of this cord. In this embodiment, the belt layer 5 is composed of two plies 51 and 52, and the cords are laminated between the plies so that the cords cross each other in opposite directions.

The belt reinforcing layer 6 has one or more plies (reinforcing plies). The reinforcing ply is formed by covering a cord extending substantially in the tire circumferential direction with rubber. The above-mentioned organic fibers are preferably used as the material of this cord. By covering the end portion of the belt layer 5 with the belt reinforcing layer 6, lifting of the belt ply during high-speed running can be suppressed, and high-speed durability can be improved. A tread rubber 13 forming the outer surface of the tread 3 is provided outside the belt reinforcing layer 6 in the tire radial direction. Although not shown, the tread rubber 13 is provided with various grooves such as circumferential grooves and lug grooves that form a tread pattern.

The pneumatic tire T of the present embodiment is not a so-called side support type run-flat tire, and the sidewall 2 thereof is not provided with a side reinforcing rubber layer having a crescent-shaped cross section. However, the tire T is not limited to this, and the tire T may be a side support type run-flat tire in which the sidewall 2 is provided with a side reinforcing rubber layer.

As already mentioned, the buttress region 2B of the sidewall 2 is provided with the raised portion 7 . The buttress region 2B is a region on the outer side in the tire radial direction of the sidewall 2, more specifically, a region on the outer side of the maximum tire width position 2M in the tire radial direction, and is a portion that does not contact the ground during normal running on a flat paved road. . Since the tire sinks due to the weight of the vehicle on a soft road such as a muddy ground or a sandbox, the buttress area 2B quasi-grounds and the traction effect due to the shear resistance of the protuberance 7 is obtained. The tire maximum width position 2M is the position where the profile line 2p of the sidewall 2 in the tire meridional section is the farthest from the tire equatorial plane TE in the tire width direction.

The raised portion 7 rises from the profile line 2p of the sidewall 2. As shown in FIG. The profile line 2p is the contour of the sidewall 2 excluding protrusions such as rim protectors. In FIGS. 1 and 2, part of the profile line 2p is indicated by broken lines. The profile line 2p is formed by a series of circular arcs smoothly connecting a plurality of circular arcs with different curvature radii. The profile line 2p may be formed by a single arc, may have a radius of curvature that varies continuously, or may partially include a straight line. A plurality of raised portions 7 are arranged on the sidewall 2 at intervals in the tire circumferential direction. The meridional section of the tire shown in FIGS.

The raised portion 7 extends along the tire radial direction. In the present embodiment, the length of the raised portion 7 in the tire radial direction is greater than the length of the raised portion 7 in the tire circumferential direction. An inclined surface 71 is formed at the tire radially outer end of the raised portion 7 so that the height of the raised portion gradually decreases outward in the tire radial direction. An inclined surface 72 is formed at the tire radially inner end of the raised portion 7 so that the height of the raised portion gradually decreases toward the tire radial direction inner side. The tire radially inner end of the raised portion 7 (the boundary between the profile line 2p and the inclined surface 72) is positioned radially outward of the tire maximum width position 2M. A tire meridional cross-section of the raised portion 7 includes a pair of inclined surfaces 71 and 72 rising from the profile line 2p and a top surface 73 connecting them. The top surface 73 has a step 73s that changes the raised height. The raised height is obtained as the height in the tire width direction with reference to the profile line 2p.

The buttress region 2B is provided with an annular rib 8 extending annularly along the tire circumferential direction across the raised portion 7 . The annular rib 8 , like the ridge 7 , rises from the profile line 2 p of the sidewall 2 . In the present embodiment, the annular rib 8 has a top portion that protrudes outward in the tire width direction from the top surface 73 of the raised portion 7 . However, it is not limited to this, and the annular rib 8 may be formed flush with the raised portion 7 . The raised height of the step 73 s of the top surface 73 is greater than the raised height of the annular rib 8 . The shapes of the raised portion 7 and the annular rib 8 are not particularly limited.

As shown in FIG. 3 , the top of the annular rib 8 is preferably formed at the mold splitting position Ps, which is the boundary between the tread mold 30 that molds the tread 3 and the side mold 20 that molds the sidewall 2 . The mold splitting position Ps may sometimes be identified from the parting line formed on the outer surface of the buttress region 2B. In the meridional section of the tire, the annular rib 8 forms a stratovolcanic shape in which the slope is gently curved and constricted. However, the shape is not limited to this, and other shapes such as a rectangular shape, a trapezoidal shape, or a triangular shape may be adopted.

The top of the annular rib 8 is set, for example, at a position where the distance Da shown in FIG. 1 is within the range of 20-40 mm. The distance Da is determined as the tire radial distance from the outermost radial position of the tire T to the top of the annular rib 8 . Moreover, the top of the annular rib 8 is set at a position where the distance Db shown in FIG. 1 is 75% or more of the half width HW of the tire section, for example. The distance Db is obtained as the distance in the tire width direction from the tire equatorial plane TE to the top of the annular rib 8 . The tire cross-sectional half width HW is determined as the tire width direction distance from the tire equatorial plane TE to the tire maximum width position 2M.

The raised portion 7 includes a maximum raised height position 7M located radially inward of the mold splitting position Ps. The maximum raised height position 7M is the outermost position in the tire radial direction in the portion where the raised portion 7 has the highest raised height (that is, the top surface 73 is the farthest from the profile line 2p in the tire width direction). In this embodiment, the maximum raised height position 7M is set at the outer end of the step 73 in the tire width direction. The raised height of the raised portion 7 gradually decreases inward in the tire radial direction from a maximum raised height position 7M. In this way, since the protrusion height is increased at the radially outer portion of the tire in the region between the step 73s and the inclined surface 72, which is likely to come into contact with traumatic factors, it contributes to the improvement of the trauma resistance. However, the shape is not limited to this, and for example, the shape may extend from the maximum raised height position 7</b>M to the inner side in the tire radial direction at a constant raised height and continue to the inclined surface 72 .

Of the rolled-up end 41e of the first ply 41 and the rolled-up end 42e of the second ply 42, the rolled-up end 41e, which is one of them, is arranged at a position overlapping the raised portion 7 in the tire width direction. That is, the roll-up end 41e is arranged within a projected area A7 of the raised portion 7 toward the inside in the tire width direction. Nevertheless, the roll-up end 41e is arranged radially inward of the maximum raised height position 7M. In addition, of the rolled-up end 41e of the first ply 41 and the rolled-up end 42e of the second ply 42, the rolled-up end 42e that is the other is arranged inside the tire radially inner end of the raised portion 7 in the tire radial direction. ing.

In the sidewall 2, the region outside the mold splitting position Ps in the tire radial direction tends to be bent more when a load is applied. Strain tends to concentrate relatively easily in the raised portion 7 at the maximum raised height position 7M. In addition, strain tends to concentrate on the member ends such as the winding ends 41e and 42e. In this tire T, the maximum protrusion height position 7M is arranged radially inward of the mold splitting position Ps, and the roll-up end 41e overlaps the protrusion 7 radially inward of the maximum protrusion height position 7M. A roll-up end 42e is arranged inside the raised portion 7 in the tire radial direction. As a result, locations where there is concern about strain concentration are distributed, and the sidewall 2 has excellent durability. Moreover, by arranging the roll-up end 41e at a position overlapping the protruding portion 7, the rigidity of the protruding portion 7 is increased, and the sidewall 2 is excellent in resistance to external damage.

From the viewpoint of ensuring a sufficient distance between the mold splitting position Ps and the maximum protrusion height position 7M, the tire radial distance Dd between the mold splitting position Ps and the maximum protrusion height position 7M is set to the maximum protrusion height position 7M. is preferably 50% or more, more preferably 70% or more, of the tire radial direction distance De between . Further, from the viewpoint of ensuring a sufficient distance between the raised portion 7 and the rolled-up end 42e, the tire radial distance Df between the tire radially inner end of the raised portion 7 and the rolled-up end 42e is less than the tire radial direction distance De. It is preferably 15% or more, more preferably 20% or more.

The rolled-up end 41e of the first ply 41 and the rolled-up end 42e of the second ply 42 are each separated from the bead filler 1b in the tire radial direction via a distance of 80% or more of the tire radial length L1b of the bead filler 1b. It is preferable that it is arranged on the outer side in the tire radial direction of the outer end. Therefore, the tire radial distance D41e from the tire radial outer end of the bead filler 1b to the roll-up end 41e and the tire radial distance D42e from the tire radial outer end of the bead filler 1b to the roll-up end 42e It is preferably 80% or more of the radial length L1b.

The tire radial distances D41e and D42e are each more preferably 90% or more of the tire radial length L1b, and still more preferably 100% or more. The tire radial distance D42e is 120% or less of the tire radial length L1b in order to arrange the rolled-up end 42e, which is arranged relatively inward in the tire radial direction, at an appropriate height among the rolled-up ends 41e and 42e. Preferably. From the viewpoint of appropriately spacing the raised portion 7 from the bead filler 1b, the tire radially inner end of the top surface 73 of the raised portion 7 (boundary between the top surface 73 and the inclined surface 72) from the tire radially outer end of the bead filler 1b. The tire radial distance D7 to is preferably 100% or more of the tire radial length L1b.

In the present embodiment, the rolled-up end 41e of the first ply 41 is arranged outside the rolled-up end 42e of the second ply 42 in the tire radial direction. As a result, since the roll-up end 42e is covered from the outside in the tire width direction by the first ply 41, the occurrence of cracks originating from the roll-up end 42e can be suppressed and the durability can be effectively improved. However, it is not limited to this, and the positional relationship between the winding end 41e and the winding end 42e may be reversed. In that case, the roll-up end 41e is disposed radially inward of the tire radial direction inner end of the raised portion 7, and the rolled-up end 42e overlaps the raised portion 7 in the tire width direction and is located at the maximum raised height position 7M. It is arranged inside in the tire radial direction.

Both of the winding ends 41e and 42e are places where strain tends to concentrate, so keeping them apart from each other is beneficial for improving durability. From this point of view, it is preferable that a gap of 15 mm or more is provided in the tire radial direction between the rolled-up end 41e of the first ply 41 and the rolled-up end 42e of the second ply 42 . That is, the tire radial distance Dc between the roll-up end 41e and the roll-up end 42e is preferably 15 mm or more. Arranging the roll-up end 41e inside the raised portion 7 in the tire width direction and placing the rolled-up end 42e inside the raised portion 7 in the tire radial direction ensures an interval (distance Dc in the tire radial direction) between them. is convenient.

The rolled-up end 41e of the first ply 41 is preferably arranged at a position that does not overlap the inclined surface 72 in the tire width direction. That is, it is preferable that the roll-up end 41e is arranged outside the projection area A72 of the inclined surface 72 toward the inside in the tire width direction. A projection area A72 of the inclined surface 72 tends to have a relatively easy concentration of strain in the projection area A7 of the raised portion 7 . Therefore, according to such a configuration, it is possible to more appropriately suppress the strain concentration at the winding end 41e and improve the durability. Such a configuration is also useful from the viewpoint of arranging the winding end 41e and the winding end 42e away from each other.

In this embodiment, the height of the raised portion 7 is relatively small in the region between the inclined surface 71 and the step 73s, and relatively large in the region between the step 73s and the inclined surface 72. there is According to such a configuration, since the portion of the raised portion 7 having a relatively large raised height is provided near the tire maximum width position 2M, it contributes to the improvement of resistance to trauma. Further, the rolled-up end 41e of the first ply 41 is arranged at a position overlapping the region between the step 73s and the inclined surface 72 in the tire width direction. As a result, since the rolled-up end 41e is arranged in a region having a relatively large protruded height, the strain generated in the rolled-up end 41e can be suppressed and the durability can be improved.

Considering the tire radially outer region Xa when the region from the maximum raised height position 7M to the inclined surface 72 is divided into two equal parts, and the remaining tire radially inner region Xb, the tire diameter It is preferable that the winding end 41e located on the direction outer side is arranged within the region Xa. As a result, the rolled-up end 41e is arranged in a region having a relatively large raised height, and the rolled-up end 42e is covered with the first ply 41, so that the strain generated in them can be suppressed and the durability can be improved.

The positional relationship between the mold splitting position Ps, the protuberance 7, and the roll-up ends 41e and 42e described above may be applied to at least one of the pair of sidewalls 2 . However, in order to enhance the improvement effect, it is preferable to apply it to both of the pair of sidewalls 2 . In this embodiment, the positional relationship of each member shown in FIG. 2 is also applied to the sidewall 2 on the left side of FIG.

Unless otherwise specified, the shapes, dimensions, and the like described in this specification are based on a normal state with no load in which the tire is mounted on a normal rim and filled with a normal internal pressure. A regular rim is a rim defined for each tire in a standard system including the standard on which the tire is based. For example, JATMA "standard rim", TRA "design rim", or ETRTO "measuring rim" is. The normal internal pressure is the air pressure determined for each tire by each standard in the standard system including the standards on which the tire is based. or "INFLATION PRESSURE" in ETRTO.

As described above, the pneumatic tire T of the present embodiment includes a pair of bead portions 1, a pair of sidewalls 2 extending radially outward from each of the pair of bead portions 1, and a pair of sidewalls 2. The tread 3 continuous to the tire radial direction outer end of the tire, the bead filler 1b embedded in the bead portion 1, the raised portion 7 provided in the buttress region 2B of at least one of the pair of sidewalls 2, and the bead filler 1b are sandwiched. The carcass 4 is wound up from the inside to the outside in the tire width direction, and the raised portion 7 includes a maximum raised height position 7M arranged inside the mold splitting position Ps in the tire radial direction, and the carcass 4 has a first ply 41 laminated relatively inside in the tire radial direction in the tread 3 and a second ply 42 laminated relatively outside in the tire radial direction in the tread 3, and the first ply 41 One of the rolled-up end 41e and the rolled-up end 42e of the second ply 42 is arranged at a position overlapping the raised portion 7 in the tire width direction and radially inward of the maximum raised height position 7M. The other of the rolled-up end 41e of the ply 41 and the rolled-up end 42e of the second ply 42 is arranged inside the tire radially inner end of the raised portion 7 in the tire radial direction.

According to such a configuration, the parts where there is concern about strain concentration, such as the mold splitting position Ps, the maximum raised height position 7M, and the roll-up ends 41e and 42e, are dispersedly arranged, so that the sidewall 2 is excellent in durability. becomes. Moreover, since the roll-up end 41e is arranged at a position overlapping the raised portion 7 in the tire width direction, the rigidity of the raised portion 7 is increased, so that the sidewall 2 is excellent in resistance to external damage.

The rolled-up end 41e of the first ply 41 and the rolled-up end 42e of the second ply 42 are each separated from the bead filler 1b in the tire radial direction via a distance of 80% or more of the tire radial length L1b of the bead filler 1b. It is preferable that it is arranged on the outer side in the tire radial direction of the outer end. According to such a configuration, locations where there is concern about concentration of strain, including the tire radial direction outer end of the bead filler 1b, are dispersedly arranged, so that the durability of the sidewall 2 is further improved.

It is preferable that the rolled-up end 41e of the first ply 41 is arranged outside the rolled-up end 42e of the second ply 42 in the tire radial direction. According to this configuration, since the wound-up end 42e of the second ply 42 is covered from the outside in the tire width direction by the first ply 41, the occurrence of cracks originating from the wound-up end 42e is suppressed, and durability is effectively improved. can be improved to

An inclined surface 72 that gradually decreases in height inward in the tire radial direction is formed at the radially inner end of the protruding portion 7, and is located between the mold split position Ps and the maximum protruding height position 7M. The tire radial distance Dd is preferably 50% or more of the tire radial distance De between the maximum raised height position 7M and the inclined surface 72 . According to such a configuration, the distance between the mold splitting position Ps and the maximum protrusion height position 7M can be ensured, and the durability of the sidewall 2 can be appropriately improved.

The pneumatic tire of the present disclosure can be employed as various tires for passenger cars, light trucks, trucks, buses, and the like.

The pneumatic tire of the present disclosure is by no means limited to the above-described embodiments, and various modifications and improvements are possible without departing from the scope of the invention.

1 bead portion 1b bead filler 2 sidewall 2B buttress region 3 tread 4 carcass 7 raised portion 7M maximum raised height position 41 first ply 41e rolled-up end 42 of first ply 42e rolled-up end 72 of second ply inclined surface Ps Mold split position

Claims (4)

a pair of beads;
a pair of sidewalls extending outward in the tire radial direction from each of the pair of bead portions;
a tread connected to the tire radial direction outer end of each of the pair of sidewalls;
a bead filler embedded in the bead;
a raised portion provided in a buttress region of at least one of the pair of sidewalls;
A carcass wound up from the inside to the outside in the tire width direction so as to sandwich the bead filler,
The raised portion includes a maximum raised height position arranged radially inward of the mold splitting position,
The carcass has a first ply laminated relatively inside in the tire radial direction in the tread and a second ply laminated relatively outside in the tire radial direction in the tread,
One of the rolled-up end of the first ply and the rolled-up end of the second ply is arranged at a position overlapping the raised portion in the tire width direction and radially inward of the maximum raised height position. ,
A pneumatic tire, wherein the other of the rolled-up end of the first ply and the rolled-up end of the second ply is arranged radially inward of the tire radially inner end of the raised portion. The rolled-up end of the first ply and the rolled-up end of the second ply are respectively from the tire radially outer end of the bead filler via a distance of 80% or more of the tire radial length of the bead filler. 2. The pneumatic tire according to claim 1, which is arranged radially outward of the tire. The pneumatic tire according to claim 1 or 2, wherein the rolled-up end of the first ply is arranged radially outward of the rolled-up end of the second ply. An inclined surface that gradually decreases in height inward in the tire radial direction is formed at an end portion of the raised portion on the inner side in the tire radial direction,
Claim 1, wherein the tire radial distance between the mold splitting position and the maximum elevation height position is 50% or more of the tire radial distance between the maximum elevation height position and the inclined surface. 3. The pneumatic tire according to any one of items 1 to 3.

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