pneumatic tires

Abstract

Pneumatic tire (1), comprising: a projection portion (30) projecting outward in a tire transverse direction and disposed in a support portion (6), and a linear portion (32) having a linear shape when viewed in a tire meridian cross-section, the linear portion (32) forming a surface of the protrusion portion (30) at a position inward from a corner portion (31) in the tire radial direction, the corner portion (31) being an end portion of the protrusion portion (30) outward in the tire transverse direction; wherein the corner portion (31) is located within a position of the retreading development width (15), which is a range in the tire radial direction in which a limit for removing a tread (2) during retreading is located, the linear portion (32) has an angle in the range of 45° to 90° with respect to an imaginary line (H) parallel to a tire rotation axis at a position inward from the linear portion (32) in the tire transverse direction, the corner portion (31) of the projection portion (30) shares the same position with an outer carcass end portion (11), which is an outermost portion of a carcass in the tire transverse direction, in the tire transverse direction or is arranged inwardly from a position of the outer carcass end portion (11) in the tire transverse direction, and wherein a distance D in the tire transverse direction exists from the end portion (4) of the tread contact surface (3) in the tire transverse direction to the outer carcass end portion (11), wherein there is a distance L in the tire transverse direction from the corner portion (31) to the outer carcass end portion (11), which is an outermost portion of a carcass (10) in the tire transverse direction, wherein in the projection portion (30), the distance L and the distance D have a relationship within the range 0.5 ≤ (L / D) ≤ 0.7.

Description

Technical area

[0001] The present invention relates to a pneumatic tire. State of the art

[0002] In the prior art of pneumatic tires, a retreading tire is known. When the tread of such a tire reaches the end of its service life, and the groove depth of a groove formed in the tread is smaller than a predetermined depth, a tread rubber can be replaced and the tire can be reused. The following paragraph lists documents referred to as Patent Documents 1 to 6. For example, a pneumatic retreading tire described in Patent Document 1 includes a semicircular protrusion at a designated rubbing point on the surface of a support portion. This configuration enables rubbing, i.e., removal of the worn tread, to be performed appropriately and increases the accuracy of the bonded tread surface.The pneumatic tire disclosed in Patent Document 2 includes a tread portion with lug grooves and side portions adjacent to the tread portion. Protrusions differing in at least one shape and one size are arranged on a side portion in a plurality of rows in the tire radial direction. The opening positions of the lug grooves on both sides of the tread portion are designed to coincide with a straight line passing through the protrusion and extending in the tire radial direction. Patent Document 3 discloses a water-repellent tire with improved heating characteristics, including a water-repellent protrusion for splash protection. The splash-preventing protrusion protrudes from the surface of a sidewall.A plurality of radiating ribs are formed at intervals between the water-repellent protrusion and the sidewall surface. Each of the radiating ribs is arranged on a virtual radial line passing through the pivot point of the water-splash tire. Each of the radiating ribs has a predetermined inclination angle with respect to the virtual radial line. Patent Document 4 discloses a pneumatic tire in which turbulent flow generating ribs extending from the inner peripheral side to the outer peripheral side are formed at intervals in the tire circumferential direction on the outer circumference or tire surface of a tire side portion. Patent Document 5 discloses a pneumatic tire having a tread portion with lug grooves and side portions adjacent to the tread portion.Protrusions differing in at least one shape and one size are arranged on a side portion in a plurality of rows in the tire radial direction. The opening positions of the small lug grooves on both sides of the tread portion are designed to coincide with a straight line passing through the protrusion and extending in the tire radial direction. Patent Document 6 discloses a pneumatic tire comprising two bead portions and two side portions extending outward from the respective bead portions in the tire radial direction, two side rubber layers constituting an outer surface of the tire, and a tread portion bridging the side portions and composed of a tread rubber layer.Patent Document 7 discloses a pneumatic tire in which at least one outer wall surface of a sidewall portion is provided with a breaker having an annular protrusion protruding from the outer wall surface and extending in the circumferential direction of the tire. The breaker has a maximum protrusion with a maximum protrusion height near the outer end in the tire radial direction of the breaker. The protrusion height gradually decreases from the maximum protrusion toward the inner end in the tire radial direction of the breaker. List of citationsPatent literature Patent Document 1: JP 2004-098953 A Patent document 2: JP 5 750 541 B1 Patent document 3: KR ​​10 2010 0 123 226 A Patent document 4: WO 2008 / 114 668 A1 Patent document 5: US 2016 / 0 129 733 A1 Patent document 6: JP 2013- 6 572 A Patent document 7: JP 2003- 112 505 A Summary of the inventionTechnical problem

[0003] In many known pneumatic retreading tires, a wide pre-vulcanization is used as the pre-vulcanization tread, that is, as the tread for replacement, and a development width sufficient to bond the wide pre-vulcanization tread is ensured. Thus, the area from the tread edge to the support portion is curved in a manner protruding outward in the tire transverse direction. However, the rubber volume constituting the support portion area is larger in a configuration in which the area from the tread edge to the support portion is curved in a manner protruding outward in the tire transverse direction than in a configuration in which the support mold does not protrude outward in the tire transverse direction. Thus, the heat buildup resistance is reduced.However, a development width sufficient to bond the wide pre-cure tread for retreading is difficult to achieve with a configuration in which the area from the tread edge to the support portion is not curved in a manner protruding outward in the tire transverse direction. Thus, it is extremely difficult to ensure a retreading development width sufficient to bond the pre-cure tread while simultaneously suppressing a decrease in heat buildup resistance.

[0004] In view of the foregoing, it is an object of the present invention to provide a pneumatic tire which can ensure a retreading development latitude while suppressing a decrease in heat build-up resistance. Solution to the problem

[0005] To solve the above-described problems and achieve the above-described object, a pneumatic tire according to an embodiment of the present invention includes: a projection portion projecting outward in the tire transverse direction and disposed in a support portion; and a linear portion having a linear shape when viewed in a tire meridian cross section, the linear portion constituting a surface of the protrusion portion at a position inward from a corner portion in the tire radial direction, the corner portion being an end portion of the protrusion portion outward in the tire transverse direction; wherein the corner portion is located within a position of the retreading development width, which is a range in the tire radial direction in which a boundary for removing a tread during retreading is located, and the linear portion has an angle in the range of 45° to 90° with respect to an imaginary line parallel to a tire rotation axis at a position inward of the linear portion in the tire transverse direction, the corner portion of the protrusion portion shares the same position with an outer carcass end portion, which is an outermost portion of a carcass in the tire transverse direction, or is arranged inward from a position of the outer carcass end portion in the tire transverse direction, and wherein a distance D in the tire transverse direction from the end portion of the tread contact surface in the tire transverse direction to the outer carcass end portion exists, wherein a distance L in the tire transverse direction exists from one of the corner portions to the outer carcass end portion, which is an outermost portion of a carcass in the tire transverse direction, wherein in the protrusion portion, the distance L and the distance D have a relationship within the range 0.5 ≤ (L / D) ≤ 0.7.

[0006] In the pneumatic tire described above, preferably, the protrusion portion includes a curved portion forming a surface of the protrusion portion at a position outward from the corner portion in the tire radial direction, the curved portion being curved protrudingly inward in a cross-sectional direction as viewed in the tire meridian cross section.

[0007] In the pneumatic tire described above, preferably, the curved portion includes an end portion on a side opposite to an end portion located closer to the corner portion, the end portion being located inward in the tire radial direction from an end portion of a tread contact surface in the tire transverse direction.

[0008] In the pneumatic tire described above, preferably the distance L to the corner portion is in a range of 0 mm < L ≤ 30 mm and a distance L' in the tire transverse direction from an inner end portion of the linear portion in the tire radial direction to the outer carcass end portion is in a range of 0 mm ≤ L' ≤ 30 mm. Advantageous effects of the invention

[0009] A pneumatic tire according to the present invention achieves the effects of ensuring a retreading development width while suppressing a decrease in heat buildup resistance. Brief description of the drawings Fig. 1 is a meridian cross-sectional view illustrating a main portion of a pneumatic tire according to an embodiment. Fig. 2 is a detailed view of section A of Fig. 1. Fig. 3 is a detailed view of section B of Fig. 2. Fig. 4 is an explanatory diagram of the arrangement configuration of a protrusion portion. Fig. 5 is an explanatory diagram of a configuration in which a retread development width is ensured by the shoulder shape being semicircular. Fig. Figure 6A is a table showing the results of performance tests of pneumatic tires. Fig. Figure 6B is a table showing the results of performance tests of pneumatic tires. Fig. Figure 6C is a table showing the results of pneumatic tire performance tests. Description of embodiments

[0010] Pneumatic tires according to embodiments of the present invention will be described in detail below with reference to the drawings. However, the invention is not limited to these embodiments.

[0011] Herein, "tire transverse direction" refers to the direction parallel to a tire's rotation axis. "Tire transverse inward" refers to the direction toward the tire's equatorial plane in the tire's transverse direction. "Tire transverse outward" refers to the direction opposite to the tire's equatorial plane in the tire's transverse direction. Furthermore, "tire radial direction" refers to the direction perpendicular to the tire's rotation axis. "Tire radial inward" refers to the direction toward the tire's rotation axis in the tire's radial direction. "Tire radial outward" refers to the direction away from the tire's rotation axis in the tire's radial direction. "Tire circumferential direction" refers to the direction of rotation around the tire's rotation axis.

[0012] Fig. 1 is a meridian cross-sectional view illustrating a main portion of a pneumatic tire 1 according to an embodiment. Fig. The pneumatic tire 1 illustrated in Fig. 1 is provided with a tread 2 in the outermost portion in the tire radial direction in a meridian cross-sectional view. The surface of the tread 2, that is, the portion that comes into contact with the road surface when a vehicle (not shown) on which the pneumatic tire 1 is mounted runs, is formed as a tread contact surface 3. A plurality of circumferential main grooves 21 extending in a tire circumferential direction are formed in the tread contact surface 3, and a plurality of lug grooves (not shown) crossing the circumferential main grooves 21 are formed in the tread contact surface 3. A plurality of land portions 20 are defined by the plurality of circumferential main grooves 21 and the lug grooves in the tread contact surface 3.

[0013] It should be noted that the number of circumferential main grooves 21, the pitch between the lug grooves in the tire circumferential direction, the length and angle of the lug grooves, the groove width and groove depth of the grooves, and the like are preferably set appropriately. That is, the so-called tread pattern formed in the tread contact surface 3 is preferably set appropriately. The pneumatic tire 1 according to an embodiment of the present invention is a retreading tire. When the tread 2 reaches the end of its service life, with the tread contact surface 3 being worn to the point where the groove depth of a circumferential main groove 21 or another groove is less than a predetermined depth, the tread rubber constituting the tread 2 can be replaced, and the tire can be reused.

[0014] The ends of the tread 2 in the tire transverse direction are formed as shoulder portions 5. Sidewall portions 7 are arranged to extend inward from the shoulder portions 5 to predetermined positions in the tire radial direction. In other words, the sidewall portions 7 are arranged at two portions on each side of the pneumatic tire 1 in the tire transverse direction.

[0015] Further, a bead portion 25 is arranged inwardly of each sidewall portion 7 in the tire radial direction. The bead portions 25 are arranged at two portions on both sides of an equatorial plane of the tire CL in a similar manner to the sidewall portions 7. That is, the pair of bead portions 25 are arranged on both sides of the equatorial plane of the tire CL in the tire transverse direction. The pair of bead portions 25 are each provided with a bead core 26, and a bead filler 27 is provided outwardly of each bead core 26 in the tire radial direction. The bead core 26 is formed by winding a bead wire, which is a steel wire, into a ring shape. The bead filler 27 is a rubber material arranged in the space formed by turning one end of a carcass 10 (described below) outward in the tire transverse direction at the position of the tire bead core 26.

[0016] The bead portion 25 is configured to be mounted on a predetermined rim with a taper of 15°. Here, "prescribed rim" refers to an "applicable rim" as defined by the Japan Automobile Tire Manufacturers Association (JATMA), a "design rim" as defined by the Tire and Rim Association (TRA), or a "measuring rim" as defined by the European Tire and Rim Technical Organization (ETRTO). That is, the pneumatic tire 1 according to an embodiment of the present invention can be mounted on a predetermined rim with the portion engaging the bead portion 25 inclined at an inclination angle of 15° with respect to the rotation axis.

[0017] A belt layer 8 is provided inward in the tire radial direction from the tread 2. The belt layer 8 has a multi-layer structure including four layered belts 81, 82, 83, 84. The belts 81, 82, 83, 84 are manufactured by a method of covering a plurality of belt cords made of steel or an organic fiber material such as polyester, rayon, and nylon with a rubber coating, followed by a rolling process. Furthermore, the belts 81, 82, 83, 84 have variously set inclination angles of the fiber directions of the belt cords with respect to the tire circumferential direction, and the belts are layered so that the fiber directions of the belt cords cross each other, that is, in a cross-ply structure.

[0018] The carcass 10 is provided in a continuous manner from the belt layer 8 in the tire radial direction inward and on the tire equatorial plane CL side of the sidewall portions 7, and includes radial ply cords. The carcass 10 has a single-layer structure made of one carcass ply or a multi-layer structure made of a plurality of carcass plies, and extends between the bead cores 26 on both sides in the tire transverse direction in a toroidal shape, thereby forming the framework structure for the tire. More specifically, the carcass 10 is arranged from one bead portion 25 to the other bead portion 25 located on both sides in the tire transverse direction, and bends back outward in the tire transverse direction along the bead portions 25 and the bead cores 26, wrapping around the bead cores 26 and the bead fillers 27.In addition, the carcass ply of the carcass 10 is manufactured by a process of covering a plurality of carcass cords formed of steel or an organic fiber material such as aramid, nylon, polyester and rayon with a coating rubber and then a rolling process.

[0019] In addition, an inner liner 12 is formed along the carcass 10 from the carcass 10 inward or on the inside of the carcass 10 in the pneumatic tire 1.

[0020] Fig. 2 is a detailed view of section A of Fig. 1. A support portion 6 is the portion located on both sides of the tread 2 in the tire transverse direction, which faces outward in the tire transverse direction, or the portion of the sidewall portion 7 in the upper end region in the tire radial direction. The support portion 6 is provided with a protrusion portion 30 protruding outward in the tire transverse direction. The protrusion portion 30 includes a corner portion 31, which is the outer end portion in the tire transverse direction, and a curved portion 35 located outward from the corner portion 31 in the tire radial direction. A linear portion 32 is provided inward from the corner portion 31 in the tire radial direction. The corner portion 31 is the portion of the protrusion portion 30 located outermost in the tire transverse direction.The corner portion 31 is located within a position of the retreading development width 15, which is the range in the tire radial direction where the boundary for removing the tread 2 during retreading is located. The position of the retreading development width 15 is the range defined by a groove bottom side reference line 16 and a belt side reference line 17, and is the range between the groove bottom side reference line 16 and the belt side reference line 17. In addition, the position of the retreading development width 15 is also the range where a retreading development width is located. The retreading development width is the width in the tire transverse direction of the portion where the new tread rubber is adhered after the tread 2 is removed during retreading.That is, the position of the retreading development width 15 is the range in which the portion corresponding to the outer peripheral surface of a base tire, which is the pneumatic tire 1 with the tread 2 removed during retreading, is located.

[0021] The groove bottom side reference line 16, which defines the position of the retread development width 15, is an imaginary line parallel to the tread pattern, which is the profile of the tread contact surface 3, and extends from the groove bottom of the outermost circumferential main groove 21 in the tire transverse direction. The belt side reference line 17 is an imaginary line parallel to the tread pattern, which extends from the end of the belt 83 in the tire transverse direction, which corresponds to the outermost layer located in the region in the tire transverse direction where the outermost circumferential main groove 21 is located in the tire transverse direction. That is, the belt side reference line 17 is an imaginary line parallel to the tread pattern, which extends from the end of the belt 83 located below the circumferential main groove 21 in the tire transverse direction, which is used as a reference for the groove bottom side reference line 16.

[0022] It should be noted that the tread pattern in such a configuration refers to the profile of the tread contact surface 3 when the pneumatic tire 1 is mounted on a specified rim, the pneumatic tire 1 is inflated to the specified internal pressure, and is in an unloaded state. "Normal internal pressure" refers to a "maximum air pressure" as defined by JATMA, the maximum value in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" as defined by TRA, or "INFLATION PRESSURES" as defined by ETRTO.

[0023] The position of the retreading development width 15 is the range between the groove bottom side reference line 16 and the belt side reference line 17. During retreading, the tread 2 is removed from the outer peripheral surface to a position within the range of the position of the retreading development width 15. The protrusion portion 30 is formed in such a shape that the corner portion 31 is located within the position of the retreading development width 15.

[0024] The curved portion 35 forms the surface of the protrusion portion 30 at a position outward from the corner portion 31 in the tire radial direction and is curved to protrude inward in the cross-sectional direction when viewed in a tire meridian cross-section. That is, the curved portion 35 is curved to protrude inward in the tire transverse direction or tire radial direction. Thus, the curved portion 35 has a depressed shape when viewed from the surface side. The curved portion 35 includes an end portion 36 on the side opposite the end portion and located closer to the corner portion 31. The end portion 36 is located inward in the tire radial direction from an end portion 4 of the tread contact surface 3 in the tire transverse direction.That is, the curved portion 35 located outward from the corner portion 31 in the tire radial direction does not extend to a position of the tread contact surface 3, and the end portion 36 on the side opposite to the end portion located closer to the corner portion 31 is not connected to the end portion 4 of the tread contact surface 3 and is connected to a position near the end portion 4 of the tread contact surface 3 on the surface of the support portion 6.

[0025] Furthermore, the linear portion 32 forms the surface of the protrusion portion 30 at a position inward from the corner portion 31 in the tire radial direction and has a linear shape when viewed in a tire meridian cross section. That is, the linear portion 32 is formed from the corner portion 31 extending inward in the tire radial direction.

[0026] Fig. 3 is a detailed view of section B of Fig. 2. The linear portion 32 extending inward in the tire radial direction is formed at an angle α in the tire transverse direction from the linear portion 32 in the tire transverse direction within a range of 45° to 90° with respect to a horizontal line H, which is an imaginary line parallel to the tire rotation axis. That is, in a configuration where the horizontal line H is an imaginary line passing through the corner portion 31 and parallel to the tire rotation axis, the linear portion 32 is formed between the inner surface of the linear portion 32 in the tire transverse direction and the horizontal line H in the range of 45°≤α≤90° with the angle α. Thus, the linear portion 32 extends inward from the corner portion 31 in the tire radial direction, or extends inward from the corner portion 31 in the tire radial direction, with an inclination directed inward in the tire transverse direction.An end portion 33 of the linear portion 32 formed in this way on the side opposite to the end portion closer to the corner portion 31 is connected to the surface of the side wall portion 7.

[0027] The corner portion 31 of the protrusion portion 30 is the portion where the linear portion 32 and the curved portion 35 connect. By connecting the linear portion 32 and the curved portion 35, this portion is bent and protrudes outward in the tire transverse direction. Note that in a configuration in which the angle α between the linear portion 32 and the horizontal line H is 90°, the corner portion 31 and the linear portion 32 share the same position in the tire transverse direction, and the linear portion 32 and the corner portion 31 correspond to the outer end portion of the protrusion portion 30 in the tire transverse direction. Also in this configuration, the corner portion 31 is the portion where the linear portion 32 and the curved portion 35 connect.

[0028] Fig. 4 is an explanatory diagram of the arrangement configuration of the protrusion portion 30. In the protrusion portion 30, a distance L in the tire transverse direction from a carcass outer end portion 11, which is the outermost portion of the carcass 10 in the tire transverse direction, to the corner portion 31 is in the range of 0 mm ≤ L ≤ 30 mm. The carcass outer end portion 11 of such a configuration is the portion of the carcass 10 with the maximum width in the tire transverse direction, and the width is measured between the portions of the carcass 10 on each side in the tire transverse direction.

[0029] According to the invention, the corner portion 31 of the protrusion portion 30 shares the same position with the outer carcass end portion 11 in the tire transverse direction or is arranged inwardly from the position of the outer carcass end portion 11 in the tire transverse direction. In the protrusion portion 30, the distance L in the tire transverse direction between the corner portion 31 arranged as such and the outer carcass end portion 11 is in the range of 0 mm < L ≤ 30 mm, and the entire protrusion portion 30 is arranged inwardly from the outer carcass end portion 11 in the tire transverse direction.

[0030] Thus, in the protrusion portion 30, the inner end portion 33 of the linear portion 32 in the tire radial direction is also located inward from the carcass outer end portion 11 in the tire transverse direction. A distance L' in the tire transverse direction from the inner end portion 33 of the linear portion 32 in the tire transverse direction to the carcass outer end portion 11 is within the range of 0 mm ≤ L' ≤ 30 mm. Here, the angle α between the linear portion 32 and the horizontal line H is in the range of 45° ≤ α ≤ 90°. Thus, the distance L in the tire transverse direction from the corner portion 31 to the carcass outer end portion 11 and the distance L' in the tire transverse direction from the end portion 33 of the linear portion 32 to the carcass outer end portion 11 have the relationship L ≤ L'.

[0031] It is to be noted that, in the protrusion portion 30, a tire transverse direction distance D from the tire transverse direction end portion 4 of the tread contact surface 3 to the carcass outer end portion 11 and the tire transverse direction distance L from the corner portion 31 to the carcass outer end portion 11 have a relationship within the range of 0.5 ≤ (L / D) ≤ 0.7 according to the present invention.

[0032] When such a pneumatic tire 1 is mounted on a vehicle and the vehicle is driven, the pneumatic tire 1 rotates while the tread contact surface 3 of the lower tread contact surface 3 comes into contact with the road surface. A frictional force is generated between the ground contact portion of the tread contact surface 3 and the road surface. Thus, via this frictional force between the tread contact surface 3 and the road surface, the vehicle on which the pneumatic tire 1 is mounted is driven, transmitting the driving force and the braking force to the road surface and generating a rotational force.

[0033] Here, frictional force is generated between the road surface and the tread contact surface 3 because the tread contact surface 3 comes into contact with the road surface, and the tread contact surface 3 is gradually worn, generating frictional force. Thus, the tread contact surface 3 of the pneumatic tire 1 gradually wears as the distance traveled by the vehicle increases. Grooves such as the circumferential main grooves 21, which contribute to drainage properties, are formed in the tread contact surface 3. However, as the tread contact surface 3 wears, the groove depth of the grooves becomes shallow. When the groove depth of the grooves formed in the tread contact surface 3 becomes shallow, the drainage properties are reduced. Accordingly, when the vehicle runs on wet road surfaces, wet performance gradually decreases as the groove depth becomes shallow.In this way, when the groove depth of the grooves, which relates to wet performance and the like, decreases below a predetermined depth due to the wear of the tread contact surface 3, the life of the tread 2 ends.

[0034] In the pneumatic tire 1 according to an embodiment of the present invention, when the service life of the tread 2 ends, the tread 2 is removed from the pneumatic tire 1 to obtain a base tire, and a pre-cured tread with grooves is bonded to the surface of the base tire. Thus, the pneumatic tire 1 is retreaded by newly providing it with a tread 2 having grooves with a predetermined groove depth.

[0035] Specifically, when retreading is performed after the life of the tread 2 ends, the tread 2 is gradually removed from the tread contact surface 3 side by abrading from the tread contact surface 3 side. The abrading is performed from the tread contact surface 3 inward in the tire radial direction and is performed up to an arbitrary position within the position of the retreading development width 15. That is, the boundary between the removed tread 2 and the base tire is set within the position of the retreading development width 15, and the tread 2 is removed by abrading to this set boundary.In this case, by rubbing, the protrusion portion 30 is removed from the outside in the tire radial direction downward to a portion near the corner portion 31 because the corner portion 31 is located in the position of the retread development width 15.

[0036] After the tread 2 is removed from the pneumatic tire 1, a pre-vulcanized tread is bonded to the outer peripheral surface of the base tire. In this case, the pre-vulcanized tread is also bonded to the abraded surface of the protrusion portion 30. In this way, the pneumatic tire 1 is retreaded by newly providing it with a tread 2 having grooves such as the circumferential main grooves 21 with a groove depth capable of ensuring drainage properties.

[0037] In the pneumatic tire 1 according to an embodiment of the present invention, retreading can be performed by replacing the tread 2 in this way. However, the support portion 6 is provided with the protrusion portion 30 that sandwiches the corner portion 31 within the position of the retreading development width 15. Thus, during retreading, when a pre-vulcanized tread is bonded to the base tire, it can also be bonded to the portion of the protrusion portion 30, thereby ensuring the retreading development width, which is the tire transverse width of the portion to which the pre-vulcanized tread is bonded during retreading.

[0038] The protrusion portion 30 thus contributes to ensuring the retreading development width. Furthermore, the protrusion portion 30 is provided so as to protrude outward from the support portion 6 in the tire transverse direction, and since the angle α of the linear portion 32 of the protrusion portion 30 with respect to the horizontal line H is in the range of 45°≤α≤90°, the retreading development width can be ensured without expanding the amount of rubber.

[0039] Fig. Figure 5 is an explanatory diagram of a configuration in which the retreading development width is ensured by making the shoulder shape semicircular. To ensure the retreading development width during retreading, for example, as shown in Fig. 5, the shape of the support portion 6 disposed in the shoulder portion 5 may have a semicircular shape, be slightly curved, and protrude outward in the tire transverse direction. Accordingly, the support portion 6 protrudes outward in the tire radial direction, whereby the retreading development width can be ensured. However, in a configuration in which the support portion 6 is given a semicircular shape, the rubber volume used in the area of ​​the shoulder portion 5 is increased. A large rubber volume means a larger volume of elements that generate heat due to deflection and the like when the vehicle is running. This causes an increase in the amount of heat buildup and a decrease in the ability to dissipate heat.Accordingly, a configuration in which the shape of the area of ​​the shoulder portion 5 is a semicircular shape has lower heat buildup resistance than a configuration in which the support portion 6 extends inward from the shoulder portion 5 in the tire radial direction in a substantially straight manner and is not curved outwardly in the tire transverse direction, that is, it is a square-shaped shoulder portion 5.

[0040] In contrast, in the pneumatic tire 1 according to an embodiment of the present invention, the retreading development width is similar to that of a configuration having a semicircular-shaped support portion 6, and compared with a semicircular-shaped support portion 6, the areas except the protrusion portion 30 can be trimmed, thereby forming a trimmed portion 40. As a result, the used rubber volume in the area of ​​the shoulder portion 5 can be reduced. That is, since the protrusion portion 30 protrudes from the support portion 6 in a shape located within the position of the retreading development width 15, compared with a semicircular-shaped support portion 6, the rubber in the area corresponding to the trimmed portion 40 on both sides of the corner portion 31 in the tire radial direction can be reduced.Thus, the amount of elements that generate heat when the vehicle is moving can be reduced, thereby reducing heat buildup. This, in turn, increases the ability to dissipate heat in the area of ​​shoulder portion 5.

[0041] In such a configuration, if the angle α of the linear portion 32 with respect to the horizontal line H is greater than 90°, the amount of trimmed rubber is reduced, and the effect of suppressing heat buildup is reduced. If the angle α of the linear portion 32 with respect to the horizontal line H is less than 45°, the rigidity of the protrusion portion 30 is reduced. This may result in the rigidity in the end portion region in the tire transverse direction being reduced when the pre-vulcanization tread is bonded. In contrast, in the pneumatic tire 1 according to an embodiment of the present invention, the angle α of the linear portion 32 with respect to the horizontal line H is in the range of 45°≤α≤90°. Thus, the amount of rubber and thus the heat buildup can be suppressed.Furthermore, since the rigidity of the protrusion portion 30 is ensured, the protrusion portion 30 can be used as a portion of the effective retreading development width during retreading. As a result of the above, the retreading development width can be ensured while suppressing a decrease in heat buildup resistance.

[0042] Furthermore, the curved portion 35 is curved inwardly in the cross-sectional direction. This allows the amount of rubber trimmed from the position outward from the corner portion 31 in the tire radial direction to be reliably larger compared to a configuration with a semicircular shaped portion of the shoulder portion 5. Thus, heat buildup can be further reliably suppressed. As a result, a decrease in heat buildup resistance can be further reliably suppressed with respect to ensuring the retreading development latitude.

[0043] Furthermore, the curved portion 35 includes an end portion 36 on the side opposite the end portion and located closer to the corner portion 31. Since the end portion 36 is located inward in the tire radial direction from the end portion 4 of the tread contact surface 3 in the tire transverse direction, the amount of rubber trimmed from the corner portion 31 in the tire radial direction can be further increased. As a result, heat buildup can be further reliably suppressed. Therefore, a decrease in heat buildup resistance with respect to ensuring the retreading development latitude can be further reliably suppressed.

[0044] The distance L in the tire transverse direction from the outer carcass end portion 11 to the corner portion 31 is in the range of 0 mm < L ≤ 30 mm. This can further reliably ensure the width of the portion where the pre-vulcanized tread can be bonded during retreading. The distance L' in the tire transverse direction from the inner end portion of the linear portion 32 in the tire radial direction to the outer carcass end portion 11 is in the range of 0 mm ≤ L' ≤ 30 mm. This can ensure the rigidity of the portion of the protrusion portion 30 inward from the corner portion 31 in the tire radial direction. Accordingly, the rigidity of the end portion region in the tire transverse direction for bonding the pre-vulcanized tread can be ensured, and the protrusion portion 30 can be used as a portion of the effective retreading development width during retreading.As a result of the above, the retreading development breadth can be further reliably ensured.

[0045] According to the present invention, the protrusion portion 30 is formed such that the tire transverse direction distance D from the tire transverse direction end portion 4 of the tread contact surface 3 to the carcass outer end portion 11 and the tire transverse direction distance L from the corner portion 31 to the carcass outer end portion 11 have a relationship within the range of 0.5≤(L / D)≤0.7. This makes it possible to ensure the retreading development width while further reliably suppressing the rubber amount. That is, when (L / D)<0.5 holds, the protrusion amount of the protrusion portion 30 is too large, and effective rubber amount trimming may be difficult. When (L / D)>0.7 holds, the protrusion amount of the protrusion portion 30 is too small, and ensuring the retreading development width may be difficult.On the other hand, when the protrusion portion 30 is formed such that the relationship is within the range of 0.5≤(L / D)≤0.7, the retreading development width can be further reliably ensured, and the amount of rubber sufficient to ensure the retreading development width can be suppressed. This further enables the retreading development width to be reliably ensured while suppressing a decrease in heat buildup resistance.

[0046] Note that in the pneumatic tire 1 according to the above-described embodiments, the linear portion 32 and the curved portion 35 are connected, whereby the corner portion 31 of the protruding portion 30 becomes a bent portion protruding outward in the tire transverse direction. However, the corner portion 31 may be formed in a shape other than a bent shape when viewed in a tire meridian cross section. For example, the corner portion 31 of the protruding portion 30 may be a portion curved protruding outward in the tire transverse direction, or it may be formed as a flat surface having a predetermined width in the tire radial direction when viewed in a tire meridian cross section.

[0047] In the pneumatic tire 1 according to the above-described embodiments, the protrusion portion 30 includes the curved portion 35 formed inward from the corner portion 31 in the tire radial direction, the curved portion 35 being curved to protrude inward in the cross-sectional direction. However, the portion extending outward from the corner portion 31 may be formed in a manner different from that of the curved portion 35. For example, the portion of the protrusion portion 30 extending outward from the corner portion 31 in the tire radial direction may be curved to protrude outward in the cross-sectional direction, or may be formed in a linear manner similar to that of the linear portion 32 arranged inward in the tire radial direction.

[0048] In the pneumatic tire 1 according to the above-described embodiments, the curved portion 35 of the protrusion portion 30 includes the end portion 36 on the side opposite the end portion located closer to the corner portion 31. The end portion 36 is located inward in the tire radial direction from an end portion 4 of the tread contact surface 3 in the tire transverse direction. However, the end portion 36 of the curved portion 35 may be connected to the end portion 4 of the tread contact surface 3. That is, the protrusion portion 30 may be formed from the position of the end portion 4 of the tread contact surface 3. Examples

[0049] Fig. 6A to 6C are tables each showing the results of performance tests of pneumatic tires 1. With respect to the pneumatic tire 1 described above, performance evaluation tests conducted on pneumatic tires 1 of prior art examples and comparative examples and pneumatic tires 1 according to embodiments of the present invention will be described below. In the performance evaluation tests, tests were conducted for heat buildup resistance, retread width assurance, and retreaded tread end portion rigidity.

[0050] The pneumatic tire 1 used in the evaluation tests was a pneumatic tire 1 with a nominal size of 245 / 70 R19 defined by the Japan Automobile Tire Manufacturers Association (JATMA), mounted on the rim wheel of a JATMA standard rim measuring 19.5 x 6.75, and adjusted to an air pressure of 660 kPa. In the heat buildup resistance evaluation tests, an inner drum test was conducted on each pneumatic tire 1 to measure the temperature of the support portion 6 after 7 hours of running at a speed of 80 km / h and a load of 20.19 kN. The heat buildup resistance evaluation results were calculated as index values, with the temperature of the support portion 6 of the pneumatic tire 1 of the prior art example 1 described below being assigned an index value of 100. Larger values ​​indicate heat buildup resistance and thus better heat buildup resistance.

[0051] In the evaluation test for retreading width assurance, the pneumatic tires 1 were measured for testing to determine how much tire protrusion was located outward from the end portion 4 of the tread contact surface 3 in the tire transverse direction for bonding with the pre-vulcanized tread. The evaluation results for retreading width assurance were calculated as index values, with the index value 100 assigned to the outward protrusion amount in the tire transverse direction from the end portion 4 of the tread contact surface 3 of the pneumatic tire 1 of the prior art example 1 described below. Larger values ​​indicate larger outward protrusion amounts in the tire transverse direction and that a retreading development width is assured.

[0052] In the evaluation tests for the stiffness of the retreaded tread end portion, an inner drum test was conducted on each pneumatic tire 1 after retreading with the tread 2, with each pneumatic tire 1 being driven for 150 hours at a speed of 80 km / h and a load of 20.19 kN. Afterward, damage was visually observed and evaluated by an evaluator based on the number of cracks and the length of the cracks in the support portion 6 area. The evaluation results for the stiffness of the retreaded tread end portion were calculated as index values, with the damage in the support portion 6 area of ​​the pneumatic tire 1 of the prior art example 1 described below being assigned an index value of 100. Larger values ​​indicate less cracking in the support portion 6 area after retreading and thus better stiffness of the retreaded tread end portion.

[0053] Evaluation tests were conducted on 12 different pneumatic tires 1: the pneumatic tire 1 of Prior Art Examples 1 and 2, which are examples of known pneumatic tires; Examples 1 to 6, which are pneumatic tires 1 according to embodiments of the present invention; and Comparative Examples 1 to 4, which are pneumatic tires for comparison with the pneumatic tires 1 according to embodiments of the present invention. In these pneumatic tires 1, in the pneumatic tires 1 of Prior Art Examples 1 and 2, the protrusion portion 30 is not arranged in the retreading position of the support portion 6.In the pneumatic tires 1 of Comparative Examples 1 to 4, the profile of the protruding portion 30 in the tire radial direction inward is a curved line when viewed in a tire meridian cross section, or the profile in the tire radial direction inward is a straight line such that the angle α of the straight line with respect to the horizontal line H is not in the range of 45° ≤ α ≤ 90°.

[0054] In Examples 1 to 6, which are pneumatic tires 1 according to embodiments of the present invention, the entire profile of the protruding portion 30 in the tire radial direction is a straight line when viewed in a tire meridian cross section, and the angle α of the straight line with respect to the horizontal line H is in the range of 45° ≤ α ≤ 90°. The pneumatic tires according to Examples 1 to 6 differ in the profile of the protruding portion 30 inward in the tire radial direction when viewed in a tire meridian cross section and the distance L in the tire transverse direction between the corner portion 31 of the protruding portion 30 and the carcass outer end portion 11. It should be noted that in Fig. 6A to 6C, for the distance L in the tire transverse direction from the corner portion 31 to the carcass outer end portion 11, the direction from the tire transverse direction position of the carcass outer end portion 11 in the tire radial direction inward is defined as + (plus) and the direction from the tire radial direction position of the carcass outer end portion 11 outward is defined as - (minus).

[0055] As in Fig.6A to 6C, the results of the evaluation tests when using the pneumatic tires 1 show that the pneumatic tires 1 of Examples 1 to 6 can suppress a decrease in heat buildup resistance, ensure the rigidity of the retreaded tread end portion, and ensure a retreading development width better than the pneumatic tires 1 of Prior Art Examples 1 and 2 and Comparative Examples 1 to 4. That is, the pneumatic tires 1 according to Examples 1 to 6 can ensure a retreading development width while suppressing a decrease in heat buildup resistance. List of reference symbols 1 pneumatic tire 2 Running surface 3 Tread contact surface 4 Final section 5 shoulder section 6 support section 7 Side wall section 8 Belt layer 81, 82, 83, 84 Belts 10 carcass 11 Outer carcass end section 12 Inner core 15 Position of the retreading development width 16 Groove bottom side reference line 17 Belt-side reference line 20 bridge section 21 Main circumferential groove 25 tire bead section 26 tire bead core 27 Bead Fillers 30 projection section 31 corner section 32 Linear section 33, 36 final section 35 Curved section 40 Cut section

Claims

[1] Pneumatic tyre (1), comprising: a projection portion (30) projecting outward in a tire transverse direction and disposed in a support portion (6), and a linear portion (32) having a linear shape when viewed in a tire meridian cross-section, the linear portion (32) forming a surface of the protrusion portion (30) at a position inward from a corner portion (31) in the tire radial direction, the corner portion (31) being an end portion of the protrusion portion (30) outward in the tire transverse direction; wherein the corner portion (31) is located within a position of the retreading development width (15), which is a range in the tire radial direction in which a limit for removing a tread (2) during retreading is located, the linear portion (32) has an angle in the range of 45° to 90° with respect to an imaginary line (H) parallel to a tire rotation axis at a position inward from the linear portion (32) in the tire transverse direction, the corner portion (31) of the projection portion (30) shares the same position with an outer carcass end portion (11), which is an outermost portion of a carcass in the tire transverse direction, in the tire transverse direction or is arranged inwardly from a position of the outer carcass end portion (11) in the tire transverse direction, and wherein a distance D in the tire transverse direction exists from the end portion (4) of the tread contact surface (3) in the tire transverse direction to the outer carcass end portion (11), wherein there is a distance L in the tire transverse direction from the corner portion (31) to the outer carcass end portion (11), which is an outermost portion of a carcass (10) in the tire transverse direction, wherein in the projection portion (30), the distance L and the distance D have a relationship within the range 0.5 ≤ (L / D) ≤ 0.

7. [2] Pneumatic tire (1) according to claim 1, wherein the projection portion (30) comprises a curved portion (35), which forms a surface of the projection portion (30) at a position outward from the corner portion (31) in the tire radial direction, wherein the curved portion (35) is curved inwardly projecting in a cross-sectional direction when viewed in the tire meridian cross-section. [3] A pneumatic tire (1) according to claim 2, wherein the curved portion (35) comprises an end portion (36) on a side opposite an end portion (33) located closer to the corner portion (31), the end portion (36) being located inward in the tire radial direction from an end portion (4) of a tread contact surface (3) in the tire transverse direction. [4] Pneumatic tire (1) according to one of claims 1 to 3, wherein the distance L to the corner section (31) is in a range of 0 mm < L ≤ 30 mm; and a distance L' in the tire transverse direction from an inner end portion (33) of the linear portion (32) in the tire radial direction to the outer carcass end portion (11) is in a range of 0 mm ≤ L' ≤ 30 mm.

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