Pneumatic tire

Abstract

To provide a pneumatic tire which enables air resistance to be reduced.SOLUTION: A pneumatic tire 100 comprises a shoulder 11. A recess 40 is formed in the shoulder 11. The recess 40 is formed by a first slope 41 facing the outside in a tire axial direction and a second slope 42 formed to be connected to the first slope 41 and facing the outside in a tire radial direction. A holding angle θ1 forming the first and second slopes 41 and 42 is 123°-127°. A distance D2 from the inner end to the outer end of the second slope 42 in the tire axial direction is 11 mm-16 mm. An inclination angle θ2 from a reference line of the second slope 42 in the tire radial direction is 73°-75°.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to pneumatic tires.

Background Art

[0002] Pneumatic tires may have depressions formed in the shoulders (for example, Patent Document 1). The formation of depressions in pneumatic tires improves the snow traction performance or off-road traction performance of the pneumatic tires.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, in order to improve the fuel efficiency performance of vehicles, it has been required to reduce air resistance even in pneumatic tires. However, the formation of the above-described depressions in pneumatic tires may increase air resistance. Therefore, a shape for reducing air resistance in the above-described depressions is required.

[0005] Therefore, an object of the present invention is to provide a pneumatic tire capable of reducing air resistance.

Means for Solving the Problems

[0006] The pneumatic tire according to the present invention is a pneumatic tire having a shoulder, and a recess is formed in the shoulder. The recess is formed by a first inclined surface facing the outer side in the tire axial direction and a second inclined surface continuously formed with the first inclined surface and facing the outer side in the tire radial direction. The clamping angle formed by the first inclined surface and the second inclined surface is 123° to 127°, the distance from the inner end to the outer end of the second inclined surface in the tire axial direction is 11 mm to 16 mm, and the inclination angle of the second inclined surface from the reference line along the tire radial direction is 73° to 75°.

[0007] In the pneumatic tire according to the present invention, the distance from the inner end to the outer end of the first inclined surface in the tire radial direction is preferably 8 to 17 mm.

Effect of the Invention

[0008] According to the pneumatic tire of the present invention, air resistance can be reduced.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0010] Hereinafter, an example of an embodiment of the present invention will be described in detail. In the following description, specific shapes, materials, directions, numerical values, etc. are examples for facilitating the understanding of the present invention, and can be appropriately changed according to applications, purposes, specifications, etc.

[0011] [Pneumatic Tire] The pneumatic tire 100 will be described with reference to FIGS. 1 and 2.

[0012] Hereinafter, the pneumatic tire (hereinafter referred to as tire) 100 will be described according to the tire axial direction (hereinafter referred to as the axial direction), the tire radial direction (hereinafter referred to as the radial direction), and the tire circumferential direction (hereinafter referred to as the circumferential direction).

[0013] As shown in FIGS. 1 and 2, the tire 100 includes a tread 10, a pair of shoulders 11, a pair of sidewalls 12, and a pair of beads 13. The tread 10 is disposed at the center in the axial direction and includes a ground contact surface 10A that contacts the road surface. The tread 10 is composed of, for example, a tread rubber composition made of crosslinked rubber. A plurality of grooves are provided on the outer peripheral surface of the tread 10. The plurality of grooves include a plurality of main grooves 21 extending along the circumferential direction and a plurality of lateral grooves 22 extending in a direction intersecting the main grooves 21. The main grooves 21 are provided for purposes such as draining water, discharging soil, and effectively obtaining propulsion force from a rough road. The plurality of grooves partition a plurality of blocks.

[0014] The shoulders 11, sidewalls 12, and beads 13 are portions that form the side surface of the tire 100 and are provided on both axial sides of the tire 100. The shoulders 11, sidewalls 12, and beads 13 extend radially inward from both axial ends of the tread 10.

[0015] The shoulder 11 is the shoulder portion of the tire 100, projects axially outward from both axial ends of the tread 10, and extends radially inward. The shoulder 11 is provided annularly along the circumferential direction, similar to the tread 10. The ground contact ends (tread ends) E1, E2 of the tire 100 may be defined as the boundary positions between the tread 10 and the shoulder 11. Note that the ground contact ends E1, E2 mean both axial ends of the portion that contacts the ground when the tire 100 is mounted on a regular rim, the internal pressure is adjusted to the regular internal pressure, and a regular load is applied. A recess 40 is formed in the shoulder 11. Details of the recess 40 will be described later.

[0016] The sidewall 12 is present on the tire sidewall and includes the location where the tire 100 bends the most. By bending smoothly, the sidewall 12 plays a role in withstanding impacts or centrifugal forces. The sidewall 12 is disposed between the shoulder 11 and the bead 13 and is composed of an integral sidewall rubber composition. The sidewall 12 protects the carcass 14 and plays a role in preventing its elongation. The sidewall 12 extends radially inward from the shoulder 11 and is provided annularly along the circumferential direction. The sidewall 12 includes the maximum tire width position 12A where the tire 100 protrudes most axially outward and is gently curved so as to be convex toward the outside.

[0017] The bead 13 extends radially inward from the sidewall 12 and is formed annularly along the circumferential direction. The bead 13 is the part fixed to the rim of the wheel and constitutes the inner peripheral portion of the tire 100. The bead 13 is gently curved so as to be convex toward the inside and is located axially inward of the sidewall 12.

[0018] The bead 13 includes a bead core 15 and a bead filler 16. The bead core 15 and the bead filler 16 are provided on both axial sides. The bead core 15 is a ring-shaped member in which bundled steel wires are coated with rubber. Also, the bead filler 16 is composed of hard rubber and has a function of enhancing the rigidity of the bead 13. The bead filler 16 is disposed radially outside of the bead core 15.

[0019] The tire 100 includes a carcass 14 which is a cord layer coated with rubber. The carcass 14 is composed of, for example, two carcass plies and forms a tire skeleton that can withstand loads, impacts, air pressure, etc. The carcass 14 has a radial structure in which carcass cords are arranged in a direction orthogonal to the circumferential direction. The carcass 14 is coated with a plurality of rubber members such as the above tread rubber composition and sidewall rubber composition. The inner liner 17 is a rubber layer for maintaining air pressure and is attached to the inner peripheral surface of the carcass 14.

[0020] The tire 100 includes a belt 18 between a tread 10 and a carcass 14. The belt 18 is a circumferentially stretched reinforcing belt that tightly clamps the carcass 14 to increase the rigidity of the tread 10. The belt 18 has, for example, a two-layer structure in which two steel belts with rubber topping on steel cords are stacked. However, the number of steel belts to be laminated is not limited to two, and instead of the steel belt, a belt including a tire cord using aramid fibers or the like may be used. Furthermore, the belt may be composed of only one layer. By providing the belt 18, the rigidity of the tire 100 can be ensured, and the contact state between the tread 10 and the road surface can be improved.

[0021] The tire 100 includes a belt reinforcing material 19 between the belt 18 and the tread 10. The belt reinforcing material 19 has, for example, a two-layer structure and includes two cap plies. The cap ply is composed of, for example, an insulating organic fiber layer such as a polyamide fiber and is covered with topping rubber. The belt reinforcing material 19 is installed for the purpose of improving durability and reducing road noise during driving. Note that the number of cap plies to be laminated is not limited to two. The belt reinforcing material 19 is arranged in the entire region of the position radially overlapping the tread 10 and a partial region of the shoulder 11 in the axial direction. The outer end 19A of the belt reinforcing material 19 in the axial direction extends axially outside the belt 18.

[0022] The carcass ply constituting the carcass 14 is arranged so as to be spanned over a pair of bead cores 15. The carcass ply is spanned from the inner side in the axial direction over the bead core 15 and is folded back toward the sidewall 12 side so as to wrap the bead core 15 and the bead filler 16. In the example shown in FIG. 1, the ply end 14E, which is the end of the carcass ply, is located on the inner side in the axial direction of each sidewall 12. When the carcass 14 includes two carcass plies, generally, the ply end of the other carcass ply is located at each bead 13.

[0023] The tire 100 is assumed to be used off-road. The sidewall 12 has a side protector 25 on the radially outer side. The side protector 25 is a portion that bulges (protrudes) axially outward in the sidewall 12. The side protector 25 suppresses the main body from being damaged when a foreign object such as a stone flying from the side of the tire collides with the main body while the vehicle is traveling on a rough road.

[0024] As described above, on the outer peripheral surface of the tread 10, a plurality of main grooves 21 extending along the circumferential direction and a plurality of lateral grooves 22 extending in a direction intersecting the main grooves 21 are provided. In the present invention, the patterns and shapes of the main grooves 21 and the lateral grooves 22 are not particularly limited. The main grooves 21 and the lateral grooves 22 partition a plurality of blocks.

[0025] The blocks include a plurality of shoulder blocks 31 formed axially outside the main groove 21 and arranged along the circumferential direction at both axial ends, a plurality of intermediate blocks 32 defining the axially central edge of the main groove 21, and a plurality of center blocks 33 formed axially inside the intermediate blocks 32. In the present invention, the patterns and shapes of the shoulder blocks 31, the intermediate blocks 32, and the center blocks 33 are not particularly limited.

[0026] [Indentation] The indentation 40 is formed in the shoulder 11 as described above. More specifically, the indentation 40 is formed in the shoulder 11 so as to be stepped outward in the tire axial direction from the tread 10 toward the sidewall 12. In other words, the indentation 40 is formed by the radially outer end of the shoulder block 31 being recessed axially inward on the side surface facing the axial direction of the shoulder block 31.

[0027] In this embodiment, shoulder blocks 31 in which recesses 40 are formed and shoulder blocks 31 in which recesses 40 are not formed are alternately formed in the circumferential direction. In other words, when the shoulder 11 is divided into regions partitioned by the transverse grooves 22, a region in which the recess 40 is formed and a region in which the recess 40 is not formed are alternately formed in the circumferential direction.

[0028] Using FIG. 3, the shape of the recess 40 will be described in detail.

[0029] The recess 40 is formed by a first inclined surface 41 facing the outer side in the axial direction and a second inclined surface 42 formed continuously with the first inclined surface 41 and facing the outer side in the radial direction. The first inclined surface 41 and the second inclined surface 42 are formed along the tire circumferential direction in the shoulder block 31 in which the recess 40 is formed.

[0030] Here, when viewed from the circumferential direction (in a cross-sectional view including the radial direction and the axial direction), the angle formed by the first inclined surface 41 and the second inclined surface 42 is defined as the included angle θ1. In this embodiment, the included angle θ1 is 123° to 127°, preferably 124° to 126°. By forming the recess 40 in this way, the air resistance of the tire 100 can be reduced.

[0031] Also, when viewed from the circumferential direction, the distance from the inner end to the outer end in the radial direction of the first inclined surface 41 is defined as the distance D1. In this embodiment, the distance D1 is 8 mm to 17 mm, preferably 9 mm to 15 mm. By forming the recess 40 in this way, it is possible to achieve both reduction of the air resistance of the tire 100 and improvement of the off-road traction performance.

[0032] Furthermore, when viewed from the circumferential direction, the distance from the inner end to the outer end in the axial direction of the second inclined surface 42 is defined as the distance D2. In this embodiment, the distance D2 is 11 mm to 16 mm, preferably 13 mm to 14 mm. By forming the recess 40 in this way, it is possible to achieve both reduction of the air resistance of the tire 100 and improvement of the off-road traction performance.

[0033] Furthermore, when viewed in the circumferential direction, let the inclination angle from the reference line along the radial direction of the second inclined surface 42 be the inclination angle θ2. In this embodiment, the inclination angle θ2 is 73° to 75°, and more preferably, it is 74°. By forming the recess 40 in this way, the air resistance of the tire 100 can be reduced.

[0034] As described above, by forming the recess 40 in the shoulder 11 of the tire 100, it is possible to achieve both the reduction of the air resistance of the tire 100 and the improvement of the off-road traction performance.

[0035] Note that the present invention is not limited to the above-described embodiments and their modifications, and it goes without saying that various changes and improvements can be made within the scope of the matters described in the claims of the present application.

Explanation of Reference Numerals

[0036] 10 Tread, 10A Ground Contact Surface, 11 Shoulder, 12 Sidewall, 12A Tire Maximum Width Position, 13 Bead, 14 Carcass, 14E Ply End, 15 Bead Core, 16 Bead Filler, 17 Inner Liner, 18 Belt, 19 Belt Reinforcement, 19A End, 21 Main Groove, 22 Lateral Groove, 25 Side Protector, 31 Shoulder Block, 32 Intermediate Block, 33 Center Block, 40 Recess, 41 First Inclined Surface, 42 Second Inclined Surface, 100 Tire (Pneumatic Tire), D1 Distance, D2 Distance, E1 Ground Contact End, E2 Ground Contact End, θ1 Clamping Angle, θ2 Inclination Angle

Claims

1. A pneumatic tire having a shoulder, wherein a recess is formed in the shoulder, the recess is formed by a first inclined surface facing outward in the tire axial direction and a second inclined surface formed continuously with the first inclined surface and facing outward in the tire radial direction, the included angle formed by the first inclined surface and the second inclined surface is 123° to 127°, the distance from the inner end to the outer end of the second inclined surface in the tire axial direction is 11 mm to 16 mm, the inclination angle of the second inclined surface from a reference line along the tire radial direction is 73° to 75°, A pneumatic tire.

2. The pneumatic tire according to Claim 1, wherein the distance from the inner end to the outer end of the first inclined surface in the tire radial direction is 8 mm to 17 mm, A pneumatic tire.

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