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JP-7857186-B2 - pneumatic tires

JP7857186B2JP 7857186 B2JP7857186 B2JP 7857186B2JP-7857186-B2

Inventors

  • 中村 昌

Assignees

  • ＴＯＹＯ ＴＩＲＥ株式会社

Dates

Publication Date
20260512
Application Date
20220818

Claims (4)

  1. Multiple landmasses forming the contact surface, The tire sidewall, which is the outer surface of the sidewall, The device comprises a narrow groove extending inward along the tire radial direction and continuously along the tire circumferential direction from the contact surface of the land, which is the land furthest outward in the tire axial direction among the plurality of land, Of the aforementioned plurality of landmasses, the landmass furthest outward in the tire axial direction is divided by the narrow groove into a landmass body and a sacrificial rib located further outward in the tire axial direction than the landmass body and including the edge of the contact surface. The sacrificial rib comprises a first annular groove extending from the tire sidewall surface along the tire radial direction and continuously along the tire circumferential direction, and a second annular groove extending from the tire sidewall surface along the tire axial direction and continuously along the tire circumferential direction. The first annular groove is provided radially outward of the tire from the split position between the tread mold that forms the tread and the side mold that forms the sidewall. The second annular groove is provided inward in the tire radial direction from the split position, A pneumatic tire in which the inclination angle of the center line of the first annular groove with respect to the tire's radial direction is 30 degrees or less.
  2. The pneumatic tire according to claim 1, wherein the inclination angle of the center line of the second annular groove with respect to the tire axis is -30 degrees or more and 30 degrees or less.
  3. The tread is equipped with multiple belt plies embedded in it. The pneumatic tire according to claim 1, wherein the second annular groove is provided radially outward of the belt end of the plurality of belt plies that is furthest outward in the tire axial direction.
  4. The pneumatic tire according to any one of claims 1 to 3, wherein the second annular groove extends further inward in the tire axial direction than the side wall surface of the narrow groove on the tire axial direction side.

Description

This disclosure relates to pneumatic tires. It is known that pneumatic tires used on trucks and buses tend to experience stress concentration at the edges of the contact patch during driving, leading to wear and tear on the contact patch. Patent Document 1 discloses a pneumatic tire in which a sacrificial rib is formed on the axial side of the shoulder ridge by providing a groove extending inward from the contact surface in the tire radial direction. By providing this sacrificial rib, stress concentration during driving is dispersed, thereby suppressing wear on the shoulder ridge excluding the sacrificial rib. The sacrificial rib is provided with an annular groove extending from the outer surface in the tire axial direction to the inner surface in the tire axial direction. This annular groove distributes the force applied to the sacrificial rib. Incidentally, the annular groove in question is located radially outward from the split point between the tread mold forming the tread and the side mold forming the sidewall, resulting in poor release of the tread mold from the mold. Japanese Patent Publication No. 2019-147541 A tire meridian cross-sectional view showing the main parts of a pneumatic tire according to one embodiment.Side view of the pneumatic tire of the same embodimentEnlarged view of area III in Figure 1 The pneumatic tire 1 of this disclosure will be described below with reference to the drawings. In the drawings, "CD" represents the circumferential direction of the tire, "AD" represents the axial direction of the tire, and "RD" represents the radial direction of the tire. Each drawing shows the shape of a new tire. As shown in Figures 1 and 2, the pneumatic tire 1 (hereinafter simply referred to as "tire 1") comprises a pair of beads (not shown), sidewalls 2 extending radially outward RD1 from each bead, and a tread 3 connecting the radially outward RD1 ends of the sidewalls 2. The bead is provided with an annular bead core (not shown) made of a converging body such as steel wire covered in rubber, and a bead filler (not shown) made of hard rubber. The bead is mounted on the bead seat of the rim (not shown), and if the air pressure is a predetermined pressure (for example, the air pressure specified by JATMA), the tire's internal pressure properly fits it to the rim flange, and the tire 1 is fitted onto the rim. The tire 1 comprises a toroidal carcass 4 extending from the tread 3 through the sidewall 2 to the bead. The carcass 4 is positioned between a pair of beads, and its ends are secured by being wound up via the bead core. An inner liner rubber 5 is provided on the inner circumference of the carcass 4 to maintain air pressure. On the outer radial side RD1 of the carcass 4, multiple belt prisms 6a, 6b, 6c, and 6d (four in this embodiment) for reinforcing the carcass 4, and the tread rubber 30 are provided sequentially from the inside to the outside of the tire radial RD. The multiple belt prisms 6a, 6b, 6c, and 6d are provided between the carcass 4 and the tread rubber 30. The multiple belt prisms 6a, 6b, 6c, and 6d are provided between the contact surface 33 formed by the tread rubber 30 and the carcass 4. On the outer surface of the tread 3, multiple main grooves 31 extending along the tire circumferential direction CD and land 32 partitioned by the main grooves 31 and continuous with the tire circumferential direction CD are formed. Since the tire 1 according to this embodiment is a rib tire, the land 32 is not divided in the tire circumferential direction CD (no blocks are formed). In this embodiment, the tire 1 has two main grooves 31 formed on one side of the tire 1, and has a total of four main grooves 31. Note that tire 1 is not limited to the above; for example, it may have two or three main grooves in total, or it may have five or more main grooves. Multiple landforms 32 are separated by main grooves 31. In this embodiment, the multiple landforms 32 are shoulder landforms 32a, quarter landforms 32b, and center landforms 32c, but are not limited to these. The number of landforms 32 can be changed as appropriate. The center landform 32c is the landform closest to the tire equatorial plane CL. The shoulder landform 32a is the landform formed in the tire axial direction AD1 further outward than the main groove 31 that is furthest outward in the tire axial direction AD1 among the multiple main grooves 31. That is, the shoulder landform 32a is the landform furthest outward in the tire axial direction AD1 among the multiple landforms 32. The quarter landform 32b is the landform provided between the shoulder landform 32a and the center landform 32c. Depending on the number of main grooves 31, the quarter landform 32b may be omitted. The four belt plies 6a, 6b, 6c, and 6d each contain multiple steel cords arranged in a curtain-like parallel pattern, which are then covered with rubber. Of the four belt plies 6a, 6b, 6c, and 6d, the cords of the second and third belt plies 6b and 6c, which ex