JP7704522B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire equipped with sound-damping material.

When a pneumatic tire is fitted to a vehicle, cavity resonance occurs due to the air inside the tire as the vehicle moves. The sound generated by tire cavity resonance is transmitted to the vehicle and becomes noise inside the vehicle cabin, so measures have been taken to reduce tire cavity resonance.

Patent Document 1 discloses a pneumatic tire with sound-damping material, which comprises a toroidal pneumatic tire and a sound-damping material made of a sponge material that is fixed to the inner surface of the tire and extends in the tire circumferential direction. The pneumatic tire with sound-damping material has a plurality of ridges formed on the inner surface of the tire by a bladder during vulcanization. The ridges include a first ridge that extends through a fixing region Y where the sound-damping device is fixed to the inner surface. Patent Document 1 describes that the fixing region is composed of a smooth central region where no ridges are formed and uneven regions on both sides of the central region where only the first ridges are provided, and that the central region has a width that is 20% or more and less than 100% of the fixing region.

JP 2019-73246 A

Patent Document 1 does not disclose the percentage of the adhesive area that the protrusions formed by the bladder occupy. If there are protrusions within the adhesive area, the thickness of the adhesive layer becomes smaller in the protrusion area, reducing the adhesive strength and causing insufficient adhesion.

The present invention was made in consideration of these circumstances, and its purpose is to provide a pneumatic tire that can suppress insufficient adhesion of the sound-damping material to the tire inner surface.

One aspect of the present invention is a pneumatic tire. The pneumatic tire comprises a tire body and a sound-damping material attached to the inner surface of the tire body by an adhesive, the tire body having a convex ridge formed by pressing a bladder against the inner surface during molding, and the ratio of the area where the adhesive and the ridge overlap to the area where the adhesive is disposed is 30% or less.

The present invention makes it possible to prevent insufficient adhesion of the sound-damping material to the tire inner cavity surface.

1 is a cross-sectional view showing a longitudinal section of a pneumatic tire equipped with a noise-damping material according to an embodiment. FIG. 2 is a perspective view showing the appearance of the sound-damping material when disposed in the tire cavity. FIG. 2 is a cross-sectional view showing a longitudinal section of a tire body and an adhesive body. 4 is a cross-sectional view of the pneumatic tire taken along line AA shown in FIG. 3. FIG. 4 is an enlarged view of a central portion in the tire width direction in FIG. 3 . 6(a) and 6(b) are schematic diagrams for explaining an adhesive body according to a modified example. 7(a) and 7(b) are schematic diagrams for explaining an adhesive body according to another modified example.

The present invention will be described below based on a preferred embodiment with reference to Figures 1 to 7. The same or equivalent components and parts shown in each drawing are given the same reference numerals, and duplicated explanations will be omitted as appropriate. Furthermore, the dimensions of the parts in each drawing are enlarged or reduced as appropriate to facilitate understanding. Furthermore, some of the parts that are not important for explaining the embodiment are omitted in each drawing.

(Embodiment)
1 is a cross-sectional view showing a longitudinal section of a pneumatic tire 1 including a noise-damping material 30 according to an embodiment. The pneumatic tire 1 includes a tire body 10, a wheel 20, the noise-damping material 30, and an adhesive body 40. The tire body 10 comes into contact with the ground via a tread portion 11 formed in a ring shape. Side portions 12 are provided continuously to both ends of the tread portion 11 in the axial direction (the tire width direction), and bead portions 13 are formed at the ends of the side portions 12 on the wheel 20 side.

A wheel 20 is fitted to the center of the tire body 10. The wheel 20 supports a cylindrical rim portion 23 with a disk portion 22 extending radially from a hub portion 21 that connects the axle. The bead portion 13 of the tire body 10 is fitted to the rim portion 23. The tire cavity 14 surrounded by the tire body 10 and the rim portion 23 is filled with air.

The sound-damping material 30 is attached to the tire cavity surface 14a, which is the surface of the tread portion 11 on the tire cavity 14 side, by an adhesive 40. The sound-damping material 30 is a sponge formed of a foam material, and is an open-cell body having a large number of pores and having air permeability to the outside air. The sound-damping material 30 is made of, for example, soft urethane foam, and from the viewpoint of weight balance in the pneumatic tire 1, it is preferable that the density of the sound-damping material 30 is 60 kg/m ³ or less, and more preferably 40 kg/m ³ or less. In addition, from the viewpoint of durability, it is preferable that the sound-damping material 30 has a tensile strength of 30 kPa or more and a tear strength of 2.0 N/cm or more (JIS K 6400-5). The sound-damping material 30 is arranged in a ring shape on the tire cavity surface 14a with at least one member. The sound-damping material 30 may be configured to be a ring with two or more members.

Figure 2 is a perspective view showing the appearance of the sound-damping material 30 when it is disposed in the tire cavity 14. As described above, the sound-damping material 30 is ring-shaped when it is disposed on the tire cavity surface 14a. Figure 2 also shows an adhesive 40 for attaching the sound-damping material 30 to the tire cavity surface 14a. After the adhesive 40 is applied to the tire cavity surface 14a, the sound-damping material 30 is attached by pressing it against the tire cavity surface 14a.

The adhesive 40 is formed in a line extending in the circumferential direction and applied to the tire cavity surface 14a in a ring shape as a whole, and three adhesives 40 are provided in FIG. 2. The number of adhesives 40 is not limited to the three shown in the figure, and may be two or more. The outer peripheral surface 32 of the sound-damping material 30 is attached to the tire cavity surface 14a by the adhesive 40, and the inner peripheral surface 31 faces the tire cavity 14. For the adhesive 40, it is preferable to use an adhesive with a viscosity of 300 Pa.s (Brookfield viscosity at 25°C and 20 rpm, the same applies below) or more and 400 Pa.s or less, for example, 340 Pa.s. The viscosity range of the adhesive 40 is not limited to this example.

Before being placed in the tire cavity 14, the sound-damping material 30 is in the form of a long, thin plate, which is deformed into a ring shape and attached to the tire cavity surface 14a. When the sound-damping material 30 is attached to the tire cavity surface 14a, both ends in the circumferential direction of the sound-damping material 30 are butted together, and are preferably joined by an adhesive 41 to prevent wear due to rubbing between the ends.

3 is a cross-sectional view showing a longitudinal section of the tire body 10 and the adhesive body 40. The tire cavity surface 14a of the tire body 10 is formed with a rib portion 50 by pressing a bladder against the tire cavity surface 14a during molding. The rib portion 50 is formed in a convex shape. In the example shown in FIG. 3, the rib portion 50 is provided so as to extend in a direction inclined with respect to the circumferential direction, and is formed on both sides of the axial center of the tire body 10. The rib portion 50 extends outward from a position close to the axial center of the tire body 10, and is formed to the bead portion 13. The rib portion 50 may also be provided so as to extend in a direction perpendicular to the circumferential direction. The adhesive body 40 extends in the circumferential direction as described above, and intersects with the rib portion 50.

Figure 4 is a cross-sectional view of the pneumatic tire 1 taken along line A-A in Figure 3. Figure 4 shows cross sections of the tire body 10, the noise-damping material 30, and the adhesive body 40. Line A-A in Figure 3 is a line segment extending in the circumferential direction at a position including the adhesive body 40.

As shown in FIG. 4, the adhesive 40 is applied to the convex rib portions 50 and between the rib portions 50, and adheres and fixes the sound-damping material 30 to the tire cavity surface 14a. The thickness of the adhesive 40 is thinner at the convex rib portions 50 and thicker between the rib portions 50. Since the adhesive strength is low at the rib portions 50 where the adhesive 40 is thin, the ratio of the area where the adhesive 40 and the rib portions 50 overlap to the area of the area where the adhesive 40 is arranged is set to a predetermined value or less (30% or less).

Figure 5 is an enlarged view of the center in the tire width direction in Figure 3. The areas of the three adhesive bodies 40 are SA1, SA2, and SA3. Area SA1 is for the adhesive body 40 that is located in the center in the tire width direction among the three adhesive bodies 40. The areas of the areas where the adhesive body 40 and the rib portion 50 overlap in each of the three adhesive bodies 40 are SB1, SB2, and SB3. As shown in Figure 3, since no rib portion 50 is formed in the center in the tire width direction, area SB1 is 0. Areas SB1, SB2, and SB3 are the sum of the areas of multiple areas where the adhesive body 40 and the rib portion 50 overlap all around the circumference.

When the adhesive body 40 is viewed as a whole, the ratio of the area where the adhesive body 40 and the ridge portion 50 overlap with respect to the area of the area where the adhesive body 40 is arranged satisfies the following formula.
100×(SB1+SB2+SB3)/(SA1+SA2+SA3)≦30[%]...(1)

By arranging the adhesive 40 so as to satisfy the formula (1), the adhesive strength of the adhesive 40 as a whole can be set to a desired value or more. In addition, focusing on the portion of the adhesive 40 that is continuous as a region, the following formula is satisfied.
100 × SB1/SA1≦30 [%] … (2)
100 × SB2 / SA2 ≦ 30 [%] ... (3)
100× SB3 / SA3 ≦30[%]...(4)

By arranging the adhesive 40 so as to satisfy formulas (2) to (4), the adhesive strength of each part of the adhesive 40 that is continuous as a region can be set to a desired value or higher. Furthermore, it is preferable that the ratio of the area of the region where the adhesive 40 and the ridge portion 50 overlap with respect to the area of the region where the adhesive 40 is arranged is 20% or less, in which case the right-hand side of each of formulas (1) to (4) is 20%.

Next, the operation of the pneumatic tire 1 will be explained, focusing on the noise-damping material 30 and the adhesive 40. When a vehicle equipped with the pneumatic tire 1 is running, cavity resonance generated in the tire cavity 14 is absorbed by the noise-damping material 30 and dissipated as thermal energy, thereby reducing noise in the pneumatic tire 1.

As shown in the above formula (1), the pneumatic tire 1 can suppress insufficient adhesion overall by setting the ratio of the area of the overlapping area of the adhesive body 40 and the ridge portion 50 to the area of the area where the adhesive body 40 is arranged to 30% or less when viewed as a whole of the adhesive body 40. Also, as shown in the above formulas (2) to (4), the pneumatic tire 1 can suppress insufficient adhesion overall by setting the ratio of the area of the overlapping area of the adhesive body 40 and the ridge portion 50 to the area of the area where the adhesive body 40 is arranged to 30% or less for each part of the adhesive body 40 that is continuous as an area.

In the pneumatic tire 1, the adhesive body 40 is arranged in a line extending in the circumferential direction of the tire body 10, which simplifies the process of applying the adhesive as the adhesive body 40 and reduces the impact on the tire weight.

The pneumatic tire 1 is formed so that the convex rib portion 50 extends in a direction intersecting the circumferential direction of the tire body 10. In the pneumatic tire 1, a plurality of convex rib portions 50 are formed in the circumferential direction of the tire body 10, and the adhesive body 40 is formed to extend in the circumferential direction, so that the adhesive body 40 and the plurality of rib portions 50 intersect with each other. As shown in the above formula (1) or formulas (2) to (4), the pneumatic tire 1 can suppress insufficient adhesion by setting the ratio of the area of the area where the adhesive body 40 and the rib portion 50 overlap to the area of the area where the adhesive body 40 is arranged to 30% or less.

(Modification)
6(a) and 6(b) are schematic diagrams for explaining an adhesive body 40 according to a modified example. 6(a) and 6(b) correspond to external views of the tire cavity surface 14a viewed from the tire cavity 14. In FIG. 6(a), the adhesive body 40 is applied narrowly in the center in the tire width direction, and applied broadly on both sides, thereby preventing the sound-damping material 30 from peeling off at both side portions in the tire width direction. In FIG. 6(b), the adhesive body 40 is applied broadly and generally evenly in the tire width direction, thereby increasing the adhesive strength of the sound-damping material 30.

Even for the arrangement of the adhesive body 40 shown in Figures 6(a) and 6(b), by satisfying the above formula (1) or formulas (2) to (4), it is possible to suppress insufficient adhesion of the sound-damping material 30 in the pneumatic tire 1.

7(a) and 7(b) are schematic diagrams for explaining an adhesive body 40 according to another modified example. 7(a) and 7(b) correspond to external views of the tire cavity surface 14a as viewed from the tire cavity 14. In FIG. 7(a), the adhesive body 40 is formed in a line shape that is inclined with respect to the circumferential direction. The line of the adhesive body 40 may be inclined in the same direction as the convex ridge portion 50 so as not to intersect with the ridge portion 50, or may be inclined in the opposite direction to the convex ridge portion 50 so as to intersect with the ridge portion 50. In FIG. 7(b), the adhesive body 40 is formed in a wave shape that goes back and forth on both sides in the tire width direction, so that the sound-damping material 30 can be attached evenly in the tire width direction all around.

Even for the arrangement of the adhesive body 40 shown in Figures 7(a) and 7(b), by satisfying the above formula (1) or formulas (2) to (4), it is possible to suppress insufficient adhesion of the sound-damping material 30 in the pneumatic tire 1.

Next, features of the pneumatic tire 1 according to the embodiment and the modified example will be described.
The pneumatic tire 1 includes a tire body 10 and a noise-damping material 30. The noise-damping material 30 is attached to the tire cavity surface 14a of the tire body 10 by an adhesive 40. The tire body 10 has a convex ridge portion 50 formed by pressing a bladder against the tire cavity surface 14a during molding. The ratio of the area of the region where the adhesive 40 and the ridge portion 50 overlap with respect to the area of the region where the adhesive 40 is arranged is 30% or less. As a result, the pneumatic tire 1 can suppress insufficient adhesion by setting the area of the region where the adhesive 40 and the ridge portion 50 overlap to a predetermined ratio or less.

The adhesive body 40 is formed in a linear shape that extends in the circumferential direction. This allows the pneumatic tire 1 to simplify the adhesive application process for the adhesive body 40 and reduce the impact on the tire weight.

The convex rib portion 50 is formed to extend in a direction intersecting the circumferential direction of the tire body 10. As a result, in the pneumatic tire 1, the adhesive body 40 is formed to extend in the circumferential direction, so that the adhesive body 40 and the multiple rib portions 50 intersect, but by setting the area of the overlapping region between the adhesive body 40 and the rib portions 50 to a predetermined ratio or less, insufficient adhesion can be suppressed.

The above describes the embodiments of the present invention. These embodiments are illustrative, and it will be understood by those skilled in the art that various modifications and changes are possible within the scope of the claims of the present invention, and that such modifications and changes are also within the scope of the claims of the present invention. Therefore, the descriptions and drawings in this specification should be treated as illustrative rather than restrictive.

1 pneumatic tire, 10 tire body, 14a tire inner cavity surface (inner cavity surface),
30 Sound damping material, 40 Adhesive body, 50 Strip section.

Claims (3)

The tire body,
A noise-damping material attached to an inner cavity surface of the tire body by an adhesive;
Equipped with
The tire body has a convex ridge formed by pressing a bladder against the inner cavity surface during molding,
The adhesive body is provided in a line extending in a circumferential direction, the number of the adhesive bodies is two or more, and the adhesive bodies are arranged at intervals in the tire width direction,
A pneumatic tire characterized in that, for each of the plurality of adhesive bodies, the ratio of an area where the adhesive body overlaps with the ridge portion to an area where the adhesive body is arranged is 30% or less. The pneumatic tire according to claim 1, characterized in that three or more of the adhesive bodies are provided, at least one of the adhesive bodies is applied to an area in the center in the tire width direction where the rib portion is not formed, and at least one of the adhesive bodies is applied to each of the areas on both sides in the tire width direction where the rib portion is formed. The pneumatic tire according to claim 2, characterized in that the width of the adhesive applied to the region on both sides in the tire width direction where the rib is formed is wider than the width of the adhesive applied to the region in the center in the tire width direction where the rib is not formed.

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