JPH08132816A - Tire assembly - Google Patents

Abstract

PURPOSE: To reduce road noises by arranging a vibration damping sheet made of a nonwoven fabric entangled with organic fibers having a prescribed specific gravity and a high hysteresis loss on the inner face of a cavity for filling tire air. CONSTITUTION: A pneumatic tire 2 is fitted to a rim 3, a ring-like cavity H for filling tire air is formed, and a vibration damping sheet 4 is arranged on the cavity H face of a tire assembly 1 facing the cavity H. The vibration damping sheet 4 is made of a nonwoven fabric entangled with thermoplastic organic fibers, the apparent specific gravity is 0.02-0.20, and the hysteresis loss (tan δ) at 40 deg.C is 0.05-2.00. The organic fibers having high viscosity and small restoring force at the time of deformation are arranged on the cavity H face, the vibration transmission of the tire assembly 1 itself can be suppressed, and road noises are reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire assembly capable of reducing road noise without impairing fuel efficiency.

[0002]

2. Description of the Related Art In recent years, as the performance of automobiles has improved,
While quietness in a vehicle is strongly desired, demands for low fuel consumption and weight reduction are strict, and therefore, both quietness and low fuel consumption are required.

As the noise caused by the tire, there is known so-called road noise, etc., in which the tire spreads unevenness on the road surface, and this vibration is transmitted to the vehicle through the suspension and becomes a muffled noise in the vehicle interior. However, the peak of the sound pressure level appeared in the frequency range of 80 to 400 Hz, and this was particularly perceived as an unpleasant sound by the tower occupants.

As a main cause of road noise, it has been known that resonance inside the tire cavity causes air in the tire cavity to resonate due to vibration in the tread portion received from the road surface.
Therefore, conventionally, in order to reduce road noise, for example, the tread rigidity is reduced to enhance the envelope effect, and the impact of the tread at the time of ground contact is alleviated.
As shown in JP-A-3-275404, JP-A-64-789024, JP-A-6-40206 and the like, a foamed polyurethane is formed on the inner peripheral surface of the inner liner layer or the outer peripheral surface of the rim facing the tire cavity. It has been proposed to provide a sound absorbing material made of a foam material such as foam rubber to absorb the resonance sound.

[0005]

However, such a conventional one has an insufficient road noise reducing effect, and particularly, one having a reduced tread rigidity increases the rolling resistance of the tire and reduces the fuel efficiency. Induce the problem of doing.

In view of such a situation, the present inventor studied the generation mechanism of road noise. As a result, in the road noise, as shown in FIG. 13, in addition to the peak P1 around 250 Hz caused by the resonance in the cavity, the peak P2 around 80 Hz due to the primary resonance in the tire circumferential direction,
Also, there is a peak P3 around 320 Hz due to secondary resonance in the tire cross-sectional direction, and in order to reduce road noise, in addition to the resonance in the cavity, these circumferential primary resonance and cross-sectional secondary resonance are suppressed. It was found that it is necessary to change the vibration transmission characteristics of the tire.

FIG. 13 shows the results of a tire vibration transmission test (hereinafter referred to as an impact test) using an impact hammer, and FIG. 14 shows the test method.
Here, an assembly A of a tire T and a rim R filled with a standard internal pressure is prepared by using a jig B having a sufficiently high rigidity and an axle portion C.
And the vibration (output) transmitted to the axle portion C is measured by using, for example, a piezoelectric type three-axis load cell E while the tire is supported by the impact hammer D on the tire equator of the tread portion T1. is there.

As shown in FIG. 13, the resonance point is
From the left, the primary resonance in the circumferential direction, the resonance in the cavity, and the secondary resonance in the sectional direction are the primary resonance in the circumferential direction and the secondary resonance in the sectional direction.
It has been found that the damping material that suppresses the vibration of the tire body can be controlled, and the resonance in the cavity can be controlled by the sound absorbing material in the tire cavity.

That is, the present invention is based on disposing a non-woven fabric damping sheet in which organic fibers having a high hysteresis loss are entangled on the inner surface of the tire air-filling cavity (assembly cavity surface). An object of the present invention is to provide a tire assembly capable of suppressing circumferential primary resonance, intracavity resonance, and sectional secondary resonance and reducing road noise.

[0010]

In order to achieve the above-mentioned object, a tire assembly of the present invention comprises a tread portion, a side wall portion extending inward in the radial direction from both ends of the tread portion, and a radially inner end of each side wall portion. A pneumatic tire having a bead portion located at a rim is mounted on a rim to form a cavity for tire air filling, and the assembly cavity surface facing the cavity of the tire assembly has a thermoplastic A damping sheet made of a nonwoven fabric in which organic fibers are intertwined is arranged, the damping sheet has an apparent specific gravity of 0.02 to 0.20, and the organic fiber has a hysteresis loss (tan δ) at 40 ° C. ) Is set to 0.05 to 2.00.

The vibration damping sheet has at least one of a region corresponding to a tread portion, a region corresponding to a sidewall portion, a region corresponding to a bead portion, or a region corresponding to a rim portion of the cavity surface of the assembly. , The apparent specific gravity is in the range of 0.03 to 0.06, and the thickness is 5
It is preferably less than 0 mm. Further, the organic fiber is preferably a triblock copolymer in which polystyrene and vinylated polyisoprene are bonded.

[0012]

A damping sheet is provided on the inner surface of the assembly cavity, which is the inner surface of the cavity for filling the tire air.

Since the vibration damping sheet is formed of a non-woven fabric in which thermoplastic organic fibers are entangled with each other, air can be wrapped between the fibers and the void ratio can be increased as compared with the foam material. Further, since the bubbles of the foam material are independent of each other, the voids of the non-woven fabric are electrically connected to each other, so that the sound absorbing effect is extremely large and the resonance in the cavity can be effectively suppressed.

The organic fiber used for the vibration damping sheet is made of a viscoelastic body having a high hysteresis loss (tan δ) and its value is 0.05 to 2.00. That is, the organic fiber has a high viscosity and a small restoring force upon deformation,
Therefore, by being arranged on the cavity surface of the assembly, it is possible to suppress the vibration transmission of the tire assembly itself, and particularly to reduce the circumferential primary resonance and the cross sectional secondary resonance. The road noise can be effectively reduced by having both the sound absorbing effect and the vibration damping effect.

The damping sheet has an apparent specific gravity of 0.0.
When it is less than 2, the sound absorbing effect is not sufficiently exerted, and it is 0.20.
When it is larger, the tire weight is increased to deteriorate rolling resistance and fuel consumption performance, and unbalance is generated to reduce uniformity. Therefore, preferably 0.
It is in the range of 03 to 0.06.

The damping sheet has a hysteresis loss of 0.
If it is less than 05, the vibration damping effect cannot be obtained, and if it exceeds 2.00, heat generation is intense and fuel efficiency is impaired.

As such an organic fiber, a styrene-vinylated isoprene-based triblock copolymer in which polystyrene and vinylated polyisoprene are bonded can be used.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, a tire assembly 1 of the present invention has a pneumatic tire 2 mounted on a rim 3 to form an annular cavity H for tire air filling, and a set facing the cavity H. The vibration damping sheet 4 is arranged on the solid cavity surface 1S.

The rim 3 has rim flanges 3C for receiving side surfaces of the bead portion 7 via rim sheets 3B on which the bead portion 7 of the tire 2 is seated, on both side edges of a cylindrical rim body 3A having a well portion. It projects radially outward.

The pneumatic tire 2 is, in this example,
A radial tire for a passenger vehicle, comprising a tread portion 5,
Sidewalls 6 extending radially inward from both ends
And a bead portion 7 located at the radially inner end of each side wall portion 6 to form a toroidal shape. By fitting the bead portion 7 on the rim seat 3B, the pneumatic tire 2 is It is attached to 3.

Further, the pneumatic tire 2 has the tread portion 5
From the inside to the outside of the bead core 11 of the bead portion 7 at both ends of the main body portion 10A extending from the side wall portion 6 to the bead portion 7.
A carcass 10 provided with B and a belt layer 12 arranged radially outside of the carcass 10 and inside the tread portion 5.
And the body portion 10A and the folded portion 1 of the carcass 10.
0B, and a bead apex rubber 13 having a triangular cross-section that rises from the bead core 11 outward in the radial direction.

The carcass 10 is a carcass cord made of organic fibers such as polyester, nylon, rayon, and aromatic polyamide. In this embodiment, the tire equator CO
Is formed from at least one carcass ply arranged at an angle of 70 to 90 degrees, in this example, one carcass ply.
In addition, the carcass 10 cooperates with the bead apex rubber 13 by terminating the upper end of the folded-back portion 10B near the tire maximum width position to reinforce the bead portion 7 to the side wall portion 6 and enhance the tire lateral rigidity. ing.

The belt layer 12 is made of the polyester,
Belt cords made of organic fiber cords such as nylon, rayon and aromatic polyamide or steel cords arranged at an angle of 10 to 30 degrees with respect to the tire equator CO, and in this example, two belt plies 12A. , 12B
The plies are arranged in different orientations so that the belt cords intersect each other between the plies.

In the present invention, the damping sheet 4 is provided on the assembly cavity surface 1S facing the cavity H for tire air filling.
Is arranged.

The assembly cavity surface 1S is composed of a tire-side cavity surface which is the inner peripheral surface of the pneumatic tire 2 and a rim-side cavity surface which is the outer peripheral surface of the rim body 3A. The cavity surface on the rim side constitutes a region Y1 corresponding to the rim portion of the assembly cavity surface 1S. The hollow surface on the tire side is divided into a region Y2 corresponding to the tread portion 5, a region Y3 corresponding to the sidewall portion 6, and a region Y4 corresponding to the bead portion 7.

Further, in the present example, the damping sheet 4 arranged on the cavity surface 1S of the assembly includes the damping sheet 4A for tread arranged in the area Y2 and the damping sheet for sidewalls arranged in the area Y3. The vibration sheet 4B is included.

The tread damping sheet 4A is shown in FIG.
As shown in (A), a rectangular shape, in this example, a horizontally long rectangular shape, and as shown in FIG.
The short sides are faced to each other and are attached substantially uniformly over the entire circumference of the region Y2.

The side wall vibration damping sheet 4B is
As shown in FIG. 2B, it has a rectangular shape, in this example, a trapezoidal shape, and as shown in FIG.
The side sides thereof are opposed to each other and are attached substantially uniformly over the entire circumference of the region Y3 in the circumferential direction.

The vibration damping sheets 4A and 4A and the vibration damping sheets 4B and 4B can be arranged not only in close proximity but also in a large distance. It is preferable to distribute over 50% or more. Further, it is preferable that the vibration damping sheets 4A and 4B have at least a gap Q of 10 mm or more in the radial direction so as not to become a resistance when the tire is deformed.

Each damping sheet 4 can be formed in various shapes and sizes according to the tire shape, tire size, etc. FIG. 5A shows the damping sheet 4C for beads used in the region Y4. FIG. 5B is a schematic view showing an example of the rim damping sheet 4D used for the region Y1.

Each damping sheet 4 is composed of a non-woven fabric 15 having a thickness t of less than 50 mm, more preferably 5 to 30 mm. The non-woven fabric 15 is formed by intertwining organic fibers 16 having viscoelasticity. are doing. The thickness t is 50
If it is more than mm, the weight of the vibration damping sheet 4 becomes too heavy,
Aggravates rolling resistance. Further, as the organic fiber 16 having such viscoelasticity, as shown in the structural conceptual diagram of FIG. 6, a plurality of hard parts 20 among the block copolymers composed of blocks of the hard part 20 and the soft part 21 are used. A styrene-based elastomer that is a triblock copolymer that is connected via the soft part 21 can be used.
By setting the glass transition temperature of 1 in the room temperature region, a large hysteresis loss (tan δ) is exhibited near room temperature, as shown in FIG. 7. This includes, for example, the hard part 20 made of polystyrene and the soft part 2
There is a styrene-vinylated isoprene-based triblock copolymer (trademark: Hybler, manufactured by Kuraray) 1 in which vinylated polyisoprene is used, and the molecules of the hard part and the soft part are shown in FIGS. An outline of the structure is shown.

Further, such organic fibers 16 are entwined with each other to form the non-woven fabric 15, and the non-woven fabric is formed by a melt blow method,
And the melt spinning method. The melt-blowing method is a method in which a molten polymer is blown out from a large number of nozzles together with high-speed air to form a nonwoven fabric, and fine fibers can be formed. In the melt spinning method, a polymer is spun into a fiber and then processed into a non-woven fabric, and a high strength is obtained.

The apparent specific gravity of the nonwoven fabric 15 is 0.
Hysteresis loss (tan δ) at 40 ° C. of the organic fiber 16 used in the range of 02 to 0.20.
Is in the range of 0.05 to 2.00. The value of the hysteresis loss (tan δ) is a value measured at 110 Hz with a viscoelasticity measuring instrument (Rheovibron).

As described above, since the organic fiber 16 is a viscoelastic body having a high hysteresis loss (tan δ), the restoring force upon deformation is small and an excellent vibration damping effect can be exhibited. It should be noted that, as shown in FIGS. 9A and 9B showing the vibration damping curves of the composite in which the non-woven fabric 15 is impregnated with the epoxy resin and the epoxy resin alone, the non-woven fabric 15 exhibits excellent vibration damping properties. I understand.

The nonwoven fabric 15 has a large void ratio of the air wrapped between the organic fibers 16, and the voids are electrically connected to each other. Therefore, the sound absorbing effect is extremely large such that the sound absorbing is exerted over the entire thickness, and the resonance in the cavity can be effectively suppressed. When the apparent specific gravity is less than 0.02, the sound absorbing effect is not sufficiently exerted, and when it is more than 0.20, the tire weight is unnecessarily increased to deteriorate the rolling resistance and the fuel efficiency. Causing an imbalance,
Reduce uniformity. Therefore, preferably,
It is in the range of 0.03 to 0.06.

The hysteresis loss (tan δ) is 0.05
If it is less than 2.00, the vibration damping effect cannot be obtained, and if it exceeds 2.00, heat generation becomes intense and fuel efficiency is impaired. The damping sheet may be arranged only in each of the areas Y1, Y2, Y3, and Y4 as shown in FIGS. 10A to 10D, or may be arranged in a plurality of areas.

[0037]

[Specific example] The tire size of the structure shown in FIG. 1 is 195/6.
A 5R14 tire was prototyped based on the specifications shown in Table 1. In addition, the rolling resistance of the sample tire was measured and
Comparison is made with an index of 0, and the vibration transmission characteristics of each sample tire in the impact test are shown in FIG.
12 (D) and FIGS. 12 (A) to 12 (C).

[0038]

[Table 1]

[0039]

As described above, the tire assembly of the present invention has a non-woven fabric vibration damping sheet in which organic fibers having high hysteresis loss are entangled with each other on the cavity surface of the assembly. Road noise can be effectively reduced without damaging it.

[Brief description of drawings]

FIG. 1 is a meridional sectional view of a tire assembly showing an embodiment of the present invention.

FIG. 2A is a perspective view showing an example of a vibration damping sheet for a tread. (B) is a perspective view showing an example of a vibration damping sheet for sidewalls.

FIG. 3 is a schematic perspective view showing an example of an arrangement state of a tread vibration damping sheet.

FIG. 4 is a schematic side view showing an example of an arrangement state of a side wall vibration damping sheet.

FIG. 5A is a plan view showing an example of a bead damping sheet. (B) is a plan view showing an example of a vibration damping sheet for rims.

FIG. 6 is a structural conceptual diagram illustrating a molecular structure of an organic fiber.

FIG. 7 is a diagram showing a relationship between temperature of organic fiber and hysteresis loss.

FIG. 8A is a schematic view showing a molecular structure of a hard portion of an organic fiber. (B) is a schematic diagram showing a molecular structure of a soft portion of an organic fiber.

9A and 9B are diagrams illustrating the damping effect of the damping sheet.

10 (A) to (D) are schematic cross-sectional views showing the positions of the damping sheets in the sample tires of Table 1.

11 (A) to (D) are diagrams showing vibration characteristics of sample tires shown in Table 1. FIG.

12 (A) to (C) are diagrams showing vibration characteristics of sample tires shown in Table 1. FIG.

FIG. 13 is a diagram showing vibration characteristics of a conventional tire.

FIG. 14 is a diagram illustrating an impact test.

[Explanation of symbols]

 1S Assembly cavity surface 2 Pneumatic tire 3 Rim 4, 4A, 4B, 4C, 4D Vibration damping sheet 5 Tread portion 6 Side wall portion 7 Bead portion 15 Nonwoven fabric 16 Organic fiber H cavity

Claims (5)

[Claims] 1. A pneumatic tire comprising a tread portion, a side wall portion extending inward in the radial direction from both ends thereof, and a bead portion located at an inner end in the radial direction of each side wall portion is mounted on a rim. A damping sheet made of a non-woven fabric in which thermoplastic organic fibers are entangled with each other is provided on the cavity surface of the tire assembly that forms the cavity for filling the tire with The tire assembly, wherein the vibrating sheet has an apparent specific gravity of 0.02 to 0.20, and the organic fiber has a hysteresis loss (tan δ) at 40 ° C. of 0.05 to 2.00. . 2. The damping sheet has an apparent specific gravity of 0.0.
The tire assembly according to claim 1, wherein the tire assembly is 3 to 0.06. 3. The tire assembly according to claim 1, wherein the organic fiber is a triblock copolymer in which polystyrene and vinylated polyisoprene are bonded. 4. The damping sheet is one of a region corresponding to the tread portion, a region corresponding to a sidewall portion, a region corresponding to a bead portion, or a region corresponding to a rim portion of the cavity surface of the assembly. The tire assembly according to claim 1, wherein the tire assembly is arranged in the above region. 5. The tire assembly according to claim 1, wherein the vibration damping sheet has a thickness of less than 50 mm.