JP5499569B2 - Tire noise reduction device and pneumatic tire provided with the same - Google Patents

Description

  The present invention relates to an apparatus for reducing cavity resonance generated in a pneumatic tire and a pneumatic tire including the same, and more specifically, a sound absorbing material made of a plurality of porous materials is used as a tread portion of the pneumatic tire. Tire noise reduction device which can be arranged on the inner surface of the tire intermittently along the tire circumferential direction and can effectively reduce the occurrence of body vibration even when the number of sound absorbing materials on the circumference is reduced And a pneumatic tire including the same.

  In a pneumatic tire, one of the causes for generating noise is cavity resonance sound caused by vibration of air filled in the tire. The cavity resonance sound is generated when the tread portion vibrates due to road surface irregularities when the tire rolls, and the vibration of the tread portion vibrates the air inside the tire.

  As a technique for reducing noise due to such a cavity resonance phenomenon, it has been proposed to install a sound absorbing material made of a porous material on the inner surface of a tread portion of a pneumatic tire (see, for example, Patent Document 1). Here, when the band-shaped sound absorbing material is continuously arranged over the entire circumference on the inner surface of the tread portion of the pneumatic tire, the sound absorbing material is particularly at each tire rotation at a portion where both ends of the sound absorbing material in the tire circumferential direction are connected to each other. Since the stress generated by the compression and expansion of the material acts repeatedly, there is a drawback that the portion is easily broken due to the stress concentration. In addition, when the sound absorbing material is divided in the tire circumferential direction and a plurality of divided sound absorbing materials are intermittently arranged on the inner surface of the tread portion, the stress generated in the sound absorbing material is reduced, so that the durability of the tire noise reduction device is reduced. It is possible to improve.

  However, when the number of divided sound absorbing materials is small, that is, when the number of sound absorbing materials on the circumference is small, there is a problem that vibrations are likely to occur in the vehicle body during traveling due to the influence of the sound absorbing material arranged intermittently. Further, when the number of the sound absorbing materials is increased, that is, when the number of the sound absorbing materials is increased, there is a problem that although the vehicle body vibration is reduced, the manufacturing cost of the tire noise reducing device is increased. For this reason, it is desired to reduce the number of sound absorbing materials on the circumference as much as possible.

Japanese Patent No. 4148777

  An object of the present invention is when a sound absorbing material made of a plurality of porous materials is intermittently arranged along the tire circumferential direction on the inner surface of a tread portion of a pneumatic tire, and the number of sound absorbing materials on the circumference is reduced. Even if it exists, it is providing the tire noise reduction apparatus which enabled it to reduce generation | occurrence | production of a vehicle body vibration effectively, and a pneumatic tire provided with the same.

In order to solve the above-described object, a tire noise reduction device of the present invention includes a sound absorbing material made of N (3 ≦ N ≦ 9) porous materials having unequal lengths in the tire circumferential direction, and these N sound absorbing materials. A tire noise reduction device in which a material is intermittently disposed along the tire circumferential direction on the inner surface of a tread portion of a pneumatic tire, and an N-order component mass unbalance index C obtained from the following equation (1) _N satisfies the relationship of C _N <C _N ′ × 0.9 with respect to the mass unbalance index C _N ′ of the N-order component when the lengths and intervals of the N sound absorbing materials are averaged. It is characterized by.

但し、ｎは次数（１≦ｎ≦Ｎ）であり、θは周上の位相であり、ｘ（θ）は微小角における相対線密度であり、吸音材がある部分の相対線密度を１とし、吸音材がない部分の相対線密度を０とする。

Where n is the order (1 ≦ n ≦ N), θ is the phase on the circumference, x (θ) is the relative linear density at a minute angle, and the relative linear density of the portion where the sound absorbing material is present is 1. The relative linear density of the portion where there is no sound absorbing material is zero.

  Moreover, the pneumatic tire of the present invention for solving the above object is characterized in that the tire noise reduction device is provided in the cavity.

In the present invention, when the N sound absorbing materials having unequal lengths are intermittently disposed along the tire circumferential direction on the inner surface of the tread portion of the pneumatic tire, the mass imbalance of the order component is obtained using Fourier series expansion. An index C _n is obtained. Then, the mass unbalance index C _{N of} the Nth order component is equal to the mass unbalance index C _N ′ of the Nth order component when the lengths and intervals of the N sound absorbing materials are averaged (virtual model). _Since the relationship of _N <C _N ′ × 0.9 is satisfied, the occurrence of vehicle body vibration can be effectively reduced even when the number of sound absorbing materials on the circumference is reduced.

  In the present invention, the tire noise reduction device includes a band member for fixing N sound absorbing materials, and the N sound absorbing materials are arranged on the inner surface of the tread portion of the pneumatic tire based on the elastic restoring force of the band members. A structure that is intermittently mounted along the direction is preferable. Thereby, N sound-absorbing materials can be easily disposed at appropriate positions in the tire circumferential direction on the inner surface of the tread portion.

It is preferable that the interval between the sound absorbing materials is larger than the thickness of the sound absorbing material, and the sum of the intervals between the sound absorbing materials is smaller than 10% of the inner peripheral length of the tread portion of the pneumatic tire. Thus, durability can be ensured by making the individual intervals of the sound absorbing material larger than the thickness of the sound absorbing material, and the total interval of the sound absorbing materials is smaller than 10% of the inner peripheral length of the tread portion. By doing so, an increase in the mass unbalance index C ₁ of the primary component can be prevented.

Furthermore, in the present invention, it is preferable that the mass unbalance indices C _{1 to} C _N-1 of the components of order lower than the Nth order are each smaller than the value of C _N '× 0.5. Thereby, generation | occurrence | production of a vehicle body vibration can be reduced more effectively.

1 is a perspective sectional view showing a pneumatic tire according to an embodiment of the present invention. 1 is a perspective view showing a tire noise reduction device according to an embodiment of the present invention. 1 is a side view showing a tire noise reduction device according to an embodiment of the present invention. It is a graph which shows the mass unbalance index of the order component of the tire noise reduction apparatus of FIG. It is a side view which shows the tire noise reduction apparatus (virtual model) used as a comparison object. It is a graph which shows the mass unbalance index of the order component of the tire noise reduction apparatus of FIG.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a pneumatic tire according to an embodiment of the present invention, and FIGS. 2 and 3 show a tire noise reduction device according to an embodiment of the present invention. In FIG. 1, the pneumatic tire includes a tread portion 1, a pair of left and right bead portions 2, and a sidewall portion 3 that connects the tread portion 1 and the bead portion 2 to each other. And the ring-shaped tire noise reduction apparatus 4 shown in FIG.

  The tire noise reduction device 4 includes N (3 ≦ N ≦ 9, preferably 3 ≦ N ≦ 5) sound absorbing materials 5 made of a porous material intermittently disposed along the tire circumferential direction, and these sound absorbing materials. And a band member 6 for fixing the material 5. As the porous material of the sound absorbing material 5, foamed polyurethane may be used. On the other hand, a thermoplastic resin such as polypropylene can be used as the constituent material of the band member 6. The band member 6 is formed in an annular shape so as to continuously extend in the tire circumferential direction, and holds the sound absorbing material 5 on the tire inner surface based on its own elastic restoring force. Therefore, the N sound absorbing materials 5 can be easily arranged at appropriate positions in the tire circumferential direction on the inner surface of the tread portion 1. The noise reduction device 4 configured as described above is detachable from a normal pneumatic tire, and the attachment / detachment work is easy. If the band member 6 is not used, the sound absorbing material 5 may be directly attached to the tire inner surface.

  As shown in FIG. 3, the N sound absorbing materials 5 have unequal lengths in the tire circumferential direction. The unequal length means that all the sound absorbing materials 5 do not have the same length. Accordingly, the N sound absorbing materials 5 may include those having the same length. Of course, it is preferable that all the sound absorbing materials 5 have different lengths. In FIG. 3, the lengths La, Lb, Lc and Ld of the four sound absorbing materials 5 are set to different values. The sound-absorbing material 5 is basically assumed to be square or rectangular in plan view, but may be trapezoidal or parallelogram-shaped in plan view, for example. In the case of a trapezoid or parallelogram, the length of the sound absorbing material 5 is an average length calculated from the area of the sound absorbing material 5 in plan view and the dimensions in the tire width direction.

  Further, the interval (length in the tire circumferential direction) between the N sound absorbing materials 5 is also unequal. These intervals may be set to equal values. In FIG. 3, the intervals Ta, Tb, Tc, and Td of the four sound absorbing materials 5 are set to different values.

In the tire noise reduction device 4 described above, when the mass unbalance index C _n of the order component is obtained based on the following formula (1) using Fourier series expansion, the mass unbalance index C _N of the Nth order component is For the mass unbalance index C _N ′ of the N-order component when the lengths and intervals of the N sound absorbing materials 5 are averaged, the relationship of C _N <C _N ′ × 0.9 is satisfied. Yes.

但し、ｎは次数（１≦ｎ≦Ｎ）であり、θは周上の位相であり、ｘ（θ）は微小角における相対線密度であり、吸音材がある部分の相対線密度を１とし、吸音材がない部分の相対線密度を０とする。

Where n is the order (1 ≦ n ≦ N), θ is the phase on the circumference, x (θ) is the relative linear density at a minute angle, and the relative linear density of the portion where the sound absorbing material is present is 1. The relative linear density of the portion where there is no sound absorbing material is zero.

FIG. 4 is a graph showing the mass unbalance index of the order component of the tire noise reduction device according to the embodiment of the present invention. As shown in FIG. 4, the order component is obtained by integrating the relative linear density over one circumference of the tire with x (θ) = 1 in the portion with the sound absorbing material and x (θ) = 0 in the portion without the sound absorbing material. Mass unbalance index C _n can be obtained. In the tire noise reduction device 4 of FIG. 3, since the four sound absorbing materials 5 are intermittently arranged on the circumference, the value of the mass unbalance index C ₄ of the quaternary component is relatively large. The numerical value on the vertical axis in FIG. 4 is an index value where the mass unbalance index C ₄ ′ of the fourth-order component in the virtual model described later is 100.

  Here, a tire noise reduction device to be compared will be described. FIG. 5 shows a tire noise reduction device (virtual model) to be compared. The tire noise reduction device 4 is obtained by averaging the lengths and intervals of N sound absorbing materials 5. That is, in FIG. 5, the lengths La ′, Lb ′, Lc ′, and Ld ′ of the four sound absorbing materials 5 are set to equal values, and the values are the average values of the lengths La, Lb, Lc, and Ld. Is equivalent. Further, the intervals Ta ′, Tb ′, Tc ′, Td ′ of the four sound absorbing materials 5 are set to the same value, and the values are equivalent to the average values of the intervals Ta, Tb, Tc, Td.

FIG. 6 is a graph showing the mass unbalance index of the order component of the tire noise reduction device of FIG. In the tire noise reduction device 4 of FIG. 5, since the four sound absorbing materials 5 having the same length on the circumference are arranged at equal intervals, the value of the mass unbalance index C ₄ of the _fourth order component and the value of the eighth order component are obtained. The value of the mass unbalance index C ₈ is extremely large. That is, when equal objects are arranged at equal intervals, mass imbalance based on a specific order component is increased. The values of the vertical axis of FIG. 6 is an exponential value to 100 mass unbalance index C ₄ 'of the fourth-order components.

As can be seen from the comparison between FIG. 4 and FIG. 6 described above, in this embodiment, N sound absorbing materials 5 having unequal lengths are intermittently provided on the inner surface of the tread portion 1 of the pneumatic tire along the tire circumferential direction. In the arrangement, the mass unbalance index C _N of the Nth order component is equal to the mass unbalance index C _N ′ of the Nth order component when the lengths and intervals of the N sound absorbing materials are averaged (virtual model). Thus, the relationship of C _N <C _N '× 0.9 is satisfied. More specifically, when the four sound absorbing materials 5 having unequal lengths are intermittently disposed along the tire circumferential direction on the inner surface of the tread portion 1 of the pneumatic tire, the mass unbalance index C of the quaternary component. ₄ is the relationship of C ₄ <C ₄ ′ × 0.9 with respect to the mass unbalance index C ₄ ′ of the fourth-order component when the lengths and intervals of the four sound absorbing materials are averaged (virtual model) Meet.

  According to the knowledge based on the experiment results of the present inventors, when the number of the sound absorbing material 5 on the circumference is reduced (3 ≦ N ≦ 9, preferably 3 ≦ N ≦ 5), the above relationship is satisfied. Thus, it is possible to effectively reduce the occurrence of vehicle body vibration.

In the tire noise reduction device 4, the intervals Ta to Td of the sound absorbing material 5 are respectively larger than the thickness of the sound absorbing material 5, and the sum of the intervals Ta to Td of the sound absorbing material 5 is the tire equator position of the tread portion 1 of the pneumatic tire. It is better to make it smaller than 10% of the inner peripheral length at. If the individual intervals Ta to Td of the sound absorbing material 5 are smaller than the thickness of the sound absorbing material 5, the adjacent sound absorbing materials 5 and 5 are likely to come into contact with each other, resulting in a decrease in durability. The thickness of the sound absorbing material 5 means the thickness at the end of the sound absorbing material 5, and when the thickness at the end of the sound absorbing material 5 is changed, the thickness is the average value. A sum of spacing Ta~Td of the noise absorbing member 5 is 10% larger than the inner circumferential length of the tread portion 1, so that the ride quality and mass imbalance index C ₁ of the first-order component is increased to deteriorate. In particular, the sum of the intervals Ta to Td of the sound absorbing material 5 is desirably smaller than 5% of the inner peripheral length of the tread portion 1 of the pneumatic tire at the tire equator position.

Further, in the tire noise reduction device 4, as shown in FIG. 4, the mass unbalance indexes C _{1 to} C _N-1 of the components of the order lower than the N order are each smaller than the value of C _N ′ × 0.5. It is preferable. In other words, it is a necessary condition to reduce the mass unbalance index C _N , but at the same time, in order to more effectively reduce the occurrence of vehicle body vibration, the mass unbalance index C of the component of the order lower than the Nth order. It is necessary to suppress the increase of _{1 to} CN _-1 .

  A sound absorbing material composed of four porous materials and a band member for fixing the four sound absorbing materials, and the four sound absorbing materials are arranged on the inner surface of the tread portion of the pneumatic tire based on the elastic restoring force of the band member. In the tire noise reduction device that is mounted intermittently along the tire circumferential direction, the lengths La to Ld and the intervals Ta to Td of the sound absorbing material are set as shown in Table 1 and Comparative Examples 1-2 and Examples 1-3 tire noise reduction devices were manufactured.

In Comparative Examples 1-2 and Examples 1-3, the thickness of the sound absorbing material was 15 mm, and the total length and total weight of the sound absorbing material were the same. The mass unbalance indices C _{1 to} C ₄ are as shown in Table 1. These mass unbalance indices C _{1 to} C ₄ are the mass unbalance indices C ₄ of the quaternary component of Comparative Example 1 corresponding to the virtual model. It is converted as 100.

  The tire noise reduction devices of Comparative Examples 1 and 2 and Examples 1 to 3 are respectively mounted on pneumatic tires having a tire size of 215 / 60R16, and the pneumatic tires are assembled to a wheel having a rim size of 16 × 7J to have a displacement of 3000 cc. The vehicle is run on a smooth asphalt road surface at an air pressure of 210 kPa at a speed of 60 km / h, the cabin floor vibration (acceleration) at that time is measured, and an overall value of vibration energy of 0 to 80 Hz is obtained. Asked. The evaluation result of the floor vibration is indicated by an index with Comparative Example 1 as 100. A smaller index value means less floor vibration.

As can be seen from Table 1, in the tire noise reduction devices of Examples 1 to 3, the four sound absorbing materials are unequal in length, and the mass unbalance index C ₄ of the fourth order component is set to the length and interval of the sound absorbing material. Since it was smaller than 0.9 times the value in the case of averaging (Comparative Example 1), the floor vibration could be reduced. On the other hand, although the tire noise reduction device of Comparative Example 2 has four sound absorbing materials of unequal length, the mass unbalance index C _{4 of} the fourth order component averages the length and interval of the sound absorbing materials (comparison) On the contrary, the floor vibration increased because it was larger than 0.9 times the value of Example 1).

DESCRIPTION OF SYMBOLS 1 Tread part 2 Bead part 3 Side wall part 4 Tire noise reduction device 5 Sound absorption material 6 Band member

Claims (5)

A sound-absorbing material composed of N (3 ≦ N ≦ 9) porous materials having unequal lengths in the tire circumferential direction is provided, and these N sound-absorbing materials are arranged along the tire circumferential direction on the inner surface of the tread portion of the pneumatic tire. The tire noise reduction device is arranged intermittently, and the mass unbalance index C _{N of the} Nth order component obtained from the following equation (1) is an average of the lengths and intervals of the N sound absorbing materials. The tire noise reduction device satisfying the relationship of C _N <C _N ′ × 0.9 with respect to the mass unbalance index C _N ′ of the N-order component in the case of conversion into the first order.

Where n is the order (1 ≦ n ≦ N), θ is the phase on the circumference, x (θ) is the relative linear density at a minute angle, and the relative linear density of the portion where the sound absorbing material is present is 1. The relative linear density of the portion where there is no sound absorbing material is zero.   A band member for fixing the N sound absorbing materials is provided, and the N sound absorbing materials are intermittently mounted along the tire circumferential direction on the inner surface of the tread portion of the pneumatic tire based on the elastic restoring force of the band member. The tire noise reduction device according to claim 1, wherein the tire noise reduction device is provided.   The interval between the sound absorbing materials is made larger than the thickness of the sound absorbing material, respectively, and the sum of the intervals between the sound absorbing materials is made smaller than 10% of the inner peripheral length of the tread portion of the pneumatic tire. The tire noise reduction device according to claim 2. 4. The mass unbalance index C _{1 to} C _N−1 of the component having a lower order than the Nth order is smaller than a value of C _N ′ × 0.5, respectively. Tire noise reduction device.   A pneumatic tire comprising the tire noise reduction device according to any one of claims 1 to 4 in a hollow portion.

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