JP2008120391A - Low-noise pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-noise pneumatic tire improved in low-noise performance by sound absorbing materials attached to the inner peripheral surface of a tire, improved in the durability of the sound absorbing materials, and suppressed in tire vibration. <P>SOLUTION: The sound absorbing materials 5 formed of multiple porous materials are attached to the inner peripheral surface of the tire intermittently in the circumferential direction of the tire. The number of the sound absorbing material 5 is 5 to 50, and the cumulative length thereof in the circumferential direction of the tire is set more than 75% of the maximum inner peripheral length of the tire, and an interval between the sound absorbing materials 5 is set to one or more times the maximum thickness of the sound absorbing material 5 at the end of the sound absorbing materials in the circumferential direction of the tire and equal to or less than 15% of the maximum inner peripheral length of the tire. The sound absorbing materials 5 are fixed to either of the inner peripheral surface and the outer peripheral surface of an elastic band 6 extended in the circumferential direction of the tire, and attached to the inner peripheral surface of the tire through the elastic band 6. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a low-noise pneumatic tire, and more specifically, while improving the low-noise performance of the sound-absorbing material attached to the inner peripheral surface of the tire, the durability of the sound-absorbing material can be improved and the tire vibration can be suppressed. It relates to low noise pneumatic tires.

  As one of noises generated by a pneumatic tire, there is a cavity resonance sound generated by vibration of air filled in the tire. This cavity resonance sound is a resonance sound generated when the tread portion vibrates due to the unevenness of the road surface when the tire runs on the road surface, and the air inside the tire vibrates due to the vibration of the tread portion. It is known that the frequency of the cavity resonance sound of this pneumatic tire is around 250 Hz.

  Conventionally, as a means for reducing cavity resonance noise of a pneumatic tire, as illustrated in FIGS. 7A and 7B, the tire inner peripheral surface of the tread portion 1 of the pneumatic tire T is made of a porous material. There has been proposed a structure in which the sound absorbing material 5 is continuously or intermittently attached in the tire circumferential direction and the sound absorbing material 5 absorbs the cavity resonance sound (see, for example, Patent Documents 1 and 2). In order to improve the effect of reducing the cavity resonance noise by such a sound absorbing material, it is necessary to attach the sound absorbing material to the tire inner peripheral surface with as wide an area as possible.

However, when the sound absorbing material 5 is continuously arranged so as to extend over the entire circumference of the tire inner peripheral surface as shown in FIG. 7A, the pneumatic tire T is attached to a portion where both ends of the sound absorbing material 5 in the tire circumferential direction are connected. Since compression and expansion are alternately repeated every rotation, there is a drawback that the connecting portion is easily broken due to stress concentration. Further, in order to prevent the sound absorbing material from being destroyed, if the sound absorbing material 5 is intermittently arranged as shown in FIG. 7B and the two sound absorbing materials 5 adjacent to each other in the tire circumferential direction are separated greatly, the rotational balance of the tire is obtained. Collapses and vibrations are generated when the tire is running.
JP-A-62-216803 JP 2003-252003 A

  An object of the present invention is to provide a low noise pneumatic tire capable of improving the durability performance of the sound absorbing material and suppressing the tire vibration while enhancing the low noise performance by the sound absorbing material attached to the inner peripheral surface of the tire. It is in.

  The low-noise pneumatic tire of the present invention that achieves the above object is provided with a number of sound absorbing materials that are intermittently arranged in the tire circumferential direction on a tire inner circumferential surface. The total length accumulated in the tire circumferential direction is 75% or more of the maximum tire inner circumferential length, and the distance between the sound absorbing materials is the maximum thickness at the end portions of the sound absorbing material in the tire circumferential direction. The elastic band is fixed to either the inner peripheral surface or the outer peripheral surface of an elastic band extending to the tire circumferential direction and at least 15% of the maximum inner peripheral length of the tire. It attached to the said tire inner peripheral surface via.

  In the pneumatic tire of the present invention, since a large number of sound absorbing materials are intermittently arranged in the tire circumferential direction on the tire inner peripheral surface as described above, the bending deformation of the sound absorbing material accompanying the deformation of the tire ground contact portion is alleviated and continuously. The durability can be improved as compared with the sound absorbing material to be arranged. Further, since the number of the sound absorbing materials is 5 to 50 and the interval between the sound absorbing materials is set to be equal to or larger than the maximum thickness at the ends of the sound absorbing materials, interference between the ends of the sound absorbing materials during tire traveling is prevented. Therefore, the sound absorbing material can be prevented from being damaged, and the total length of these sound absorbing materials integrated in the tire circumferential direction is set to 75% or more of the tire maximum inner circumferential length. It is possible to secure a sufficient amount of absorption and to exhibit high low noise performance. Furthermore, the number of sound absorbing materials is 5 to 50, and the interval between the sound absorbing materials is 15% or less of the maximum inner circumferential length of the tire, so that the weight balance in the tire circumferential direction is made uniform and the tire vibration during high speed running is reduced. Can be suppressed. Further, when the sound absorbing material is indirectly attached through the elastic band, it is easy to change the mounting between different tires.

  1 and 2, the pneumatic tire T is formed on the left and right sides of the tread portion 1 so that a pair of left and right sidewall portions 3, 3 and bead portions 2, 2 are connected to each other. When this pneumatic tire T is mounted on the rim R, a cavity 4 is formed inside the tire, and the cavity 4 is filled with air having a pressure defined in the standard.

  An elastic band 6 is supported on the tire inner circumferential surface 1a of the tread portion 1 so as to be pressure-bonded annularly in the tire circumferential direction, and a sound absorbing material 5 composed of a plurality of independent pieces is intermittently provided along the longitudinal direction of the elastic band 6. Fixed. These sound absorbing materials 5 are made of a porous material having open cells. As shown in FIG. 3, the plurality of sound absorbing materials 5 are intermittently fixed to one side of a linear elastic band 6 at a constant interval D, and then the elastic band 6 is annularly bent to form an inner circumferential surface 1a of the tire. And both ends are connected via hooks 7 and the like.

  The sound-absorbing material 5 may be fixed to the elastic band 6 by using ultrasonic waves or the like, or by using an adhesive. Moreover, you may perform the connection of the both ends of the elastic band 6 with the clasp 8 as shown in FIG. Or you may connect the both ends of the elastic band 6 by adhesion | attachment with an adhesive agent, or melt | fusion.

  As described above, when the sound absorbing material 5 is indirectly attached to the tire inner peripheral surface 1a of the pneumatic tire T through the elastic band 6, the tires in use can be easily replaced between different tires. If the tire becomes unusable due to wear or puncture, the sound absorbing material used in the unusable tire can be reused for another new tire together with the elastic band.

  As a method of attaching the sound absorbing material 5 to the tire inner peripheral surface 1a by the elastic band 6, the sound absorbing material 5 is arranged on the inner peripheral side of the elastic band 6 and the elastic band 6 is attached to the tire inner peripheral surface as in the illustrated example. It is preferable to attach so as to be in direct pressure contact with la. Of course, conversely, the sound absorbing material 5 may be disposed on the outer peripheral side of the elastic band 6, and the sound absorbing material 5 may be attached to be pressed against the tire inner peripheral surface 1 a by the elastic band 6. In the latter case, since a part of the surface of the sound absorbing material 5 is blocked by the elastic band 6, the sound absorbing effect of the sound absorbing material 5 is reduced by that amount. However, in the former case, since the elastic band 6 does not block the surface of the sound absorbing material 5, a higher noise reduction effect can be obtained, and the entire circumferential direction of the elastic band 6 is in close contact with the tire inner peripheral surface 1a. A high frictional force is obtained, and the sound absorbing material 5 can be held more stably.

  Further, as a method of attaching the sound absorbing material 5 to the tire inner peripheral surface 1a, a method of supporting the elastic band 6 by penetrating through an intermediate portion in the thickness direction of the sound absorbing material 5 can be considered. Since it is easy to concentrate a large stress on the part due to the pressing of the elastic band 6, it tends to be damaged early.

  The sound absorbing material 5 is made of a porous material. The porous material is preferably a foamed resin having open cells. More preferably, a foamed urethane resin may be used. Among the urethane foam resins, particularly a low-density polyether-based urethane foam is preferable because it is difficult to compress and deform against the tire internal pressure and has excellent pressure resistance. The material of the elastic band 6 may be either metal or resin, but is preferably resin. As the resin, a polypropylene resin or a polyethylene resin is particularly preferable because it has a high tensile elastic modulus.

  In the pneumatic tire of the present invention, in the above configuration, the number of the sound absorbing materials 5 arranged as a plurality of independent pieces in the tire circumferential direction is 5 to 50, and the length of all of the sound absorbing materials 5 is the tire circumferential direction. Is 75% or more, preferably 85% or more of the maximum inner circumferential length of the tire. Further, in the plurality of sound absorbing materials 5, the interval D between the tire circumferential directions is 1 time or more, preferably 1.2 times or more the maximum thickness at the tire circumferential direction end portion of the sound absorbing material 5. And 15% or less of the maximum inner circumferential length of the tire, preferably 10% or less.

  As described above, the number of sound absorbing materials 5 arranged in the tire circumferential direction is 5 to 50, and the total length accumulated in the tire circumferential direction is 75% or more of the maximum inner circumferential length of the tire. Since a sufficient amount of sound absorption is ensured, high low noise performance can be exhibited and tire vibration during high speed running can be suppressed. When the number of the sound absorbing materials 5 is 4 or less, the weight balance in the tire circumferential direction is lost, so that tire vibration during high-speed running increases. Further, when the number of the sound absorbing materials 5 exceeds 50, the length L in the tire circumferential direction of the sound absorbing material 5 per one becomes too short, so that the sound absorbing materials 5 are easily damaged. Further, if the total length obtained by integrating the lengths of all the sound absorbing materials 5 in the tire circumferential direction is less than 75% of the tire maximum inner circumferential length, it is difficult to obtain a noise reduction effect and the weight balance is lost. Tire vibration is also likely to occur.

  In the pneumatic tire of the present invention, the distance D between the two sound absorbing materials 5 and 5 adjacent in the tire circumferential direction is equal to or greater than the maximum thickness of the end portion in the tire circumferential direction of the sound absorbing material 5, thereby rotating the tire. Sometimes the interference between the ends of the sound absorbing material is prevented and the sound absorbing material is prevented from being damaged. Further, by setting the distance D between the sound absorbing materials 5 and 5 to 15% or less of the tire maximum inner circumferential length, the weight balance of the sound absorbing material can be made uniform and tire vibration can be suppressed.

  If the distance D between the sound absorbing materials 5 and 5 is narrower than the maximum thickness of the end portion of the sound absorbing material 5 in the tire circumferential direction, the ends of the two adjacent sound absorbing materials interfere with each other, which easily causes damage. On the other hand, if the distance D is larger than 15% of the maximum inner circumferential length of the tire, the weight balance of the sound absorbing material is lost, so that tire vibration is generated during high-speed running.

  The length L of the sound absorbing material 5 in the tire circumferential direction is preferably 2 to 15% of the maximum tire inner circumferential length. If the length L of the sound-absorbing material 5 is less than 2% of the maximum inner circumferential length of the tire, the bending rigidity in the tire width direction is excessively lowered, so that it is easily damaged. Further, if the length L of the sound absorbing material 5 is greater than 15% of the maximum inner circumferential length of the tire, the sound absorbing material 5 is greatly deformed in the tire radial direction during tire rotation, and the sound absorbing material is easily damaged. In order to suppress tire vibration, the plurality of sound absorbing materials 5 are preferably the same in length L, but may be different as long as vibration is allowed.

  The maximum width W of the sound absorbing material 5 is preferably 50 to 90% of the maximum width of the tire, and more preferably 55 to 80%. If the maximum width W of the sound absorbing material 5 is narrower than 50% of the maximum width of the tire, the effect of reducing the cavity resonance noise cannot be obtained sufficiently. Further, if the maximum width W of the sound absorbing material 5 is larger than 90% of the maximum tire width, the sound absorbing material 5 extends to the sidewall portion 3, so that the durability of the sound absorbing material 5 is lowered.

  The thickness of the sound absorbing material 5 is preferably 5 to 50 mm, and more preferably 10 to 40 mm. Further, the thickness of the sound absorbing material is preferably the same for all of the plurality of sound absorbing materials 5 arranged in the tire circumferential direction in order to suppress the tire vibration, but is different from each other as long as the tire vibration can be tolerated. It may be. Moreover, the thickness of the sound absorbing material per piece may be uniform as a whole, or may vary in the longitudinal direction and / or the width direction.

  The shape of the sound-absorbing material 5 in plan view is not particularly limited, but is preferably a pentagon or more polygon having an obtuse angle as an internal angle, such as an octagon illustrated in FIG. These pentagonal or more polygons can suppress damage that is likely to occur in the vicinity of the end of the sound absorbing material. Further, the planar shape of the sound absorbing material 5 is a quadrangle having an internal angle as a right angle as shown in FIG. 5A, a circle as shown in FIG. 5B, and an ellipse as shown in FIG. 5C. Etc. can be illustrated. As a planar view shape of the sound-absorbing material 5, it is preferable that all the internal angles are obtuse polygons, circles or ellipses.

  Moreover, the planar view shape of the sound-absorbing material 5 can also be a parallelogram having a corner E with an acute inner angle θ as shown in FIG. However, when the inner angle θ has a sharp corner E, the corner E having an acute inner angle is preferably chamfered in an arc shape. By this chamfering, damage to the corner E of the sound absorbing material can be reduced.

  In the present specification, the “maximum tire inner circumference” means the inner circumference at the equator position of the tire inner circumferential surface in a state where a pneumatic tire is assembled to a rim prescribed by JATMA and normal internal pressure is filled. Say. The “maximum tire width” is the maximum tire width in a state where a pneumatic tire is assembled to a rim similarly defined by JATMA and a normal internal pressure is filled.

  A sound absorbing material obtained by processing open-cell polyurethane foam resin into the following three types on the tire inner peripheral surfaces of three pneumatic tires having the same tire size 215 / 60R16 has the following mounting structure. It was installed as follows.

(A) Example 1
Mounting structure: Fig. 2
Shape of sound-absorbing material: Width W: 150 mm, thickness: 20 mm, length L: 180 mm, octagonal shape with each corner chamfered to 60 mm × 60 mm: Number of sound-absorbing materials: 9 (disposed with spacing D of about 30 mm) )
(B) Conventional example 1
Mounting structure: Fig. 7 (b)
Shape of sound absorbing material: Width W: 150 mm, thickness: 20 mm, length L: 200 mm, octagonal shape with each corner chamfered to 60 mm × 60 mm Number of sound absorbing materials: 4 (90 ° with respect to tire axis) Evenly arranged at an angle)
(C) Conventional example 2
Mounting structure: Fig. 7 (a)
Shape of sound-absorbing material: width W: 150 mm, thickness: 20 mm, circumference: 1890 mm, continuous belt-like number of sound-absorbing materials: 1 (continuously arranged on the entire circumference of the tire inner peripheral surface)

  These three types of pneumatic tires were each assembled with a rim on a wheel, the air pressure was 150 kPa, and the durability and vibration performance of the sound absorbing material in each tire were measured by the following test methods. The results are shown in Table 1.

[Durability of sound absorbing material]
The test tire was brought into contact with the rotating drum of the drum tester with a load of 7.8 kN and was run at a speed of 80 km / h, and the distance until the sound absorbing material was damaged was measured. The measurement results are shown as an index with the measured value of Conventional Example 1 being 100. The larger the index value, the better the durability of the sound absorbing material.

(Vibration performance)
Using a uniformity-measuring machine, the secondary component of radial force variation (RFV) when the test tire was run at a speed of 100 km / h was measured. The measurement results are shown as an index with the measured value of Conventional Example 2 as 100. A smaller index value means better vibration performance.

  From the results in Table 1, it can be seen that the durability and vibration performance of the sound absorbing material are improved in a well-balanced manner in the pneumatic tire of Example 1 compared to the pneumatic tires of Conventional Examples 1 and 2.

It is sectional drawing of the meridian direction shown in the state which assembled the rim | limb of the pneumatic tire which consists of embodiment of this invention. It is sectional drawing which showed the tire of FIG. 1 in the cross section of the equator direction. It is a top view which shows an example of the sound-absorbing material used for this invention. It is a side view which illustrates the state before inserting the sound absorption material used for this invention into a pneumatic tire with an elastic band. (A)-(c) is a top view which shows other embodiment of the sound-absorbing material used for this invention, respectively. It is a top view which shows other embodiment of the sound-absorbing material used for this invention. (A) And (b) is sectional drawing which showed the conventional tire as the cross section of the equator direction, respectively.

Explanation of symbols

5 Sound absorbing material 6 Elastic band

Claims (6)

  A number of sound absorbing materials made of porous materials are attached to the tire inner circumferential surface so as to be intermittently arranged in the tire circumferential direction, and the total number of the sound absorbing materials is 5 to 50 and integrated in the tire circumferential direction. The height of the tire is set to 75% or more of the maximum inner circumferential length of the tire, and the interval between the sound absorbing materials is set to one time or more of the maximum thickness at the end portion in the tire circumferential direction of the sound absorbing material. %, And the sound absorbing material is fixed to either the inner peripheral surface or the outer peripheral surface of an elastic band extending in the tire circumferential direction, and attached to the tire inner peripheral surface via the elastic band. tire.   The low-noise pneumatic tire according to claim 1, wherein the sound absorbing material is fixed to an inner peripheral side of the elastic band, and the elastic band is pressed against the inner peripheral surface of the tire.   The low noise pneumatic tire according to claim 1 or 2, wherein the maximum width of the sound absorbing material is 50 to 90% of the maximum width of the tire.   The low noise pneumatic tire according to claim 1, wherein the sound absorbing material has a thickness of 5 to 50 mm.   The low-noise pneumatic tire according to any one of claims 1 to 4, wherein the sound absorbing material is made of a foamed resin having open cells.   The low-noise pneumatic tire according to any one of claims 1 to 5, wherein the elastic band is formed of a resin molded body.

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