TIRE NOISE REDUCTION DEVICE AND PNEUMATIC TIRE PROVIDED WITH SAME

Abstract

A tire noise reduction device includes a sound absorbing member made of a porous material; and a band member disposed between the sound absorbing member and the tire inner surface and provided for attaching the sound absorbing member to a tire inner surface, the band member including chamfered portions on both surface sides at both ends in a width direction of the band member.

Claims

1. A tire noise reduction device, comprising: a sound absorbing member made of a porous material; and a band member formed in an annular shape along a tire inner surface disposed on a radially outer side of the sound absorbing member and configured to attach the sound absorbing member to the tire inner surface, the band member including chamfered portions on both surface sides at both ends in a width direction of the band member; wherein the both surface sides include a first side of the band member extending along a length direction of the band member and facing the tire inner surface and a second side opposite the first side; and the chamfered portions are intermittently disposed along a length of the band member.

2. The tire noise reduction device according to claim 1, wherein each of the chamfered portions in the band member is formed as a flat surface, and an angle θ1, with respect to the width direction of the band member, of a chamfered portion C1 positioned on an inner circumferential surface side of the band member, and an angle θ2, with respect to the width direction of the band member, of a chamfered portion C2 positioned on an outer circumferential surface side of the band member are respectively set to be in a range of 110°≤θ1≤160° and 110°≤θ2≤160°.

3. The tire noise reduction device according to claim 2, wherein the angle θ1 is larger than the angle θ2.

4. The tire noise reduction device according to claim 1, wherein each of the chamfered portions in the band member is formed as a curved surface, and a radius of curvature r1 of a chamfered portion R1 positioned on an inner circumferential surface side of the band member, and a radius of curvature r2 of a chamfered portion R2 positioned on an outer circumferential surface side of the band member are respectively set to be in a range of 0.1 T.sub.B≤r1≤0.5 T.sub.B and 0.1 T.sub.B≤r2≤0.5 T.sub.B with respect to a thickness T.sub.B of the band member.

5. The tire noise reduction device according to claim 4, wherein the radius of curvature r1 is larger than the radius of curvature r2.

6. A pneumatic tire comprising the tire noise reduction device according to claim 5.

7. A pneumatic tire comprising the tire noise reduction device according to claim 1.

8. The tire noise reduction device according to claim 1, further comprising locking members coupled to the band member, wherein the sound absorbing member is sandwiched between the band member and the locking members.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0014] FIG. 1 is a perspective cross-sectional view illustrating a pneumatic tire provided with a tire noise reduction device according to an embodiment of the present technology.

[0015] FIG. 2 is a perspective view illustrating a tire noise reduction device according to an embodiment of the present technology.

[0016] FIG. 3 is a cross-sectional view schematically illustrating an example of a band member in a tire noise reduction device according to an embodiment of the present technology.

[0017] FIG. 4 is a cross-sectional view schematically illustrating a modified example of a band member in a tire noise reduction device according to an embodiment of the present technology.

[0018] FIG. 5 is a cross-sectional view schematically illustrating another modified example of a band member in a tire noise reduction device according to an embodiment of the present technology.

[0019] FIG. 6 is a cross-sectional view schematically illustrating another modified example of a band member in a tire noise reduction device according to an embodiment of the present technology.

[0020] FIGS. 7A to 7C are each a cross-sectional view schematically illustrating another modified example of a band member in a tire noise reduction device according to an embodiment of the present technology.

[0021] FIGS. 8A and 8B illustrate a state in which a known tire noise reduction device is installed on a tire inner surface, and FIGS. 8A and 8B are cross-sectional views illustrating a sound absorbing member and a band member in a noise reduction device.

DETAILED DESCRIPTION

[0022] A configuration of the present technology is described in detail below with reference to the accompanying drawings. FIG. 1 illustrates a pneumatic tire according to an embodiment of the present technology, and FIG. 2 illustrates a tire noise reduction device according to an embodiment of the present technology. FIG. 3 illustrates a band member in the tire noise reduction device according to an embodiment of the present technology.

[0023] In FIG. 1, the pneumatic tire includes a tread portion 1 that is annular and extends in a tire circumferential direction, a pair of sidewall portions 2 disposed on both sides of the tread portion 1, and a pair of bead portions 3 disposed inside of the sidewall portions 2 in a tire radial direction. Furthermore, a tire noise reduction device 6 that is ring-like and illustrated in FIG. 2 is attached to a cavity portion 4 that is surrounded by the tread portion 1, the sidewall portions 2, and the bead portions 3. The tire noise reduction device 6 is disposed in a region, of a tire inner surface 5, corresponding to the tread portion 1. In FIG. 3, Tw indicates a tire lateral direction, and Tr indicates the tire radial direction.

[0024] The tire noise reduction device 6 includes a sound absorbing member 7 made of a porous material, and a band member 8 configured to attach the sound absorbing member 7 to the tire inner surface 5. The band member 8 is formed in an annular shape so as to extend along the tire inner surface 5, and the sound absorbing member 7 is bonded to an inner circumferential surface of the band member 8 along a circumferential direction of the band member 8. A number of the sound absorbing members 7 is not particularly limited. A plurality of the sound absorbing members 7 may be included, and the sound absorbing members 7 can be bonded to the inner circumferential surface of the band member 8 while spaced apart from each other. The sound absorbing member 7 includes many internal cells and has predetermined sound absorbing properties based on the porous structure thereof. Polyurethane foam is preferably used as the porous material of the sound absorbing member 7. The band member 8 holds the sound absorbing member 7 on the tire inner surface 5 using an elastic restoring force of the band member 8. The tire noise reduction device 6 configured as described above can be freely attached to and removed from a normal pneumatic tire, and removal and attachment operations of the tire noise reduction device 6 can be easily performed.

[0025] In the tire noise reduction device 6 described above, ultrasonic welding is adopted as bonding means for bonding the sound absorbing member 7 and the band member 8. Specifically, the sound absorbing member 7 is disposed between the band member 8 and a locking member 9, and the locking member 9 is ultrasonically welded to the band member 8 via the sound absorbing member 7. The same type of thermoplastic resin, such as polypropylene, is preferably used as a constituent material of the band member 8 and the constituent material of the locking member 9. In this way, bonding by the ultrasonic welding described above can be easily performed. Further, although the ultrasonic welding described above is preferably used as the bonding means for bonding the sound absorbing member 7 and the band member 8, a bonding method thereof is not particularly limited, and thermal bonding, an adhesive, double-sided tape, or mechanical locking means can also be used.

[0026] In the tire noise reduction device 6 described above, chamfered portions C1 and C2 are formed on the band member 8 illustrated in FIG. 3, on both surface sides at both ends in a width direction thereof. Of the chamfered portions C1 and C2, the portions disposed on an inner circumferential surface side (on the inside in the tire radial direction) of the band member 8 and adjacent to the sound absorbing member 7 are the chamfered portions C1, and the portions disposed on an outer circumferential surface side (on the outside in the tire radial direction) of the band member 8 and adjacent to the tire inner surface 5 are the chamfered portions C2. Further, the chamfered portions C1 and C2 are preferably formed along the circumferential direction of the band member 8, but may be formed intermittently in the circumferential direction of the band member 8.

[0027] In the tire noise reduction device 6 described above that is provided with the sound absorbing member 7 made of the porous material and the band member 8 for attaching the sound absorbing member 7 to the tire inner surface 5, the band member 8 being disposed between the sound absorbing member 7 and the tire inner surface 5, by including the chamfered portions C1 and C2 on both surface sides at both ends in the width direction of the band member 8, breakage of the sound absorbing member 7 and damage to the tire inner surface 5 that are caused by friction between the band member 8 and the sound absorbing member 7 and between the band member 8 and the tire inner surface 5 can be inhibited.

[0028] In contrast, when the band member 8 has a rectangular cross-section in the tire noise reduction device 6 which is known and illustrated in FIG. 8A, the band member 8 has a higher strength than a band member provided with the chamfered portions, since the band member 8 has a larger cross-sectional area. However, as illustrated in FIG. 8B, when the vehicle is driven at high speeds, the sound absorbing member 7 is repeatedly caused to warp toward the outside in the tire radial direction due to the centrifugal force generated as a result of the tire rolling, and the friction between the sound absorbing member 7 and the band member 8 is caused. As a result, the breakage of the sound absorbing member 7 occurs at edge portions (illustrated by dashed lines in FIG. 8B) of the band member 8.

[0029] As illustrated in FIG. 3, the chamfered portions C1 and C2 are each chamfered as a flat surface. Angles at which the chamfered portions C1 and C2 are inclined with respect to the width direction of the band member 8 are respectively referred to as angles θ1 and θ2. At this time, the angle θ of the chamfered portion C1 is in a range of 110°≤θ1≤160°, and the angle θ2 of the chamfered portion C2 is in a range of 110°≤θ2≤160°. Both the angles θ1 and θ2 of the chamfered portions C1 and C2 are more preferably set to be in a range from 135° to 160°. Further, in an aspect illustrated in FIG. 3, the angle θ1 of the chamfered portion C1 and the angle θ2 of the chamfered portion C2 are identical. Specifically, the band member 8 has an axial-symmetrical shape, with a center line that is parallel with the width direction of the band member 8 being an axis of symmetry. By forming the chamfered portions C1 and C2 in this way, the breakage of the sound absorbing member 7 and the damage to the tire inner surface 5 that are caused by the friction between the band member 8 and the sound absorbing member 7 and between the band member 8 and the tire inner surface 5 can be more effectively inhibited. Here, when the angles θ1 and θ2 of the chamfered portions C1 and C2 are smaller than 110°, the edge portions of the band member 8 become closer to right angles, and a level of the damage caused by the friction between the band member 8 and the sound absorbing member 7 and between the band member 8 and the tire inner surface 5 worsens. On the other hand, when the angles θ1 and θ2 of the chamfered portions C1 and C2 exceed 160°, an effect on inhibiting the breakage of the sound absorbing member 7 and the damage to the tire inner surface 5 deteriorates.

[0030] In an example illustrated in FIG. 4, the angle θ1 of the chamfered portion C1 is set to be larger than the angle θ2 of the chamfered portion C2. Both the angles θ1 and θ2 of the chamfered portions C1 and C2 are preferably set to be in a range from 135° to 160°. Since durability of the sound absorbing member 7 is lower than that of the tire inner surface 5 with respect to the friction with the band member 8, by making the angle θ1 of the chamfered portion C1 on the sound absorbing member 7 side relatively larger, the durability of the sound absorbing member 7 with respect to the friction with the band member 8 is improved. On the other hand, by making the angle θ2 of the chamfered portion C2 on the tire inner surface 5 side relatively smaller, the cross-sectional area of the band member 8 is made as large as possible, and thus, weakening of the strength of the band member 8 can be minimized.

[0031] In an example illustrated in FIG. 5, chamfered portions R1 and R2, on which chamfering is performed, are formed on both surface sides at both ends in the width direction of the band member 8. Of the chamfered portions R1 and R2, the portions disposed on the inner circumferential surface side (on the inside in the tire radial direction) of the band member 8 and adjacent to the sound absorbing member 7 are the chamfered portions R1, and the portions disposed on the outer circumferential surface side (on the outside in the tire radial direction) of the band member 8 and adjacent to the tire inner surface 5 are the chamfered portions R2.

[0032] The chamfered portions R1 and R2 are each chamfered as a curved surface. Radii of curvature of the chamfered portions R1 and R2 are respectively referred to as radii of curvature r1 and r2. At this time, with respect to a thickness T.sub.B of the band member 8, a radius of curvature r1 of the chamfered portion R1 and a radius of curvature r2 of the chamfered portion R2 respectively have relationships of 0.1 T.sub.B≤r1≤0.5 T.sub.B and 0.1 T.sub.B ≤r2≤0.5 T.sub.B. The radii of curvature r1 and r2 are more preferably set to be in a range of 0.3 T.sub.B≤r1≤0.5 T.sub.B and 0.3 T.sub.B≤r2≤0.5 T.sub.B, respectively. Further, in an aspect illustrated in FIG. 5, the radius of curvature r1 of the chamfered portion R1 and the radius of curvature r2 of the chamfered portion R2 are identical. Specifically, the band member 8 has the axial-symmetrical shape with the center line that is parallel with the width direction of the band member 8 being the axis of symmetry. By forming the chamfered portions R1 and R2 in this way, the breakage of the sound absorbing member 7 and the damage to the tire inner surface 5 that are caused by the friction between the band member 8 and the sound absorbing member 7 and between the band member 8 and the tire inner surface 5 can be more effectively inhibited. Here, when the radii of curvature r1 and r2 of the chamfered portions R1 and R2 are smaller than 0.1 T.sub.B, the effect on inhibiting the breakage of the sound absorbing member 7 and the damage to the tire inner surface 5 cannot be obtained sufficiently. On the other hand, when the radii of curvature r1 and r2 of the chamfered portions R1 and R2 exceed 0.5 T.sub.B, the effect on inhibiting the breakage of the sound absorbing member 7 and the damage to the tire inner surface 5 deteriorates.

[0033] In an example illustrated in FIG. 6, the radius of curvature r1 of the chamfered portion R1 is set to be larger than the radius of curvature r2 of the chamfered portion R2. Since the durability of the sound absorbing member 7 is lower than that of the tire inner surface 5 with respect to the friction with the band member 8, by making the radius of curvature r1 of the chamfered portion R1 on the sound absorbing member 7 side relatively larger, the durability of the sound absorbing member 7 with respect to the friction with the band member 8 is improved. On the other hand, by making the radius of curvature r2 of the chamfered portion R2 on the tire inner surface 5 side relatively smaller, a cross-sectional area of the band member 8 is made as large as possible, and thus, the weakening of the strength of the band member 8 can be minimized.

[0034] A cross-sectional shape of the chamfered portions of the band member 8 is not particularly limited. Examples can include a case in which the chamfered portions C1 and C2 formed as flat surfaces are formed so as to have large and identical angles with respect to the width direction of the band member 8, as illustrated in FIG. 7A, a case in which the chamfered portions R1 and R2 formed as curved surfaces are formed so as to have small and identical radii of curvature, as illustrated in FIG. 7B, and a case in which both ends of the band member 8 in the width direction are bent toward the outside in the tire radial direction, and the chamfered portions R1 and R2 formed as curved surfaces are formed at all the edge portions of the band member 8, as illustrated in FIG. 7C.

EXAMPLES

[0035] In a tire noise reduction device provided with a sound absorbing member made of a porous material and a band member provided for attaching the sound absorbing member to a tire inner surface and disposed between the sound absorbing member and the tire inner surface, Comparative Examples 1 to 4 and Examples 1 to 5 of noise reduction devices, in which chamfered portions formed as flat surfaces were formed in the band member, were manufactured, the chamfered portions of the band member having various different configurations. Further, Conventional Example 1 was prepared as a known noise reduction device in which the chamfered portions were not provided in the band member. These noise reduction devices are suitable for a pneumatic tire of a tire size of 245/50R18.

[0036] In Comparative Examples 1 to 4 and Examples 1 to 5, the presence of the chamfered portions, positions of the chamfered portions (in the width direction of the band member), positions of the chamfered portions (in the thickness direction of the band member), the angle θ1 of the chamfered portion C1, and the angle θ2 of the chamfered portion C2 were set as shown in Table 1.

[0037] In Table 1, with respect to the positions of the chamfered portions (in the thickness direction of the band member), a case in which the chamfered portions are provided only on the inner circumferential surface side of the band member is referred to as a “sound absorbing member side,” a case in which the chamfered portions are provided only on the outer circumferential surface side of the band member is referred to as a “tire inner surface side,” and a case in which the chamfered portions are provided both on the inner circumferential surface side and the outer circumferential surface of the band member is referred to as “both surface sides.”

[0038] Each of the noise reduction devices of the Conventional Example 1, Comparative Examples 1 to 4, and Examples 1 to 5 described above was tested according to the following test method and evaluated for a breakage occurrence speed of the sound absorbing member and a degree of damage to the tire inner surface, and the results are shown in Table 1.

Breakage Occurrence Speed of Sound Absorbing Member

[0039] Each of the noise reduction devices was mounted in a cavity portion of a pneumatic tire with a tire size of 245/50R18, that was subjected to dry heat treatment at 80° C. for 120 hours with oxygen filled inside. The pneumatic tires were then assembled on wheels having a rim size of 18×8J, and a traveling test was conducted under the conditions of an air pressure of 200 kPa and a load of 7.8 kN using a drum testing machine. More specifically, an initial speed was set at 120 km/h, and the speed was increased by 10 km/h every 24 hours. Each of the pneumatic tires traveled until the breakage occurred in the sound absorbing member, and the speed reached at that point was measured.

Degree of Damage to Tire Inner Surface

[0040] After the breakage occurrence speed test of the sound absorbing member described above was carried out, conditions of the tire inner surface were examined. The degree of damage to the tire inner surface was indicated as “A” when there were no scratches on an inner liner, “B” when there were scratches on the inner liner, and “C” when there was peeling of the inner liner.

TABLE-US-00001 TABLE 1 Conventional Comparative Comparative Comparative Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Presence of No Yes Yes Yes Yes chamfered portions Positions of — Both ends Both ends Both ends Both ends chamfered portions (in width direction of band member) Positions of — Tire inner Sound Sound Sound chamfered portions surface side absorbing absorbing absorbing (in thickness direction member side member side member side of band member) Angle θ1 of chamfered — — 110° 135° 160° portions C1 Angle θ2 of chamfered — 135° — — — portions C2 Breakage occurrence 150 150 170 180 190 speed of sound absorbing member (km/h) Degree of damage to C A C C C tire inner surface Example 1 Example 2 Example 3 Example 4 Example 5 Presence of Yes Yes Yes Yes Yes chamfered portions Positions of Both ends Both ends Both ends Both ends Both ends chamfered portions (in width direction of band member) Positions of Both surface Both surface Both surface Both surface Both surface chamfered portions sides sides sides sides sides (in thickness direction of band member) Angle θ1 of chamfered 110° 135° 160° 135° 160° portions C1 Angle θ2 of chamfered 110° 135° 160° 110° 135° portions C2 Breakage occurrence 170 180 190 180 190 speed of sound absorbing member (km/h) Degree of damage to B A A B A tire inner surface

[0041] As illustrated in Table 1, compared with Conventional Example 1, both the breakage occurrence speed of the sound absorbing member and the degree of damage to the tire inner surface were improved in the noise reduction devices of Examples 1 to 5. In contrast, in Comparative Example 1, since the chamfered portions were provided only on the tire inner surface side, an improvement effect on the breakage occurrence speed of the sound absorbing member was insufficient. In Comparative Examples 2 to 4, since the chamfered portions were provided only on the sound absorbing member side, the damage to the tire inner surface was observed.

[0042] Next, similarly to Comparative Examples 1 to 4 and Examples 1 to 5, noise reduction devices of Comparative Examples 5 to 8 and Examples 6 to 10, in which chamfered portions formed as curved surfaces were formed in the band member, were manufactured, the chamfered portions of the band member having various different configurations. In Comparative Examples 5 to 8 and Examples 6 to 10, the presence of the chamfered portions, the positions of the chamfered portions (in the width direction of the band member), the positions of the chamfered portions (in the thickness direction of the band member), the radius of curvature r1 of the chamfered portion R1, and the radius of curvature r2 of the chamfered portion R2 were set as shown in Table 2. Further, Conventional Example 2 was prepared as the known noise reduction device in which the chamfered portions were not provided in the band member.

[0043] Each of the noise reduction devices of the Conventional Example 2, Comparative Examples 5 to 8, and Examples 6 to 10 was tested according to the test method described above and evaluated for the breakage occurrence speed of the sound absorbing member and the degree of damage to the tire inner surface, and the results are shown in Table 2.

TABLE-US-00002 TABLE 2 Conventional Comparative Comparative Comparative Comparative Example 2 Example 5 Example 6 Example 7 Example 8 Presence of No Yes Yes Yes Yes chamfered portions Positions of — Both ends Both ends Both ends Both ends chamfered portions (in width direction of band member) Positions of — Tire inner Sound Sound Sound chamfered portions surface absorbing absorbing absorbing (in thickness direction member side member side member side of band member) Radius of curvature r1 — — 0.1T.sub.B 0.3T.sub.B 0.5T.sub.B of chamfered portion R1 Radius of curvature r2 — 0.3T.sub.B — — — of chamfered portion R2 Breakage occurrence 150 150 170 180 190 speed of sound absorbing member (km/h) Degree of damage to C A C C C tire inner surface Example 6 Example 7 Example 8 Example 9 Example 10 Presence of Yes Yes Yes Yes Yes chamfered portions Positions of Both ends Both ends Both ends Both ends Both ends chamfered portions (in width direction of band member) Positions of Both surface Both surface Both surface Both surface Both surface chamfered portions sides sides sides sides sides (in thickness direction of band member) Radius of curvature r1 0.1T.sub.B 0.3T.sub.B 0.5T.sub.B 0.3T.sub.B 0.5T.sub.B of chamfered portion R1 Radius of curvature r2 0.1T.sub.B 0.3T.sub.B 0.5T.sub.B 0.1T.sub.B 0.3T.sub.B of chamfered portion R2 Breakage occurrence 170 180 190 180 190 speed of sound absorbing member (km/h) Degree of damage to B A A B A tire inner surface

[0044] As illustrated in Table 2, compared with Conventional Example 2, both the breakage occurrence speed of the sound absorbing member and the degree of damage to the tire inner surface were improved in the noise reduction devices of Examples 6 to 10. In contrast, in Comparative Example 5, since the chamfered portions were provided only on the tire inner surface side, the improvement effect on the breakage occurrence speed of the sound absorbing member was insufficient. In Comparative Examples 6 to 8, since the chamfered portions were provided only on the sound absorbing member side, the damage to the tire inner surface was observed.