Patent Application
20100276049
This invention relates to a pneumatic tire with noise reducer which is capable of suppressing cavity resonance by a noise reducer attached to a tire cavity surface.
As a tire noise, a road noise is known, which is generated in a frequency range between about 50 and 400 Hz. This arises principally due to columnar resonance (cavity resonance) occurred in the tire cavity. Thereupon, to reduce such a road noise, the following Patent Document 1 proposes a technique of applying a noise reducer made of sponge material to a tire cavity surface, for example. This noise reducer is formed in a jointless ring shape and is mounted inside the tire cavity in a compressed state.
Patent Document 1: Japanese Unexamined Patent Application
Publication No. 2005-254924.
However, the above-described noise reducer for a tire has a ring body made of jointless sponge, so that a shaping die is needed for each size of the tires. Therefore, there is a problem of high cost in manufacturing.
It is therefore, in view of the above-mentioned problem, an object of the present invention to provide a pneumatic tire with noise reducer which is capable of reducing cost to manufacture a not se reducer while keeping suppressive effect of the cavity resonance.
The present invention is related to a pneumatic tire with noise reducer comprising a pneumatic tire and a noise reducer attached to a tire cavity surface of the tire, characterized in that the above-mentioned noise reducer is formed in a ring shape by butting both end faces of an elongated sponge material disposed along the tire circumferential direction, and a butt-joint face of the above-mentioned end faces is a substantive plane.
The above-mentioned butt-joint face may form a part of a tire meridian section including a tire rotational axis, for example. Additionally, the above-mentioned butt-joint face may be inclined with respect to a reference surface forming a part of the tire meridian section including the tire rotational axis. In this case, it is preferable that the above-mentioned butt-joint face is inclined, for example, around a tire axial-directional line on the reference surface and/or a tire radial-directional line on the reference surface with respect to the above-mentioned reference surface.
Moreover, the above-mentioned noise reducer may be provided on a side of an inner circumferential surface with an indication specifying an attaching direction to the tire cavity surface.
Subsequently, the above-mentioned noise reducer may be made of a number of elongated sponge materials so as to have two or more of the above-mentioned butt-joint faces.
Moreover, an overall length of the elongated sponge material making up the above-mentioned noise reducer is preferably formed longer before being attached to the tire cavity surface than an inner circumference length of the tire.
In the pneumatic tire with noise reducer according to the present invention, the noise reducer is mounted on the tire cavity surface. This noise reducer is formed in a ring shape by butting both end faces of the elongated sponge material disposed along the tire circumferential direction. Such a noise reducer can be easily made from sponge material and the like which is made by cutting the continuously-formed sponge material into a necessary length, for example. Therefore, the suppressive effect of cavity resonance can be kept, and manufacturing costs can be significantly reduced compared with the noise reducer formed in a jointless ring shape. Moreover, in the noise reducer, the butt-joint face made by butting both of the above-mentioned end faces is a substantive plane. It is therefore not necessary to perform a complex cut process, end-face process, and the like, so that the manufacturing process of the sponge material can be simplified, and the costs can be much more reduced.
a) is a partial perspective view of a sponge material, and
a) is a partial cross-sectional view enlarging a neighborhood of a butt-joint face of the noise reducer, and
a) is a front view showing a joint of the noise reducer of the present embodiment,
a) is a front view showing a joint of the noise reducer of another embodiment,
a) is a cross-sectional view of the noise reducer having the butt-joint face shown in
a) is a front view of showing a joint of the noise reducer of another embodiment,
a) is a front view showing a joint of the noise reducer of another embodiment,
Hereinafter, embodiments of the present invention will be described with referent to the drawings.
As an embodiment of the present invention,
The above-mentioned pneumatic tire with noise reducer 1 comprising a pneumatic tire (hereinafter, may be simply called a “tire”) 3 and a noise reducer 7 attached to a tire cavity surface 6 of the tire.
The above-mentioned tire 3 comprises a troidal carcass 3d extending from a tread position 3a through respective sidewall portions 3b to bead cores 3f of bead portions 3c, and a belt layer 3e disposed outside the carcass in the radial direction of the tire. When the tire 3 is mounted on a rim 2 (in other word, an assembly of tire mounted on a rim), a tire cavity 5 is surrounded by the tire cavity surface 6 and an outer surface of the wheel rim. Meanwhile, in the present embodiment, the tire 3 is a radial tire for a passenger car for which improving noise reduction performance is eagerly anticipated.
In the above-mentioned noise reducer 7, an elongated sponge material 12 is disposed on the tire cavity surface 6 inside the tread position 3 and is curved along the tire circumferential direction as shown in
As shown in
The above-described sponge material 12 can be easily obtained by cutting an original member of linear sponge successively-molded in the longitudinal direction into a specific length at right angles to the above-mentioned longitudinal direction, for example. It is not necessary to conduct any complex cutting process and end-portion process. Therefore, reduction in cost of the noise reducer 7 can be significantly achieved. Moreover, in the noise reducer 7, the above-mentioned end faces 12e, 12e of the sponge material 12 are planes in the same shape with each other and can be cohered together, thereby forming easily the noise reducer into a continuous ring shape and raising productivity. Therefore, in the pneumatic tire with noise reducer 1 of the present invention, the suppressive effect of cavity resonance can be kept as is conventionally done while achieving the reduction in manufacturing cost of the noise reducer 7 significantly.
The noise reducer 7 of above-mentioned embodiment is made of a single elongated sponge material 12. However, the noise reducer can be made of the sponge materials 12, which are shorter in the circumferential direction, by butting each other in the tire circumferential direction to form into a ring shape include two or more butt-joint faces 8 as shown in
The noise reducer 7 of the present embodiment is a horizontally-long rectangle in cross-sectional shape on the tire meridian section including the tire rotational axis. The cross-sectional shape of the noise reducer 7 may be a trapezoidal shape and the like in which a width of the noise reducer is tapered toward an inside in the tire radial direction. Furthermore, the cross-sectional shape of the noise reducer 7 may be different from these shapes.
The sponge material 12 comprising the above-mentioned noise reducer 7 preferably has continuous bubbles and/or independent bubbles made by foaming rubber or resin, for example. Such a sponge material has high vibration absorption and high sound absorbability, so that this can absorb effectively sound energy occurred in the tire cavity 5, thereby surely reducing the road noise. Also, for a sponge material, as not especially limited, it is preferable to use ether-based polyurethane sponge in view of noise suppressing performance, weight reduction, ease of conditioning of foaming, durability and the like. Moreover, the specific gravity of the sponge material 12 is preferably set in a range of 0.005 to 0.060. Such a sponge material with a low specific gravity can reduce the tire weight, can suppress deterioration of the tire balance, and can increase porosity, thereby improving excellent sound absorbability.
Furthermore, the above-mentioned noise reducer 7 at a longitudinal state before being attached to the tire cavity surface 6 has an overall length longer than an inner circumferential length of the tire cavity surface 6 at a position where the noise reducer 7 is attached. In this way, the noise reducer 7 is attached to the tire cavity surface 6 in a compressed state. Therefore, as shown in
When the overall length of the above-mentioned noise reducer 7 before being attached to the tire cavity surface 6 is much longer than the inner circumferential length of the tire cavity surface 6, the noise reducer 7 will be excessively compressed at the time of mounding on the tire, and it is possible to get wrinkled and the like. However, when the overall length is greatly small, adhesiveness between the not se reducer 7 and the tire cavity surface 6 deteriorates, and the noise reducer may possibly go off. From the viewpoint of this, the overall length of the noise reducer 7 before being attached is preferably not less than 1.0 times, more preferably not less than 1.01 times, and is preferably not more than 1.1 times, more preferably not more than 1.05 times the inner circumferential length of the tire cavity 6.
The end faces 12e, 12e of the noise reducer 7 are preferably fixed together as shown in an enlarged view of
For the above-mentioned double-faced tape 20, acrylic adhering agent is preferably used. The above-mentioned adhesive agent 21 is preferably made of isocyanate compound or isocyanate terminated prepolymer which can adhere strongly sponge material, specifically ether-based polyurethane sponge material. However, when the end faces 12e are not directly butted together such as the double-faced tape and the like mediating therebetween, the above-mentioned butt-joint face 8 is defined as an intermediate face between the end faces 12e, 12e.
a) is a front view showing the joint portion of the noise reducer 7 of the present embodiment as viewed from a side of the tire cavity;
Moreover, the above-mentioned butt-joint face 8 may be inclined with respect to a reference surface Ds forming a part of the tire meridian section including the tire rotational axis such as other embodiments shown in
In the embodiment as shown in
Moreover, to improve the durability of the butt-joint face 8, it is preferable to incline the butt-joint face 8 to the first ground contacting side with respective to the tire rotational direction T from an inner surface 12b toward an outer surface 12a in the tire radial direction of the sponge material 12 as shown in the present embodiment. As shown in
In contrast, as shown in
An angle θ1 between the above-mentioned butt-joint face 8 and the reference surface Ds is preferably more than 0 deg. and not more than 85 deg. when the above-mentioned angle 01 is 0 deg., the area of the butt-joint face 8 does not increase too much. When the above-mentioned angle θ1 is too large, the area of the end faces 12e, 12e becomes excessively large, thereby making the cutting process thereof and the like complicated. Moreover, the end faces 12e, 12e become slippery when butting, and it may possibly cause decrease in efficiency when attaching function of the noise reducer 7. From these viewpoints, the above-mentioned angle θ1 is preferably not less than 5 deg., more preferably not less than 30 deg., and is preferably not more than 70 deg., more preferably not more than 60 deg.
Moreover, in the embodiment shown in
Furthermore, the embodiment shown in
As shown in
As shown in
The indication 9 of the present embodiment includes a first indication 10 indicating the rotational direction of the sponge material 12, and a second indication 11 indicating the side of the inner surface 12b of the sponge material 12 to conform the noise reducer to the predetermined tire rotational direction T. Incidentally, it may include any one of them.
The above-mentioned first indication 10 comprises a mark such as an arrow and the like indicating a rotational di reaction, and the second indication 11 comprises letters that denote an inner side (“INSIDE”, for example) and patterns and the like, for example. Such a indication 9 is useful in correctly applying the noise reducer so as to an inclining di reaction of the butt-joint face 8 faces the right direction with respect to a rotational direction of the tire and in preventing errors in attaching when the butt-joint face 8 of the noise reducer 7 inclines as an aspect shown in
Also, the indication 9 can be provided not only on the inner surface 12b of the sponge material 12 but also on the outer surface 12a. Incidentally, as shown in the present embodiment, when the indication is provided on the side of the inner surface 12b, it is preferable to check whether a state of attaching is right or wrong after an attachment of the noise reducer 7. Moreover, when the indication 9 comprises three-dimensional convexo-concave patterns, it is preferable that a position of the indication 9 is confirmable promptly not only with the naked eye but also with hand feeling in attaching function. Also, there are various methods to provide the above-mentioned indication 9 on the noise reducer 7 such as branding, printing, sticker, and/or embossment, for example.
The above-mentioned indication 9 is preferably provided near to the butt-joint face 8, for example, in both regions Ta situated within 40 cm from the butt-joint face in the tire circumferential direction, respectively. To provide the indication 9 near the butt-joint face 8 in this way makes it possible a worker to confirm the indication 9 at the same time as butting the above-mentioned end faces 12 together when attaching the noise reducer 7 on the tire 3. Meanwhile, the above-mentioned region Ta is a region within 40 cm in the tire circumferential direction from a boundary line 8i between the inner surface 12b of the sponge material 12 and the butt-joint face 8. When the boundary line 8i of the butt-joint face 8 inclines with respect to the tire axial direction as shown in
Hereinbefore, an especially preferred embodiment of the present invention was described, but it will be obvious that various changes may be made without limitation to the embodiments shown in the drawings.
Noise reducers were manufactured for trial based on a specification shown in Table 1, and were tested their properties. In Comparative Example 1, used was a jointless noise reducer, which was formed in a ring shape. In Comparative Example 2, used was a noise reducer in which end faces of a sponge material were not butted but separated. In Comparative Example 3, used was a noise reducer in which end faces of a sponge material were in a convexo-concave state, and a butt-joint face was also in a convexo-concave state.
Common specification was as follows:
Tire size: 215/45R17
Rim size: 17×7jj
Inner pressure: 200 kPa
Specification of noise reducer:
The process time that ten sponge materials cut into elongated bodies take to form in respective ring shapes was measured. Meanwhile, an adhesive time to a tire cavity surface was also included when the noise reducer was fixed on the tire cavity surface. The smaller the numeric values are, the higher and the more favorable the efficiency of process is.
Each pneumatic tire with noise reducer having twenty butt-joint faces per noise reducer was mounted on the above-mentioned rim. The pneumatic tire was rolled about 20000 km on a drum tester in accordance with the following condition. Presence of separations of the butt-joint face of the noise reducer was checked by the naked eye, and the number of separations were counted. The less the number of separations is, the more preferable the durability is.
Load: 4.0 kN
Rolling speed: 100 km/h
Diameter of drum: 1.7 m
Each pneumatic tire with noise reducer having a single butt-joint face per noise reducer was mounted on the above-mentioned rim. The pneumatic tire was rolled on the drum tester in accordance with the same condition as the above. Presence of separations of the butt-joint face of the noise reducer was checked by the naked eye once every 1000 km, and a distance at the onset of separation was measured. Evaluation is displayed using indices with the Comparative Example 1 being 100. The larger the numeric value is, the more favorable the durability is.
Cost of manufacturing (including labor costs) per pneumatic tire with noise reducer having a single butt-joint face was displayed using indices with the Comparative Example 1 being 100. The smaller the numeric value is, the more favorable the cost of manufacturing is.
Each tire was loaded on a passenger car, and the car ran on an asphalt road smooth surface at the speed of 60 km/h. Presence of vibration while running was confirmed by driver's ear.
A transportation test was conducted as follows: a pneumatic tire with noise reducer not mounted on a rim was rolled about 15 meters to load into a truck box. Then, the pneumatic tire was dropped down from the truck box, rerolled to where it started, and was laid out flat. Thus, thirty tires were tested every Example to check whether attaching condition of the noise reducer to the tire cavity surface was kept alive. When the attaching was alive, the condition was indicated by “OK”; and when the noise reducer came off from the tire cavity surface, the condition was indicated by the number of such tires.
Test results are shown in Table 1.
According to the tests, it was found that the pneumatic tire with noise reducer used in Examples could reduce manufacturing cost of the noise reducer and could suppress vibration while running. Moreover, according to measurement of the vibration while running, it was also confirmed that the pneumatic tire with noise reducer could keep the suppressive effect of cavity resonance.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-018025 | Jan 2008 | JP | national |
| 2008-141372 | May 2008 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2009/050973 | 1/22/2009 | WO | 00 | 7/6/2010 |
