Source: http://www.freepatentsonline.com/6273162.html
Timestamp: 2019-05-23 23:13:28
Document Index: 124403375

Matched Legal Cases: ['art 15', 'art 40', 'art 12', 'art 15', 'art 12', 'art 15', 'art 15']

Pneumatic tire with specified bead portion - Sumitomo Rubber Industries, Ltd.
Pneumatic tire with specified bead portion
United States Patent 6273162
A pneumatic tire comprises a carcass ply extending between bead portions and is turned up around a bead core in each bead portion to form two turnup portions and a main portion therebetween; each of the turnup portions extends radially outwardly and adjoins the main portion from a certain height above the bead core; a space is surrounded by the carcass ply main portion, and each turnup portion and the bead core is filled with a small size bead apex rubber or a gas; and the bead portion is provided between the carcass ply and the bead core with a bead core cover for preventing the carcass cords from direct contacting with the bead core.
Ohara, Yoshio (Shirakawa, JP)
Endo, Yukio (Shirakawa, JP)
Ueyoko, Kiyoshi (Kobe, JP)
Numata, Kazuki (Shirakawa, JP)
Ikeda, Ikuji (Shirakawa, JP)
09/288506
152/539, 152/541, 152/546, 152/547
B60C1/00; B60C15/04; B60C15/06; (IPC1-7): B60C15/00; B60C15/04; B60C15/06
152/540, 152/541, 152/539, 152/546, 152/547
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3612139 NOVEL BEAD STRUCTURE FOR PNEUMATIC TIRES 1971-10-12 Marzocchi et al. 152/540
a carcass comprising a carcass ply extending between the bead portions and turned up around the bead core in each bead portions to form two turnup portion and a main portion there between,
each said turnup portion extending radially outwardly and adjoining the main portion from a certain height above the bead core so as to form an adjoining part,
a bead core cover disposed between the carcass ply and the bead core for preventing cords of the carcass from direct contacting with the bead core, the bead core cover made of a textile fabric and/or a rubber layer, and
a space in each bead portion surrounded by the carcass ply main portion, the turnup portion and the bead core and filled with a gas to form a cavity.
the bead core cover is made of a textile fabric of organic fiber yarn.
3. The pneumatic tire according to claim 1, wherein the cavity tapers towards the radially outside from the bead core, and the height of the cavity is in the range of from 0.7 to 3.0 times the height of a flange of a wheel rim for the tire.
4. The pneumatic tire according to claim 1, wherein said cavity is surrounded by a gas-tight rubber layer.
the cavity tapers towards the radially outside from the bead core, and the height of the cavity is in the range of from 0.7 to 3.0 times the height of a flange of a wheel rim for the tire.
6. The pneumatic tire according to claim 1, wherein said cavity is surrounded by a gas-tight rubber layer made of a butyl rubber.
7. The pneumatic tire according to claim 6, wherein
The present invention relates to a pneumatic tire, and more particularly to a bead structure being capable of reducing the weight of the bead portions without deteriorating the bead durability.
In pneumatic tires used under relatively heavy loads such as heavy duty tires for trucks and buses, light truck tires and the like, a large volume of bead apex rubber is disposed between a carcass ply turnup portion and a main portion to increase the bead rigidity and thereby to decrease deformation of the tire under heavy loads.
In such tires of which the bead apex rubber is very small, the movements and bending deformation of the carcass plies under loads are relatively large. Therefore, as the tension of the carcass cords is large and a large stress concentrates on contacting points with the bead core, the carcass cords are liable to be cut.
It is therefore, an object of the present invention to provide a pneumatic tire, in which the carcass cords are prevented from being cut and the durability of the bead portions are improved.
a carcass ply extending between the bead portions and turned up around the bead core in each bead portion to form two turnup portions and a main portion therebetween,
each said turnup portion extending radially outwardly so as to adjoin the main portion from a certain height above the bead core,
a bead core cover disposed between the carcass ply and the bead core for preventing cords of the carcass from direct contacting with the bead core, the bead core cover made of a textile fabric and/or a rubber layer.
FIG. 1 is a cross sectional view of a heavy duty tire according to the present invention.
First, the terms used in this specification, namely: "standard rim", "standard pressure", "standard load", "bead base line" and "radial height" are defined as follows:
Standard rim is the "standard rim" specified in JATMA, the "Measuring Rim" in ETRTO, the "Design Rim" in TRA or the like;
Standard pressure is the "maximum air pressure" in JATMA, the "Inflation Pressure" in ETRTO, the maximum pressure given in the "Tire Load Limits at Various Cold Inflation Pressures" table in TRA or the like;
Standard load is the "maximum load capacity" in JATMA, the "Load Capacity" in ETRTO, the maximum value given in the above-mentioned table in TRA or the like;
In the drawings FIGS. 1, 4 and 6, the tire 1 (1A, 1B, 1C) according to the present invention comprises a tread portion 2, a pair of sidewall portions 3, a pair of axially spaced bead portions 4 with a bead core 5 therein, a carcass 6 extending between the bead portions 4, a belt 7 disposed radially outside the carcass 6 in the tread portion 2.
The bead core 5 is made of at least one inextensible material, for example, a coiled rubberized steel wire or wires, a coiled high-elastic-modulus organic cord or cords such as aromatic polyamide fiber cord, a wound tape-like material, and the like. As to the sectional shape of the bead core 5, a hexagonal shape is preferably used. In the case of heavy duty tires to be mounted on a 15-degrees taper rim, a hexagonal shape, of which the aspect ratio is low is preferred and the major axis is inclined at the substantially same angle (10 to 17 degrees) as the inclination of the rim seat (15 degrees).
The carcass 6 comprises at least one ply 9 of cords 21 arranged radially at an angle of 70 to 90 degrees with respect to the tire equator CO, and extending between the bead portions 4 through the tread portion 2 and sidewall portions 3, and turned up around the bead core 5 in each bead portion 4 from the inside to the outside of the tire to form a pair of carcass ply turnup portions 9B and a main portion 9A therebetween.
For the carcass cords 21, steel cords are preferably used in the case of heavy duty tires. However, organic fiber cords, e.g. nylon, rayon, polyester, aromatic polyamide and the like can be also used.
As to the carcass ply turnup portions 9B, the distance from the carcass ply main portion 9A gradually decreases towards the radially outside from the bead core 5, and then, from a certain radial height (h), the distance becomes a substantially-constant minimum value. (FIG. 2) This part (hereinafter adjoining part 15) in which the distance between the turnup portion 9B and the main portion 9A is minimum and thus these portions adjoin each other has a certain length L2.
A space defined as surrounded by the carcass ply turnup portion 9B and main portion 9A and the bead core 5 is filled with a small size bead apex rubber 10 or a gas (usually air). (FIG. 4)
The bead portion 4 is provided along the bottom and axially outside thereof with a chafer 11. (FIG. 7)
The chafer 11 is made of a relatively hard rubber having a 100% modulus of from 55 to 75 kgf/sq.cm, whereas the sidewall rubber 10 has a 100% modulus of from 10 to 20 kgf/sq.cm. The chafer 11 extends radially outwards from the underside of the bead core 5, while abutting on the axially outside of the carcass 6. The chafer rubber 11 tapered-overlaps the sidewall rubber 10 above the radially outer end of the rim flange Jf. In the overlapped portion, the chafer rubber 11 is positioned on the axially inside of the sidewall rubber 10. On the outer surface of the tire, the radial height L4 of the radially outer edge of the chafer rubber 11 is preferably set in the range of from 1.2 to 2.5 times the flange height H.
As a First Embodiment, FIG. 1 and FIG. 2 show a heavy duty radial tire 1A according to the present invention, wherein a state of the tire mounted on a standard rim J (a center drop 15-degree taper rim) and inflated to an internal pressure of 50 kpa is shown.
Wheel rim: 22.5×8.25 standard rim
The specifications of the tires and test results are shown in Table 1. TABLE 1 Tire Ref.A1 Ex.A1 Ex.A2 Ex.A3 Ex.A4 Carcass Height Hk (mm) 211 211 211 211 211 Straight part of exist exist exist exist exist main portion Adjoining part 40 40 40 40 40 length L2 (mm) Bead apex rubber JIS-A hardness 90 90 90 90 90 (deg.) Height h (mm) 40 40 40 40 40 Textile fabric -- nylon nylon nylon nylon -- 940dtex/2 940dtex/2 1670- 1670- dtex/2 dtex/2 Layer -- single double single double Bead durability 500 550 600 580 600 (hrs.)
Second Embodiment is illustrated in FIG. 4 and FIG. 5 which show a light truck tire 1B according to the present invention, wherein the tire is mounted on a standard rim J and inflated to an internal pressure of 50 kpa.
The belt 7 is composed of at least two cross plies. In this example, two cross plies 7B and 7C of high-elastic-modulus cords such as steel cords are employed.
The carcass 6 comprises one to three plies. In this example two plies 9 and 14 of organic fiber cords 21, e.g. polyester, rayon, nylon, aromatic polyamide are arranged at an angle of 75 to 90 degrees with respect to the tire equator CO.
The bead apex 10 is made of a relatively hard rubber having a JIS-A hardness of 70 to 100 degrees tapering towards the radially outside from the bead core 5. The radial height (h) of the radially outer end 13 thereof is set in the range of from H -15 mm to H +15 mm, wherein H is the rim flange height.
In this embodiment, (FIG. 7) the chafer 11 extends radially outwards, while abutting the axially outside of the outer carcass ply 14.
Light truck tires of size 7.00R16 having the structure shown in FIG. 4 and FIG. 5 were prepared and tested bead durability.
Wheel rim: 5.50F×16 standard rim
The specifications of the test tires and test results are shown in Table 2. TABLE 2 Tire Ref.B1 Ref.B2 Ex.B1 Carcass Straight part of main portion non exist exist Adjoining part length L2 (mm) - 40 40 Bead apex rubber JIS-A hardness (deg.) 90 90 90 Height h (mm) 85 28 28 Flange height H (mm) 12.7 12.7 12.7 Rubber layer 16 Thickness T1 (mm) -- -- 2 JIS-A hardness (deg.) -- -- 70 Thickness T2 (mm) -- -- 4 Length L1 (mm) -- -- 10 JIS-A hardness (deg.) -- -- 70 Bead durability (hrs) 400 500 600
A Third Embodiment shown in FIG. 6 and FIG. 7 shows a heavy duty radial tire 1C according to the present invention, wherein the tire is mounted on a standard rim J and inflated to a standard pressure but loaded with no tire load.
In this embodiment, the belt 7 is composed of four plies 7a, 7b, 7c and 7d of parallel steel cords disposed in this order from the inside to outside. The cord angle of the first ply 7a is 50 to 70 degrees, and the angles of the second, third and fourth plies 7b to 7d are not more than 30 degrees with respect to the tire equator CO.
The carcass 6 comprises a single ply 9 of steel cords arranged at substantially 90 degrees with respect to the tire equator CO.
Similar to the former tires 1A and 1B, a substantially straight part Y of the carcass ply main portion 9A, a curved part 12 of the carcass turnup portion 9B, and an adjoining part 15 of the carcass ply main portion and turnup portion are formed. The curved part 12 extends axially inside or on a straight line X, the straight line X drawn between the axially outmost point BP of the bead core 5 and the outer end 8e of the cavity 8.
The adhesion of the butyl rubber layer 20B is not so good when compared with the topping rubber. Therefore, to prevent separation, inserting length L5 of the sealing layer 20B between the carcass ply main portion 9A and turnup portion 9B is set to be not more than 5 mm. Further, the radial height L6 of the upper end of the sealing layer 20B is preferably not more than 3.0 times the flange height H.
As shown in FIG. 10, in the adjoining part 15, the rubber thickness N between the carcass cords 21 of the main portion 9A and the carcass cords 21 of the turnup portion 9B is set in the range of from 0.15 to 4.5 times, preferably 1.3 to 3.5 times the diameter K of the carcass cords 21. If the thickness N is less than 0.15 times K, it is difficult to mitigate the shearing force, and there is the danger that the carcass cords 21 directly contact each other, and thus a carcass ply separation is caused. If the thickness N is more than 4.5 times K, the turnup portion 9B is liable to be broken by a compressive stress and the heat generation is liable to increase.
The length L2 of the adjoining part 15 is in the range of from 0.5 to 5.0 times preferably 1.0 to 4.0 times the maximum section width BW of the bead core 5. (See FIG. 7) If the length L2 is less than 0.5 times BW, the bead durability decreases. If the length L2 is more than 5.0 times BW, it is difficult to improve the bead durability, and the tire surface is liable to undulate and a carcass ply edge separation is liable to occur because the outer end of the turnup portion 9B reaches a position where the sidewall rubber is relatively thin.
Heavy duty radial tires of size 11R22.5 having the structure shown in FIG. 6 and FIG. 9 were prepared and tested for the bead durability, steering stability and tire weight. The test tires had a carcass composed of a single ply of steel cords (3×0.17+7×0.20) arranged at an angle of 90 degrees with respect to the tire equator at a cord count of 21 (/5 cm) at the tread center, and a belt composed of four plies of steel cords (3×0.20+6×0.35) laid parallel with each other at a cord count of 26 (/5 cm). The cord angles of the four plies were +67/+18/-18/-18 degrees (from inside to outside).
Wheel rim: 8.25×22.5 standard rim
The specifications of the test tires and test results are shown in Table 3. TABLE 3 Tire Ex. C1 Ex. C2 Ex. C3 Ex. C4 Ex. C5 Ex. C6 Ex. C7 Ex. C8 Ex. C9 Ex. C10 Ref. C Cavity height h (mm) 28 40 28 28 28 28 28 28 28 28 -- Ratio h/H 2.2 3.1 2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.2 -- Sealing rubber layer Thickness Ta (mm) 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 -- Thickness T (mm) 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 -- Inserting Length L5 (mm) 3.0 3.0 6.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 -- Carcass Adjoining part Length L2 (mm) 55 55 55 7 55 55 55 55 55 55 55 Ratio L2/BW 3.7 3.7 3.7 0.4 5.2 3.7 3.7 3.7 3.7 3.7 3.7 Rubber thickness N (mm) 1.3 1.3 1.3 1.3 1.3 0.1 3.6 1.3 1.3 1.3 1.3 Ratio N/K 1.7 1.7 1.7 1.7 1.7 0.13 4.7 1.7 1.7 1.7 1.7 Chafer Height L3 (mm) 65 65 65 65 65 65 65 25 25 25 25 100% modulus (kgf/sq. cm) 60 60 60 60 60 60 60 60 54 76 60 Test Results Bead durability 150 105 130 102 150 80 101 75 105 110 100 Steering stability 105 103 105 100 105 103 100 90 95 100 100 Tire weight 98 97 98 96 103 97 102 98 98 98 100
From the test results, it was confirmed that test tires according to the present invention can be improved in bead durability and weight while maintaining steering stability.
A Tire Manufacturing Method is illustrated in FIG. 11 to FIG. 14 which show a method of manufacturing the tire 1C having the cavity 8.
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