JPH08197908A - Pneumatic tire - Google Patents

Abstract

PURPOSE: To provide the pneumatic tire which is light in weight, enhances its external wound resistance and a vibration absorbing property of a carcass layer, concurrently is excellent in uniformity, and also enhances control stability, durability and the appearance of the tire. CONSTITUTION: In the pneumatic tire including a carcass layer 2 mounted across paired right and left bead cores 1 and 1, the winding of a rubber tape 12 thereby allows a cylindrical body the outer circumferential surface of which is covered in a surface shape by the rubber tape 12, to be formed, and also allows the aforesaid cylindrical body to be formed into a carcass layer wherein the rubber tape comprises a plurality of organic fiber cords 10 buried in parallel in a coated rubber 11, and is wound more than two windings around the ring of each bead cores 1 across the two bead cores 1 and 1 while being reciprocated in zigzags with the respective bead cores 1 enclosed, and also with each space W relatively maintained between the adjacent tapes along the circumferential direction of each bead core 1.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a pneumatic tire which is light in weight and has improved carcass layer resistance to external damage and vibrations, good uniformity, and improved steering stability, durability and tire appearance. Regarding

[0002]

BACKGROUND OF THE INVENTION Pneumatic radial tires have been widely used in recent years because they have advantages such as high cornering force, excellent wear resistance, and high speed durability as compared with general bias tires. It's starting to happen. By the way, there is an ever-increasing demand for lightweight radial tires, and there is a great demand for weight reduction that greatly contributes to fuel efficiency of vehicles. Therefore, as a result of reducing the thickness of all parts (tire component parts) as much as possible, the external damage resistance is remarkably reduced. Particularly, in the carcass layer of a pneumatic radial tire, the carcass cords are arranged substantially parallel to each other at about 90 ° with respect to the tire circumferential direction, so that the damage resistance is largely reduced.

In addition, the present situation is that the vibration absorption performance of the tire is deteriorated due to the weight reduction and the road noise is worsened due to the unevenness of the road surface. Especially, in the carcass layer, the carcass cord is almost 90 ° to the tire circumferential direction.
Since the carcass cords move substantially independently of each other when the tire rotates, and the carcass cords do not move in relation to each other like a bias tire, vibration absorption performance deteriorates.

Further, in the carcass layer of a pneumatic radial tire, a joint portion called a splice due to its structure is formed in the tire width direction, so that the carcass layer is superposed at that portion to cause unevenness on the tire surface, resulting in a tire appearance. There is also the problem of getting worse.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to improve the carcass layer's external damage resistance and vibration absorption while being lightweight, and to improve the uniformity, steering stability, durability and tire appearance. To provide a pneumatic tire.

[0006]

SUMMARY OF THE INVENTION The present invention provides a pneumatic tire having a carcass layer mounted on a pair of left and right bead cores, in which a plurality of organic fiber cords are embedded in parallel in a coat rubber to form two rubber tapes. By enclosing each bead core between the bead cores and reciprocating in zigzag with a gap between the rubber tapes along the circumferential direction of the bead cores, the rubber tapes are wound around the bead core two or more times to form a peripheral surface. It is characterized in that a tubular body that covers in a circular shape is formed, and the carcass layer is constituted by the tubular body.

Since the carcass layer is constituted by the rubber tape that wraps each bead core between the two bead cores and reciprocates in a zigzag manner as described above, the carcass layer as a whole is in a state where two rubber tapes are always overlapped with each other and the carcass cords thereof are kept together. Crosses between the layers, and a plurality of cords are associated with each other when the tire rotates, so that the carcass layer can be improved in external damage resistance and vibration absorption. Further, since the rigidity of the tire casing is increased, steering stability is improved. Further, since the carcass layer does not splice in the tire width direction as in the conventional radial tire, the tire appearance is not deteriorated. Furthermore, since the carcass layer is wound in a zigzag manner by opening a gap between the tapes, it is possible to reduce the difference in the actual length of the carcass layer in the width direction, thereby improving the tire uniformity (UF). You can Moreover, unlike the conventional case, since there is no winding end around the bead core of the carcass layer, weight reduction can be achieved, and tire durability can be improved because separation does not occur at the winding end. Become.

The structure of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a cross-sectional explanatory view in the meridian direction of an example of the pneumatic tire of the present invention. In FIG. 1, in a pair of left and right bead portions B, B, a carcass layer 2 is mounted on two bead cores 1, 1 and rubber fillers 99, 99. In the tread 3, two belt layers 4 and 4 are provided outside the carcass layer 2 in the tire circumferential direction over the entire circumference of the tire.

On the surface of the tread 3, a plurality of main grooves 5 extending in the tire circumferential direction and a quasi-main groove 6 narrower than the main groove 5 are provided in the center. A belt cover layer 7 is arranged at the widthwise end of the outer belt layer 4 to protect the end. Depending on the type of tire, a belt structure different from that shown in FIG. 1 can be appropriately adopted. As shown in FIG. 2, the carcass layer 2 has a space between the two bead cores 1 and 1, each bead core 1 and a rubber filler 99 (not shown).
It is composed of a rubber tape 12 that wraps around and reciprocates zigzag. A plurality of rubber tapes 12, preferably 30 to 150
The organic fiber cord 10 of a book is embedded in a coat rubber 11 in parallel. The zigzag reciprocating movement in this case is performed while opening a gap between the rubber tapes 12 along the circumferential direction of the bead core 1. Then, while reciprocating the rubber tape 12 in a zigzag manner as described above, the rubber tape 12 is moved along the ring of the bead core 2
By winding the rubber tape 12 around the circumference or more, a cylindrical body is formed in which the outer peripheral surface is covered with the rubber tape 12, and the carcass layer 2 is formed by the cylindrical body. That is, the zigzag reciprocating movement in this case is performed while providing the gap W between the side edges 12a of the rubber tape 12, so that the bead core 1 is wound around the rubber tape 12 for two or more turns along the ring, and the previous winding is performed. The resulting gap W is filled with the rubber tape 12 in the next winding.
Then, by overlapping the starting end and the terminating end of the rubber tape 12, as shown in FIG. 3, a tubular body 30 having a two-layer structure in which two rubber tapes 12 are overlapped is formed. In this case, the cord angle with respect to the tire circumferential direction of the organic fiber cord 10 can be freely determined by appropriately determining the size of the gap W in consideration of the width d of the rubber tape 12, but this cord angle is 60 degrees to 80 degrees. It is good to make it in degrees. Further, in the space formed by the rubber tape 12 inside the bead core 1, rubber having a triangular cross section (rubber filler 99) is provided to fill the space.
Should be arranged in advance. When the longitudinal ends of the rubber tape 12 are connected to each other during the zigzag reciprocating movement, it may be performed in the vicinity of the bead core 1 or at a position corresponding to the belt layer when the belt layer is arranged. Rubber tape 12
The width d may be a width obtained by substantially dividing the inner peripheral length of the bead core into a plurality of parts. Needless to say, the width d of the rubber tape 12 is adjusted according to the cord angle of the carcass layer.

By the way, Japanese Patent Laid-Open No. 4-257703 discloses that
A "pneumatic tire in which a carcass layer is formed by a narrow band-shaped ply which is inclined at an angle of 45 to 90 degrees and which folds the outer peripheral surface of each bead core between two bead cores and spirally circulates" is described. However, in this case, as shown in FIG. 4, the rubber tape 12 is arranged so that no gap is formed between the side edges of the rubber tape 12, and the tubular body 30 as shown in FIG. 5 is formed. As shown in FIG. 4, there is a problem that wrinkles T occur at the bent portion of the rubber tape 12 on the inner diameter portion of the bead core 1. If wrinkles T occur, air will accumulate in the rubber tape 12 at this location, causing tire failure. Furthermore, it is difficult to endure, because the carcass layer with tension is spirally wound on the bead wire that is extremely difficult to hold, that is, the bead interval at the winding start portion is narrowed in order to continue winding, and the difference in the actual carcass layer length is likely to occur. However, there is a problem that tire uniformity, especially RFV, deteriorates.

The organic fiber cord 10 is not particularly limited, but for example, aromatic polyamide fiber cord, polyarylate fiber cord, polyparaphenylenebenzbisoxazole fiber cord, polyvinyl alcohol fiber cord, polyethylene terephthalate fiber cord. , Polyethylene 2,6-naphthalate fiber cord, nylon fiber cord (66 nylon cord, 46 nylon cord)
A rayon fiber cord or the like may be used. It is particularly preferable to use a nylon cord. This organic fiber cord
The total number of denier of 10 is 5000 denier or less and 500 denier or more, preferably 3500 denier or less and 800 denier or more. If it exceeds 5000 denier, the bent part becomes thicker and the durability around the bead core is reduced. If it is less than 500 denier, not only it becomes difficult to secure sufficient carcass strength, but also the productivity is significantly reduced. Coat rubber
As 11, a usual rubber composition used for forming a carcass layer (a mixture of rubber and a compounding agent such as carbon black) may be used.

[0012]

[Examples] The following pneumatic tires having a tire size of 195 / 70R14 91H and a bead core inner peripheral length of 1120 mm in common (tires 1-2 of the present invention, conventional tires 1-2, comparative tires 1- 1)
3) was prepared, and the presence or absence of wrinkles under the bead (wrinkles at the bent portion of the rubber tape 12 on the inner diameter of the bead core 1) was checked for these tires, and tire uniformity (RFV), high-speed durability, and load durability were determined as follows. The steering stability, vibration absorption of the carcass layer (road noise), carcass weight (lightening), tire appearance, and external damage resistance of the carcass layer were evaluated. In this case, air pressure 1.9kg / cm ² ,
The rim is 14 x 5 1 / 2JJ. Table 1 shows the results.

Conventional tire 1 1000 denier 2 twisted polyethylene terephthalate fiber cord 60 sheets / 5 cm sheet was cut at 460 mm and 540 mm at a cord angle of 90 degrees with respect to the tire circumferential direction, and two sheets were stacked to form a carcass layer. Conventional tire 2 1500 denier 2-ply twisted polyethylene terephthalate fiber cord 50 pieces / 5 cm sheet was cut at 540 mm at a cord angle of 90 degrees with respect to the tire circumferential direction to form one carcass layer.

Comparative tire 1 1000 denier 2 strands Polyethylene terephthalate fiber cord 60 strands / 5 cm wide 40 mm wide rubber tape was continuously applied from one bead core to the other bead core, with a distance of 6 mm between the side edges of the rubber tape and a height of 40 mm. The carcass layer was formed by interposing the rubber filler of, folding back every 360 mm, and reciprocating. The cord angle with respect to the tire circumferential direction is substantially 85 degrees.

Tire 1 of the Invention 1 1000 denier 2 twisted polyethylene terephthalate fiber cord 60 pieces / 5 cm width 40 mm wide rubber tape is continuously formed from one bead core to the other bead core, with a gap of 6 mm between the side edges of the rubber tape and a height. A carcass layer was formed by interposing a 40 mm rubber filler, folding back every 360 mm, and reciprocating. In this case, put a rubber tape on the bead core.
It wound 28 times and filled the gap. The cord angle with respect to the tire circumferential direction is substantially 75 degrees.

Tire of the Invention 2 1000 denier 2 strands Polyethylene terephthalate fiber cord 60 strands / 5 cm width 40 mm wide rubber tape is continuously stretched from one bead core to the other bead core with a gap of 6 mm between the side edges of the rubber tape and height. A carcass layer was formed by interposing a 40 mm rubber filler, folding back every 360 mm, and reciprocating. In this case, put a rubber tape on the bead core.
It wound 28 times and filled the gap. The cord angle with respect to the tire circumferential direction is substantially 65 degrees.

Comparative tire 2 1000 denier 2-ply twisted polyethylene terephthalate fiber cord 60 pieces / 5 cm width 40 mm wide rubber tape was continuously adhered from one bead core to the other bead core, and the side edges of the rubber tape were adhered to each other every 360 mm A carcass layer was formed by folding back and reciprocating. The cord angle with respect to the tire circumferential direction is substantially 55 degrees.

Comparative tire 3 1000 denier 2 twisted polyethylene terephthalate fiber cord 60 pieces / 5 cm width 160 mm width rubber tape was continuously adhered from one bead core to the other bead core, and the side edges of the rubber tape were adhered to each other every 360 mm A carcass layer was formed by folding back and reciprocating. The cord angle with respect to the tire circumferential direction is substantially 75 degrees.

Tire Uniformity (Radial
Variation (RFV) : Complies with JASO C607 "Uniformity test method for automobile tires". Table 1
In the table, “◯” means good, “Δ” means bad, and “x” means extremely bad. High-speed durability : After the completion of JIS D-4230, JIS high-speed durability test with a drum diameter of 1707 mm, the test was continued every 30 minutes by accelerating 10 km / hr until the tire broke. This result is compared with conventional tire 1
It is shown as an index of 100. The higher the number, the better.

From these results, it is clear that a lower carcass layer cord angle gives better high-speed durability. Load durability : After the completion of JIS D-4230, JATMA standard load durability test with a drum diameter of 1707 mm, the load was accelerated every 20% / 5 hr and the test was continued until the tire broke.

From these results, it is apparent that the higher the carcass layer cord angle, the better the load durability. Steering stability : Tires were attached to a domestic 2.5-liter class vehicle and the feeling was evaluated by three test panelists. In Table 1, "○" means good, "◎" means very good,
Each "x" represents bad.

Vibration absorption of carcass layer (actual vehicle road noise
Evaluation of road feeling ): Tires were mounted on a domestic 2.5-liter class car, and the road noise feeling of an actual car was evaluated by three test panelists. In Table 1, “◯” means good, “Δ” means bad, and “x” means extremely bad. Tire carcass weight (weight reduction ): The weight of the tire carcass part was measured by a conventional method. This result is compared with conventional tire 1
It is shown as an index of 100. The smaller the number, the better.

Tire appearance inspection : Evaluation was performed by comparing tire appearances by five experts. In Table 1, “⊚” represents extremely good, “∘” represents good, “Δ” represents bad, and “x” represents extremely bad. Trauma resistance of carcass layer : Using an indoor trauma resistance tester,
The maximum number of tires was 70 cm, the height was 70 cm, the impact weight was 20 kg, and the impact area of the cutter was 5 mm x 25 mm. The more times you have, the better.

[0024]

[Table 1]

As is clear from Table 1, the tire 1 of the present invention
~ 2 are wrinkles under the bead, tire uniformity (RF) as compared with the conventional tires 1-2 and the comparative tires 1-3.
V), high-speed durability, load durability, steering stability, carcass layer vibration absorption (road noise feeling), carcass weight (weight reduction), tire appearance, and carcass layer scratch resistance You can see that

[0026]

As described above, according to the present invention, in a pneumatic tire having a carcass layer mounted on a pair of left and right bead cores, a rubber tape in which a plurality of organic fiber cords are embedded in parallel in a coat rubber is provided. By enclosing each bead core between two bead cores and reciprocating in zigzag with a gap between the rubber tapes along the circumferential direction of the bead core, the rubber tape is wound around the bead core for two or more revolutions. Forming a tubular body that covers the surface in a planar manner, and because the carcass layer is constituted by this tubular body, it is lightweight and improves the trauma resistance and vibration absorption of the carcass layer, and also the steering stability and the tire appearance. It is possible to improve. Further, in the present invention, the carcass layer does not have a splice in the tire width direction unlike in the conventional case, so that a good tire appearance can be maintained. Since the carcass layer is wound in a zigzag manner by opening a gap between the tapes, the tire uniformity can be enhanced and a desired winding angle can be selected. Further, unlike the conventional case, since there is no winding end around the bead core of the carcass layer, it is possible to reduce the weight and it is possible to improve tire durability because separation does not occur at the winding end. Become. Moreover, in the present invention, since the carcass material is constituted by continuously zigzag reciprocating the rubber tape with the organic fiber cords embedded therein, it is sufficient to prepare a calendering equipment having a rubber tape width directly connected to the molding machine, which is a large scale. Since the calendering equipment and the cutting equipment are not required, it is possible to inexpensively carry out the production of a wide variety of products in small quantities.

[Brief description of drawings]

FIG. 1 is a meridional direction cross-sectional explanatory view of an example of a pneumatic tire of the present invention.

FIG. 2 is a perspective explanatory view showing a formation state of a tubular body forming a carcass layer in the present invention.

FIG. 3 is a perspective explanatory view showing this tubular body.

FIG. 4 is a perspective explanatory view showing a conventional formation state of a tubular body forming a carcass layer.

FIG. 5 is a perspective explanatory view showing this tubular body.

[Explanation of symbols]

1 bead core 2 carcass layer 3 tread
4 Belt layer B Bead part

Claims (3)

[Claims] 1. A pneumatic tire having a carcass layer mounted on a pair of left and right bead cores, wherein a rubber tape obtained by burying a plurality of organic fiber cords in parallel in a coat rubber is used to wrap each bead core between two bead cores. Further, while forming a gap between the rubber tapes along the circumferential direction of the bead core and reciprocating in zigzag, the rubber tape is wound two or more times along the ring of the bead core to form a tubular body covering the outer peripheral surface in a planar manner. Then, a pneumatic tire in which the carcass layer is composed of this tubular body. 2. The organic fiber cords are aromatic polyamide fiber cords, polyarylate fiber cords, polyparaphenylenebenzbisoxazole fiber cords, polyvinyl alcohol fiber cords, polyethylene terephthalate fiber cords, polyethylene 2,6-naphthalate fiber cords, The pneumatic tire according to claim 1, which is one type of cord selected from the group consisting of a nylon fiber cord and a rayon fiber cord. 3. The pneumatic tire according to claim 1, wherein the carcass layer is substantially two layers.