JPH04166402A - Radial tire - Google Patents

Abstract

PURPOSE:To improve driving stability and durability during high speed running by a method wherein a band layer formed such that narrow plies where organic fibers are embedded in topping rubber are spirally wound in a winding direction opposite to each other on both sides of an equator is arranged outside a carcass formed of organic fiber cords having a given orientation angle and a belt layer of a steel cord. CONSTITUTION:A belt layer 7 formed of a plurality of steel cords or more is formed radially outwardly of a carcass 6 formed of organic fiber cords inclined at an angle of 70-90 deg. with a tire equator. A bead apex 9A is disposed between the bead winding up part of the carcass 6 and the body part of the carcass 6. Further, a band layer 8 formed such that beltlike narrow plies where organic fiber cords are embedded in tread rubber are spirally wound in a winding direction opposite to each other on both sides of a tire equator C is formed outside the belt layer 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a radial tire that can improve straight-line stability, turning stability, and high-speed durability during high-speed running.

[Conventional technology]

Radial tires are often used, which include a carcass in which carcass cords are arranged radially, and a belt layer using belt cords inclined at a small angle with respect to the tire equator.

In addition, in such radial tires, a band layer covering the outer peripheral surface of the belt layer using reinforcing cords made of organic fibers such as nylon enhances the tagging effect of the belt layer and improves rolling characteristics and wear resistance. In addition, by disposing the belt layer on the side portion of the tire axial direction, it prevents the belt layer from lifting up during high-speed rotation of the tire, and prevents rubber peeling at the end of the belt layer, i.e. Efforts are being made to prevent belt ends from coming loose.

In addition, this band layer includes one band layer B that covers the entire belt layer A, as shown in FIG.
As shown in Fig. 6, a narrow band layer B covering the side portion of the belt layer A is used, and as shown in Fig. 7, a band ply b1 covering the entire belt layer A is used. , a band layer B consisting of narrow band braids b2 and b2 that cover the side portions.

On the other hand, in order to form such a band layer B, conventionally, the required long ply is attached to the belt layer A as shown in FIG.
In addition, a cut band was used in which the starting end and the ending end of the band were attached to each other in the circumferential direction and were connected to each other via a joint J that overlapped with each other.

As a result, the joint J has two overlapping plies, and there is a gap in thickness between the ply and the circumferential part, which impairs the uniformity of the tire and changes the longitudinal direction when the tire is rotated under no load. The above RRO (Radl) which is the amount of deflection (mm)
It also became a source of vibration during driving, causing poor balance and force fluctuations in the longitudinal direction.

In order to solve one part of such problems, when forming the band layer B spanning the gold mine of the belt layer A, the present applicant
According to Japanese Utility Model Application No. 61-15604, as shown in Fig. 9, the belt-shaped tape T is wound continuously in a spiral shape from one edge of the belt layer in the tire axial direction to the other edge, and overlaps each other at the side edges. We are proposing a band layer B that rotates.

[Problem to be solved by the invention]

However, in the case shown in FIG. 9, a band layer B with the same cord arrangement angle and the same thickness was formed over the axial direction of the belt layer A, so that the band layer B closest to the tread surface was Since the cord continues in a spiral shape from one end to the other, the cord is regularly inclined at a constant angle with respect to the tire equator. As a result, even if this angle of inclination is small, this combined with the fact that the tread rubber of this tire is relatively thin causes plysteer to occur during straight running, impeding straight running performance. Furthermore, since one to several cords are wound in a spiral manner from one end of the band to the other end, this is not preferable from the viewpoint of productivity.

The present invention employs a narrow ply using one or more reinforcing cords, and arranges the cords in parallel in opposing directions on both sides of the tire's equator to increase productivity and improve the hoop effect. can effectively improve
The present invention also aims to provide a radial tire that can reduce RRO (RadlalRUNOUT) and plysteer phenomena.

[Means to solve the problem]

The present invention has a main body part extending from the tread part through the sidewall part to the repeat part, and a winding part continuous to the main body part and folded around the bead core of the bead part, and at an angle of 70 to 90 degrees with respect to the tire equator. Consisting of a carcass using one or more carcass plies having a carcass cord made of inclined organic fibers, and a belt ply consisting of two or more steel cords arranged inside the tread portion and radially outward of the carcass. a belt layer, a band layer disposed radially outside the belt layer, and a bead apex extending from the bead core in the direction of the sidewall between the main body portion and the winding portion; A radial tire formed by embedding a band cord of organic fibers in the tread rubber and winding a long narrow ply in a spiral shape in opposite directions on both sides of the tire equator. It is.

[Effect]

Since the band is formed by winding small and medium plies with the band cord embedded in the topping rubber, there is no seam in the direction inclined to the tire equator, making it possible to improve steering stability when going straight and turning. .

Furthermore, since the band layer is wound in the opposite way on both the left and right sides of the band layer that sandwich the tire equator, the cord angles are in opposite directions, causing so-called plysteer to cancel each other out and make an appearance. The top is zero, and straight-line stability is significantly improved, and the band layer suppresses the heavy steel belt layer, which eliminates the belt layer that tends to occur in conventional belt layers due to increased centrifugal force due to high-speed rotation. Since the lifting of the tire edge is suppressed and the standing wave phenomenon is prevented, the high-speed durability of the tire is further improved.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

In the figure, a radial tire 1 includes a tread portion 2, a sidewall portion 3 extending radially inward from both ends of the tread portion 2, and a bead portion 4 located at the radially inner end of the sidewall portion 3.

Also, between the bead portions 4.4, both ends of the main body portion of the carcass ply 6 extending from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4 are wound around the bead core 5 from the inside to the outside. The toroidal carcass 6, which is locked by the toroidal carcass 6, is passed over the rack, and a belt layer 7 and a band layer 8 are sequentially wound on the outside of the carcass 6 in the radial direction.

The carcass 6 is made of, for example, polyester, nylon,
In this example, carcass cords made of organic fibers such as rayon and aromatic polyamide are arranged at an angle of 70 to 90 degrees with respect to the tire equator.In this example, two carcass plies 6A and 6B, inside and outside, are used.
The rolled end of the inner carcass ply 6A covers the rolled end of the outer carcass ply 6B and is interrupted near the maximum middle position of the tire. This helps disperse stress concentrated at the ends of the ply. Also, the carcass 6
A bead apex 9A that tapers up from the bead core 5 toward the outside in the radial direction is interposed between the main body portion and the turned-up portion, and together with the high turn-up structure of the carcass 6, the lateral rigidity of the tire is improved.

The bead apex 9A is reinforced by, for example, a bead fin 9B folded back from the bottom surface of the bead core 5, thereby increasing bead rigidity and preventing the carcass 6 from wearing against the bead core 5, which moves as the tire deforms. Furthermore, the bead portion 4 is provided with a chafer 9C for preventing rim displacement. In addition to the Naori-cascord, inorganic fiber cords such as steel can also be used depending on the tire performance.

In this example, the belt layer 7 is composed of two inner and outer belt plies 7A and 7B, and the inner belt ply 7A has a bridle width W7A that is 1.01 to 1 larger than the outer belt ply 7B's ply width W7B. By making it about 20 times wider,
This prevents the concentration of a difference in rigidity between the edges A and H and the surrounding rubber due to the coincidence of the edges A and H.

In this example, each belt ply 7A, 7B is a cord array body in which steel belt cords are arranged parallel to each other at an angle of about 10 to 30 degrees with respect to the tire equator. A cross-ply structure in which the plies intersect with each other enhances the hoop effect and improves the uniformity of the tire.

Note that the outer belt ply 7B can be made wider than the inner belt ply 7A, and other suitable belt cords include polyester cord, nylon cord, aromatic polyamide fiber cord, and carbon fiber cord layer. In addition, the belt layer 7 may include a mixture of belt plies made of different belt cord materials.

The band layer 8 covers the belt layer 7 by having both edges F extending beyond the edge E of the belt layer 7 outward in the tire axial direction.

As shown in FIGS. 2 to 4, the band layer 8 is formed by winding a strip-shaped and long small and medium ply 10 in a spiral shape from the outer tire equator to the left and right sides of the belt layer 7.

The small and medium ply 10 has one belt cord or a plurality of belt cords 11 arranged in parallel, in this embodiment two belt cords 11, and a topping rubber 12.
The belt cord 11 has an elastic modulus of 60.
An organic fiber cord having a high elastic modulus of 0 kg f 7 mm 2 or more, such as high modulus polyester, aromatic polyaramid, polyester, etc., is used.

When the elastic modulus is less than 600 kgf/mm2, the rigidity of the tread portion 2 is insufficient, and high-speed straight running performance and high-speed turning performance are reduced.

When aromatic polyaramid is used as the wire,
The organic cord made of the strands with a twist number in the range of 20 x 20 T to 57 x 57 T per 10 cm has high tensile strength and flexibility between steel and roads, and can further improve steering stability when going straight and turning. .

Further, in this embodiment, the small and medium ply 10 has a flat rectangular cross section, and the belt cord 1 located outermost from the side edge 10a
The distance N to the center of belt cord 11 is set to 1/2 or less of the pitch P between belt cords 11 and 11.

In this embodiment, the small and medium plies 10 are arranged at a small angle with respect to the tire equator C, with a starting point G near the equator C as shown in FIG. By spirally winding the cords in the same direction, left and right band plies 8a and 8b having a cord arrangement tilted in opposite directions are formed. In addition, the small width ply 10 may be wound toward the tire equator C from both sides of the trailing edge and the root edge. In that case, when winding the small and medium ply 10, as shown in FIG. By wrapping and winding, small and medium ply 10
The small and medium ply 10 at the edge of the belt layer 7 can prevent loosening at the starting point of the belt layer 7 and where a large force is applied during running.
peeling can be prevented.

By using the two band layers 8a and 8b with opposite inclination angles on both sides of the equator as described above, the belt layer 7
It is now possible to simultaneously wind two small and medium plies 10.10 on the top, making it possible to form two band layers 8a, 8b in a short time, and further reducing ply steer.

The Bead Apex 9A has a JISA hardness of 5.
It is made of relatively soft rubber with a hardness of 0 to 70 degrees. If the rubber hardness is less than 50 degrees, the rigidity of the bead portion 4 and sidewall portion 3 will be insufficient, causing the bead portion 4 to buckle, making it difficult to maneuver when going straight or turning. While the stability is poor,
If the angle exceeds 70 degrees, the rigidity will be high and the handling performance will be reduced.

〔Concrete example〕

It has the structure shown in Figure 1 and the tire size is 185/7.
A prototype 0R14 tire was manufactured based on the specifications shown in Table 1. The wear resistance, handling stability, high-speed durability, transferability, and weight of the tire were compared with conventional tires based on the ECE30 standard, and the comparison results are listed in Table 1 as an index with Conventional Tire 1 set as 100. In addition, the smaller the index value, the lighter the weight, and the higher the index value, the better the other performances.

〔Effect of the invention〕

Like the ridges, the radial tire of the present invention can effectively suppress separation from the tire rubber due to lifting while increasing tread rigidity with the band layer, and can greatly improve handling stability and high-speed durability.

Furthermore, since the band layers are arranged with the slopes of the pan de gords in opposite directions on both sides of the equator, plysteer can be canceled out and straight-line stability can be improved.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an embodiment of the present invention, Fig. 2 is a perspective view showing an example of small and medium ply, Fig. 3 is a sectional view illustrating a band layer, and Fig. 4 is a winding of small and medium ply. 5 to 8 are line diagrams showing the prior art, and FIG. 9 is a sectional view illustrating a conventional band layer. 5.-Zade core, 6-,-,-carcass, 7-.
...-belt layer, 7 A, 7 B-1-belt ply, 8-...-band layer. Patent Applicant Sumitomo Rubber Industries Co., Ltd. Agent Patent Attorney Tadashi Naemura 1 Figure IC2r! IJ Figure 4- Figure 3C 8L

Claims (1)

[Scope of Claims] 1. A main body extending from the tread through the sidewall to the bead, and a winding part continuous to the main body and folded back around the bead core of the bead, and having a diameter of 70 to 90 with respect to the tire equator. A carcass made of one or more carcass plies comprising a carcass cord made of organic fibers inclined at an angle of 100 degrees, and two or more steel cords arranged inside the tread portion and outside the carcass in the radial direction. The belt layer includes a belt layer made of belt plies, a band layer disposed on the outside of the belt layer in the radial direction, and a bead apex extending from the bead core in the direction of the sidewall between the main body part and the winding part, and the band The layer is
A radial tire made by winding a long narrow ply of one or more organic fiber band cords embedded in the tread rubber in a spiral shape in opposite directions on both sides of the tire equator. tire. 2. The radial tire according to claim 1, wherein the band cord is made by twisting wires made of aromatic polyaramid in a range of 20 x 20 T to 57 x 57 T per 10 cm.