JP2568062B2 - Radial tire - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to radial tires with improved high speed performance.

[0002]

2. Description of the Related Art Generally, a radial tire for a passenger car is a carcass having cords arranged in a radial direction, and cords arranged outside a crown portion of the carcass and relatively shallow with respect to a tire circumferential direction. The belt layer is made of a ply in which highly elastic cords such as steel are arranged at an angle, and the belt layer imparts a hoop effect to the tread portion and enhances the rigidity of the tread portion. The radial tire is excellent in wear resistance and steering stability due to the increased rigidity of the tread portion, but stress concentration is likely to occur at both edges of the belt layer and rubber peeling is likely to occur. Note that this rubber peeling causes a lifting effect in which both edges of the belt layer float outward in the radial direction due to centrifugal force caused by high-speed rotation of the tire during high-speed running, and when the steel cord is used for the belt layer, the belt is separated. This rubber peeling is likely to occur together with the poor adhesion between the rubber and the cut ends of the steel cords cut at both ends of the layer.

In order to prevent such rubber peeling, Japanese Patent Publication No.
In Japanese Patent Laid-Open No. 5-45402, as shown in FIG. 5, the entire outer side of the belt layer B is covered with a band M using a wide ply having at least the same width as the belt layer B, and a pretension is applied to the belt layer by the band M. Suggest to give. As shown in FIG. 6, the band M is formed by winding the wide ply once or twice in the tire circumferential direction, whereby the cords are arranged in the tire circumferential direction and vulcanization molded. At this time, in order to prevent the ply from slipping, both ends of the ply are bonded by lap joint (column 8, line 4 to column 9, line 30 of the same publication).

However, such a lap joint portion J
In the tire having the band M including the band M, although the band M is made of a non-metal fiber cord such as nylon or rayon,
As a result of the lap joint portion J extending in the tire axial direction becoming thicker than other portions, the tire uniformity is inferior, and at the same time as the high speed running, the joining of the both ends becomes insufficient in the lap joint portion. The tightening force is insufficient, the lifting of the belt layer cannot be sufficiently suppressed, the original function of the band cannot be achieved, and high-speed running performance cannot be sufficiently improved.

Japanese Unexamined Patent Publication No. 58-206401 discloses a radial tire for passenger cars, which has only one purpose, as shown in FIG. 7, to prevent the rubber peeling from occurring, as shown in FIG. It is proposed to provide narrow bands N1 and N1 in which organic fiber cords are arranged in the tire circumferential direction. Further, according to this proposal, in addition to the case where the band layer N1 is formed by winding a small width ply in the tire circumferential direction and splicing the end portions thereof,
It is shown that the two cords are formed by spirally turning the required number of times (page 2, lower right column, lower column 5 of the same publication).
Line to page 3, upper left column, line 1). However, with this proposal in which the band layer is provided only on the tread edge portion, a step difference in rigidity and thickness of the tread portion occurs in the tire axial direction, and the ground pressure is likely to be uneven.

Further, JP-A-54-126305 discloses a large tire mainly used for large vehicles such as buses and trucks, in which metal cords are arranged in the circumferential direction of the tire on the outer side of two belt layers made of metal cords. Band-shaped third
As shown in FIG. 8, this third layer has a layer of No. 1 and a portion S1 on the tread edge side where the number of cords is increased to increase the tensile force and a central portion where the number of cords is decreased. It is shown to be divided into S2.

This third layer considers the effect of centrifugal force on the high speed rotation of a large tire,
Further, in this proposal, each of the portions S1 and S2 is wound with a ply of a predetermined width in the tire circumferential direction, or as shown in FIG. It is disclosed that it is formed by spirally winding at different winding pitches (the same publication, page 4, lower right column, lower line, lines 3 to 5).
(Upper left column, line 6).

In Japanese Patent Publication No. 57-61601, one or a small number of heat-shrinkable fiber cords are bundled on the entire outer surface of the belt layer for the purpose of suppressing waviness of the tire during high-speed traveling, that is, a standing wave. It is shown that a belt-shaped belt auxiliary layer formed by spirally winding the tread edge portion densely is used as one.

On the other hand, JP-A-51-55505 discloses that
A large number of cords around the carcass, preferably metal cords, more preferably steel cords (page 2, upper right column 8 to 1)
(2 rows), that is, a tire having a reinforcing frame formed by spirally winding a long strip ply is proposed.

However, as described above, the reinforcing frame is a so-called belt layer which is required to use steel cords and is preferably provided on the carcass, and enhances the tread effect of the tread and increases the rigidity in the circumferential direction. It's meant to improve, not a band. It has been confirmed by an experiment that a tire using a belt layer having such a cord wound in a spiral and extending in the tire circumferential direction has a significantly reduced cornering force.

An object of the present invention is to provide a radial tire capable of improving the uniformity of the tire and improving the high speed durability, and the tire of the present invention is also excellent in productivity.

[0012]

In the radial tire of the present invention, a belt-shaped ply in the form of a long belt is formed by arranging a plurality of low-elasticity organic fiber cords in parallel in the longitudinal direction on the outer side in the radial direction of the belt layer. A band that is spirally wound so as to cover the entire width of the band, and the bands are spirally wound so that the side edges of the adjacent band-shaped plies contact each other or the side edges are separated from each other. It is characterized by having a gap formed in.

[0013]

As described above, in the radial tire of the present invention, since the belt covering the entire width of the belt layer made of steel cord is provided, the belt layer is provided with a tightening effect over the entire width, and the rigidity and thickness in the tire axial direction are increased. By eliminating the level difference and also covering the tread edge, lifting which tends to occur at both edges of the belt layer due to the centrifugal force generated due to the high speed rotation of the steel cord belt layer is prevented.

In the radial tire of the present invention, the band is formed by spirally winding a long band-shaped ply. Therefore, since there is no lap joint, it is possible to improve the uniformity of the tire, and further, it is possible to prevent the tightening effect from being deteriorated due to insufficient joining force of the lap joint and effectively prevent lifting at the edge portion of the belt layer. By doing so, high speed and high speed durability can be improved.

Further, in the present application, a band is formed by using a long strip-shaped ply in which a plurality of organic fiber cords are arranged in parallel in the longitudinal direction. As a result, a plurality of cords can be pre-aligned on the strip-shaped ply, and the cords are covered with topping rubber to form a strip-shaped ply, so that one or a few cords are bundled into one cord. It is clear that the winding work can be made more efficient than when using, and in addition to improving productivity and facilitating practical application, the cord spacing inside the ply can be adjusted and can be easily made uniform. Therefore, the accuracy of code arrangement in the band can be improved. Further, the band has a side edge of adjacent band-shaped plies contacting each other by being wound or having a gap, and since they do not overlap each other in the radial direction,
Suppresses an increase in tread thickness, improves tire heat dissipation and lightweight, does not reduce tire durability, and increases the tread rubber thickness when the tread has the same total thickness, and wear resistance To improve. In addition, productivity is improved compared to the case of lap winding.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 and 2, the radial tire 1 includes a pair of left and right bead cores 2, 2 and a tread portion 10 and a side wall portion 11 extending from the tire core inside to the outside around the bead core 2 of the bead portion 12 with both ends folded back. And the belt layer 4 arranged inside the tread portion 10 and outside in the radial direction of the carcass 3.
And a band 5 arranged outside the belt layer 4.

The carcass 3 is formed by using one or more carcass plies in which carcass cords made of organic fiber cords such as nylon, polyester, rayon, and aramid or steel cords are arranged in the radial direction.

Further, the belt layer 4 has two or more sheets made of steel cord, in this example, two wide and narrow plies 4A, 4B.
And a wide ply 4A is positioned and disposed on the carcass 3 side. The steel cord is inclined at an angle of 5 ° to 40 ° with respect to the tire circumferential direction, and in each ply, as shown in FIG. 2, the high elastic cords are arranged in directions intersecting with each other, whereby the carcass cord is formed. At the same time, the cords are intersected with each other in the triangular structure to give the tread portion 10 a hoop effect and give rigidity. If the angle is less than 5 °, the lateral rigidity of the belt layer is insufficient, the cornering force is reduced, and the steering stability is impaired. On the other hand, if it exceeds 40 °, the rigidity of the belt layer in the circumferential direction becomes insufficient, resulting in poor wear resistance.

The band 5 is a long strip-shaped ply 6
Is formed by spirally winding so as to cover the entire width of the belt layer 4 on the outer side in the tire radial direction of the belt layer 4. The strip-shaped ply 6 has a plurality of low-elasticity cords, such as nylon, polyester, and rayon, which are lighter in weight and smaller in elastic modulus than the steel cords used in the belt layer 4 and are arranged in parallel in the longitudinal direction. It is a long strip ply having a width of 10 mm to 50 mm in which cords are embedded in rubber by attaching rubber sheets to both surfaces of low elastic organic fiber cord rows arranged in parallel.

The number of cords to be driven is usually about 3 to 15 per 10 mm, and the number is selected according to the purpose together with the cord size.

The band 5 starts winding the strip-shaped ply 6 from one edge 4a of the belt layer, and in the embodiment of FIGS. A band 5 is formed by spirally winding the outer edges of the belt layer 4 a plurality of times continuously over the entire width, in this example, until the other edge 4b of the belt layer 4 is abutted against each other and in contact with each other. As a result, in this embodiment, the band 5 covers the entire outer side of the belt layer 4 without the overlapping portions where the band-shaped plies overlap each other in the radial direction. The band 5 can have a width that exceeds the side edge of the wide ply 4A of the belt layer 4, and thus the lifting of the belt layer 4 can be effectively suppressed.

By thus forming the band 5 by spirally winding the band-shaped ply 6 a plurality of times, the band 5 is inclined in the axial direction or the axial direction like a band formed by winding a wide ply once or twice. There is no continuous splicing part,
It improves the uniformity of the tire, and can give a uniform hoop effect to the belt layer, reduces lifting at the edge of the belt layer, prevents rubber peeling, and improves high-speed performance. Also,
The productivity is improved and the accuracy of the code arrangement is improved, as compared with the case of winding one to a small number of codes.

As for the band 5, as described above, in addition to the case where the side edges of the strip-shaped ply 6 are butted against each other, as shown in FIG.
As shown in FIG. 3, in order to reduce the weight and reduce the cost, the strip-shaped ply 6 is wound with a gap 6b between the side edges thereof.
A band 5 having b and covering the outer belt layer 4 over the entire width of the belt layer 4 may be formed.

As shown in FIG. 4, the band-shaped ply 6 of the band
The tire of Comparative Example A having side portions of the strip-shaped plies 6 adjacent to each other and the overlapping portion 6a as a result of being wound;
The tire of Comparative Example B disclosed in JP-B-55-45402 shown in FIG. 2 was prototyped, and the lifting amount at high speed rotation, the high speed durability, and the uniformity of the tire were compared. As described below, the tire of Comparative Example A is superior to the tire of Comparative Example B in uniformity, lifting, and durability, but the tire of the present invention also has a cord size of the band, an elastic modulus, It is presumed that similar effects are produced when the tire of Comparative Example A is made equivalent to the tire in consideration of the number of hits.

Tire size is 195 / 60R14, carcass material polyester, cord size 1000d
/ 2, using two plies in which a carcass cord of 49/5 cm is placed radially, and as a belt layer,
Material steel, cord size 1 × 5 /. 25, two plies in which cords with a driving number of 35/5 cm are tilted at an angle of 19 ° opposite to each other with respect to the tire circumferential direction are used. The width of the ply near the carcass is 164 mm, and the width of the outer ply is 154 mm. Further, in the tire of Comparative Example A, a strip-shaped ply of 10 mm width in which 10 size 1260d / 2 nylon cords were aligned in parallel was used, and a half width overlapping portion 6a was used.
And forming a band by spirally winding. Therefore, the band is substantially a two-layer body. Further, in the tire of Comparative Example B, a band is formed by winding a wide ply in which 10 same cords are embedded every 10 mm twice with a lap joint portion J having a peripheral length of 15 mm.
In addition, in the example product, the cord is wound about 0.
It is inclined by 5 ° with respect to the tire circumferential direction. In addition, the carcass, the belt layer, and the like have the same specifications except for the method of forming the band.

When the lifting amount was measured at a rotation speed corresponding to 280 km / h, the tire of Comparative Example A was about 7 mm at the center of the tread portion, whereas
The tire of Comparative Example B had a thickness of about 7.8 mm. This difference affects the tread edges and makes a big difference in tire performance.

Next, a bench drum durability test was conducted based on the ECE high-speed durability test method V standard. The ECE high-speed endurance test method V standard is a bench drum tester with a load of 375 kgf and an internal pressure of 3.0 kgf / cm ² from 0 to 200 km / h for 10 minutes, 200 km / hour for 10 minutes, and 21/21.
It is run at 0km for 10 minutes, at 220km for 10 minutes, and at 230km for 20 minutes. In this test,
Further, the test was continued for 20 minutes at each speed of 10 km per hour, and the tires were stepped up until they were destroyed.

As a result, the tire of Comparative Example A has a speed of 2
While the tread part was damaged in 80km steps,
In the tire of Comparative Example B, similar damage occurred at a 270 km / h step.

Under the same conditions, tire size 2
When a tire of 05 / 65R15 was experimentally manufactured and compared, the tread portion of the tire of Comparative Example A was damaged at 280 km / h, and the tire of Comparative Example B was damaged at 270 km / h.

Further, the results of measuring the uniformity using the laser rangefinder are shown in FIGS. 11 and 12 show the tire of Comparative Example B at a speed of 5 k / h.
The shake of the entire circumference when the tire is rotated at the rotation speeds corresponding to m and 120 km, respectively, is measured. In FIGS. 11 and 12, the position indicated by J is the runout caused by the lap joint portion, and FIGS.
In Comparative Example B, the comparatively sharp runout due to the spliced portion did not occur, which was found to be excellent in uniformity.

[0031]

As described above, in the tire of the present invention, since the band-shaped ply is wound plural times in a spiral to form a band, the uniformity of the tire is improved, the high speed durability is improved, and the productivity is improved. Is also excellent.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a tire of the present invention.

FIG. 2 is a partial plan view showing an arrangement state of a belt layer and bands of FIG.

FIG. 3 is a partial plan view showing another example of the band.

FIG. 4 is a partial plan view showing a tire of Comparative Example A having overlapping portions of bands.

FIG. 5 is a cross-sectional view illustrating a conventional tire.

FIG. 6 is a diagram illustrating a wound state of a band of the tire of FIG.

FIG. 7 is a partial plan view illustrating a conventional tire.

FIG. 8 is a cross-sectional view illustrating another conventional band.

FIG. 9 is a diagram showing a uniformity measurement result.

FIG. 10 is a diagram showing a result of uniformity measurement.

FIG. 11 is a diagram showing the measurement results of uniformity.

FIG. 12 is a diagram showing a measurement result of uniformity.

[Explanation of symbols]

 1 tire 2 bead core 3 carcass 4 belt layer 5 band 6 strip ply

Claims (3)

(57) [Claims] 1. A pair of left and right bead cores, a carcass having a cord of a radial arrangement which is folded around the bead cores and locked, and a carcass which is arranged outside the crown portion of the carcass and is 5 to 40 in the tire circumferential direction. A belt layer composed of at least two plies using steel cords inclined at an angle of °, and a plurality of low-elasticity organic fiber cords are arranged in parallel in the longitudinal direction with a belt layer in which the steel cords of each ply are arranged so as to intersect with each other. And a band formed by spirally winding a long band-shaped band-shaped ply embedded and arranged in rubber so as to cover the outer side in the tire radial direction of the belt layer over the entire width of the belt layer. Is wound spirally so that the side edges of the adjacent strip plies come into contact with each other or the side edges are separated from each other to form a shape between the side edges. Radial tire having a clearance portion. 2. The strip ply has a width of 10 mm to 50.
The radial tire according to claim 1, wherein the radial tire is mm. 3. The organic fiber cord of the strip-shaped ply comprises:
The radial tire according to claim 1, which is made of nylon, polyester, or rayon.