JPH09226313A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve uniformity of a tire and reinforced element breakage resistance of an inclined belt layer while attempting reduction of weight. SOLUTION: It has an inclined belt layer 6 and a circumferential belt layer 7 between an outer periphery of a crown part 4 of a carcass 3 and a tread 10, the inclined belt layer 6 is constituted by continuously arranging belt bodies covering reinforced elements with rubber zigzag in the tire circumferential direction and forming a bent part 8a of the belt body 8 by arranging it at a position corresponding to ends 9a, 9b of the inclined belt layer in the cross direction, the reinforced element of the inclined belt layer 6 is made of one or more than one of steel monofilaments formed spiral, a volume modulus of covered rubber of the inclined belt layer 6 is more than 200kgf/mm<2> , breaking strength per width 50mm of the inclined belt layer 6 is more than 1000kgf, and the circumferential belt layer 7 is materially arranged in parallel with a tire equatorial surface by spirally winding around its cord.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire having a so-called endless belt structure, and relates to a pneumatic radial tire having both excellent uniformity and good durability while achieving weight reduction, In particular, it is suitable for passenger car tires and light truck tires.

[0002]

2. Description of the Related Art A pneumatic tire generally has a so-called cross belt in which at least two inclined belt layers are laminated around the crown portion of a carcass so that their steel cords cross each other. Target.

However, the inclined belt layer is formed by cutting a cord rubberized sheet into a predetermined width obliquely according to the arrangement angle of the cord, and in this inclined belt layer, the cutting portion of the cord is an end portion. Inevitably will be located in. This is not desirable from the viewpoint of durability and the like, because separation tends to occur at the end portion of the belt layer.

In order to prevent the cut portion of the cord from being located at the end portion of the inclined belt layer, a belt-shaped body obtained by coating one or a plurality of cords with rubber is continuously arranged in a zigzag shape in the circumferential direction. By arranging the bent portion of the zigzag-arranged strip at the widthwise end position of the inclined belt layer, and covering the entire circumference of the tire (substantially the entire outer surface of the carcass crown portion) with this strip. It is useful to form an inclined belt layer, which is disclosed in Japanese Utility Model Application Laid-Open No. 48-96259, Japanese Patent Application Laid-Open No. 4-274904, and Japanese Patent Application Laid-Open No. 5-319.
No. 017 is disclosed.

In the tires described in these publications, although the cutting portion of the cord is not located at the end of the inclined belt layer,
For example, as shown in FIG. 4, a linear step 11 (indicated by a thick line) inevitably occurs, and in addition, depending on the winding method,
There may be a zigzag step 12. The zigzag step 12 is generated by the arrangement in which the strips alternately intersect and overlap each other, and the cords are constrained to each other, which has the advantage of improving the shear rigidity of the belt, whereas The uneven step 11 has no particular advantage, and has a great drawback that the uniformity of the tire is deteriorated. This is a fatal drawback especially for passenger car tires and light truck tires,
It was necessary to develop a means for reducing the linear step 11.

On the other hand, it is necessary to reduce the weight of the tire.

For this reason, attempts have been made to use, as the reinforcing element of the inclined belt, an organic fiber cord or a reinforcing element composed of one or more high strength steel monofilaments having a relatively small diameter. It was

[0008]

However, the organic fiber cord is liable to melt under use of a high load and high speed running condition, and the belt strength tends to be insufficient. The current situation is that it is difficult to satisfy Further, a reinforcing element composed of one or two or more steel monofilaments having a relatively small diameter and having a linear arrangement shape is apt to cause insufficient belt strength and breakage of the reinforcing element.

Therefore, an object of the present invention is to reduce the weight by constructing the reinforcing element of the inclined belt layer with one or more high-strength steel monofilaments whose layout shape is optimized. To provide a pneumatic radial tire having excellent uniformity and good durability by preventing breakage resistance of a reinforcing element of an inclined belt layer, and particularly to provide a passenger car tire and a light truck tire. .

[0010]

In order to achieve the above object, a pneumatic radial tire of the present invention is provided with a rubber of a reinforcing element on the outer periphery of a crown portion of a carcass that is in a toroidal shape and straddles at least a pair of bead cores. A sloping belt layer comprising a pulling layer and at least one circumferential belt layer located on the sloping belt layer and comprising a rubberized layer of cord, the sloping belt layer having a spiral shape 1 A belt-shaped body formed by rubber-covering a reinforcing element composed of two or more steel monofilaments is continuously arranged in a zigzag shape in the tire circumferential direction, and the bent portion of the zigzag-arranged belt-shaped body is formed into an inclined belt layer. be formed by placing in the width direction end position, the bulk modulus of the coating rubber of the inclined belt layer has a 200 kgf / mm ² or more, the inclination belt layer, breaking strength per width 50mm And at 1000kgf or more circumferential belt layers, the cord becomes parallel arrangement on substantially with respect to the tire equatorial plane wound spirally.

When the belt covers the entire circumference of the tire with a predetermined width of the slant belt layer, one set of slant belt layers is provided, and the number of slant belt layers is two sets. More preferably, the cord is an organic fiber cord made of polyethylene terephthalate, polyethylene naphthalate, vinylon or nylon.

The vinylon referred to herein is one having good adhesiveness, high rigidity and high strength, and having a large number of polyvinyl alcohol hydroxyl groups on the fiber surface as a molecular structure, As the cord for the circumferential belt layer, a high bulk modulus, high strength vinylon having a yarn elongation of 2% or less under a stress of 4.5 g / d and a strength of 15.0 g / d or more is twisted and used. Preferably.

Further, as shown in FIG. 3 (a), the bulk modulus of the rubber is as follows: In the cavity of the steel jig 16 having a cylindrical cavity having a diameter d of 14 mm and a height h of 28 mm, After filling the rubber test piece 17 without any gap, the jig 16
As shown in (b), the test piece was set in the tensile / compression tester 18, and the upper and lower surfaces of the rubber test piece 17 were set to 0.6 mm / min. The load W is applied at the speed of, and the displacement amount at this time is measured by the laser displacement meter 19 and calculated from the relationship between the load and the displacement.

Further, the breaking strength per width 50 mm of the inclined belt layer means the breaking strength when the reinforcing elements placed per width 50 mm are collectively pulled in the longitudinal direction.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a cross section in the width direction of a typical pneumatic tire according to the present invention, in which 1 is a pneumatic radial tire, 2 is a bead core, 3 is a carcass, and 4 is a carcass.
Is a crown portion of the carcass, 6 is an inclined belt layer, 7 is a circumferential belt layer, 9a and 9b are widthwise ends of the inclined belt layer, and 10 is a tread.

The pneumatic radial tire 1 is composed of a rubberized layer of a reinforcing element between a tread 10 and an outer circumference of a crown portion 4 of a carcass 3 having a toroidal shape extending over at least a pair of bead cores 2. An inclined belt layer 6,
It is disposed on the inclined belt layer 6 and at least one circumferential belt layer 7 made of a rubberized layer of a cord is arranged.

As shown in FIG. 4, the inclined belt layer 6 is formed by continuously arranging strip-shaped bodies 8 coated with a reinforcing element in a zigzag shape in the tire circumferential direction 5, and bending the strip-shaped bodies 8 in the zigzag arrangement. The portion 8a is formed by being arranged at the widthwise ends 9a and 9b of the inclined belt layer. The reinforcing element consists of one or more steel monofilaments shaped in a spiral. Specifically, one steel monofilament, a steel monofilament bundle in which two or more steel monofilaments are aligned, or a steel cord in which two or more steel monofilaments are twisted is given a spiral shape. FIG. 8 shows an example in which one steel monofilament is spirally shaped. The shape of the spirally shaped steel monofilament drawn on the cross section along the tire meridian may be not only the perfect circle shown in FIG. 8 (b) but also the ellipse shown in FIG. It is advantageous for

The inclined belt layer 6 has, for example, as shown in FIG. 5 or 6, a belt-shaped body 8 with one widthwise end 9a or
From 9b toward the other width direction end 9b or 9a, after winding at a predetermined inclination angle, bent at this width direction end 9b or 9a (bending angle α), then the other width direction end 9b or 9a Is arranged in a zigzag shape by winding from one side toward the one end 9a or 9b in the width direction, and is repeatedly formed. Specifically, a total of M (integer) bends per N (integer) rotation of the tire. By alternately performing the widthwise ends 9a and 9b, the circumferential pitch of shifting the strip-shaped body to the front or back is arranged so that the strip-shaped body wound first and the strip-shaped body to be wound next are arranged at a predetermined interval. By determining the inclined belt layer 6
To form

In FIG. 6, starting from the position 13, a total of M times are bent at the widthwise ends 9a and 9b of the inclined belt layer 6 during N times of tire rotation, and then a belt-like shape is formed at a position 14 adjacent to the starting point 13. Shows the state that the body has reached. By this method, it becomes possible to arrange the strips at a substantially desired inclination angle without forming a gap in the adjacent strips. The inclined belt layer 6 obtained by this method has zigzag steps 12 as shown in FIG. That is, in the inclined belt layer 6 shown in FIG. 4, the strip-shaped bodies 8 intersect and overlap,
Since the reinforcing elements are constrained to each other, the shear rigidity of the belt can be improved as compared with the inclined belt layer shown in FIG.

In the inclined belt layer, if the bulk elastic modulus of the covering rubber is too small, the reinforcing element of the inclined belt layer is likely to move, breakage of the reinforcing element due to buckling is likely to occur, and the inclined belt layer has a predetermined thickness. If the breaking strength is too small, the reinforcing element is likely to break due to insufficient belt strength. Therefore, the bulk elastic modulus of the covering rubber of the inclined belt layer is 200 kgf / mm ² or more, and
By setting the breaking strength per width 50 mm of the tilted belt layer to 1000 kgf or more, breakage of the reinforcing element of the tilted belt layer can be prevented.

Incidentally, FIG. 7 illustrates the relationship of the forces acting on the tire when the pneumatic radial tire 1 is loaded. Regarding the back ring, the tread rubber 24 and the belt 20 are the tire internal pressure P1 and the ground contact. The pressure P2 and the tire receive the radial compression force, and the side portion 21 receives the compression force 23 in the width direction of the tire due to the collapse as shown by the arrow 22, and further receives the compression force in the tangential direction of the tire. If the bulk modulus of the rubber is not sufficient in this state, the movement of the reinforcing element forming the orbiting belt layer becomes large, and the reinforcing element is liable to cause local buckling and break easily.

The number of layers of the inclined belt layer 6 is preferably a small number from the viewpoint of weight reduction, but in particular, in small truck tires, it is often used at an internal pressure about twice that of passenger car tires, and the strength is high. In order to maintain the above, it is preferable that when the belt covers the entire circumference of the tire with a predetermined width of the inclined belt layer and one set of inclined belt layers is provided, the inclined belt layers are provided in two sets. In addition, the number of hammered-in one steel monofilament or a bundle of two or more steel monofilaments, which are reinforcing elements of the inclined belt layer, is 50 mm per 50 mm from the viewpoint of satisfying both circumferential rigidity and weight saving. It is preferably in the range of 15 to 50 lines.

The cord of the circumferential belt layer is for avoiding the joint portion, that is, for reducing the step difference,
Wind it in a spiral and arrange it substantially parallel to the equatorial plane of the tire.

In addition, as the cord for the circumferential belt layer, it is preferable to use an organic fiber cord made of polyethylene terephthalate, polyethylene naphthalate, vinylon or nylon from the viewpoint of weight reduction.

The number of the circumferential belt layers 7 is preferably about 1 to 2 from the viewpoint of weight reduction. When it is necessary to effectively suppress the protrusion of the crown center portion during high-speed traveling, the circumferential belt layer preferably has two layers in the crown center portion and one layer in the remaining crown portion. When it is necessary to effectively suppress the belt edge separation, the circumferential belt layer 7 has a crown edge portion of 2 mm.
It is preferable that the layer and the remaining crown portion are made into one layer, which can be appropriately selected according to the application.

[0026]

Next, specific examples of the pneumatic tire according to the present invention will be described with reference to the drawings. (1) Passenger Car Tires Passenger car radial tires of Examples 1 and 2 and Comparative Examples 1 to 3 have a width direction cross section shown in FIG. 1, and the tire size is 195 / 65R14, and a pair of tires is used. An inclined belt layer 6 made of a rubberized layer of a reinforcing element is provided between the tread 10 and the outer circumference of the crown portion 4 of the carcass 3 which forms a toroidal shape across the bead cores 2, and the inclined belt layer 6
Overlying, at least one consisting of a rubberized layer of cord
A circumferential belt layer 7 of layers was provided. The inclined belt layer 6 was formed by bending a reinforcing element made of a single steel monofilament, which was helically shaped, at the widthwise ends 9a, 9b of the inclined belt layer at an angle of 22 ° with respect to the tire equatorial plane. It is arranged in a zigzag pattern and consists of one set of inclined belt layers. The arrangement shape of the reinforcing element, the number of driving, and the presence or absence of the circumferential belt layer 7 are shown in Table 1. When the circumferential belt layer 7 is provided, the cord material is PET (polyethylene terephthalate),
The structure was 1500d / 2.

The inclined belt layer 6 has a plane shape shown in FIG. 4, and according to the state shown in FIG. 6, M = 9 and N =
4, that is, a value close to the circumferential pitch f = 9/4. The circumferential belt layer 7 is formed by winding cords in a spiral shape and arranging the cords at an angle of approximately 0 ° with respect to the tire equatorial plane. The circumferential belt layer 7 has a width of 130 m.
m, narrower than the width of the inclined belt layer 6 (140 mm), and the widthwise end of the circumferential belt layer 7 is 5 mm wider than the widthwise ends 9a and 9b of the inclined belt layer 6 in the tire width direction. It was placed inside.

In Conventional Example 1, ± 22 with respect to the equatorial plane 5 of the tire.
Two inclined belt layers 6 extending at an angle of 0 ° and having a plurality of steel cords having a cord structure of 1 × 5 × 0.23 are cross-laminated, and the circumferential belt layer 7 is not provided. .

[0029]

[Table 1]

(1) Small Truck Tires The small truck radial tires of Examples A to B and Comparative Examples A to C have a cross section in the width direction shown in FIG. 1, and the tire size is 195 / 85R16. 12PR, a slanted belt layer 6 formed of a rubberized layer of a reinforcing element between the tread 10 and the outer circumference of the crown portion 4 of the carcass 3 that forms a toroidal shape across the pair of bead cores 2.
Positioned on the inclined belt layer 6 was at least one circumferential belt layer 7 made of a rubberized layer of cords. In addition, the inclined belt layer 6 is 25 degrees with respect to the tire equatorial plane.
A reinforcing element made of one steel monofilament spirally shaped at an angle of ° is bent in zigzag at the widthwise ends 9a and 9b of the inclined belt layer, and is composed of two sets of inclined belt layers. . Arrangement shape of the reinforcing element,
Table 2 shows the number of driving and the presence or absence of the circumferential belt layer 7. When the circumferential belt layer 7 is provided, the cord material is PET, and the structure is 1
It was set to 500d / 2.

The inclined belt layer 6 has a plane shape shown in FIG. 4, and according to the state shown in FIG. 6, M = 9 and N =
4, that is, a value close to the circumferential pitch f = 9/4. The circumferential belt layer 7 is formed by winding cords in a spiral shape and arranging the cords at an angle of approximately 0 ° with respect to the tire equatorial plane. The circumferential belt layer 7 has a width of 100 m.
and the inclined belt layer 6 (lower layer 125 mm, upper layer 110
mm) and the widthwise end of the circumferential belt layer 7 is arranged 5 mm further inward than the widthwise ends 9a and 9b of the upper layer of the inclined belt layer 6 in the tire width direction.

The conventional example A is ± 25 with respect to the tire equatorial plane 5.
Two inclined belt layers 6 each having a plurality of steel cords having a cord structure of 1 + 6 × 0.28 extending at an angle of 0 ° are cross-laminated, and the circumferential belt layer 7 is not provided.

[0033]

[Table 2]

(Test Method) With respect to each of the above-mentioned test tires, the uniformity and the durability were evaluated separately for passenger car tires and small truck tires.

(1) Uniformity test A tire filled with a specified internal pressure is pressed against a drum with a specified load, and the drum is rotated so that the tire rotates 60 times per minute. The unbalance amount of the force in the direction and the longitudinal direction was measured to evaluate the uniformity. The test results of the passenger car tire and the light truck tire are shown in Table 1 and Table 2, respectively. The uniformity values in Table 1 are those of the conventional example 1.
Is shown as an index ratio, and the uniformity values in Table 2 are shown as an index ratio with Conventional Example A as 100. In any case, the smaller the value, the better.

(2) Durability test A maximum load specified by JATMA was applied at a tire internal pressure of 1.0 kgf / cm ² and the tire was allowed to run for 4 hours at a slip angle of 8 °, after which the tire was disassembled to form a slanted belt layer. In, whether or not breakage occurred in the reinforcing element was investigated, and durability was evaluated. Table 1 shows the measurement results of passenger car tires.
Table 2 shows the measurement results of the small truck tires. In these tables, if there is a break in the reinforcing element, "Yes"
When the reinforcing element does not break, it is described as “none”.

From the test results shown in Table 1, the passenger car tires of Examples 1 and 2 are superior to the passenger car tire of Conventional Example 1 in uniformity, and breakage of the reinforcing element of the inclined belt layer is recognized. There wasn't. In addition, in Comparative Example 1 in which the breaking strength of the inclined belt layer is not appropriate and in Comparative Example 2 in which the bulk elastic modulus of the covering rubber of the inclined belt layer is not appropriate, breakage of the reinforcing element was observed, and in addition, Comparative Example 3 having no circumferential belt layer had poor uniformity.

On the other hand, from the test results of Table 2, the small truck tires of Examples A and B are superior in uniformity to the small truck tire of Conventional Example A, and moreover, the reinforcing elements of the inclined belt layer are excellent. No breakage was observed. Further, in Comparative Example A in which the rupture strength of the inclined belt layer is outside the proper range and Comparative Example B in which the bulk elastic modulus of the covering rubber of the inclined belt layer is outside the proper range, breakage of the reinforcing element was observed. Comparative Example C, which has no circumferential belt layer, had poor uniformity.

[0039]

According to the present invention, it is possible to provide a pneumatic radial tire for passenger cars and a pneumatic radial tire for small trucks, which has good uniformity and good durability.

[Brief description of drawings]

FIG. 1 is a cross-sectional view in the width direction of a typical pneumatic tire for passenger cars according to the present invention.

FIG. 2 is a cross-sectional view in the width direction of a typical pneumatic tire for a small truck according to the present invention.

FIG. 3 is a diagram for explaining a method for measuring the bulk modulus of elasticity of rubber, (a) is a jig filled with a rubber test piece, and (b) is a jig pulled in this state. It is a figure which shows the measurement state set to a compression tester.

FIG. 4 is a plan view showing a part of an inclined belt layer for showing a linear step 11.

FIG. 5 is a diagram showing a method of forming an inclined belt layer.

FIG. 6 is a diagram showing a method for forming an inclined belt layer.

FIG. 7 is an explanatory diagram of forces acting on a tread and a belt when a load is applied to a tire.

FIG. 8 is an explanatory view of shaping applied to a steel monofilament used for the inclined belt layer.

FIG. 9 is an explanatory diagram showing another shaping shape.

[Explanation of symbols]

 1 Pneumatic tire 2 Bead core 3 Carcass 4 Carcass crown 5 Tire circumferential direction 6 Tilt belt layer 7 Circumferential belt layer 8 Band 9 Tilt belt layer width end 10 Tread 11 Linear step 12 Zigzag step 13 Starting point 14 Adjacent position to starting point 13 Reinforcing element of inclined belt layer 6 Jig 17 Rubber test piece 18 Tensile / compression tester 19 Laser displacement meter 20 Belt 21 Side part 22 Arrow 23 Compressive force 24 Tread rubber

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B60C 9/22 B60C 9/22 BA D02G 3/48 D02G 3/48

Claims (3)

[Claims] 1. An inclined belt layer and a circumferential direction of at least one layer positioned on the inclined belt layer between a tread and a crown portion outer periphery of a carcass that forms a toroidal shape across at least a pair of bead cores. In a pneumatic radial tire having a belt layer, the inclined belt layer is a belt-shaped body in which a reinforcing element is covered with rubber, is continuously arranged in a zigzag shape in the tire circumferential direction, and the bent portion of the zigzag-arranged belt-shaped body is formed. , The reinforcing element of the inclined belt layer is composed of one or more steel monofilaments spirally shaped, The bulk elastic modulus of the coated rubber of the layer is 200 kgf / mm ² or more, and the inclined belt layer has a breaking strength of 1000 kg per 50 mm width.
f or more, and the circumferential belt layer is a pneumatic radial tire characterized in that its cords are spirally wound to be arranged substantially parallel to the tire equatorial plane. 2. The pneumatic radial tire according to claim 1, wherein when the belt-shaped body covers the entire circumference of the tire with a predetermined width of the inclined belt layer, one set includes two sets of inclined belt layers. . 3. The cord of the circumferential belt layer is an organic fiber cord made of polyethylene terephthalate, polyethylene naphthalate, vinylon or nylon.
Or the pneumatic radial tire according to 2.