JPS63145108A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE:To intend to improve high speed durability without lowering maneuver stability by laminating the first and the second belt layer in fixed constitution respectively with interlayer rubber in fixed thickness between them, and moreover folding back tread side belt layer on both ends by fixed width. CONSTITUTION:Belt layer (V) is formed through laminating the first belt layer (10) on carcass layer (K) side and the second belt layer (20) on tread (T) side with interlayer rubber (30), whose thickness (D) is 1.5-3.0mm, arranged between them. And the first belt layer (10) is formed with winding steel cord (10a) around a tire in spiral nearly in parallel to periphery direction. The second belt layer (20) is formed with organic fiber cord (20a) whose cord angle to the periphery direction is made to be 10-15 deg. while both ends of the same are fold back in such wise that the fold back width (l) is 20-55% of the width (L) of the second belt layer (20). According to such a constitution, high speed durability can be improved without lowering maneuver stability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pneumatic radial tire that can significantly improve high-speed durability without reducing handling stability.

[Conventional technology]

Conventionally, tires that have a belt layer with a structure in which reinforcing cords are arranged spirally at almost 0 degrees to the circumferential direction of the tire can greatly improve high-speed durability because there are no splices in the belt layer. known from. (Unexamined Japanese Patent Publication No. 5
(Refer to Japanese Patent No. 5-8966) However, with only the roof layer having the above-mentioned structure, when the steering angle is turned, the generated lateral force is small and the steering stability is low, so it is not practical.

Therefore, in order to solve the above-mentioned problems, a method has been proposed in which a reinforcing layer is added in which cords are inclined with respect to the circumferential direction of the tire and are crossed at an appropriate angle. (Unexamined Japanese Patent Publication No. 58
(Refer to Japanese Patent Publication No. 188703) However, the tire having this structure has a problem in that the entire belt layer has excessive rigidity, which greatly reduces the durability of the tire.

The present invention was achieved as a result of experiments and studies aimed at solving the above-mentioned problems.

Therefore, an object of the present invention is to provide a pneumatic radial tire that can significantly improve high-speed durability without reducing handling stability.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention comprises a pair of left and right bead portions, a pair of left and right sidewall portions connected to the bead portions, and a tread portion located between the sidewall portions, and a tread portion located between the respective bead portions. In a tire in which a carcass layer having a cord angle with respect to the circumferential direction of the tire is substantially 90° is mounted, and a belt layer is arranged on the carcass layer in the trend part, the belt layer is arranged on the carcass stone side. A second belt layer is arranged on the tread side of the first belt layer with an interlayer rubber layer interposed therebetween, and the first belt stone is formed of a steel cord with respect to the circumferential direction of the tire. The second belt layer is made of organic fiber cords that are wound approximately parallel to each other in a spiral shape, and the second belt layer is made of organic fiber cords with a cord angle of 10 to 50 degrees with respect to the tire circumferential direction, both ends of which are folded back. 20 to 55% of 111 of this second belt store, Top: il! It is characterized in that the thickness of the interlayer rubber layer disposed between the first belt layer and the second belt layer is set within the range of 1.5 to 3.01 mm.

[Effect]

The present invention can significantly improve high-speed durability without reducing handling stability.

〔Example〕

The present invention will be explained below by way of examples with reference to the drawings.

The figure is an explanatory radial cross-sectional view of a pneumatic radial tire according to an embodiment of the present invention.

In the figure, E denotes a pneumatic radial tire according to an embodiment of the present invention, which includes a pair of left and right bead portions B, and this bead portion B.
It consists of a pair of left and right sidewall portions S connected to the left and right sidewall portions, and a tread portion T located between the sidewall portions S, and the cord angle between each of the above and the tread portion B with respect to the circumferential direction of the tire is substantially 90°. A carcass layer K is mounted,
Further, a belt layer V is arranged on the carcass layer of the tread portion T.

In the present invention, in particular, the belt layer (1) includes a first belt layer 10 disposed on the side of the carcass layer, and a
The second belt layer 20 is disposed on the tread T side of the belt layer 10 with an interlayer rubber layer 30 interposed therebetween.

Moreover, the first belt layer 10 includes steel cord 10
a spirally wound approximately parallel to the circumferential direction of the tire, and the second belt layer 20 is made of an organic fiber cord 20a with a cord angle of 10 to 50 degrees with respect to the circumferential direction of the tire. , its both ends are folded back, and the folded width l of these folded parts 20b is set to 20 to 55% of the inside of this second belt layer 20, respectively.
Further, the thickness D of the interlayer rubber layer 30 disposed between the first belt layer 10 and the second belt layer 20 is set to 1.5 to 3.0w.
Set within the range.

To explain further, in the present invention, as described above,
The first belt layer 10 is formed by winding the steel cord 10a spirally approximately parallel to the circumferential direction of the tire.
With this structure, it is possible to eliminate the joint portion of the first belt layer 10, which is a reinforcing member of the tire. As a result, the high elastic modulus and breaking strength of the steel cord 10a can be utilized as they are. Therefore, it is possible to prevent the tire from increasing in diameter due to the large centrifugal force generated when the vehicle runs at high speed, and the high speed durability can be greatly improved.

Note that the steel cord 10a has an elongation at break of 2.7.
% or more, and the diameter of the wire composing this cord is 0.2fl
It is preferable that it is K or less.

This is because if the elongation at break is less than 2.7%, there is a risk that the steel cord 10a will fatigue and break when it climbs over protrusions many times or when it travels over long distances with low internal pressure. This is because, if the diameter of the strands is set to 0.21- or less, the fatigue resistance against repeated compressive strain can be dramatically improved.

Further, the cord angle of the organic fiber cord 20a constituting the second belt layer 20 is set to 10 to 5 in the tire circumferential direction.
The reason why it is set within the range of 0° is to punish the elastic modulus (rigidity) against out-of-plane bending deformation in the radial direction.

In this way, by increasing the elastic modulus (rigidity) against out-of-plane bending deformation in the radial direction, changes in the shape of the tire's contact with the road surface when turning a corner can be reduced.
It is possible to secure high cornering power and maintain good longitudinal stability.

The reason why the cord angle of the cord 20a is set within the range of 10 to 50' with respect to the tire circumferential direction is because if the cord angle of the organic fiber cord 20a is less than 10', out-of-plane bending in the radial direction may occur. It is not possible to increase the elastic modulus (rigidity) against deformation, and if the angle exceeds 50°, the above elastic modulus (rigidity) cannot be increased.
This is because the rigidity becomes too high, which is undesirable.

Furthermore, the reason why both ends of the second belt layer 20 are folded back is to prevent stress from being concentrated at both ends of the second belt layer 20, and to improve the "high-speed durability" obtained by the first belt layer 10. This is to avoid deteriorating its excellent properties.

The folding width l of the above-mentioned folding portion 20b is set within the range of 20 to 55% of the width of the second belt layer 20, because if it is less than 20% or more than 55%, This is because the effects cannot be expected and it is not desirable.

Moreover, the thickness D of the interlayer rubber layer 30 disposed between the first belt layer 10 and the second belt layer 20 is 1.5 to 3.
．． The one set within the range of 0 Tsuru is the interlayer rubber F! If the thickness D of the belt 30 is less than 1.5 mm, the rigidity of the belt as a whole becomes too high, reducing the degree of freedom of the steel cord 10a constituting the first bell I [10, and as a result, the steel cord This is because the tire 10a becomes easily fatigued, which may reduce the durability of the tire, and if it exceeds 3.0, the responsiveness at a minute steering angle decreases, which is not preferable.

The range of the thickness D of the interlayer rubber layer 30 mentioned above is determined by the steel cord 10a of the first belt layer 10 and the organic fiber cord 20 of the second belt layer 20 during the tire manufacturing process.
As a, since a cord coated with coating rubber with a thickness of about 0.51 mm is used, the thickness is 1.0 to 2 mm.
．． The interlayer rubber layer 30 of 0 Tsuru may be used.

Further, the reinforcing cord 20a constituting the second belt layer 20
The reason for using an organic fiber cord as follows is as follows.

That is, since the tire E of the present invention is configured as described above, the main groove M substantially disposed in the tread portion T
The distance from the bottom of the groove to the second belt layer 20 is smaller than that of a normal conventional tire, and if a rigid steel cord is used for the second belt layer 20, the ride comfort performance will deteriorate, This is because there is a risk that the cord may break if a momentary high input is applied, such as by climbing over a protrusion while driving.

Therefore, even among organic fiber cords with excellent bending durability, the elastic modulus is 3. OX 10dyne/crM ~30. O
It is preferable to use an organic fiber cord having a relatively low elastic modulus of about X 10 dyne/cJ.

Furthermore, for the same reason, the first belt layer 10 and the second belt r
The hardness of the rubber composition constituting the interlayer rubber layer 30 disposed between f20 is JIS hardness (JISK 6301 A
type) is preferably in the range of 30 to 48.

This is because if the hardness is less than 30, there is a problem with durability because almost no reinforcing inorganic filler can be added, and if the hardness exceeds 48, it cannot be expected to work in alleviating momentary large inputs. This is because it will be put away.

Note that the rubber composition of the interlayer rubber layer 30 disposed between the first belt layer 10 and the second belt layer 20 has a large effect on the rolling resistance of the tire, and when the rebound resilience is set to 60% or more, the tire's Resistance to transfer can be changed.

[Experiment example]

In order to confirm the effects of the present invention, the following experiment was conducted.

(Specifications of the tires used in the experiment) F Example 1 of the present invention - Tire size: 175/70HR13 - First belt layer: Steel cord coated with rubber (0 degrees with respect to the tire circumferential direction) -Second belt layer: 6°6 nylon cord coated with rubber is folded back,
During folding of the layer... 52% of the width of this second belt layer Angle with respect to the tire circumferential direction... 14° Modulus of elasticity of cord - 16,
OX 10dyne/+J・Interlayer rubber layer gauge...1.41 (1st belt layer cord and 2nd
The maximum value of the distance between cords of F is 2.2. Resilience...62% JIS, A hardness...48 - Elongation at break of the steel cord of the first belt layer...2.8% Wire diameter: 0.15 "Comparative Example 1" Radial wire 175/70HR of the same size as Example 1 using the technology disclosed in JP-A-58-188703
13 was created.

・Steel cord coated with first belt layer rubber (25 degrees to the tire circumferential direction) *Steel cord coated with second belt layer rubber (0 degrees to the tire circumferential direction) *Third belt layer 1st belt Folded layers (Put the second belt layer inside and wrap it.) Folded... Belt middle (width of the second belt layer) 52
% in the whole belt...Same as Example 1.

"Comparative Example 2" One steel cord was coated with coating rubber in advance, and this was wound around the coil at 0 degrees in the circumferential direction.
A tire in which the belt layer and the second belt layer are made in the same way. (A technique disclosed in Japanese Patent Application Laid-open No. 55-8966 was used.) <Evaluation method> (1) Durability test (high load drum) Internal pressure 3.0 kg/cm, load JI 3200%,
The vehicle was run at a speed of 5Qkm/hr until the tire broke down.

(2) Steerability load 300 kg, slip angle 2°, internal pressure 1.7 kg
The cornering power generated at 30 km/hr was evaluated.

Note that the measured values were expressed as an index with the value of Comparative Example 1 as 100. Therefore, a larger value is better.

The results of the implementation are shown in Table 1.

From the experimental results shown in Table 1, it can be seen that the tires of the present invention are superior in both durability and steering performance when compared to the tires of each comparative example.

"Examples 2 to 4" In Examples 2 to 4, as shown in Table 2, only the second belt layer was changed, and the rest was the same as in Example 1, and tires were produced as J-size tires.

(Margin below) The results of the experiment are shown in Table 3.

From the results in Table 3, the cord direction of the second belt layer is 10~
At 50 degrees, the width of the folded part is 20 to 5 times the width of the second belt layer.
It can be seen that the tire with a ratio of 5% is superior in both durability and steering performance.

"Examples 5 and 6" Tests were conducted by changing only the thickness of the interlayer rubber layer between the first belt layer and the second belt layer in Example 1 as shown in Table 4.

(Margin below) The results of the experiment are shown in Table 5.

From the results in Table 5, in Examples 5 to 6, the thickness of the interlayer rubber layer between the first belt layer and the second belt layer was 1.5 to 3.
．． It can be seen that the tire with a diameter of 0 mm is superior in both durability and steering performance.

[Examples 7 to 8] The cord of the first belt layer in Example 1 was adjusted to A as shown in Table 6 so that the overall strength was constant, and the diameter of the wire and the number of wires were set as shown in Table 6. As shown, I made a substitute tire using a#.

Durable drum〉 Run the drum at 60km/hr with an internal pressure of 1.7kg/cJ and a JI 5100% load, and if there is no failure,
Observe whether or not the cord is broken using X-rays. (It was run for 60,000 km.) The results of the experiment are shown in Table 7.

From the results in Table 7, the elongation at break of the steel cord is 2.
7% or more, and the diameter of the pilgrimage line that makes up this cord is 0.2m
It turns out that it is preferable that it is less than m.

〔Effect of the invention〕

Since the present invention is configured as described above, high-speed durability can be significantly improved without reducing steering stability.

[Brief explanation of the drawing]

The figure is an explanatory radial cross-sectional view of a pneumatic radial tire according to an embodiment of the present invention. B...Bead part S...Sidewall part T...Tread part K...Carcass layer ■...Belt layer 10... ...First belt layer 10a...Steel cord 20...Second belt layer 20a...Organic fiber cord 20b...Folded portion 30 of second belt layer...Interlayer rubber layer

Claims (1)

[Claims] Consisting of a pair of left and right bead portions, a pair of left and right sidewall portions connected to the bead portions, and a tread portion located between the sidewall portions, there is a tread portion located between the bead portions in the circumferential direction of the tire. In a tire equipped with a carcass layer having a cord angle of substantially 90° with respect to the carcass layer, and a belt layer disposed on the carcass layer in the tread portion, the belt layer is a first belt layer disposed on the carcass layer side. , and a second belt layer disposed on the tread side of the first belt layer via an interlayer rubber layer, and the first belt layer has a steel cord spirally arranged approximately parallel to the circumferential direction of the tire. The second belt layer is made of an organic fiber cord with a cord angle of 10 to 50 degrees with respect to the tire circumferential direction, both ends of which are folded back, and the folded widths of these two ends are defined as follows: The width of the second belt layer was set to 20 to 55%, and the thickness of the interlayer rubber layer disposed between the first belt layer and the second belt layer was set within the range of 1.5 to 3.0 mm. A pneumatic radial tire characterized by: