JP2001277820A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the driving stability significantly while controlling the increase of the weight of tires and to eliminate a risk of fatigue break of reinforcing layer cords. SOLUTION: This tire has a belt 7 disposed on the outer side of a crown part of a carcas 6 and a bead filler 8 disposed between the main body 6a and a turn-back part 6b of the carcas 6 on the outer side of a bead core 4. A reinforcing layer 9, on which cords 9a extending at an angle of 30 degrees or less to the circumference of the tire are disposed in parallel, is disposed adjacent to the outside of the main body 6a of the carcas 6 around a position P of the largest width of the tire.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire having improved steering stability without increasing the weight of a tire, and more particularly to a radial tire.

[0002]

2. Description of the Related Art In general, the handling stability of a pneumatic tire is improved by increasing the rigidity from the bead portion to the sidewall portion of the tire.
For example, in a pneumatic radial tire for a passenger car, an insert reinforcing layer made of an organic fiber cord or a steel cord is disposed along the outside of the bead filler, and the insert reinforcing layer is used when the vehicle turns and the like.
The bead portion is prevented from falling down, and at the same time, the sidewall portion is also prevented from falling down.

[0003]

However, in order to sufficiently increase the rigidity of the tire side portion from the bead portion to the sidewall portion and to improve the steering stability as expected by using such a prior art, It is necessary to dispose the insert reinforcing layer over a wide area of the tire side portion, and there is a problem that an increase in tire weight is inevitable.On the other hand, the insert reinforcing layer disposed outside the bead filler is In the case where the bead portion is bent around the rim flange during the load rolling of the tire, the bead is located inside the neutral axis of the bend and is greatly compressed and deformed. There is also a problem that fatigue rupture due to deformation tends to occur.

An object of the present invention is to solve such problems of the prior art, and the object of the present invention is to provide a reinforcing layer most necessary for increasing the rigidity of a tire side portion. By arranging it in an effective area, particularly under the advantageous manner of extending the cord, and adjacent to the carcass body, it suppresses an increase in tire weight and greatly improves steering stability. Another object of the present invention is to provide a pneumatic tire in which the cord is subjected to the compressive deformation caused by the above-described bending deformation in the vicinity of the bead portion, and furthermore, the possibility of the cord causing fatigue fracture is sufficiently eliminated.

[0005]

SUMMARY OF THE INVENTION A pneumatic tire of the present invention, for example, a pneumatic radial tire for a passenger car, is toroidally extended between a pair of bead cores provided in each bead portion, and has a side portion formed by a bead core. Around the carcass ply, which is composed of one or more carcass plies wrapped from the inside to the outside in the tire width direction, and the carcass forming the skeleton of the tire is provided, and one or more belt layers are provided on the outer peripheral side of the crown portion of the carcass Where the bead filler is disposed and the bead filler is disposed between the carcass main body portion and the rewind portion on the outer peripheral side of the bead core, and extends at an angle of 30 ° or less with respect to the tire circumference. A code, more specifically, a virtual circumferential line segment in a side view of a tire, and a tangent to the circumferential line segment at a virtual intersection with the code and the code. The reinforcing layer corners becomes parallel arrangement of 30 degrees or less code, in vicinity of the maximum tire width position,
It is arranged adjacent to the outside of the carcass body.

In order to improve the steering stability of the pneumatic tire, it is particularly effective to restrain the side deformation of the tire, that is, the falling down of the carcass. When turning the vehicle, the reinforcement layer restrains the deformation of the maximum width portion of the tire where the carcass collapses or expands the most, thereby effectively suppressing the increase in tire weight and improving steering stability. It can be advantageously improved.

Further, the inclination angle of the reinforcing layer cord with respect to the tire circumference is 30 ° or less, more preferably 25 °.
With the following small angle, the occurrence of the collapse or the bulging deformation can be more effectively prevented under a high tensile strength of the reinforcing layer cord extending over a wide range in the circumferential direction.

Further, by arranging the reinforcing layer adjacent to the main body of the carcass, a tensile force acts on the reinforcing layer cord when the above-described bending deformation occurs in the vicinity of the bead portion. It is possible to sufficiently eliminate the possibility of fatigue breakage of the cord, and at the same time, restrain the deformation of the carcass, especially at the outer part of the turning of the tire, and maneuver under high restraining force. Stability can be greatly improved.

When the reinforcing layer is provided in a range from the vicinity of the tire maximum width position to the side edge of the belt, the amount of deformation restricts the deformation of the buttress portion which is the second largest after the tire maximum width portion. Therefore, the steering stability can be further improved.

Here, when the outer end portion in the radial direction of the reinforcing layer and the side portion of the belt are overlapped, particularly when the outer end portion is inserted into the inner peripheral side of the belt, the buttress portion is formed. Of course, the deformation of the maximum width portion of the tire can be restrained more advantageously.

On the other hand, when the radially inner end portion of the reinforcing layer is inserted between the carcass main body portion and the bead filler, the bead filler is disposed between the bead portion and the tire maximum width portion. By reducing the rigidity step between the region and the radially outer portion thereof, the deformation of the tire side portion can be effectively restrained.

More preferably, the reinforcing layer is a rubber-coated cord layer, and the initial compression resistance of the reinforcing layer is in the range of 1 to 1/5 times the initial tensile resistance.

Here, the "initial compression resistance" is 50 m in width.
m is set in a cylindrical shape in a test tube as shown in FIG. 1 and is compressed in the direction of the cord axis to draw a stress-displacement curve. As a result, as shown in FIG. From the graph, the maximum point A of the load change with respect to the compressive displacement near the origin was obtained, and the value obtained based on the following equation was used. The number of tests was two, and the average was calculated to one decimal place. Initial compression resistance (kPa) = P / (l ′ / l × d) where P: load at maximum point A of tangent angle (mN) l: test length (mm) l ′: TH length (mm) ) (H is a perpendicular foot, T is an intersection of a tangent and a horizontal axis) d: 50 mm × thickness of rubber-coated cord layer (mm ² )

The "initial tensile resistance" is 50 m in width.
After taking out the rubber-coated cord layer having a length of 200 mm and a length of 200 mm, a load-displacement curve of each rubber-coated cord layer was drawn using an Instron tensile tester, and from the resulting graph as shown in FIG. The degree of the load change with respect to the elongation change near the origin (A when the maximum point A is present) is determined, and the value obtained based on the following equation is used. The number of tests was set to 10, and the average was calculated to one decimal place. Initial tensile resistance (GPa) = P / (l '/ lxd) where P: load (N) at tangent angle (at maximum point A) l: test length (mm) l': length of TH (Mm) (H is perpendicular foot, T is intersection of tangent and horizontal axis) d: 50 mm × thickness of rubber-coated cord layer (mm ² )

According to this, by selecting a cord material having a high compression resistance, the deformation of the tire portion located inside the turning in the direction of shortening the circumferential length is advantageously restrained, and the driving and braking directions are reduced. The deformation of the tire with respect to the force of the tire can be advantageously restrained.

[0016] Preferably, the initial tensile resistance of the reinforcing layer is 7 GPa or more, thereby further increasing the restraining force of the tire side portion against the deformation in the tensile direction as described above.

This is particularly remarkable when a steel cord is used as the reinforcing layer cord. When the cord forming the reinforcing layer extends substantially in the circumferential direction of the tire, one cord or one cord or the like is used. This is even more noticeable when a plurality of pulling cords are spirally extended around the tire center axis. In addition, according to the spirally wound structure, the cord ends exist only at the winding start and end ends, so that the occurrence of cord end separation can be effectively prevented.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a half of a tire according to an embodiment of the present invention, in which 1 is a tread portion, 2 is a sidewall portion extending inward in a radial direction from a side portion of the tread portion 1. Reference numeral 3 denotes a bead portion which is continuous with the radially inner end of the sidewall portion 2, and reference numeral 4 denotes a bead core provided in each bead portion 3.

Here, a carcass 6 is constituted by at least one carcass ply 5 made of, for example, a radial ply cord, and in the figure, two carcass plies 5, and a body portion 6a of the carcass 6 is toroidally extended between a pair of bead cores. The side portion is wound around the bead core 4 from the inner side to the outer side in the tire width direction and locked, and the outer peripheral side of the crown portion of the carcass 6 is formed of, for example, a two-layer belt layer 7a. A belt 7 is provided, and a bead filler 8 is provided on the outer peripheral side of the bead core 4 between the carcass body portion 6a and the rewind portion 6b.

Further, here, a reinforcing layer 9 is disposed in the vicinity of the maximum width position P of the tire, for example, in a region including the position P, adjacent to the outside of the carcass main body portion 6a, and the reinforcing layer 9 is provided. A large number of cords extending at an angle of 30 degrees or less with respect to the tire circumference are arranged in parallel. Thus, as shown conceptually in FIG. 5, each reinforcing layer cord 9a has a tangent t to its circumferential line 10 at a virtual intersection 10a between the virtual circumferential line 10 and the code 9a in a side view of the tire. Extends in a direction in which the included angle α is an angle in the range of 0 to 30 °.

Here, when the narrow angle α is set to 0 °, the side wall portion 2 and the bead portion 3 fall down or bulge when the vehicle turns, with the tensile strength of the reinforcing layer cord 9a. While it can be particularly advantageously prevented, if it is larger than 30 °, not so large deformation restraining force can be exerted. For example, in addition to the lateral rigidity of the tire described later,
It is difficult to achieve the expected increase in torsional rigidity. The angle α is set to 0 °, and the reinforcing layer cord 9a
Is substantially extended in the tire circumferential direction, the reinforcing layer cord 9a is extended in a winding form in which one or a plurality of alignment cords are spirally extended around the tire center axis. According to this extending mode, the number of cord ends can be sufficiently reduced, and the occurrence of cord end separation can be advantageously prevented.

It is generally advantageous for the reinforcing layer cord 9a to be made of an aramid fiber cord or other organic fiber cords in terms of weight, and it is advantageous to constitute it in the form of a steel cord in terms of deformation restraining force. It is. In any of these cases, the initial tensile resistance of the reinforcing layer 9 is preferably 7 GPa or more.

In this case, the reinforcing layer 9 may be formed of a rubber-coated cord layer obtained by applying a rubber coating to cords arranged in parallel with each other. In this case, as described above, the initial It is preferable that the compression resistance be 1 to 1/5 times the initial tensile resistance.

Incidentally, the reinforcing layer 9 is disposed only in the region including the tire maximum width position P as shown by the solid line in FIG. 4 and also reaches the belt side edge as shown by the phantom line in the drawing. Up to the position or the position where the outer end portion in the radial direction overlaps the inner side or the outer side of the belt side portion. On the other hand, the position shown by the solid line in the figure or the solid line thereof From the radial inner end position of the carcass body portion 6a
It can also be arranged adjacent to the carcass main body portion 6a between a position where the carcass body portion 6a and the bead filler 8 reach a position where the carcass body portion 6 enters the vicinity of the bead core.

According to the tire configured as described above, the rim-assembled tire is disposed adjacent to the carcass body portion 6a that controls the transmission of force between the wheel rim and the tread portion 1 that is in contact with the road surface. The included angle α is 30 °
The reinforcing layer 9 composed of the following cords can exert a sufficiently large restraining force against the deformation of the carcass main body portion 6a, which has a particularly large effect on the steering stability. Since the deformation is efficiently restrained in the vicinity of the maximum tire width position P, the increase in tire weight can be effectively suppressed and steering stability can be greatly improved.

Here, when a steel cord is used as the reinforcing layer cord 9a, the initial compression resistance of the reinforcing layer 9 as the rubber-coated cord layer can be particularly increased. 6a, the above-mentioned deformations can be effectively restrained to further improve the steering stability.

[0027]

(Embodiment 1) In the case where the reinforcing layer 9 is disposed in a range of 30 mm in the tire radial direction in the vicinity area including the tire maximum width position, the cord angle with respect to the tire circumference is 0 to 45. When the lateral stiffness of the tire was measured as an index of steering stability when it was changed in the range of °, Table 1
As shown with the exponent value. The larger the index value in the table, the higher the rigidity.

[0028]

[Table 1] According to Table 1, the cord angle with respect to the tire circumference is 30 °.
It is apparent that the following will sharply increase the lateral rigidity of the tire.

(Example 2) The steering stability and the tire weight of each of the example tire and the comparative tire were determined, and the results are as shown in Table 2.

Here, both the example tire and the comparative example tire have a size of 195/65 R15. As shown in FIG. 6, the comparative example tire 1 is located outside the bead filler 8 from the point g to the point e. In the tires 1 to 6, the reinforcing layer cords extend substantially in the circumferential direction over the range of the radial width of 50 mm. In addition, this is also configured by providing a reinforcing layer in which the reinforcing layer cord extends substantially in the circumferential direction.

Comparative Example Tire 1 and Example Tires 1 to 5
In each case, the reinforcing layer cord was an aramid fiber cord, the initial tensile resistance of the reinforcing layer was 19.99 GPa, the initial compressive resistance was 666.4 MPa, and the ratio of the initial compressive resistance to the initial tensile resistance was about 1/30. And

In Example Tire 6, the reinforcing layer cord of Example Tire 2 was a steel cord, and the reinforcing layer had an initial tensile resistance of 45.08 GPa and an initial compression resistance of 25.0 GPa.
At 2.54 GPa, a similar resistance ratio was about 1/2. In Example Tire 7, the initial tensile resistance was 7.35 GPa and the initial compression resistance was 245 MPa, with the reinforcing layer cord of Example Tire 2 being an aramid fiber cord.
a, and the resistance ratio was about 1/30. In addition, the comparative example tire 2 used the aramid fiber cord as the reinforcing layer cord of the example tire 2, and had an initial tensile resistance of 5.88 GPa,
The initial compression resistance was 196 MPa.

[0033]

[Table 2]

According to Table 2, it is clear that all of the example tires can advantageously improve the steering stability, and this is particularly remarkable in the example tires 3, 4 and 6, and the reinforcement is high. It can be seen that, in the example tire 6 in which the layer cord is a steel cord, an increase in tire weight can be advantageously suppressed as compared with the comparative example tire 1 in which an aramid fiber cord is a reinforcing layer cord.

[0035]

Thus, according to the present invention, in particular,
By arranging a reinforcing layer that is arranged in parallel with cords extending at an angle of 30 ° or less with respect to the tire circumference and adjacent to the outside of the carcass body portion in the vicinity of the tire maximum width position, It is possible to effectively restrain the carcass from falling down or bulging out at the side portions with its reinforcing layer, and therefore, it is possible to advantageously suppress an increase in tire weight and greatly improve steering stability. In addition, the reinforcing layer cord can be sufficiently protected from fatigue failure against bending deformation in the vicinity of the bead portion around the rim flange.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a structure of a compression test piece of a reinforcing layer.

FIG. 2 is a graph showing a compression test result of a reinforcing layer.

FIG. 3 is a graph showing a tensile test result of a reinforcing layer.

FIG. 4 is a cross-sectional view in the width direction showing the embodiment of the present invention with respect to a half portion of the tire.

FIG. 5 is a conceptual diagram showing an extension mode of a reinforcing layer cord.

FIG. 6 is a sectional view similar to FIG. 4, showing a comparative example tire.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall 3 Bead part 4 Bead core 5 Carcass ply 6 Carcass 6a Body part 6b Rewind part 7 Belt 7a Belt layer 8 Bead filler 9 Reinforcement layer 9a Reinforcement layer cord 10 Virtual circle line 10a Virtual intersection point P Maximum tire width Position α included angle t tangent

Claims (9)

[Claims] 1. A carcass comprising one or more carcass plies which are toroidally extended between a pair of bead cores and whose side portions are wrapped around the bead core from inside to outside, and an outer periphery of a crown portion of the carcass. Pneumatic tire comprising a belt disposed on the side and a bead filler disposed between the body portion and the rewind portion of the carcass on the outer peripheral side of the bead core, wherein an angle of 30 ° or less with respect to the tire circumference. A pneumatic tire in which a reinforcing layer which is arranged in parallel with cords extending in the above is disposed adjacent to the outside of the carcass main body portion in the vicinity of the tire maximum width position. 2. The pneumatic tire according to claim 1, wherein the reinforcing layer is disposed in a range from a portion near the tire maximum width position to a side edge of the belt. 3. The pneumatic tire according to claim 1, wherein a radially outer end portion of the reinforcing layer and a side portion of the belt are overlapped. 4. The pneumatic tire according to claim 1, wherein a radially inner end portion of the reinforcing layer is inserted between the carcass body portion and the bead filler. 5. The reinforcing layer is a rubber-coated cord layer, and the initial compression resistance of the reinforcing layer is 1 to 1/1 / the initial tensile resistance.
The pneumatic tire according to any one of claims 1 to 4, wherein the pneumatic tire has a factor of five. 6. The pneumatic tire according to claim 1, wherein the reinforcing layer has an initial tensile resistance of 7 GPa or more. 7. The pneumatic tire according to claim 1, wherein the cord constituting the reinforcing layer is a steel cord. 8. The pneumatic tire according to claim 1, wherein a cord constituting the reinforcing layer extends substantially in the tire circumferential direction. 9. The pneumatic tire according to claim 1, wherein a cord constituting the reinforcing layer is spirally extended.