JP2003237315A - Pneumatic radial tire, and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain excellent steering stability, in particular, excellent steering stability when a vehicle is traveling at a high speed, and the riding quality without impairing any performances such as wear resistance, heat generation and fuel consumption of the vehicle. <P>SOLUTION: In a flat tire of the flat ratio of ≤60%, a bead reinforcing layer 14 is provided on an outer surface side of a bead filler 13. The bead reinforcing layer 14 comprises a high rigidity reinforcing layer on the inside diameter side, and a low rigidity reinforcing layer on the outside diameter side. In a shoulder part 18 having a peak pressure position in a grounding surface of a tread 31 with a road surface, a cushioning layer 51 formed of rubber ribbon is provided between a body ply 21 and a width end part of a first belt 22. One reinforcing layer 52 between ply and belt is disposed on the inside diameter side of the cushioning layer 51, and covered by the cushioning layer 51 from the tire outside diameter side. The reinforcing layer 52 between ply and belt suppresses any lifting of the shoulder part 18. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire having excellent steering stability at high speed and capable of improving various performances such as high speed durability, and a method for manufacturing the same.

[0002]

2. Description of the Related Art With the extension of a highway network and the speed and performance of vehicles, especially passenger cars, the body ply is arranged in the radial direction and is made of steel cord on the outside thereof as a tire suitable for this. Radial tires with belt layers are often used. For higher speed and higher performance, flattening of tires has progressed, and flattening ratios of 50% and 45% have already become widespread.
% And 30% can be seen.

Since a conventional flat tire is required to have a high level of steering stability, at least a tread is made of a rubber having a large grip on the road surface. Further, in order to effectively transmit the grip force to the vehicle, it is necessary to improve the rigidity of the tire case. That is, in order to transmit a high gripping force to the tire wheel and the vehicle body, it has been required to increase the tire spring constant and enhance the case rigidity. To improve the rigidity of the case, increase the number of reinforcements embedded in the sidewalls and shoulders, increase the bead filler outward in the radial direction of the tire, make it harder, increase the number of body plies, etc. It was common to do

Further, as an improvement in high-speed durability, JP-A-200
In Japanese Patent No. 1-163007, a region within 10 mm from the tire axial direction outer end of the belt ply to the tire axial direction inner and outer ends extends to the end point of the sidewall portion and extends in the tire circumferential direction from 10 to 80. ° Inclined organic fiber cord reinforcement is marked.

[0005]

However, when the tread is changed to a rubber type having a high gripping force, it causes unfavorable results in wear resistance, heat generation and vehicle fuel consumption. Also, for the purpose of high rigidity, increase the above-mentioned buried reinforcing material,
Alternatively, there is also a problem that the riding comfort is deteriorated only by increasing the bead filler in the tire outer diameter direction or making it hard. Further, in the case of JP 2001-163007 A, the reinforcing layer is tilted by 10 to 80 ° with respect to the circumferential direction, so that the broom effect is weak and the weight increases, resulting in poor fuel efficiency. Further, since the reinforcing layer directly contacts the body ply, the ply cord arrangement is disturbed, which causes a problem in steering stability.

The object of the present invention is to provide excellent steering stability, particularly steering stability under high-speed running, and wear resistance,
An object of the present invention is to provide a radial tire capable of improving riding comfort and a method for manufacturing the same without impairing various performances such as heat generation and vehicle fuel consumption.

[0007]

In order to achieve the above object, in the present invention, a body ply extending between a pair of beads and folded back around a bead core,
A belt that extends in the tire circumferential direction on the outer diameter side of the crown portion of the body ply, and at least one belt cover that extends in the tire circumferential direction on the outer diameter side of the belt and covers at least both widthwise ends of the belt. A pneumatic radial tire having a tread that covers the outer diameter side of the belt cover and a sidewall that covers the outside of the side portion of the body ply, wherein the outer diameter side of the body ply and both width ends of the belt. The ply-belt reinforcing layer is arranged by spirally winding a cord covered with rubber with the inner diameter side of the portion at an angle of less than 10 ° in the tire circumferential direction, for example.

By providing the ply-belt reinforcing layer between the outer diameter side of the body ply and the inner diameter side of both width end portions of the belt, the ply-belt reinforcing layer is provided in the vicinity of the easily movable belt end portion. By sandwiching the belt cover from both sides, lifting due to centrifugal force in this part can be prevented. Therefore, the grip force of the entire tread is made uniform, the grip force of the entire tread is improved, and the steering stability is improved. Further, since the grip force of the tread is improved, it is not necessary to use a rubber type having a high grip force as the tread, and good results are obtained in wear resistance, heat generation and vehicle fuel consumption. Moreover, since the ply-belt reinforcement layer is formed by spirally winding the rubber-coated cord in the tire circumferential direction, there are no seams, it has excellent circumferential strength, and the cord ends that occur when the cord is tilted. It has no shortcomings.

If the ply-belt reinforcing layer is arranged so as to extend to the inside and outside positions in the tire width direction so as to include the tire inner point of the ground contact pressure peak position, the contact pressure peak position of the contact pressure peak position can be improved. Lifting is effectively prevented and steering stability is greatly improved.

It is even more effective if the ply-belt reinforcing layer has substantially equal widths inward and outward in the tire width direction with respect to the tire inner point at the ground contact pressure peak position. In addition, lifting of the ground pressure peak position can be prevented.

The inner layer of the ply-belt reinforcing layer is located outside of the tire inner point at the ground contact pressure peak position in the tire width direction, and the reinforcing layer is the width edge of the belt and the width edge of the belt cover. If the outer end of the belt cover is located outside of the belt cover in the width direction, lifting of the ground pressure peak position can be effectively prevented. That is,
Since the width end of the belt and the width end of the belt cover arranged at the ground pressure peak position are easy to move, lifting of this part is likely to occur, but this can be suppressed.

By winding one cord covered with rubber to form the ply-belt reinforcing layer, the cord can be wound at an arbitrary pitch. By winding a ribbon in which a plurality of parallel cords are embedded in rubber to form the ply-belt reinforcing layer, by winding the ribbon,
Since a plurality of cords are wound at the same time, the winding work can be performed efficiently.

The gauge of the reinforcing layer between the ply and the belt is
When the belt side has a value within a range of 0.5 mm to 3.0 mm and the body ply side has a value within a range of 0.5 mm to 1.0 mm, the tire performance such as steering stability and high speed durability can be balanced. If the rubber gauge is less than 0.5 mm, the durability against repeated stress due to tire running is reduced, and if the gauge on the belt side exceeds 3.0 mm, the interaction between the cord of the ply-belt reinforcing layer and the belt cord The rigidity of the composite due to is decreased because the distance between the two becomes large and the interaction is weakened, the belt supporting the tread becomes easy to move, the lifting becomes large, and the grip performance and the like decrease. Further, if the ply side exceeds 1.0 mm, the durability is increased, but there is a demerit such that the weight becomes heavy.

When the cord of the ply-belt reinforcing layer is made of organic fiber, flexibility can be ensured, tire grip performance can be improved, and steering stability can be improved. When the number of cords of the reinforcing layer between the ply and belt is set to a minimum of 10 cords / 25 mm and a maximum of 30 cords / 25 mm, steering stability and durability can be improved. That is,
If the number of 940 dtex / 2 cords is less than 10/25 mm, the reinforcing effect will be lost and steering stability at high speed will be insufficient. 30 lines / 25 with 1400 dtex / 2 code
If it exceeds mm, a rubber gauge cannot be secured between the adjacent cords, and durability against repeated stress due to tire running is deteriorated.

The cord of the reinforcing layer between the ply and the belt is
If it is an aliphatic polyamide fiber, it has good heat shrinkage surface and heat resistant adhesive surface, and prevents lifting of the body ply,
It is effective in improving high-speed durability and handling stability at high speeds.

The cord of the reinforcing layer between the ply and the belt is
If the hybrid cord of the aliphatic polyamide fiber and the aromatic polyamide fiber is used, the properties of the both can be effectively utilized and the performance of the tire can be improved with almost no increase in weight. In particular, if the cord is formed by spirally winding the aromatic polyamide fiber around the aliphatic polyamide fiber, that is, the aromatic polyamide fiber having high strength but poor flexibility and stretchability is spirally formed. As a result, flexibility and stretchability can be imparted. Therefore, durability and steering stability can be improved.

If the cord of the ply-belt reinforcing layer is a steel cord and the steel cord is stretchable, flexibility and stretchability can be imparted,
It is possible to achieve both durability and steering stability.

By adopting a corrugated process or a high elongation cord structure as the stretchable process, even with a steel cord, both flexibility and stretchability can be effectively obtained, and high tensile strength can also be obtained.

If the ply-belt reinforcing layer is a single layer, the increase in the thickness due to the ply-belt reinforcing layer is very small, so that there is no step at the shoulder portion and high grip performance is maintained. it can.

If a buffer layer is provided so as to cover the ply / belt reinforcing layer from the tire outer diameter side, the ply / belt reinforcing layer can be protected and cushioning can be imparted to this portion to provide a comfortable ride. improves.

The loss tangent (tan δ) of the rubber covering the cord of the ply-belt reinforcing layer is 0.20 to 0.0.
When the value is within the range of 5, preferably 0.15 or less, the heat generated in the shoulder portion, which moves rapidly, is reduced, and the durability of the tire can be improved. The measurement conditions of tan δ here are values at 60 ° C., initial strain of 10%, dynamic strain of 2%, and 20 Hz.

By disposing the ply-belt reinforcing layer inside the tire of the shoulder portion including the ground pressure peak position, lifting of the shoulder portion can be appropriately prevented.
On the other hand, if the bead filler is arranged on the outer surface of the bead core and the bead reinforcing layer is provided on the side portion of the bead filler, the rigidity of the bead portion can be improved. Therefore, the rotational force and the steering force from the tire wheel can be reliably transmitted to the tread side, and the grip force of the tread can be reliably transmitted to the tire wheel, which can contribute to the improvement of steering stability. On the other hand, the impact energy from the road surface can be absorbed by the unreinforced shoulders and sidewalls, and the riding comfort can be maintained.

The bead reinforcing layer may be made of one kind of reinforcing layer from the inner diameter side to the outer diameter side, but a high rigidity reinforcing layer on the inner diameter side and a low rigidity reinforcing layer on the outer diameter side. According to the constitution, the rigidity is successively and successively increased to the side wall, the low rigidity reinforcing layer, the high rigidity reinforcing layer and the bead core. Therefore, similarly to the above, it is effective in ensuring the transmission of the rotational force and the steering force from the tire wheel to the tread and improving the steering stability. Moreover, as you go to the tread side,
Since the tire rigidity is continuously reduced, the riding comfort is also improved. In this way, the division of roles is assigned to each tire portion, and since the roles are linked without being cut off, it is possible to maintain riding comfort while improving steering stability and high-speed durability.

If the inner diameter side end of the high rigidity reinforcing layer is arranged at the bead filler root part and the outer diameter side end is arranged within 10 mm from the end position of the rim flange to the tire outer diameter side, the high rigidity reinforcing layer becomes the side. Without suppressing the deformation of the wall,
Helps improve ride quality. If the high-rigidity reinforcing layer retreats significantly from the end of the rim flange toward the inner diameter side, the rigidity of the bead portion becomes insufficient, and the steering stability at high speed becomes poor. Further, if it exceeds 10 mm from the flange end portion to the outer diameter side, the feeling of lumpiness is increased and the riding comfort is deteriorated.

The low-rigidity reinforcing layer has a winding width of at least 50% of the height of the rim flange from the outer diameter side end of the high-rigidity reinforcing layer, and up to 50% of the tire cross-section height. With a winding width of, the intermediate rigidity region between the high-rigidity reinforcing layer and the sidewall tip side can be sufficiently secured. Therefore, the change curve of the rigidity becomes gentle, and it is possible to suppress the uncomfortable feeling due to stress concentration. If the winding width of the low-rigidity reinforcing layer is at least 50% of the rim flange height, the rigidity of the entire sidewall will be insufficient, and the high-low-
It loses the continuous continuity, resulting in poor steering stability and durability at high speeds. Here, the "tire cross-section height" means
JATMA YEAR BOOK (2001) describes that "a tire is attached to a standard rim and the tire outer diameter is measured with a specified air pressure filled, and the difference between the obtained tire outer diameter and the standard rim diameter is 1 / 2 ”. Further, hereinafter, a straight line passing through the rim diameter position and parallel to the tire axis is referred to as a rim diameter line.

When at least the low-rigidity reinforcing layer of the high-rigidity reinforcing layer and the low-rigidity reinforcing layer is made of an organic fiber cord, it is effective in reducing the weight of the tire, the unsprung load can be reduced, and the fuel consumption can be improved. Give effect.

If the high-rigidity reinforcing layer is made of steel cord and the low-rigidity reinforcing layer is made of 66 nylon, high rigidity and low rigidity can be effectively ensured. By subjecting the steel cord of the high-rigidity reinforcing layer to stretchable, it is possible to impart elasticity while ensuring the rigidity of the bead portion,
The durability and riding comfort can be improved.

By adopting a corrugated process or a high elongation cord structure as the stretchable process, even a steel cord can effectively obtain both rigidity and stretchability and high tensile strength.

The loss tangent (tan δ) of the rubber coating the cord of the bead reinforcing layer is 0.25 to 0.0 under the above measurement conditions.
5, preferably 0.20 or less, if the JIS hardness at room temperature measurement is set to a value within the range of A75 to A95, less heat is generated and sufficient rigidity can be secured.

If the tire has a flatness of 60 to 30%, the flat tire which realizes steering stability and riding comfort at a high level by effectively utilizing the change in rigidity in the region from the sidewall to the bead core. Can be

Further, according to the present invention, a body ply is fitted on the outer periphery of a drum core capable of retaining its shape, the diameter of the body ply is expanded to a toroidal shape, and a plurality of rubber-coated cords are provided on both outer shoulders of the body ply. It is characterized in that the reinforcing layer between the ply and the belt is arranged by winding it.

In this case, the drum core is formed of a deformable and non-stretchable bladder, and the body ply (including the ground pressure peak position is included) in a state in which the bladder is expanded to have substantially the same shape as when the tire internal pressure is filled. Since the rubber-coated cord is wound around the inside of the tire), the ply-belt reinforcing layer can be placed accurately on the shoulder portion of the tire without difficulty.

The bead reinforced by the rubber-coated cord forming the bead reinforcing layer is wound around the side portion of the bead filler in advance and assembled to the body ply on the bladder, so that the bead reinforcing layer can be easily assembled.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a pneumatic radial tire embodying the present invention will be described below with reference to the drawings.

As shown in FIGS. 1 and 2, the pneumatic tire 11 of this embodiment is a flat radial tire supported by a tire wheel 16 and having an oblateness of 45%. The flatness is selected within the range of 60 to 30% according to the vehicle type, specifications, usage conditions and the like.

The pneumatic tire 11 is provided with a hard rubber bead filler 13 standing on the outer diameter surface of the bead core 12 and a pair of left and right beads 15 composed of a bead reinforcing layer 14.

As shown in FIG. 2, the bead reinforcing layer 14
Is attached to the outer surface side of the bead filler 13 so as to extend in the tire circumferential direction, and is constituted by winding a rubber covered cord 17 in the tire circumferential direction. This bead reinforcing layer 14
Consists of a high-rigidity reinforcing layer 14a on the inner diameter side and a low-rigidity reinforcing layer 14b on the outer diameter side. The high-rigidity reinforcing layer 14a has an inner diameter side end located at the root of the bead filler 13, and an outer diameter side end located 10 mm away from the end position of the rim flange 16a of the tire wheel 16 toward the tire outer diameter side. It is located on the side. Further, the low-rigidity reinforcing layer 14b has a winding width of at least 50% of the value of the rim flange height P from the outer diameter side end portion of the high-rigidity reinforcing layer 14a, and the outer diameter end portion has a tire cross section. It is located within 50% of the height. Here, the rim flange height means the height from the rim diameter line to the rim flange apex.

The high-rigidity reinforcing layer 14a is made of rubber-coated steel cord 17a, that is, 1 × 3 × 0.27 (0.27).
The low-rigidity reinforcing layer 14b is composed of 66 nylon cord 17b, which is an organic fiber coated with rubber, that is, 1400 dtex /
It is composed of 66 nylon cord 17b having two structures. Then, the respective cords are continuously passed through the rubber extruder to be coated with the rubber. The rubber-coated steel cord 17a is spirally wound from the root of the bead filler 13 along the circumferential direction of the bead filler 13 and wound around the rim flange 16a near the upper end thereof. Subsequently, the rubber-coated 66 nylon cord 17b is spirally wound around the high rigidity reinforcing layer 14a along the circumferential direction of the bead filler 13 to form the low rigidity reinforcing layer 14b. The loss tangent (tan δ) of the rubber covered with the above-mentioned cord is
Was 0.18, and the JIS hardness at room temperature was A90.

A body ply 21 extends between the bead cores 12, and both width ends thereof are folded back so as to wrap the bead core 12. On the outer diameter side of the crown portion of the body ply 21, two belts formed by coating a steel cord with rubber are superposed so as to extend in the circumferential direction. The first belt 22 is the second belt 2
Located on the inner diameter side of 3 and wider than the second belt 23,
It projects outward from the width end of the belt 23. One belt cover 24 wider than the first belt 22 is provided so as to cover the outer diameter sides of the belts 22 and 23. Further, the tread 3 covers the outside of the belt cover 24.
1 is provided.

A sidewall 33 is provided so as to cover the outside of the side portion of the body ply 21. As shown in FIGS. 3 and 4, on the ground contact surface 41 of the tread 31 with respect to the road surface, the peak position 42 of the ground contact pressure is
It is located at the shoulder portion 18, which is the end portion of both widths of 1.
This is a region where the portions of the first and second belts 22 and 23 extending to the shoulder portion 18 are free ends, and the rigidity is reduced. Therefore, since the restraining force against the expansion due to the tire internal pressure is weaker than that at the center side of the tread, the tire tends to project outward in the radial direction of the tire, and as a result, a large load is shared and the ground contact pressure is increased.

3 to 6, the simplified curve L1 is shown.
~ L5 has shown the level of ground pressure. This is a view of the pressure distribution of the ground contact shape on the tire ground contact surface using pressure sensitive paper or the like. Note that the tire ground contact shape is JI
This is a shape in which the tread surface is formed on a flat surface when the load condition of the high-speed performance test B prescribed by SD4230, that is, the internal pressure is 220 kPa and the load is 88% of the maximum load capacity. In addition, the standard rim applied to the tire was used for the test.

As shown in FIGS. 1 and 4 to 8, the shoulder portion 18 is formed of a rubber ribbon and has a substantially flat triangular cross section between the body ply 21 and the width end portion of the first belt 22. A buffer layer 51 is provided.

The ply-belt reinforcing layer 52 is covered with the cushioning layer 51 from the tire outer diameter side, and is provided between the outer diameter side of the body ply 21 and the inner diameter sides of both width ends of the belts 22 and 23. positioned.

As shown in FIGS. 4 and 5, the ply-belt reinforcing layer 52 is substantially equal toward the inner side and the outer side in the tire width direction with the tire inner point 42a at the ground contact pressure peak position 42 as the center. Having a width dimension l1,
The width end on the outer side in the tire width direction substantially coincides with the position of the width end of the first belt 22.

The ply-belt reinforcing layer 52 is shown in FIG.
As shown in FIG. 11, one rubber-coated cord 53 or rubber-coated hybrid cord 54 is continuously wound spirally along the tire circumferential direction as described above.
Note that, as shown in FIG. 8, adjacent coating rubbers 53a are in close contact with each other and are continuous. Therefore, the covering rubber 53a may be extruded so as to have a rectangular cross section. The rubber covering the cords 53 and 54 has a tan δ of 0.
The value is 13, and the heat generation is small and appropriate.

The cord 53b covered with the rubber 53a is
Either an aliphatic polyamide fiber cord, an aromatic polyamide fiber cord, or a steel cord may be selected. However, if the extensibility of the cord itself is insufficient, such as with aromatic polyamide fiber cords and steel cords, it is necessary to make it extensible. In the case of steel cords, corrugation as shown in FIG. As shown, a high elongation cord 43 may be used in which a plurality (three in the embodiment) of strands 43c formed by twisting a plurality of (three in the embodiment) strands 43b are further twisted.

As the stretchable processing of the aromatic polyamide fiber cord, the hybrid cord structure shown in FIG. 10 is applied. This hybrid cord 54 is made of aliphatic polyamide fiber and aromatic polyamide fiber, is light and has high strength, has good heat shrinkage surface and heat resistant adhesive surface, prevents lifting of body ply, and has high durability and high speed. It is effective in improving the steering stability and reducing fuel consumption. Examples of the aliphatic polyamide fiber include 66 nylon and 6 nylon, and examples of the aromatic polyamide fiber include aramid fiber. The hybrid cord 54 is formed by using a 66 nylon bundle as a core wire and winding an aramid fiber bundle around the core wire. In addition, in FIG. 10, the core wire is drawn in a straight line so that it is easy to understand the distinction between the core wire and the wire wound around the core wire. Become.

As shown in FIG. 8, in this example, the gauges G1 and G2 of the ply-belt reinforcing layer 52 are the belt side (G
2) is 1.0 mm, body ply side (G1) is 1.0
set to mm. Therefore, at the same time as preventing lifting, the stress acting on the cords 53, 54 at the portions of the gauges G1, G2 is absorbed, which is effective in improving durability. Here, the gauges G1 and G2 are the ply-belt reinforcing layer 52.
The rubber thickness of the covered rubber 53a is shown.

The number of cords to be driven in the ply-belt reinforcing layer 52 is uniform over the entire width.
In addition, the number of driving is mainly 18 / 25mm
Was set to.

The ply-belt reinforcing layer 52 is shown in FIG.
As shown in, the structure may be extended outward in the tire width direction starting from the outside of the tire inner point 42a at the peak position. Further, as shown in FIG. 7, the outer end in the width direction may be between the position within 10 mm from the outer end of the belt cover and the outer end of the belt.

215 / 45ZR17 constructed in this way
The flat pneumatic radial tire is manufactured as follows. That is, in the shaping step of molding a tire, as shown in FIGS. 15 and 16, the cylindrical body ply 21 is fitted between the moving bodies 70 on both sides on the outer peripheral surface of the bladder 60 as the cylindrical drum core. To be dressed. The bladder 60 is non-stretchable by embedding a non-stretchable cord vertically and horizontally in the meat portion. Then, the beads 15 composed of the bead core 12 and the bead filler 13 are set in the vicinity of both width end portions of the body ply 21.

Then, both width ends of the bladder 60 are moved closer to each other by the moving movement of the moving body 70 (in the direction of the arrow in FIG. 15), and compressed air is supplied to the inner cavity of the bladder 60, so that the bladder 60 is moved to the body. The expansion starts with the ply 21 and expands to a toroidal shape. Then, the bead pressing member 81 and the bending member 82 move to the tire outer diameter side, and both width end portions of the body ply 21 wrap the bead 15. Since the bladder 60 is non-stretchable as described above, it exhibits a property close to that of a rigid body when it is expanded and expanded in a toroidal shape.

Continuing, the body ply 2 on the bladder 60
In order to form the ply-belt reinforcing layer 52 at the required position of 1, the cords 53 and 54 in which the cord of 1.2 mmφ is covered with the rubber are, for example, 1. The spiral winding is performed 13 times at a pitch of 4 mm.

Body ply 2 molded in this way
Other tire constituent members such as the belts 22 and 23, the tread 31, and the sidewalls 33 are fitted on the outer peripheral surface of 1 to form a green tire. This green tire is vulcanized to complete a 215 / 45ZR17 flat pneumatic radial tire.

The pneumatic radial tire thus produced can prevent lifting of the shoulder portion 18, and the steering stability, durability, riding comfort, etc. at high speed can be greatly improved.

The table shown in FIG. 14 has a size of 215/45.
The ZR17 tires of the conventional example and the example are manufactured,
The results of an experiment in which those tires are mounted on a rim of size 7JJ are shown. The tires of the examples are manufactured according to the technique of the above-described embodiment.

Here, "high-speed steering stability" and "riding comfort" mean that the above-mentioned tires are mounted on a passenger car having an internal pressure of 200 kPa and an engine displacement of 2000 cc, and a straight line and a lane at a speed of 60 to 180 km per hour on a circuit course. The change test and the running on the general road were evaluated by the driver's experience with 100 points as a perfect score. “High-speed durability” is an indoor high-speed durability drum test, in which the tire pressure is 200 kPa and the load is 4200 N, the drum test speed is increased according to a plurality of predetermined steps, and the speed at the time when the tire is damaged and The elapsed time is measured and indexed. Each step includes 100 km × 30 minutes, 140 km × 20 minutes, 1 hour
60km × 15 minutes, 180km × 10 minutes, 200km ×
This is a test in which each step is performed for 10 minutes, and thereafter, each time the step is completed for 10 minutes, the step is advanced to a speed-up step of 20 km, and the vehicle runs until it breaks down.

As described above, the radial tires of Examples 1 to 5 marked favorable results in comparison with the conventional example in all of high-speed steering stability, high-speed durability drum test and riding comfort.

That is, in this embodiment, the following operational effects are exhibited. By disposing the spirally wound ply-belt reinforcing layer 52 on the shoulder portion 18 between the body ply 21 and the belts 22 and 23, lifting of this portion can be prevented. For this reason, the grip force of the entire tread is made uniform, the total grip force is improved, the steering stability is improved, and it is not necessary to use a rubber type having a high grip force as the tread 31, and wear resistance, Fever,
The fuel efficiency of the vehicle has improved. In addition, here, the steering stability is
Not only running stability but also high steering characteristics are included. In addition, since the ply-belt reinforcing layer 52 is formed by spirally winding, there is no cord end that becomes a failure nucleus, and the durability is excellent.

By providing the bead reinforcing layer 14 on the side portion of the bead filler 13, the rigidity of the bead portion can be improved, the rotational force and steering force from the tire wheel can be reliably transmitted to the tread side, and The grip force can be reliably transmitted to the tire wheel, and steering stability can be improved. On the other hand, the impact energy from the road surface can be absorbed by the shoulder portion 18 and the sidewall 33 without reinforcement, and the riding comfort can be maintained. Then, the bead reinforcing layer 14
Is composed of the high rigidity reinforcing layer 14a on the inner diameter side and the low rigidity reinforcing layer 14b on the outer diameter side, the sidewall 33,
The tire rigidity sequentially and continuously increases to the low-rigidity reinforcing layer 14b, the high-rigidity reinforcing layer 14a, and the bead core 12. Therefore, the steering stability can be improved, and the tire rigidity continuously decreases toward the tread 31 side, so that the riding comfort is also improved. Further, since the rigidity of the tire side portion continuously changes, it is free from stress concentration occurring in the sudden change portion of rigidity, so that the durability can be improved and the tire failure can be reduced.

The inner diameter side end of the high-rigidity reinforcing layer 14a is the bead filler root, and the outer diameter side end is within 10 mm from the end position of the rim flange 16a to the tire outer diameter side. Therefore, the high-rigidity reinforcing layer 14a does not suppress the deformation of the sidewall, and the riding comfort can be improved.
In addition, the low-rigidity reinforcing layer 14b has a winding width of at least 50% of the rim flange height P from the outer diameter side end of the high-rigidity reinforcing layer 14a, and within 50% of the tire cross-section height at the maximum. Therefore, the high rigidity reinforcing layer 14a and the sidewall 33
An intermediate rigidity region with the tip side can be secured. Therefore, similarly to the above, the change curve of the rigidity becomes gentle, and the uncomfortable feeling due to the stress concentration can be suppressed. In addition, since the low-rigidity reinforcing layer 14b is composed of the organic fiber cord 17b, it can contribute to weight reduction of the tire, improve fuel efficiency, and give a good ride comfort.

The ply-belt reinforcing layer 52 is centered on the tire inner point 42a at the ground contact pressure peak position 42,
It has substantially the same width dimension toward the inner side and the outer side in the width direction. Therefore, the lifting of the ground pressure peak position 42 and the positions on both sides thereof can be effectively suppressed, and the steering stability can be improved. Then, the gauges G1 and G2 of the ply-belt reinforcing layer 52 are set to the belts 22 and 2
Since the value on the 3 side is 0.5 mm to 3.0 mm and the value on the body ply 21 side is 0.5 mm to 1.0 mm, durability against repeated stress due to tire running is improved and the flexibility of the shoulder portion 18 is improved. To some extent, the grip performance etc. is improved. Since the ply-belt reinforcing layer 52 is composed of the organic fiber cords 53 and 54, it effectively follows the deformation of the tread,
Similar to the above, grip performance can be improved.

Since the cords 53 and 54 of the ply-belt reinforcing layer 52 are aliphatic polyamide fiber cords, they have good functions of heat shrinkage and heat-resistant adhesion, and prevent lifting of the body ply 21, It is effective in improving high-speed durability and handling stability at high speeds. Further, if the cords 53 and 54 of the reinforcing layer 52 are constituted by cords in which aromatic polyamide fibers are spirally wound around aliphatic polyamide fibers, the characteristics of both fibers can be obtained with almost no increase in weight. It can be effectively utilized to contribute to the improvement of tire performance. That is, strength and flexibility and elasticity can be secured.

Since the buffer layer 51 is provided so as to cover the ply-belt reinforcing layer 52 from the tire outer diameter side, the ply-belt reinforcing layer 52 can be protected and the cushioning property can be imparted to provide a comfortable ride. improves.

Since the minimum number of cords to be driven into the ply / belt reinforcing layer 52 is 10/25 mm and the maximum is 30/25 mm, both steering stability and durability can be improved.

Tan δ of the rubber covering the cords 53 and 54 of the ply-belt reinforcing layer 52 is 0.20
Since the value is set to 0.05, preferably 0.15 or less, heat generation in the shoulder portion, which moves rapidly, can be suppressed, and the durability of the tire can be improved. That is, when the tan δ of the rubber exceeds 0.20, the amount of heat generated is large relative to the rigidity,
When the tan δ of the rubber is less than 0.05, the strength itself as the rubber is insufficient. The tan δ of the rubber covering the cords 17a and 17b of the bead reinforcing layer 14 is 0.25 to 0.25.
0.05, JIS hardness at room temperature is set to a value within the range of A75 to A95, so that the amount of heat generated can be suppressed and the rigidity of the bead portion can be made appropriate while ensuring sufficient rigidity as rubber. You can That is, due to the relationship with the bead filler, the hardness of the rubber exceeds A95 and the hardness is excessive. When the hardness of the rubber is less than A75, the hardness is insufficient.

When manufacturing a pneumatic tire, the body ply 21 is fitted to the outer periphery of the bladder 60, which is so-called a rigid body, which can retain its shape, and has a toroidal shape, and ply is provided at both outer diameter side positions of the body ply 21. -The rubber-coated cords 53 and 54 which become the inter-belt reinforcing layer 52 are wound a plurality of times. For this reason, unlike the case where a simple balloon is provided as the bladder, the installation position of the ply-belt reinforcement layer 52 does not move, and the ply-belt reinforcement layer 52 can be easily arranged at a predetermined position. .

The present invention is not limited to the above embodiment, but can be modified and embodied as follows. -Use of an organic fiber instead of steel as the high rigidity reinforcing layer 14a. As the organic fibers, aromatic polyamide fibers such as aramid fibers, high-rigidity polyethylene terephthalate fibers, polyethylene naphthalate fibers and the like are selected. By doing so, the weight of the pneumatic tire can be reduced.

Use of 6 nylon or the hybrid cord as described above as the low-rigidity reinforcing layer 14b. In the above-described embodiment, the number of driving the ply-belt reinforcing layer 52 is uniform over the entire width. However, the number of driving is sparse in the width direction inside from the center position of the ground contact pressure peak position 42 and outside in the width direction. Drive it densely.

As shown in FIG. 17, the belts 22, 2
The belt cover 24 in the above-described embodiment that covers the entire width of
Reinforcing layer 52 between plies and belts on both sides without providing
Provide a narrow belt cover 24 at a position corresponding to. With this structure, the belts 22 and 23 are partially covered by the belt cover 24. This can contribute to weight reduction of the tire. Alternatively, the belt cover 24 covering the entire width may be provided with the belt cover 24 having a narrower width. With this configuration, the movement of the bell and the end can be further suppressed, and the steering stability can be improved.

As shown in FIG. 18, unlike the above embodiment, the buffer rubber tape 56 is provided on the outer diameter side of the ply-belt reinforcing layer 52 without providing the buffer layer 51 having a triangular cross section. In this case, the belt side gauge G
2 includes the thickness of the buffer rubber tape 56.

As shown in FIG. 19, the bead reinforcing layer 55 is also provided on the inner surface side of the bead filler 13. As the bead reinforcing layer 55, the various organic fiber cords described above are used.

A high elongation cord is used as the cord 17 of the ply-belt reinforcing layer 52. Therefore, the cord 17 is subjected to stretchable processing, and the ply-belt reinforcing layer 52 is given elasticity.

Both the high-rigidity reinforcing layer 14a and the low-rigidity reinforcing layer 14b forming the bead reinforcing layer 14 are made of organic fibers. These differences in rigidity can be obtained by the thickness and material of the organic fibers. By doing so, it is possible to further reduce the weight of the tire.

As shown in FIGS. 12 (a) and 12 (b), as the ply-belt reinforcing layer 52, a ribbon 5 in which a plurality of parallel cord core wires 53 b are covered with rubber 53 a
7, the ribbon 57 is spirally wound around the same position as in the above embodiment. 12A, the ribbon 57 has a substantially parallelogram cross section, and in FIG. 12B, the ribbon 57 has a substantially rectangular cross section. In this way, by winding one ribbon 57, a plurality of cords are wound at the same time, and the production efficiency is improved.

[0076]

As described above in detail in the embodiments, according to the present invention, excellent steering stability, particularly steering stability under high speed running, and various performances such as wear resistance, heat generation, vehicle fuel consumption, etc. It has the excellent effect of improving the riding comfort without damaging the vehicle.

[Brief description of drawings]

FIG. 1 is a sectional view of a pneumatic tire embodying the present invention.

FIG. 2 is an enlarged sectional view showing a bead portion.

FIG. 3 is an explanatory diagram showing a relationship between a ground surface and a ground pressure.

FIG. 4 is an explanatory diagram showing a relationship between a shoulder portion and a ground pressure.

FIG. 5 is an explanatory view of a shoulder portion of a modified example.

FIG. 6 is an explanatory view of a shoulder portion of another modified example.

FIG. 7 is an explanatory view of a shoulder portion of still another modified example.

FIG. 8 is an enlarged cross-sectional view of a portion of a ply-belt reinforcing layer.

FIG. 9 is a partial perspective view showing a rubber covered cord.

FIG. 10 is a partial perspective view showing a hybrid cord.

FIG. 11 is a partial perspective view showing a stretchable cord.

FIG. 12 is a cross-sectional view showing a ribbon used for a ply-belt reinforcing layer.

FIG. 13 is a sectional view showing a high elongation cord.

FIG. 14 is a table showing a comparison between a conventional example and an example.

FIG. 15 is a partial cross-sectional view showing a bladder mechanism in tire molding.

FIG. 16 is a partial cross-sectional view showing a bladder mechanism in tire molding as well.

FIG. 17 is a cross-sectional view showing another embodiment.

FIG. 18 is a partial cross-sectional view showing a modified example of the buffer layer.

FIG. 19 is a cross-sectional view showing a modified example of the bead reinforcing layer.

[Explanation of symbols]

11 ... Pneumatic tire, 12 ... Bead core, 13 ... Bead filler, 14 ... Bead reinforcement layer, 14a ... High rigidity reinforcement layer, 14b ... Low rigidity reinforcement layer, 15 ... Bead, 18 ... Shoulder part, 21 ... Body ply, 22 … First belt, 2
3 ... 2nd belt, 24 ... Belt cover, 33 ... Side wall, 41 ... Ground contact surface, 42 ... Ground pressure peak position, 42
a ... internal points, 51 ... buffer layer, 52 ... ply / belt reinforcing layer, 53 ... rubber coated cord, 54 ... hybrid cord, 55 ... bead reinforcing layer, 60 ... bladder as core,
G1, G2 ... Gauge, P ... Rim flange height.

─────────────────────────────────────────────────── ─── Continued Front Page (51) Int.Cl. ⁷ Identification Code FI Theme Coat (Reference) B60C 9/00 B60C 9/00 DG J 9/20 9/20 GL 15/06 15/06 N

Claims (34)

[Claims] 1. A body ply extending between a pair of beads and folded back around a bead core, a belt extending in a tire circumferential direction on an outer diameter side of a crown portion of the body ply, and an outer diameter side of the belt. At least one belt cover that extends in the tire circumferential direction and covers at least both widthwise ends of the belt, a tread that covers the outer diameter side of the belt cover, and a sidewall that covers the outside of the side portion of the body ply. A pneumatic radial tire provided with, between the outer diameter side of the body ply and the inner diameter side of both width ends of the belt, by spirally winding a rubber-coated cord in the tire circumferential direction, A pneumatic radial tire featuring a reinforcement layer between the ply and belt. 2. The ply-belt reinforcing layer is arranged so as to extend to inner and outer positions in the tire width direction so as to include a tire inner point at a tire ground contact pressure peak position. The pneumatic radial tire according to claim 1. 3. The ply-belt reinforcing layer has substantially the same width dimension inward and outward in the tire width direction centering on the tire inner point at the ground contact pressure peak position. Pneumatic radial tire as described in. 4. The ply-belt reinforcing layer has an inner end located outside of the tire inner point at the ground contact pressure peak position in the tire width direction, and the reinforcing layer includes a width end portion of the belt and a belt cover. The pneumatic radial tire according to claim 1, wherein the pneumatic radial tire includes a width end portion, and an outer end of the width end portion is located outside a width direction of the belt cover. 5. The ply-belt reinforcing layer has an outer end in the width direction between a position within 10 mm outside the outer end of the belt cover and the outer end of the belt. Pneumatic radial tire as described in. 6. A pneumatic radial tire according to claim 1, wherein one cord covered with rubber is spirally wound to form the ply-belt reinforcing layer. 7. The pneumatic radial tire according to claim 1, wherein a ribbon having a plurality of parallel cords embedded in rubber is spirally wound to form the ply-belt reinforcing layer. . 8. The cord of the ply-belt reinforcing layer has a value within the range of 0.5 mm to 3.0 mm between the cord and the belt and 0.5 mm to 1.0 mm between the cord and the body ply. The pneumatic radial tire according to any one of claims 1 to 7, wherein the pneumatic radial tires are arranged at intervals. 9. The pneumatic radial tire according to claim 1, wherein the ply-belt reinforcing layer is made of an organic fiber cord. 10. The minimum number of cords to be driven into the ply-belt reinforcing layer is 10/25 mm, and the maximum is
The pneumatic radial tire according to claim 9, wherein the number is 30/25 mm. 11. The pneumatic radial tire according to claim 9, wherein an aliphatic polyamide fiber is used for the cord of the ply-belt reinforcing layer. 12. The pneumatic radial tire according to claim 9, wherein a hybrid cord made of an aliphatic polyamide fiber and an aromatic polyamide fiber is used as the cord of the ply-belt reinforcing layer. 13. The air according to claim 12, wherein the cord of the ply-belt reinforcing layer is formed by spirally winding an aromatic polyamide fiber around an aliphatic polyamide fiber to form a cord. Radial tires with. 14. The pneumatic radial according to claim 1, wherein the cord of the ply-belt reinforcing layer is a steel cord, and the steel cord is stretchable. tire. 15. The pneumatic radial tire according to claim 14, wherein the stretchable processing is corrugation processing. 16. The pneumatic radial tire according to claim 14, wherein the stretchable cord is a high elongation cord. 17. The pneumatic radial tire according to claim 1, wherein the ply-belt reinforcing layer is a single layer. 18. The pneumatic radial tire according to claim 1, wherein a buffer layer is provided so as to cover the ply-belt reinforcing layer from the tire outer diameter side. 19. The loss tangent (tan δ) of rubber covering the cord of the ply-belt reinforcing layer is 0.20 to 20.
2. A value within the range of 0.05.
19. The pneumatic radial tire according to any one of to 18. 20. The pneumatic radial tire according to claim 1, wherein the ply-belt reinforcing layer is arranged on the tire inner side of a shoulder portion including a ground contact pressure peak position. 21. The bead is configured by arranging a bead filler on an outer diameter surface of a bead core, and a bead reinforcing layer made of a rubber-coated cord extending in a tire circumferential direction on a side portion of the bead filler. The pneumatic radial tire according to any one of claims 1 to 20, wherein the pneumatic radial tire is provided. 22. The pneumatic radial tire according to claim 21, wherein the bead reinforcing layer includes a high rigidity reinforcing layer on the inner diameter side and a low rigidity reinforcing layer on the outer diameter side. 23. The high-rigidity reinforcing layer is arranged such that an inner diameter side end thereof is arranged at a bead filler root portion and an outer diameter side end thereof is arranged at an inner diameter side from a position of 10 mm from an end position of the rim flange to a tire outer diameter side. The pneumatic radial tire according to claim 22, which is characterized in that. 24. The low-rigidity reinforcing layer has a winding width of at least 50% of the rim flange height from the outer-diameter side end portion of the high-rigidity reinforcing layer, and the outer-diameter side end portion has a tire cross-section height. 24. The pneumatic radial tire according to claim 22, which is located within 50% of the height. 25. The pneumatic radial tire according to claim 22, wherein at least the low-rigidity reinforcing layer of the high-rigidity reinforcing layer and the low-rigidity reinforcing layer is made of an organic fiber cord. 26. The pneumatic radial tire according to claim 25, wherein the high-rigidity reinforcing layer is made of steel cord and the low-rigidity reinforcing layer is made of 66 nylon. 27. The pneumatic radial tire according to claim 26, wherein the steel cord is stretchable. 28. The pneumatic radial tire according to claim 27, wherein the stretchable processing is corrugated processing. 29. The stretchable cord is a high elongation cord.
The pneumatic radial tire according to 7. 30. The loss tangent (tan δ) of the rubber that coats the cord of the bead reinforcing layer is a value within the range of 0.25 to 0.05. Pneumatic radial tire. 31. The pneumatic radial tire according to claim 1, wherein the flatness is a value within a range of 60 to 30%. 32. A body ply is fitted to the outer periphery of a drum core having a shape-retaining function, and is expanded in a toroidal shape,
A rubber-coated cord is wound around the shoulders on the outer diameter side of the body ply a plurality of times in a spiral shape, and a ply-belt reinforcement layer is disposed near the inner diameter side ends of the belt. For manufacturing a pneumatic pneumatic tire. 33. The drum core is formed of a deformable and non-stretchable bladder, and a rubber-coated cord is wound around the body ply in a state where the bladder is expanded to have a shape substantially the same as that when the tire internal pressure is filled. 33. The method for manufacturing a pneumatic radial tire according to claim 32, wherein 34. The pneumatic radial according to claim 33, wherein a bead having a rubber-coated cord forming a bead reinforcing layer wound around the side of the bead filler in advance is assembled to the body ply on the bladder. Tire manufacturing method.