JP2000351305A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate cornering force and cornering power exceeding the force and power generated by conventional technology. SOLUTION: This pneumatic radial tire is provided with a tread part 1, a side wall part 2, bead part 3, carcass 4 reinforcing each part, belt 5 reinforcing the tread part, and reinforcing layer 8 arranged over the side wall part 2 from the bead part 3 by folding it back around a bead core 3a. An external end part in the radial direction of the reinforcing layer 3 is positioned on an inner peripheral side of the belt 5 on a side wall part side facing an outer side of a vehicle of the tire having mounting attitude on the vehicle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sports car, in which a cornering force and a cornering power, particularly during high-speed running, are greatly increased, so that turning performance is greatly improved and uneven wear is effectively suppressed.
The present invention relates to a pneumatic radial tire suitable for use in high-end passenger cars, competition vehicles, and the like.

[0002]

2. Description of the Related Art In order to enhance the high-speed turning performance of a pneumatic radial tire, the circumferential rigidity of a belt functioning as a so-called "haga" or the in-plane bending rigidity of the belt at a contact portion is increased. It is widely practiced to increase the lateral rigidity of a tire to improve the contact property during cornering.

[0003] According to this, regarding the contact shape and contact pressure distribution of the tire due to the lateral deformation input to the tire during turning, the contact length increases and the contact pressure increases on the outer portion of the turn. In the inner part of the turn, the tendency of the ground contact length to decrease and the contact pressure to decrease can be alleviated. In addition, for the in-plane bending input of the belt at the contact part,
In particular, the buckling deformation of the belt at the outer part of the turn, in other words, the tread tread can effectively suppress wavy deformation in the cross section in the tread width direction. Can have a certain effect on the improvement of

[0004]

However, when pursuing a further increase in the cornering force, the prior art centered on improving the belt rigidity has its own limit. It has not been possible to improve cornering force and cornering power during high-speed running.

Accordingly, an object of the present invention is to make it possible to generate a cornering force and a cornering power having a size larger than that of the prior art. Paying attention to the fact that the entire part performs a camber deformation in which the upper part against the ground contact part of the tire applies the direction of centrifugal force, in other words, the camber deformation that tilts in the direction protruding outward of the turn, and this camber deformation of the tire itself is directly By suppressing
First, to prevent the deterioration of the ground contact during lateral deformation, which cannot be avoided with conventional pneumatic radial tires,
Regardless of the turning speed, excellent ground contact is always ensured, and secondly, air that can effectively reduce the camber thrust generated in the direction opposite to the cornering force due to the camber deformation of the tire. To provide radial tires.

[0006]

SUMMARY OF THE INVENTION A pneumatic radial tire according to the present invention is particularly suitable for lateral deformation of a tire.
A new reinforcing layer that appropriately distributes the circumferential stiffness and bending stiffness of the sidewall portion, which contributes to the suppression of the camber deformation of the tire as a whole, is disposed on the sidewall portion, and the tread portion and the tread portion A pair of side walls extending radially inward from both sides of the side wall, and a bead part continuing to the radially inner end of each side wall part, and extending in a toroidal shape between bead cores arranged in the bead part. A carcass that reinforces the respective portions, a belt that is located on the outer peripheral side of the crown portion of the carcass and reinforces the tread portion, and a reinforcing layer that is folded around the bead core and disposed from the bead portion to the sidewall portion. That is folded around the bead core, at least on the side of the sidewall facing the outside of the vehicle, in the tire mounted on the vehicle. Of the reinforcing layer which is disposed, in which is located one or radially outer end portion of both the inner and outer side of the bead core on the inner peripheral side of the belt.

Therefore, in this tire, the radially outer end of the reinforcing layer on the side of the sidewall facing the inside of the vehicle is located at the same radial position as that of the reinforcing layer on the side of the outer sidewall or on the inner peripheral side thereof. However, the outer end in the radial direction is preferably located on the outer peripheral side of the tire maximum width position.

[0008] In the camber deformation of the tire due to turning, an out-of-plane displacement difference appears between the sidewall portion immediately below (on the side of the ground contact portion) and the portion immediately below the sidewall portion. Therefore, in this tire, the bead core is formed at each sidewall portion. The reinforcement layer that is folded back around the tire provides circumferential and radial bending stiffness in the direction in which the sidewalls are bent out of plane to the backbone of the tire from the bead portion to the vicinity of the tire maximum width position. By doing so, the region from the bead portion to the vicinity of the tire maximum width position can be effectively opposed to the camber deformation, and can advantageously contribute to the suppression of camber deformation.

In this case, the reinforcing layer is located on the inner peripheral side of the belt, particularly on the outer side wall portion side.
By increasing the circumferential rigidity of the region between the vicinity of the tire maximum width position and the tread portion, this region can be effectively opposed to camber deformation, so that in addition to the above, the camber deformation of the tire as a whole is reduced. It can be effectively blocked. In this case, since the region is located far from the tire axis, the increased rigidity there can contribute particularly advantageously to preventing camber deformation. On the other hand, the conventional radial tire generally has little circumferential rigidity in the above-mentioned region, so that relatively large camber deformation is forced to occur.

By the way, regarding such circumferential rigidity,
Since the reinforcing layer and, consequently, the reinforcing layer cord have a higher rigidity on the tension side than on the compression side, the circumferential tensile force due to the lateral deformation input is particularly large here, particularly in the outer wheel tires having a large load load during cornering. By extending the reinforcing layer on the side serving as the side wall portion on the outer side of the vehicle to the inner circumferential position of the belt, the circumferential rigidity of the outer circumferential region from the tire maximum width position under the tensile strength of the reinforcing layer is exhibited. To ensure an increase.

Thus, in this tire, the circumferential and radial bending stiffness of the region from the bead portion to the vicinity of the tire maximum width position and the circumferential stiffness of the region from the vicinity of the maximum width position to the tread portion are different. By achieving a good balance between them, sufficient suppression of camber deformation of the tire as a whole is realized, and as a result, the contact property is greatly improved, and the tendency of the contact shape and contact pressure distribution of the tire described in the prior art is effected. Can be improved
At the same time, the camber thrust in the direction to cancel the cornering force can be advantageously reduced.

Preferably, in the tire as described above,
The radial outer end of the reinforcing layer of the sidewall portion facing the inside of the vehicle of the tire in the mounting posture on the vehicle is located on the inner peripheral side of the radial outer end of the reinforcing layer of the sidewall portion facing the outside of the vehicle. .

As described above, in order to increase the circumferential rigidity of the tire at the time of cornering on the outer peripheral side from the vicinity of the tire maximum width position, the side wall portion of the tire on the outer side of the corner of the corner of the wheel on the outside of the corner is required. While the reinforcing layer contributes particularly effectively, the side wall portion inside the vehicle is deformed on the compression side on the contrary, and therefore, the reinforcing layer disposed there is arranged in the circumferential direction on the outer peripheral side from the maximum width position. Since it hardly contributes to an increase in rigidity, the radial outer end of the reinforcing layer of the inner side wall portion is located on the inner circumferential side as compared with that of the reinforcing layer of the outer side wall portion.
This is suitable for preventing an increase in material cost and the like.

Here, the radially outer end of the reinforcing layer of the inner side wall portion may be located on the outer peripheral side from the maximum width position of the tire, which is equivalent to the bending rigidity in the circumferential direction and the radial direction of the aforementioned tire base portion. A camber deformation suppressing effect due to the securing can be expected, which is preferable.

Preferably, the extension angle of the cord constituting the reinforcing layer of the side wall portion facing the outside of the vehicle with respect to the radial direction is in a range of approximately 0 to 50 degrees. Here, as the angle increases, the circumferential rigidity at the outer peripheral portion of the sidewall on the outside of the vehicle increases, so that camber deformation can be more effectively suppressed, and the cornering force increases. Here, the upper limit value of the extension angle is set to 50 degrees in the step of expanding the carcass at the time of manufacturing. At an angle larger than this, the uniformity (roundness) of the shape of the raw tire is likely to be impaired, Not good.

[0016] More preferably, the extension direction of the cords at the radially outer end portions of the reinforcing layers of the respective side wall portions is set such that the traveling direction is upward in a virtual deployment state of the tire mounted on the vehicle. In a plan view, the left wheel tires are both raised to the right, and the right wheel tires are both raised to the left. Here, when both radially outer ends of the inner and outer portions of the bead core of the reinforcing layer folded back around the bead core are present at the same radial position, the extension of the cord The presence direction refers to a portion located inside the bead core.

According to this, since both the reinforcing layer cords of the left and right wheel tires have the selected extending direction, the input signal in the front-rear direction at the time of driving reduces the decrease in the cornering force. By forming a circumferential rigidity balance of the pair of sidewalls that creates a torsional deformation that creates a slip angle, it is possible to further increase the cornering force and cornering power even during driving, and thereby achieve a more stable corner Can rise.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a radial sectional view of a tire showing an embodiment of the present invention,
In the figure, 1 is a tread portion, 2 is a pair of sidewall portions extending radially inward from each side portion of the tread portion 1, and 3 is a bead that is continuous with a radially inner end of each sidewall portion 2. Parts are shown.

Here, a radial carcass 4 extending toroidally between the bead cores 3a disposed in the bead portion 3 and reinforcing the respective portions is constituted by at least one carcass ply 4a, 4b in the figure. A belt 5 contributing to the reinforcement of the tread portion 1 is wound around the bead core 3a by winding up the side portion of the radial carcass 4 from the inside to the outside of the tire and locking the tread portion 1 on the outer peripheral side of the crown of the radial carcass 4. Is arranged. The belt 5 has, for example, two or more steel cord belt layers 6a and 6b in which cords cross each other, and extends substantially in the tread circumferential direction on the outer peripheral side of the steel cord belt layers 6a and 6b. At least one wide spiral wound layer 7a made of an organic fiber cord such as nylon, covering almost the entire width of the belt layers 6a and 6b, and the wide spiral wound layer 7
a narrow spiral wound layer 7b of the same kind that extends substantially in the circumferential direction of the tread and is disposed on the outer peripheral side of a and on the side thereof.
And can be composed of

Here, at least one reinforcing layer 8 which is folded around the bead core 3a and extends from the bead portion 3 to the side wall portion 2 is provided, and is constituted by, for example, a high-rigidity organic fiber cord such as an aramid fiber cord. In the reinforcing layer 8 which can be formed, as shown in the figure, the radially outer end portion 8a of the portion 8a extending inwardly of the tire with respect to the bead core 3a is joined to the inner peripheral side of the belt 5 by the respective sidewall portions 2. Preferably, for the purpose of improving the high-speed durability of the tire, the overlapping margin of the outer end portion with the belt 5 is set to 10 mm or more. On the other hand, a radially outer end of a portion 8b of the reinforcing layer 8 that extends to the outside of the tire with respect to the bead core 4 is arranged, for example, at a position of a substantially maximum width of the tire.

In this case, the outer portion 8b
It is also possible to position the radially outer end portion of the tire on the inner peripheral side of the belt 5, and in the tire in the mounting posture to the vehicle, the sidewall portion 2 facing the inside of the vehicle has the inside of the reinforcing layer 8. The respective radially outer ends of the portion 8a and the outer portion 8b are arranged at a radial position before reaching the belt 5, so that the reinforcing layer 8 of the inner sidewall portion 2 has a radially outer end height. Is preferably lower than the similar height of the reinforcing layer 8 of the outer side wall portion 2.

By the way, the cord constituting such a reinforcing layer 8 is preferably extended at an angle of approximately 0 to 50 degrees with respect to the radial direction at least in the sidewall portion 2 facing the outside of the vehicle. In the drawing, the angle is 30 degrees.

FIG. 2 is a cross-sectional view of a principal part showing another mode of disposing the reinforcing layer. In this figure, the radially outer end portion of the outer portion 8 b of the reinforcing layer 8 is located on the inner peripheral side of the belt 5. The radially outer end of the inner portion 8a is arranged at, for example, a substantially maximum width position of the tire, and the other points are substantially the same as those described above.

In the tire configured as described above, the deformation of the tire when a lateral deformation input is applied to the contact portion of the tire during cornering includes a lateral parallel deformation or displacement component and a tire axis. Considering that the camber deformation component is decomposed into a tilt component in a heavy plane, that is, a camber deformation component, a camber deformation component is relatively smaller than a lateral parallel displacement component under the action of the reinforcing layer 8. As a result, the camber deformation of the tire as a whole is effectively suppressed. This is because, for example, when the tread portion is regarded as a rigid ring, the rigidity against camber deformation is significantly increased by the reinforcing layer 8 as compared with the rigidity when the rigid ring is displaced in parallel in the lateral direction. is there.

Therefore, when the tire is actually turned, the lateral deformation of the non-contacting non-contact portion, in other words, the upper portion of the tire, is increased more than the lateral deformation at the contact portion where the restraint is large. The amount of lateral deformation of the upper part of the tire is greater than that of general radial tires, so the difference in lateral displacement between the upper part of the tire and the lower part of the tire (ground contact part) becomes smaller, resulting in tilting in the direction of increasing camber. By suppressing the deformation, the cornering force can be greatly improved as compared with a general radial tire.

By suppressing the camber deformation of the entire tire during cornering in this way, the difference between the contact length and the contact pressure described above with respect to the contact shape and contact pressure distribution of the tire can be substantially reduced to the suppression amount. In proportion to
The groundability can be greatly improved, and at the same time, the camber-thrust in the direction of reducing the cornering force can be directly reduced.

That is, in a general radial tire in which the lateral deformation of the anti-ground contact portion is extremely small, the shape of the ground contact surface at the time of cornering becomes substantially triangular due to the large camber deformation. Conventionally, since the contact pressure increases as the contact length increases and the contact pressure decreases as the contact length decreases in the inner part of the turn, conventionally, a belt that can limit the occurrence of such a contact form can be used. Although the main focus was on realizing the structure, this tire directly suppresses camber deformation itself, thereby drastically improving the contactability during turning and improving the tread. It is intended to more effectively reduce the difference between the contact length and the contact pressure in the contact surface as described above.

In a general radial tire, tilt deformation in the camber direction during cornering occurs.
In contrast to the behavior that tends to decrease the contact area as the contact shape curves into a triangle, this tire has a smaller decrease in the contact area in such a case, so the cornering force has a high nonlinearity with respect to the slip angle. A high cornering force can be provided even in a large slip angle region. Further, in this tire, by reducing the difference in the amount of lateral deformation between the contact portion and the non-contact portion, it is possible to reduce the amount of bending deformation of the belt in the contact surface. It is possible to suppress the occurrence of buckling of the belt on the entry side of the cornering force due to a decrease in the belt tension due to the deformation, and at the same time, it is possible to effectively contribute the belt to securing the cornering force in a large slip angle region.

In addition, the cornering power is increased by enabling the effective manifestation of the cornering force even in the linear region of a small slip angle based on the aforementioned reduction of the camber thrust in the direction of reducing the cornering force. In addition, the cornering force can be increased in a wide slip angle range, and at the same time, the tread shodder part's shoulder drop abrasion wear due to the tendency to equalize the ground pressure during ground contact based on the suppression of camber deformation. By relaxing the tire, a tire having high cornering force and cornering power and excellent durability can be realized.

Further, in this tire, the extension direction of the cord at the radially outer end portion of the reinforcing layer 8 of each side wall portion is changed in the traveling direction in the virtual deployment state of the tire in a mounting posture to the vehicle. In a plan view as shown in FIG. 3 in which the upper side is the upper side, it is preferable that both the left wheel tires rise rightward and the right wheel tires both rise leftward.

According to this, when viewed from the side of the tire, the reinforcing layer cord extends in the direction shown by the thin line in FIG. 4, so that the cord has high rigidity in the tensile direction of the cord and extremely high rigidity in the compressing direction. In consideration of the characteristic that the rigidity is reduced, the deformation of the driving direction due to the driving force is promoted in the sidewall portion outside the vehicle, while the driving direction deformation due to the driving force is suppressed in the sidewall portion inside the vehicle. It is clear that the stiffness of both sidewall portions is distributed in the direction. As a result, a torsional deformation around the vertical axis of the tire is generated such that the driving force increases the slip angle, and it is possible to prevent the cornering force from lowering during driving.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In a pneumatic radial tire for a passenger car having a size of 195 / 60R1588H, the basic configuration of the embodiment is as shown in FIG. 1, in which the inner end of the reinforcing layer is arranged on the inner peripheral side of the belt and the outer end is the outermost end of the tire. It was a significant position. On the other hand, in the comparative example, only the reinforcing layer of the example was changed, and each of the inner and outer ends of the reinforcing layer was set to be 1 mm away from the tire maximum width.
0 mm and 20 mm were arranged on the radially inner side of the tire.

The radial carcass consists of one ply of 1000 D / 2 polyester cord, and the belt is composed of two layers of 1 × 5 steel cord interlacing layers inclined at an angle of 22 ° with respect to the equator line, and 1260 D / 2. And a narrow spiral wound layer of the same cord.

Table 1 shows the cornering power, the cornering force, and the uneven wear (difference in the amount of wear between the center portion and the shoulder portion) in Comparative Examples and Examples.

The numerical values described here indicate that the above-mentioned tire is 6 J
The rim is filled with an air pressure of 2.4 kgf / cm ² , and then, under a mass condition of 392 kg, which is 70% of the specified maximum load capacity, using a flat belt type testing machine to which a safety walk is attached, the speed is 100 km. / H, the slip angle which is the difference between the traveling direction of the tire and the rotating surface is 0
The cornering power calculated from the difference between ° and 1 ° and the cornering force measured under the condition that the slip angle is 3 ° are each evaluated by index. In addition, the index value in the table is a control as a comparative example, the cornering force and the cornering power, as the index value is larger, conversely, for uneven wear, the smaller the index value shows better results .

[0036]

[Table 1]

[0037]

According to the present invention, in particular, the radially outer end portion of the reinforcing layer disposed from the bead portion to the sidewall portion is provided at least on the side of the sidewall portion facing the outside of the vehicle at the inner periphery of the belt. By suppressing the camber deformation of the tire as a whole, the cornering force and the cornering power can both be greatly increased, as is clear from the above embodiment, and the uneven wear resistance is also sufficient. Can be improved.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view of a main part showing another arrangement mode of a reinforcing layer.

FIG. 3 is an explanatory view showing an extending direction of a reinforcing layer cord.

FIG. 4 is a side view showing an extending direction of a reinforcing layer cord.

[Explanation of symbols]

 Reference Signs List 1 tread portion 2 sidewall portion 3 bead portion 3a bead core 4 radial carcass 4a, 4b carcass ply 5 belt 6a, 6b steel cord belt layer 7a wide spiral wound layer 7b narrow spiral wound layer 8 reinforcing layer 8a inner portion 8b outer part

Claims (4)

[Claims] 1. A tire comprising: a tread portion; a pair of sidewall portions extending radially inward from both side portions of the tread portion; and a bead portion connected to a radially inner end of each sidewall portion. A carcass extending in a toroidal shape between the bead cores disposed in the carcass and reinforcing the respective portions, a belt positioned on the outer peripheral side of the crown portion of the carcass to reinforce the tread portion, and a bead portion which is turned around the bead core and turned around the bead portion. And a reinforcing layer disposed over the portion of the belt, at least on the side of the sidewall facing the outside of the vehicle, the radially outer end portion of the reinforcing layer is attached to the tire in the mounting posture of the vehicle. A pneumatic radial tire located on the inner circumference side. 2. A radially outer end of a reinforcing layer of a sidewall portion facing inward of the vehicle of a tire in a posture of being mounted on the vehicle,
The pneumatic radial tire according to claim 1, wherein the pneumatic radial tire is located on an inner peripheral side of a radially outer end of the reinforcing layer of the sidewall portion facing the outside of the vehicle. 3. The pneumatic radial tire according to claim 1, wherein an extension angle of a cord forming a reinforcement layer of a sidewall portion facing the outside of the vehicle with respect to a radial direction is substantially in a range of 0 to 50 degrees. . 4. A plan view in which the extending direction of the cord at the outer end portion in the radial direction of the reinforcing layer of each sidewall portion is a virtual deployment state of the tire mounted on the vehicle, and the traveling direction is upward in a plan view. The right wheel tires and the right wheel tires both rise to the right, and the right wheel tires both rise to the left.
A pneumatic radial tire according to any one of claims 1 to 3.