JPH09142104A - Pneumatic tire for passenger car - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve separation resistance and ply-steering between belt layers by making belt cords right-and-left asymmetrical in the peripheral direction of a tire and specifying the orientation angle of the second outside belt layer cord to the peripheral direction of the tire and the crossing angle of the first inside belt layer cord to belt cords. SOLUTION: In a pneumatic tire, a belt cord (w) arranged in the first inside belt layer 8A is right-and-left asymmetric with a belt cord (w) arranged in the second outside belt layer 8B in the peripheral direction T of the tire. The orientation angle α of the belt cord (w) in the second belt layer 8B to the peripheral direction T of the tire is 15-25 deg.. The crossing angle β of the belt cord (w) in the second belt layer 8B to the belt cord (w) in the first belt layer 8A across the peripheral direction of the tire is set 53-57 deg.. The orientation angle θof the belt cord (w) in the first belt layer 8A to the peripheral direction T of the tire is 28-42 deg. in right-and-left asymmetry.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire for use in passenger cars, and more particularly to a pneumatic tire for passenger cars in which separation resistance between a plysteer and a belt layer is improved without deteriorating road noise. Containing tires.

[0002]

2. Description of the Related Art Structural properties of a belt layer are extremely important for tire performance. The belt layer is a band plate laminated with a relatively small bias angle, and its structure is composed of a unidirectional fiber reinforced rubber layer. In such a belt layer, considering the state of tension along the tire circumferential direction,
In addition to elongation in the tire circumferential direction and contraction in the tire width direction, shear strain occurs. Such a phenomenon is called inner coupling.
Coupling shear deformation due to tension in the tire circumferential direction
The inclination angle of the belt cord with respect to the tire circumferential direction is 0 °,
It is known that it disappears at 54.7 ° in addition to 90 °.
It is also known that in order to prevent shear deformation between the laminated belt layers, the intersecting angle of the intersecting belt cords should be close to 54.7 ° which is called a singular angle.

By the way, conventionally, a pneumatic tire used for a passenger car is generally provided with two belt layers. The belt cord has an orientation angle with respect to the tire circumferential direction in order to secure rigidity of a tread portion. They are arranged at a low angle and are arranged symmetrically. Therefore, since the crossing angle of the belt cords is much smaller than the singular angle, there is a problem that shear stress is generated between the belt layers and separation between the belt layers is easily caused.

Therefore, as a solution to the above problem, there has been proposed a pneumatic tire for a passenger vehicle in which the orientation angle of the belt cord is increased so that the intersection angle approaches a singular angle.
However, when the orientation angle is increased in this way, the separation between the belt layers can be suppressed, but the secondary resonance frequency of the cross section becomes low due to the decrease in the rigidity of the tread portion. Resonance phenomenon that matches the natural frequency of the tire occurs,
There was a problem that the road noise around 300 Hz deteriorates.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a pneumatic tire for a passenger vehicle capable of improving separation resistance between belt layers and price tear without deterioration of road noise. is there.

[0006]

In the pneumatic tire for passenger cars of the present invention which achieves the above object, two belt layers, in which belt cords are respectively arranged, are embedded in a tread portion outside a carcass having a reinforcing cord, and In a pneumatic tire for passenger cars in which the two belt layers are arranged so that the belt cords intersect each other, the belt layers are arranged so that the belt cords of the belt layers are asymmetrical with respect to the tire circumferential direction. In addition, the orientation angle of the belt cord of the outer second belt layer with respect to the tire circumferential direction is 15 to 25
And the crossing angle of the belt cord of the inner 1st belt layer with respect to the belt cord of the 2nd belt layer is 5
It is characterized in that it is set to 3 to 57 °.

In this way, the belt cords of the two belt layers are arranged so as to be asymmetric with respect to the tire circumferential direction, and the belt cords of the first belt layer and the second belt layer are crossed within the above angle range. Therefore, the intersection angle is set to a singular angle (54.7) at which shear deformation does not occur between the belt layers.
), The shear stress generated between the belt layers can be suppressed and the separation resistance between the belt layers can be improved, while the orientation angle of the belt cord of the outer second belt layer can be adjusted to the above-mentioned value. By lowering the tire circumferential direction as described above, it is possible to suppress the amount of deflection of the entire belt in the second belt layer as in the conventional case, thereby ensuring the rigidity of the tread portion. It becomes possible. Therefore, it is possible to prevent the road noise near 300 Hz from being deteriorated due to the decrease in the rigidity of the tread portion. Further, since the crossing angle of the belt cord is close to the peculiar angle (54.7 °), it is possible to reduce the price tear caused by the shear deformation.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The configuration of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows an example of a pneumatic tire for passenger cars according to the present invention, where 1 is a tread portion, 2 is a bead portion, and 3 is a sidewall portion. Left and right sidewall portions 3 are connected to the left and right bead portions 2 and extend toward the tire outer diameter side.
A tread portion 1 extending in the tire circumferential direction is provided therebetween.

A carcass 4 having a reinforcing cord f is provided inside the tire in a single layer, and both ends 4a of the carcass 4 are surrounded by an annular bead core 5 embedded in the left and right bead portions 2 from the inside of the tire. The edge end 4b is folded back to the outside and extends so as to extend beyond the outer peripheral end 6a of the bead filler 6 arranged on the outer periphery of the bead core 5. In the tread portion 1 on the outer peripheral side of the carcass 4, two belt layers 8 in which belt cords w are arrayed are embedded so that the belt cords w intersect with their orientation directions in opposite directions.

According to the present invention, in the pneumatic tire for passenger cars having the above-mentioned structure, the belt cord w arranged on the inner first belt layer 8A and the belt arranged on the outer second belt layer 8B. The cord w and the cord w are asymmetric with respect to the tire circumferential direction T. The inventors of the present invention overturned the conventional wisdom that the conventional bilateral symmetry is used for the purpose of enjoying good productivity, and even if the belt cords in the two-layered belt layers are left-right asymmetrical, the same level as the conventional one is obtained. It turns out that it is possible to secure good uniformity.

The orientation angle α of the belt cord w of the No. 2 belt layer 8B with respect to the tire circumferential direction T is in the range of 15 to 25 °, and the belt cord w of the No. 2 belt layer 8B.
The intersection angle β with the belt cord w of the first belt layer 8A sandwiching the tire circumferential direction with respect to is set to 53 to 57 °,
The orientation angle θ of the belt cord w of the first belt layer 8A with respect to the tire circumferential direction T is in the range of 28 to 42 °, which is a left-right asymmetric structure.

As described above, according to the present invention, the belt cords w of the two belt layers 8 inclined and oriented with respect to the tire circumferential direction are left-right asymmetrical, and the first belt layer 8A and the second belt layer 8B are formed. By setting the crossing angle β of the belt cord w as described above, the crossing angle can be brought close to a singular angle (54.7 °) at which shear deformation does not occur between the layers, so that the shear stress generated between the belt layers. Of the belt cord w of the outer second belt layer 8B while setting the lowering angle in the tire circumferential direction as described above. As a result, the outer second belt layer 8B can suppress the amount of flexure of the entire belt in the same manner as in the case where the conventional belt is lowered, so that the rigidity of the tread portion can be ensured. , It is possible to avoid the road noise deterioration around 300Hz due to the decrease in the tread portion stiffness. Moreover, by making the belt cords w asymmetrical to each other, the price tear which affects the straightness of the vehicle can be reduced.

If the orientation angle α is smaller than 15 °, the belt cord w rises too much, so that the rigidity of the tread portion 1 becomes too high and the riding comfort deteriorates. If the angle is larger than 25 °, the rigidity of the tread portion 1 becomes low, and the road noise deteriorates. Even if the crossing angle β is less than 53 ° or more than 57 °, the effect of improving the separation resistance between the belt layers cannot be obtained.

In the above embodiment, in the case of the radial tire in which the reinforcing cords f of the carcass 4 are arranged in the tire radial direction orthogonal to the tire circumferential direction T, the orientation angle α is set to 18 to 22 °. As a result, in addition to the above effect, the intersection angle γ between the belt cord w of the first belt layer 8A and the reinforcing cord f of the carcass 4 can be brought close to a peculiar angle at which shear deformation does not occur between the layers. It is possible to reduce the price tear.

FIG. 3 shows another example of the pneumatic tire for passenger cars of the present invention. In the above-described embodiment, further, in the carcass 4, the reinforcing cord f is composed of a fiber cord in which a plurality of organic fibers (monofilaments) are twisted together, and the twist number T and the total denier of the fiber cord are Regarding the relationship with Dc, the twisting coefficient K represented by K = T (Dc) ^1/2 is set in the range of 1000 to 2000, and the twisting number T is made smaller than before. The elongation of the fiber cord under a load of 2.25 g / d is 6% or less.

Further, the carcass both end portions 4a folded back beyond the bead filler outer peripheral end 6a have their edge ends 4b the same as the outer peripheral end 6a of the bead filler 6 or on the tire inner diameter side thereof, and the outer peripheral end of the bead filler 6 is 6a and inner peripheral edge 6
It has a so-called low turn-up structure, which is located between b and b. Therefore, in this embodiment, in addition to the above effects, in the fiber cord of the carcass 4 formed by twisting the organic fibers, the relationship between the twist number T (turns / 10 cm) and the total denier number Dc of the fiber cord is The twist coefficient K represented is set to 1000 to 2000, the twist number is lowered, and the elongation under a load of 2.25 g / d is set to 6% or less, thereby increasing the rigidity of the carcass 4 and increasing the tread portion. Since the rigidity of No. 1 can be increased, the road noise near 300 Hz can be improved.

Further, since the number of twists of the fiber cord used for the reinforcing cord f of the carcass 4 is reduced, the cord diameter becomes smaller than before, and the amount of the organic fiber constituting the fiber cord is reduced accordingly. As a result, the weight of the tire can be reduced. Further, by making the carcass 4 have a low turn-up structure, the length of the carcass both ends 4a can be shortened, which can further contribute to the weight reduction of the tire. When both ends 4a are in contact with the carcass 4 when the carcass 4 is pulled, as shown in FIG. 1, since the carcass 4 abuts and does not contact the carcass 4 extending to the sidewall portion 3. In addition, since it is possible to avoid the shear stress generated between the two, it is possible to prevent the separation of the carcass from occurring, and at the same time, it is possible to prevent the separation of the carcass.
It is also possible to improve the road noise near 100 Hz by lowering the rigidity.

If the twist coefficient K of the fiber cord in the carcass 4 is less than 1000, the fatigue resistance of the fiber cord is deteriorated and the tire durability is lowered. Twisting factor K is 2
If it exceeds 000, the number of twists increases and the carcass rigidity decreases, and the road noise near 300 Hz deteriorates.
It is preferable to set the twist coefficient K in the range of 1300 to 1700.

If the elongation of the fiber cord under a load of 2.25 g / d exceeds 6%, the elongation becomes too large and the steering stability deteriorates. The lower limit of the elongation under the load of 2.25 g / d is 3.0% or more, because if the elongation is too low, the fatigue resistance decreases. The upper limit is preferably 5% or less. The total denier number Dc of the fiber cord is preferably in the range of 2000 to 3000d. When it is less than 2000 d, the number of cords to be driven into the cord is too large to increase the carcass rigidity, and the productivity is deteriorated. On the other hand, when it exceeds 3000 d, the cord becomes too thick, the carcass layer thickness increases, and the tire weight increases.

The organic fiber used in the fiber cord is not particularly limited as long as it is conventionally known, and for example, at least polyethylene terephthalate fiber, polyethylene-4.6-naphthalate fiber, or both of them are twisted together. Those composed of one can be preferably used. The belt cord w of the belt layer 8 is composed of a wire composed of three or less wires, and the area weight ratio Mw of the wire is 6.6 × 10 ⁻⁶ kg / mm ² or less, and each belt layer using the same. The flexural rigidity Dw of 8 should be 220 kg · mm or more. Preferably, this makes it possible to reduce the amount of use of the belt cord w while ensuring the belt rigidity, and further reduce the weight. However, the area weight ratio Mw and the bending rigidity Dw are defined by the following equations.

[0021]

(Equation 1)

In the equation, Si is the cross-sectional area of one strand.
(mm ² ), γi is the specific gravity of one wire (kg / mm ³ ), Ei is the wire 1
Elastic modulus (kg / mm ² ), n is the number of strands per wire, END is the number of wires per unit width (50 mm), Ii
The around an axis extending through the belt layer thickness direction center of gravity of the strand, (in the case of circular cross-section, Ii = πd ^4/64: where, d is the diameter) single second moment strands is.

The area weight ratio Mw is 6.6 × 10 ^-6 kg / m
When it exceeds m ² , it becomes difficult to reduce the weight of the belt layer. The lower limit of the area weight ratio Mw can be appropriately selected within a conventionally known range, and is preferably 3.0 × 10 ⁻⁶ kg / mm ² or more from the viewpoint of durability. If the bending rigidity Dw is less than 220 kg · mm, it becomes difficult to secure the belt rigidity. The upper limit of the bending rigidity Dw can be appropriately selected within a known range as in the conventional case, but is preferably 1 from the viewpoint of riding comfort.
It is recommended to set it to 500 kg · mm or less.

If the number of strands of the above wire exceeds 3,
Since the number of twists increases, the elastic modulus Et of one wire decreases. A single wire is preferable, and a steel wire can be preferably used as the wire. FIG. 4 shows still another example of the pneumatic tire for passenger cars of the present invention. In the embodiment of FIG. 1 described above, further, the both end portions 8a of the first belt layer 8A are folded back to the outside of the tire, and the both end portions 8b of the second belt layer 8B are wrapped between the first belt layers 8A. It has a structure.

Further, the belt cord w of the belt layer 8
Is composed of a wire composed of three or less wires, preferably a single wire as described above, and the area weight ratio Mw of the wire is 6.6 × 10 ⁻⁶ kg / mm ² or less. The flexural rigidity Dw of the belt layer 8 is 220 kg · mm or more. Thereby, in addition to the effect in the embodiment of FIG. 1 described above, the edge portions 8b ′ of the both end portions 8b of the second belt layer 8B are covered with the both end portions 8a of the first belt layer 8A, so that the belt layer The peak value of shear stress can be reduced to further improve the separation resistance between the belt layers, and since the first belt layer 8A is folded back, the rigidity of the belt layer 8 is increased and the road noise near 300 Hz is increased. Can be improved.

Further, although the belt volume is increased by the amount of folding back the first belt layer 8A, the belt cord w has been reduced in weight.
Is used for the belt layer, the belt weight does not increase. FIG. 5 shows still another example of the pneumatic tire for passenger cars of the present invention. In the embodiment of FIG. 4 described above, the carcass 4 has the low turn-up structure described above. This makes it possible to reduce the weight of the tire, prevent separation of the carcass from occurring, and improve road noise near 100 Hz.

Further, in the embodiment of FIG. 3 described above,
Both ends 8a of the first belt layer 8A may be folded back so as to wrap both ends 8b of the second belt layer 8B, thereby further improving the separation resistance between the belt layers and reducing the road noise near 300 Hz. Can be improved. In the present invention, the belt cord w used in the belt layer 8 may be any conventionally known belt cord, and is not particularly limited. For example, a steel cord can be preferably used. Further, in the above-described embodiment, the example in which the carcass 4 is provided in one layer is shown, but two layers may be provided.

[0028]

EXAMPLE A tire of the present invention in which the tire size is 185 / 70R14 in common, and the belt cord of the belt layer is asymmetrical in the tire configuration of FIG. 1, the conventional tire 1 in which the orientation angle of the belt cord is low, and the belt A conventional tire 2 having a higher cord orientation angle was manufactured. The orientation angle of the belt cord of the belt layer is as shown in Table 1.

Each of these test tires was subjected to an evaluation test of separation resistance, noise performance, and plysteer performance of the belt layer under the following measurement conditions, and the results shown in Table 1 were obtained. Separation resistance Attach each test tire to a rim of rim size 14 x 5J,
The tire was mounted on a drum tester with an air pressure of 200 kPa, a load of 440 kgf was applied, the running speed was increased, and the speed at which the belt layer generated separation was measured. The value was evaluated. The larger this value, the better the separation resistance of the belt layer. Noise performance A sound pressure level of around 300 Hz was measured with a microphone mounted on the driver's seat window side while traveling on a paved road surface at a speed of 60 km / h, and evaluated using Conventional Tire 1 as a reference (0). The smaller the value (-), the lower the sound pressure level and the better the noise performance (road noise). Price Tear Attach each test tire to the rim of rim size 14 × 5J,
According to JASOC607, the tire was attached to a uniformity measurement tester, and the result of measuring the price tear thereof was evaluated by an index value with the conventional tire 1 being 100. The smaller this value, the better the price tear.

[0030]

[Table 1]

As is apparent from Table 1, the tire of the present invention can reduce the price tear and improve the separation resistance between the belt layers without deteriorating the road noise. Further, FIG. 6 shows the relationship between the orientation angle of the belt cord of the No. 2 belt layer with respect to the tire circumferential direction and the belt rigidity (the intersection angle of the No. 1 and No. 2 belt cords is 55
(Fixed to °), and a graph showing the relationship between the crossing angle of the belt cord of the inner 1st belt layer with respect to the belt cord of the 2nd belt layer and the belt interlaminar shear stress which is an index of the separation resistance between the belt layers. Show. From FIG. 6A, the orientation angle of the belt cord of the second belt layer with respect to the tire circumferential direction is 15 to 25 °, and from FIG. 6B, the intersection angle of the belt cord of the first belt layer is 53 to 57 ° ( It can be seen that the interlayer shear stress approaches 0 and the belt durability is good).

Further, in the tire of the present invention manufactured by using the constitution as shown in Table 2 and the conventional tire (the same structure as the conventional tire 1), the separation resistance and the noise performance of the belt layer were measured under the above-mentioned measurement conditions. , And plysteer performance evaluation tests were performed, and the results shown in Table 3 were obtained.

[0033]

[Table 2]

[0034]

[Table 3]

From Table 3, in addition to the tire of the present invention in which the orientation angle of the belt cord is regulated, other structural requirements, that is, the low turn-up structure of the carcass, the low twist carcass structure in which the number of twists of the carcass is reduced, and the belt cord are shown. Even in the tire of the present invention in which the belt layer structure in which the area weight ratio (wire) and the bending rigidity are specified to reduce the weight, and the belt layer folded structure in which the belt end portion is folded are combined, the belt noise is improved while the road noise is improved. It can be seen that it is possible to improve the separation resistance and the price tear of.

[0036]

As described above, according to the present invention, two belt layers each having belt cords arranged therein are embedded in the tread portion on the outside of the carcass having the reinforcing cords, and the two belt layers are formed by the belt cords. In a pneumatic tire for a passenger vehicle arranged so as to intersect with each other, the belt layers are arranged so that the belt cords of the belt layer are laterally asymmetric with respect to the tire circumferential direction, and the belt cord of the outer second belt layer The orientation angle of the tire with respect to the tire circumferential direction is 15
Since the crossing angle of the belt cord of the inner first belt layer with respect to the belt cord of the second belt layer is set to 53 to 57 ° within a range of up to 25 °, uniformity is improved without deteriorating road noise. It is possible to improve the separation resistance between the belt layers while maintaining the good condition.

[Brief description of the drawings]

FIG. 1 is a meridian half cross-sectional view showing an example of a pneumatic tire for passenger cars of the present invention.

FIG. 2 is an explanatory view of a main part of development of a carcass and a belt layer of FIG.

FIG. 3 is a meridian half cross-sectional view showing another example of the pneumatic tire for passenger cars of the present invention.

FIG. 4 is a meridian half cross-sectional view showing still another example of the pneumatic tire for passenger cars of the present invention.

FIG. 5 is a meridian half cross-sectional view showing still another example of the pneumatic tire for passenger cars of the present invention.

FIG. 6A is a graph showing the relationship between the orientation angle of the belt cord of the No. 2 belt layer with respect to the tire circumferential direction and the tread rigidity, and FIG. It is a graph which shows the relationship between the crossing angle of the belt cord of the number belt layer, and the shear stress between belt layers.

[Explanation of symbols]

1 Tread Part 2 Bead Part 3 Sidewall Part 4 Carcass 4a Carcass Both Ends 4b Edge Edge 5 Bead Core 6 Bead Filler 6a Outer Edge 8 Belt Layer 8A No. 1 Belt Layer 8a No. 1 Belt Layer Both Ends 8B No. 2 Belt Layer 8b 2 Ends of the number belt layer T Tire circumferential direction f Reinforcement cord w Belt cord

Claims (7)

[Claims] 1. A passenger car in which two belt layers each having belt cords arranged therein are embedded in a tread portion on the outside of a carcass having a reinforcing cord, and the two belt layers are arranged so that the belt cords cross each other. In the pneumatic tire for use, the belt layer is arranged such that the belt cord of the belt layer is asymmetrical with respect to the tire circumferential direction, and the orientation angle of the belt cord of the outer second belt layer with respect to the tire circumferential direction is set. A pneumatic tire for passenger cars, wherein the crossing angle of the belt cord of the inner first belt layer with respect to the belt cord of the second belt layer is set in the range of 15 to 25 ° and 53 to 57 °. 2. The pneumatic vehicle for passenger cars according to claim 1, wherein the reinforcing cords of the carcass are arranged in a direction orthogonal to the tire circumferential direction, and the orientation angle of the belt cords of the No. 2 belt layer is set to 18 to 22 °. tire. 3. The carcass reinforcing cord is composed of a fiber cord in which organic fibers are twisted together, and in the relation between the twist number T and the total denier number Dc of the fiber cord, K = T (Dc) ^{1 / The} twisting coefficient K represented by ² is 10
It was set in the range of 00 to 2000, the elongation of the fiber cord under a load of 2.25 g / d was 6% or less, and both ends of the carcass were folded back from the inside of the tire to the outside through a bead core, and were folded back. The pneumatic tire for passenger cars according to claim 1 or 2, wherein the edge ends of both end portions are made to be the same as the outer peripheral end of the bead filler arranged on the outer periphery of the bead core or on the tire inner diameter side than that. 4. The belt cord of the belt layer is composed of a wire composed of three or less wires, and the area weight ratio Mw of the wire is 6.6 × 10 ⁻⁶ kg / mm ² or less,
The pneumatic tire for passenger cars according to claim 3, wherein the flexural rigidity Dw of the belt layer is 220 kg · mm or more. 5. The pneumatic tire for passenger cars according to claim 3, wherein both ends of the first belt layer are folded back to wrap both ends of the second belt layer with the first belt layer. 6. The belt cord of the belt layer is composed of a wire composed of three or less wires, and the area weight ratio Mw of the wire is 6.6 × 10 ⁻⁶ kg / mm ² or less, and the belt layer Flexural rigidity Dw of 220 kg · mm or more, both ends of the No. 1 belt layer are folded back, and both ends of the No. 2 belt layer are wrapped with the No. 1 belt layer.
Alternatively, the pneumatic tire for a passenger car according to item 2. 7. Both ends of the carcass are folded back from the inside of the tire through a bead core, and edge ends of the folded back ends are the same as or equal to the outer peripheral end of a bead filler arranged on the outer periphery of the bead core. The pneumatic tire for passenger cars according to claim 6, wherein the pneumatic tire is located on the inner side of the tire.