JPS592904A - Pneumatic tyre - Google Patents

Abstract

PURPOSE:To contrive to improve the straight running property and durability at high speed running by a structure wherein carcass cord layers are laminated in two layers or an upper and a lower layers and the reinforcement cords of the respective layers are arranged so as to make the mean value of and difference between the respective angles of said reinforcement cords toward the peripheral direction of the tyre specified angles. CONSTITUTION:If the mean value beta of the angle alpha1 of the reinforcement cord of a lower carcass cord layer 4d and the angle alpha2 of the reinforcement cord of a upper carcass cord layer 4u is smaller than 96 deg., plys-tear is not made better than its conventional level, while if the value beta is larger than 108 deg., the plys-tear is improved further, however the drive comfortability and load durability get worse than ever. If the difference alpha2-alpha1 between the angles alpha2 and alpha1 is smaller than 10 deg. even under the condition that the value beta lies in the range of 96-108 deg., the plys-tear does not be improved as compared with the conventional plys-tear, while, if alpha2-alpha1 is larger than 40 deg., the plys-tear is improved, however the load durability gets worse than ever. Consequently, the difference alpha2-alpha1 must lie in the range of 10-40 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire that has a belt structure in which both sides of one belt reinforcing layer are wrapped with the other belt reinforcing layer to improve high-speed durability. This invention relates to a pneumatic tire that reduces noticeable plysteer and improves straight running performance.

Conventional radial tires for passenger cars generally have a structure in which a belt reinforcing layer consisting of at least two layers is interposed approximately parallel to the circumferential direction of the tire between the tread and the carcass cord layer. The reinforcing cord of the belt reinforcing layer is oriented at 15° to 30° with respect to the tire circumferential direction, and the reinforcing cord of the other layer is oriented at 150° to 165° with respect to the tire circumferential direction.
The two belt reinforcing layers are arranged so that both sides of the upper belt reinforcing layer are wrapped around the lower belt reinforcing layer, especially for the purpose of improving high-speed durability. On the other hand, the carcass cord layer is composed of one or two layers, and the cords of each layer are arranged at approximately 90 degrees with respect to the tire circumferential direction.
It has become a reality.

Compared to bias tires, this type of radial tire has
The effects of the belt reinforcing layer provide excellent braking performance, fuel efficiency, wear resistance, etc., but on the other hand, there is a problem in that straight running performance is poor due to the belt reinforcing layer.

This is especially noticeable in radial tires in which, as mentioned above, a belt is arranged between the tread and the carcass cord layer, with the belt having a structure in which both sides of the upper belt reinforcing layer are wrapped around the lower belt reinforcing layer. Therefore, the straight-line stability was poor not only during normal driving, but especially when driving at high speeds.

In other words, when a radial tire rotates, a lateral force is generated in either the left or right direction with respect to the direction of travel, even if the slip angle is zero, and this lateral force causes the vehicle to move in a direction different from the direction intended by the driver. There are cases where this progresses.

In general, the lateral force at a slip angle of zero consists of force components generated by two different mechanisms, one of which is called conicity (CT), and the other is Bligh, steer, (PS). It is classified as part of the tire's unique characteristics. On the other hand, the uniform test method for automobile tires (JASOC6
According to 07), when the average value of lateral force when the tire rotates once is LFD, LFDw measured on the front side of the tire, LFD measured on the back side after replacing the tire, and the above-mentioned conicity CT, price. By definition, the tare PS has a relationship expressed by the following equation.

LFD, = PS + CT...
・・・・・・・・・・・・(1) LFD8= PS −
CT・・・・・・・・・・・・(2)
(+), PS and CT are calculated from equation (2) as follows.

PS-□ ・・・・・・・・・・・・(4) The relationships in (1), (2), (3), and (4) above can be expressed as shown in Figure 1. .

By the way, among the above-mentioned conicity and plystea,
Conicity is considered to be a geometrically asymmetric tire shape with respect to the circumferential center of the tire, that is, a force generated when a tire shaped like a truncated cone 7 rolls. Since this cause is primarily influenced by the position of the belt reinforcing layer inserted into the tire tread, this can be reduced by manufacturing improvements. On the other hand, plysteer is an inherent force caused by the structure of the belt reinforcing layer, and it has been virtually difficult to reduce it significantly unless the structure of the belt reinforcing layer itself is changed.

Now, if we take the belt reinforcing layer and consider it, we can see the result in Figure 2 (
As shown in 4), both sides of the lower belt reinforcing layer 50d are bent to wrap around the upper belt reinforcing layer 50u2.
It can be represented as a layer laminate 50. When a tensile force is applied to this two-layer laminate 50 in the tire circumferential direction EE', the two-layer laminate 50 deforms not only within the two-dimensional plane on which the tension acts, but also three-dimensionally out of the plane. It is well known that this process causes twisting deformation as shown in FIG. 2(B). The above-mentioned plysteer occurs due to such torsional deformation of the belt reinforcing layer.

Compared to a normal belt structure in which two layers are laminated, the belt structure in which the inner side of the upper belt reinforcing layer is wrapped with the lower belt reinforcing layer has a particularly large torsional deformation in this □.

Conventionally, various studies have been made to reduce this plysteer by adding a new belt reinforcing layer to the belt reinforcing layer, but adding a new belt reinforcing layer in this way is This could not be said to be very desirable as it would impair characteristics such as fuel efficiency.

The purpose of the present invention is to solve the above-mentioned problems of conventional radial tires, and reduce plysteer by devising the arrangement of the cords that go down to the carcass cord layer without adding another belt reinforcing layer. An object of the present invention is to provide a pneumatic tire that has improved straight running performance and has further improved high-speed durability than conventional radial tires.

The pneumatic tire of the present invention that achieves the above object has an upper belt reinforcing layer in which the reinforcing cord has an angle of 150° to 165° with respect to the tire circumferential direction, and an upper belt reinforcing layer having an angle of 15° to 30° with respect to the tire circumferential direction. °The lower belt reinforcement layer is
A pneumatic tire in which the bent portions of the lower belt reinforcing layer, both sides of which are bent toward the tread side, are stacked so as to wrap both sides of the upper belt reinforcing layer, wherein the carcass cord layer is stacked in two layers, an upper and a lower layer. At the same time, the angle of the reinforcing cords constituting each carcass cord layer with respect to the tire circumferential direction was measured from the side where the angle of the reinforcing cord of the belt reinforcing layer on the side in contact with the carcass cord layer with respect to the tire circumferential direction was an acute angle. Sometimes, the average value i (α1+α2) of the angle α2 of the reinforcing cord of the carcass cord layer on the side in contact with the belt reinforcing layer and the angle α of the reinforcing cord of the carcass cord layer below it is 96° to 10°.
8°, and the difference (α2-α1) is 10° to 40°
It is characterized by being arranged so that.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below with reference to embodiments shown in the drawings.

FIG. 4 is a half-sectional perspective view of a pneumatic tire according to the present invention, and FIG. 5 is a developed plan view of a belt reinforcing layer and a carcass cord layer in the same pneumatic tire.

In FIGS. 4 and 5, 1 is a tread, 2 is a side wall provided to extend on both sides of the tread 1, and 3 is a bead wire embedded in the lower end of the side wall along the circumferential direction. be. A carcass cord layer 4 is provided so as to wrap around the bead wires 3 at both ends and run along the inner surfaces of the sidewall 2 and tread 1. Furthermore, a steel cord is provided between the carcass cord layer 4 and the tread 1. A belt reinforcing layer 5 consisting of the following is provided.

The carcass cord layer 4 has a two-layer laminated structure of an upper carcass hood layer 4u and a lower carcass cord layer 4d, and the belt reinforcing layer 5 also has an upper belt reinforcing layer 5u.
It has a two-layer laminated structure consisting of a lower belt reinforcing layer 5d and a lower belt reinforcing layer 5d.

(The upper bell of the two layers constituting the belt reinforcing layer 5)
Reinforcement Fit 5u is the tire circumferential direction EE of the reinforcement cord.
The angle θ2 with respect to the tire circumferential direction EE' is 150° to 165°, and the angle θ of the reinforcing cord of the lower belt reinforcing layer 5d with respect to the tire circumferential direction EE' is 15° to 30°, and both sides thereof are 150° to 165°. It is bent toward the tread side, and the bent portion is arranged so as to wrap both sides of the upper belt reinforcing layer 5u. In order to improve high-speed durability, the bending width t of this lower belt reinforcing layer 5d is set to t/L≧0.1 with respect to the total width of the belt reinforcing layer 5.
5, the upper belt reinforcing layer 5u has a width of tu.
It is folded so as to enclose it.

In this embodiment, the above-mentioned belt reinforcing layer 5 is made of steel cord for both the upper and lower layers 5u and Sd. A belt reinforcing layer made of aromatic boria J-mid fiber cord known as "Kevlar" is used, or both layers are belt reinforcing layers of textile cord such as aromatic boria I-mid fiber cord. Of course, you can use what is provided.

Also, the cord of each carcass cord layer is nylon.

It is composed of rayon, polyester, aromatic polyamide fiber cords, etc.

The angle of the cords constituting the carcass cord layer 4 with respect to the tire circumferential direction is an important configuration for reducing pliestear, and must be arranged so as to satisfy the following conditions.

That is, in both the upper and lower carcass cord layers 4u and 4d of the carcass cord layer 4, the angles of the cords with respect to the tire circumferential direction are the same as those of the lower carcass cord layer 4 located on the side of the belt reinforcing layer that is in contact with the carcass cord layer 4. Measurement shall be made from the side where the reinforcing cord of the side belt reinforcing layer 5d is at an acute angle with respect to the tire circumferential direction, and the angle α of the reinforcing cord of the lower carcass cord layer 4d and that of the upper carcass cord layer 4u shall be measured. The average value β−i(α
, +α2) must be within the range of 96° to 108°, and the difference in surface angle (α2−α1) must be within the range of 10° to 40°. Angle α1.
α2 is measured from the side where the reinforcing cords of the lower belt reinforcing layer 5d, which are in contact with the carcass cord layer 4, are at an acute angle with respect to the tire circumferential direction EE'. If the reinforcing cords of the belt reinforcing layer 5d are arranged downward to the left, measurements must be made clockwise with respect to the tire circumferential direction EE'.

The angle α1 mentioned above. As is clear from the relationship α2, the angle α2 of the reinforcing cord of the upper carcass cord layer 4u
is the angle α1 of the reinforcing cord of the lower carcass cord layer 4d
They are arranged so that they are always larger than , and they are also placed in a relationship that intersects with each other. The angle α1 mentioned above. When the average value β of α2 is smaller than 96°, plysteer is not improved from the level of conventional radial tires, and when it is larger than 108°, plysteer is further improved, but ride comfort is Also, the load durability is inferior to that of conventional radial tires, which is undesirable. Also, even if the angle α1. Average value β of α2 is 96° to 108°
Even if it is within the range of , the difference (α2−αl)
must be in the range of 100 to 4o0, and the difference (
When α2-α,) becomes smaller than 100, no improvement is seen compared to the conventional radial tire of plysteer. Moreover, if the difference (α2−α1) is larger than 40°, plysteer is improved, but the load durability becomes inferior, which is not preferable.

Further details will be explained below using specific experimental examples.

Experimental Example 1 The belt reinforcing layer and carcass cord layer had the structures shown in FIGS. 4 and 5, and the angle difference (α2−α1) between the cords of the upper and lower carcass cord layers was kept constant at 30°. Various pneumatic tires with different average angle values β were manufactured. The angles of the cords in the upper and lower layers of the belt reinforcing layer with respect to the tire circumferential direction are 20° and 160°, respectively.
The total width of the belt reinforcing layer was 140 mm, the width t of each bend on both sides of the lower belt reinforcing layer was 45 wn, and the width tu of the upper belt reinforcing layer was 120 van. Tire size is 1
95/70HR14, rim 5 V'2- JJ X 1
It was set as 4.

As a result of measuring the plysteer PS of these pneumatic tires based on the uniformity test method for automobile tires JASOC607, the results shown in FIG. 7 were obtained.

In Fig. 7, the plotted with an asterisk ★ is α, = α2 = 90°, as shown in Fig. 3, and the belt structure has reinforcing cord angles of 20° and 160° with respect to the tire circumferential direction. °
By folding the two belt reinforcing layers that intersect with each other at the bending part of the lower belt reinforcing layer, which has both sides bent toward the tread side,
It has a structure in which the upper belt reinforcing layer is laminated so as to wrap around both sides, and the total width of the belt reinforcing layer is 140 mm, and the bending width t on both sides of the lower belt reinforcing layer is 451++++1.
This is a conventional radial tire in which the width 1u of the upper belt reinforcing layer is 120 mm. As is clear from this figure, the average angle value β of the cords in the carcass cord layer is 96
It can be seen that the pliesteer PS of the tires over 10°C is smaller than that of conventional radial tires.

That is, it can be seen that the straight running performance has been improved.

Experimental Example 2 The belt reinforcing layer and carcass cord layer have the structures shown in FIGS. - False) We manufactured various pneumatic tires with different values. The specifications of the belt reinforcing layer are the same as in Experimental Example 1 described above.

Tire size is 195/70 HR14, rim 51/2
-JJ×14. Regarding these pneumatic tires,
Uniformity test method for automobile tires with z JASO
As a result of measuring plysteer PS based on C607,
The results shown in Figure 8 were obtained.

In Fig. 8, the plotted with an asterisk ★ is based on a conventional radial tire where α, = α2 = 90° as shown in Fig. 3, and the belt structure is the same as in Experimental Example 1 described above. . As is clear from this figure, when the cord angle difference (α2-α,) of the carcass cord layer is 10 degrees or more, plysteer is smaller than that of conventional radial tires, and straight-line running performance is improved. I understand.

In addition, when testing the straight-line running performance of an actual vehicle at high speed, the tire of the present invention achieved (100 to 160 Jan/h?
) A remarkable effect on straight-line stability was confirmed.

Experimental Example 3 The pneumatic tire prepared in Experimental Example 1 had a diameter of 170 mm.
High-speed durability tests were conducted using an indoor drum testing machine consisting of a 7 mm drum. Inflate each radial tire to 2
．． 1υ, initial speed 81h/hr, 8Ian every 30 minutes
The speed was increased by Zhr and the vehicle was run until it broke, and the speed at which it broke was plotted in FIG.

In Fig. 9, the star mark ☆ indicates α1−α2=90°
This conventional radial tire has a two-layer steel heald structure in which the belt reinforcing layer and reinforcing cords are simply laminated and intersect with each other at 20° and 1600° with respect to the tire circumferential direction. In addition, as shown in Figure 3, the one indicated by Kuroboshi-Usu★ has two belt reinforcing layers whose reinforcing cords intersect with each other at 20° and 160° with respect to the tire circumferential direction, and both sides are bent toward the tread surface. This is a conventional radial tire with a belt structure in which the folded portion of the lower belt reinforcing layer wraps around both sides of the upper belt reinforcing layer, and the angles of α and α are 2-90°.

As is clear from FIG. 9, the pneumatic tire according to the present invention in which β=96° to 108° wraps both sides of the upper belt reinforcing layer by the folded portion of the lower belt reinforcing layer, which has both sides bent toward the tread side. It can be seen that high-speed durability can be improved compared to conventional radial tires with a belt structure in which the tires are stacked on top of each other.

As described above, the pneumatic tire of the present invention has an upper belt reinforcing layer in which the reinforcing cord has an angle of 150° to 165° with respect to the tire circumferential direction, and an upper belt reinforcing layer having an angle of 15° to 30° with respect to the tire circumferential direction. In a pneumatic tire in which the lower belt reinforcing layer is stacked such that both sides of the upper belt reinforcing layer are wrapped by the bent portions of the lower belt reinforcing layer, which are bent on both sides toward the tread surface, the carcass cord layer is It is composed of carcass cord layers laminated in two layers, upper and lower, and the angle of the reinforcing cords constituting each carcass cord layer with respect to the tire circumferential direction is determined in the tire circumferential direction of the reinforcing cord of the belt reinforcing layer on the side in contact with the carcass cord layer. The average value i of the angle α2 of the m-strong cord of the carcass cord layer on the side in contact with the belt reinforcing layer and the angle α of the reinforcing cord of the carcass cord layer below it, when measured from the side where the angle with respect to is an acute angle (α1+α2) is 96°~108
0 and the difference (α2-α1) is 10° to 40°, so the plysteer caused by the bell I/reinforcement layer of the above structure can be reduced by the carcass cord layer.
Compared to conventional radial tires, the weight can be reduced, the straightness of running during normal driving and high-speed driving can be improved, and high-speed durability can be further improved.

[Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between the mileage and lateral force of a radial tire, Figures 2 (A) and (B) are model diagrams showing the state of deformation of the belt reinforcing layer, and Figure 3 is a diagram of the relationship between the running distance and lateral force of a radial tire. FIG. 4 is a half-sectional perspective view of a pneumatic tire according to an embodiment of the present invention, FIG. 5 is a developed plan view of the belt reinforcing layer and carcass cord layer of the same tire, and FIG. Development according to other embodiments. FIG. 9 is a diagram showing the relationship between speed and angle average value β. 1... Tread, 4... Carcass cord layer, 4u.
...Upper carcass cord layer, 4d...Lower carcass cord layer, 5...Belt reinforcement layer, 5u...Upper belt reinforcement layer, 5d...Lower belt reinforcement layer. Agent: Patent Attorney Makoto Ogawa − Patent Attorney: Ken Noguchi Patent Attorney: Kazuhiko Saishita

Claims (1)

[Claims] Between the tread and the carcass cord layer 4, an upper belt reinforcing layer in which the angle of the reinforcing cord is 1500 to 165° with respect to the tire circumferential direction and a lower belt reinforcing layer in which the angle is 15° to 30' with respect to the tire circumferential direction are provided. In a pneumatic tire in which the bent portion of the lower belt reinforcing layer bent to the side wraps both sides of the upper belt reinforcing layer in a stacked manner, the carcass cord layer is composed of two carcass cord layers stacked in upper and lower layers. When the angle of the reinforcing cords constituting each carcass cord layer with respect to the tire circumferential direction is measured from the side where the angle of the reinforcing cord of the belt reinforcing layer on the side in contact with the carcass cord layer with respect to the tire circumferential direction is an acute angle, The average value 2 (α++α2) of the angle α2 of the reinforcing cord of the carcass cord layer on the side in contact with the belt reinforcing layer and the angle α1 of the reinforcing cord of the carcass cord layer below it is 96.
°~108°, and the difference (α2−α,) is 10°~
A pneumatic tire characterized by being arranged at an angle of 40 degrees.