JPS592907A - Pneumatic tyre - Google Patents

Abstract

PURPOSE:To contrive to reduce plys-tear and consequently improve the straight running property and unsymmetrical wear proof by an arrangement wherein the angle of reinforcement cords forming a single carcass cord layer used at trucks, buses and the like toward the peripheral direction of the tyre is made a specified angle. CONSTITUTION:If the angle alpha of the cords of a carcass cord layer 4 measured from the side, from which of the peripheral direction of a tyre the reinforcement cords of a belt reinforcement layer 5s is measured acute, is larger than 85 deg., the plys-tear is not made better than its level of the conventional radial tyre, while if the angle alpha is smaller than 75 deg., the plys-tear itself is improved further, however the load durability lowers down. When the angle alpha lies in the range of 75-85 deg., the plys-tear is not only made better than that of the conventional radial tyre, the angle alpha of which is 90 deg., but also the improvement of the straight running stability and the reduction of unsymmetrical wear are made possible due to the reduction of the plys-tear.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pneumatic tire, and more particularly, a belt reinforcing layer consisting of a belt reinforcing layer and at least two belt tension-resistant layers laminated on the upper surface of the belt reinforcing layer is used to form a pneumatic tire between a tread and a carcass cord layer. In between, pneumatic tires with an improved structure of the carcass cord layer are used to reduce plysteer and improve straight-line running performance of stacked radial tires for trucks and buses or light trucks, and to suppress uneven wear. It is related to.

Conventional radial tires for trucks and buses or light trucks are arranged between the tread and the carcass cord layer, adjacent to the carcass cord layer, as shown in Figure 3, and the reinforcing cord angle is set relative to the tire circumferential direction. 40"~75
The belt reinforcing layer is laminated on the upper surface of this belt reinforcing layer and the reinforcing cord angle is 15° to 30° with respect to the tire circumferential direction.
and at least two intersecting each other at 150° to 165°
Belt reinforcing layers each consisting of a belt tension-resistant layer are laminated, and the carcass cord layer is made up of one or more layers, and the reinforcing cord has a width of about 90'' in the tire circumferential direction.
The structure is such that Compared to bias tires, this type of radial tire for trucks and buses or small trunks has the effect of the above-mentioned belt reinforcing layer.
It has excellent braking performance, low fuel consumption, 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. 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 called conicity (CT) and the other called plysteer (PS). It is classified as part of the tire's uniformity characteristics. On the other hand, the uniformity test method for automobile tires (JASOC607)
When the average value of K-base is taken as LFD, LFDw measured on the front side of the tire, LFD S measured on the back side of the tire after replacing it, and the above-mentioned conicity CT1 plysteer PS are expressed by the following formula from the definition. are in a relationship.

LFDw=PS 10CT・・・・−
・(1) LFDs2PS-CT...
... (2) (11, (Determining PS and CT from the two-layer equation is as follows.

LFDW-LFD.

CT-□ ・・・・・・(3) LFDw +
LFDs PS2□ ・・・・・・(4) Above (1),
The relationships of +2>, (3), and (4) can be represented as shown in FIG. 1.

By the way, among the above-mentioned conicity and plystea,
Conicity is considered to be the geometric asymmetrical shape of a tire with respect to its circumferential center, that is, the force generated when a truncated conical tire shifts. 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 out the belt reinforcement layer and consider it, we can see that it is shown in Figure 2 (4).
), it can be expressed as a three-layer laminate 50 including belt tension-resistant layers 50u and 50d and a belt reinforcing layer 50s. With respect to this three-layer laminate 50, the tire circumferential direction EE'
When a tensile force is applied to the three-layer laminate 5υ, the three-layer laminate 5υ deforms not only within the two-dimensional plane where the tension acts, but also three-dimensionally out of the plane, as shown in Figure 2 (B). It is well known that torsional deformation occurs. The above-mentioned plysteer occurs due to such torsional deformation of the belt reinforcing layer.

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 problem of the above-mentioned conventional radial tires for truck buses or light trucks, especially tires that shoulder one carcass cord layer, and to add another belt reinforcing layer. By carefully arranging the reinforcing cords in the carcass cord layer,
It is an object of the present invention to provide a pneumatic tire that can reduce plysteer and further improve straight running and uneven wear resistance than the above-mentioned conventional radial tires.

The pneumatic tire of the present invention that achieves the above object is arranged between a tread and a carcass cord layer, adjacent to the carcass cord layer, and has a reinforcing cord angle of 40° to 75° with respect to the tire circumferential direction. A belt reinforcing layer and a reinforcing cord laminated on the upper surface of the belt reinforcing layer have an angle of 1 with respect to the tire circumferential direction.
The lower belt tension layer is between 5° and 30° and the tension layer is between 150° and 150°.
In a pneumatic tire in which a belt reinforcing layer consisting of at least two belt tension-resistant layers of an upper belt tension-resistant layer having an angle of 65° is laminated, the carcass cord layer is composed of one layer, and the carcass cord layer is composed of one layer. The reinforcing cords constituting the belt are arranged so that the angle with respect to the tire circumferential direction is 75° to 85° when measured from the side where the angle of the reinforcing cords of the belt reinforcing layer with respect to the tire circumferential direction is an acute angle. That is.

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

FIG. 4 is a cross-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 pneumatic tire.

In FIGS. 4 and 5, 1 is a tread, 2 is a sidewall provided to extend on both sides of the tread 1, and 3 is a peed wire embedded in the lower end of the sidewall along the circumferential direction. be. A carcass cord layer 4 is provided to wrap around the bead wires 6 at both ends and run along the inner surfaces of the sidewall 2 and tread 1, and further between the carcass cord layer 4 and the tread 1 is a steel cord. A belt reinforcing layer 5 consisting of the following is provided.

The carcass cord layer 4 is composed of only one layer.

Further, in this embodiment, as shown in FIGS. 4 and 5, the belt reinforcing layer 5 includes a belt reinforcing layer 5s disposed adjacent to the carcass cord layer 4, and a belt reinforcing layer 5s disposed adjacent to the carcass cord layer 4.
Belt tension-resistant layer 5u of upper, middle and lower three layers laminated on the top surface of S
' + 5u r 5d It is composed of a 4-layer laminated structure.

Of the four layers constituting the belt reinforcing layer 5, the upper belt tension-resistant layer 5u' and the middle belt tension-resistant layer 5u
The angle θ4 of each reinforcing cord with respect to the tire circumferential direction EE'
．． θ3 is 150° to 165° in the same direction,
The angle θ2 of the reinforcing cord of the lower belt tension-resistant layer 5d with respect to the tire circumferential direction EE' is 15° to 30°, and these upper and middle belt tension-resistant layers 5u', 5u
and the lower belt tension-resistant layer 5d are laminated so that their respective reinforcing cords intersect with each other.

Further, the angle 01 of the reinforcing cords of the belt reinforcing layer 5s with respect to the tire circumferential direction EE' is 40° to 75°, and is arranged in the same direction as the reinforcing cords of the lower belt tension-resistant layer 5d described above.

The structure of the reinforcing cords in the belt reinforcing layer 5 described above is the same as that used in conventional radial tires.

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, the angle that the cords of the carcass cord layer 4 make with respect to the tire circumferential direction is the angle that the reinforcing cords of the belt reinforcing layer 5s located on the side of the belt reinforcing layer that is in contact with the carcass cord layer 4 make with respect to the tire circumferential direction. The carcass cord layer 4 is arranged so that the angle α is 75° to 85°.

This angle α is such that the reinforcing cord of a certain belt reinforcing layer 5s is on the side in contact with the carcass cord layer 4 in the tire circumferential direction E.
Since the measurement is made from the side that is at an acute angle to E', if the reinforcing cord of the belt reinforcing layer 5s is arranged at the lower right side as in the example in Fig. 6, the measurement will be made from the side that is at an acute angle to E'. must be measured counterclockwise.

The cord angle α of the carcass cord layer 4 mentioned above is 85°.
If it is larger than 75°, plysteer will not be improved from the level of conventional radial tires and will still be 75°.
If it is made smaller, the plysteer itself will be further improved, but the load durability will decrease, which is not preferable.

When the angle α is between 75° and 85°, plysteer is not only improved compared to the conventional radial tie A2 with α = 90° as described above, but also straight-line stability is improved by reducing plysteer. It is possible to reduce uneven wear.

In this example, as described above, a pneumatic tire was described in which a belt reinforcing layer consisting of a total of four layers including one belt reinforcing layer and three tension-resistant layers was arranged. A belt reinforcing layer having a three-layer structure of one belt reinforcing layer and two belt tension-resistant layers may be used, or the belt reinforcing layer is divided into two and placed on both shoulder side portions from which the tread center region is removed. Of course, it is possible to use belt reinforcing layers having a conventionally commonly used structure, such as a belt reinforcing layer having a structure such as that shown in FIG.

For example, the belt reinforcing layer having the three-layer structure described above is placed on the belt reinforcing layer disposed adjacent to the carcass cord layer.
It is constructed by laminating each of the two belt tension-resistant layers in the order of the lower belt tension-resistant layer and the upper belt tension-resistant layer. In addition, the lower belt tension layer and the upper O-belt tension layer are arranged in different directions. At this time, the angle of the reinforcing cord with respect to the tire circumferential direction is 40' to 75' in the belt reinforcing layer, 15 to 30° in the lower belt tension-resistant layer, and 150 to 150 in the upper belt tension-resistant layer. It is 165°.

The belt reinforcing layer of this embodiment described above used a belt reinforcing layer using steel reinforcing cords, but instead of the steel reinforcing cords, aromatic polyaramid fiber cords called "Kepler" were used. It may be used.

Further, the reinforcing cord of the carcass cord layer is not limited to steel cord, but a high elastic modulus material such as aromatic polyamide fiber cord having an elastic modulus of 5 x 10 K9/mt9 layer can be applied.

Note that 6 in the figure is the belt cushion rubber.

Further details will be explained below using specific experimental examples.

Experimental Example 1 Various pneumatic tires were manufactured having the configurations of the belt reinforcing layer and the force cord layer shown in FIGS. 4 and 5, and varying the force and the angle α of the cord of the single layer of casseroles.

The angle of each reinforcing cord in the belt reinforcing layer and each belt tension-resistant layer with respect to the tire circumferential direction is
θ1-60°, θ2-18°, θ3=θ4= 162°
The tire size used was 11R22,5-14P.
R, rim is 8.25 x 22.5.

For these pneumatic tires, a load of 24
As a result of measuring the plysteer (PS) under the conditions of 50 kg and air pressure of 7.25 KP/4, results as shown in FIG. 7 were obtained.

As is clear from FIG. 7, it can be seen that the tires in which the cord angle α of the carcass cord layer is 85° or less have smaller plysteer than the conventional radial tire in which α=90°. That is, it can be seen that the straight running performance has been improved.

Experimental Example 2 The load durability of each of the pneumatic tires used in Experimental Example 1 described above was measured using an indoor drum testing machine consisting of a drum with a diameter of 1707 mm. Each tire has an air pressure of 7.2
5'l', - Speed 45 K"!/hr Initial load 270
0 to 9, and after 2 hours of preliminary running, the load was set to 3915Kp.
After that, the load was increased by 9 to 270 every 10 hours, and the tire was run until it broke.

As a result of measuring the load at the time of this failure, the results shown in FIG. 8 were obtained.

In addition, each part shown in FIG. 8 is expressed by an index with the load at the time of failure of a conventional radial tire where α=90° being 100.

As is clear from FIG. 8, it can be seen that when the cord angle α of the carcass cord layer is smaller than 75°, the load durability decreases.

As described above, the pneumatic tire of the present invention is arranged between the tread and the carcass cord layer, adjacent to the carcass cord layer, and has a reinforcing cord angle of 40 mm with respect to the tire circumferential direction.
a belt reinforcing layer with an angle of 15 degrees to the tire circumferential direction;
The lower belt tensile strength layer is between 150° and 16°.
In a pneumatic tire in which a belt reinforcing layer consisting of at least two belt tension-resistant layers of an upper belt tension-resistant layer having an angle of 5° is laminated, the carcass cord layer is composed of one layer, and the carcass cord layer is composed of one layer. Since the angles of the reinforcing cords constituting the belt reinforcing layer with respect to the tire circumferential direction are 75° to 85° when measured from the side where the angle of the reinforcing cords of the belt reinforcing layer with respect to the tire circumferential direction is an acute angle, the above-mentioned Compared to conventional radial tires, plysteer caused by the reinforced belt reinforcing layer can be reduced, and straight-line running performance and uneven wear resistance can be significantly improved.

[Brief explanation of the drawing]

Figure 1 is a relationship between the running distance of a radial tire and lateral force, Figures 2 (A) and (B) are model diagrams showing the state of deformation of the belt reinforcing layer, and Figure 3 is from an example of the present invention. FIG. 5 is a cross-sectional perspective view of the pneumatic tire, and FIG. 5 is a developed plan view of the belt reinforcing layer and carcass cord layer of the same tire.
FIG. 6 is a developed plan view of another embodiment, FIG. 7 is a diagram showing the relationship between plysteer and cord angle α, and FIG. 8 is a diagram showing the relationship between load durability and cord angle α. 1... Tread, 4... Carcass cord layer, 5...
- Belt reinforcing layer, 5u, 5d...belt tension-resistant layer, 5s...belt reinforcing layer. Agent: Patent Attorney Makoto Ogawa − Patent Attorney: Ken Noguchi Patent Attorney: Kazuhiko Saishita

Claims (1)

[Claims] A belt reinforcing layer disposed between the tread and the carcass cord layer, adjacent to the carcass cord layer, and having a reinforcing cord angle of 40" to 75 degrees with respect to the tire circumferential direction, and the belt;
a lower belt tension-resistant layer laminated on the upper surface of the reinforcing layer and having a reinforcing cord angle of 15° to 30° with respect to the tire circumferential direction;
In a pneumatic tire in which a belt reinforcing layer consisting of at least two belt tension-resistant layers of an upper belt tension-resistant layer having an angle of 0° to 165° is laminated, the carcass cord layer is composed of one layer; The reinforcing cords constituting the carcass cord layer were arranged so that the angle with respect to the tire circumferential direction was 75° to 85° when measured from the side where the reinforcing cords of the belt reinforcing layer had an acute angle with respect to the tire circumferential direction. A pneumatic tire characterized by: