JPS592903A - Pneumatic tyre - Google Patents

Abstract

PURPOSE:To improve straight running stability and durability at running under low inflation pressure by a structure wherein the mean value of and difference between the respective angles of the reinforcement cords of an upper and a lower carcass cord layers are rendered to be specified values and yet the number of single strands per unit length of the lower layer is rendered to be specified times as many as that of the upper layer. CONSTITUTION:The means value beta of and the difference (alpha1-alpha2) between the angles alpha1 and alpha2 of respective reinforcement cords are taken in the range of 96-108 deg. and 10-40 deg. respectively. Within the range as mentioned above, the plys-tear caused by the torsional deformation of belt reinforcement layers 5 can be relieved, resulting in improving the straight running property of the tyre. Furthermore, the total denier per 50m/m of the lower carcass cord layer 4d is made 1.1-1.5 times as many as that of the upper carcass cord layer 4u. Consequently, the difference between the stretch applied to the reinforcement cords in the upper carcass cord layer 4u and that of the lower carcass cord layer 4d during molding and vulcanizing processes can be made smaller, resulting in obtaining the excellent durability at running even under low inflation pressure.

Description

Detailed Description of the Invention The present invention relates to a pneumatic tire, and more specifically, it reduces plysteer of a radial tire, improves straight-line running performance, and significantly improves durability, especially when running at low internal pressure. This invention relates to a pneumatic tire for passenger cars that can be improved.

Conventional radial tires for passenger cars generally have at least two belt reinforcing layers laminated between the tread and the carcass cord layer, the reinforcing cords intersecting each other at an angle of 15° to 30° with respect to the tire circumferential direction. , the reinforcing cord of the carcass cord layer is approximately 90° with respect to the tire circumferential direction.
The structure is such that Compared to bias tires, this type of radial tire is superior in braking performance, fuel efficiency, 1 la 1 abrasion resistance, etc. due to the effect of the belt reinforcing layer. There was a problem that the straight running performance was poor.

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

Generally, the lateral force when the slip angle is 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, according to the uniformity test method for automobile tires (JASOC607), LFD is the average value of lateral force during one rotation of the tire, and LFD is the value measured on the front side of the tire.
LFD measured with FDw and tires replaced and on the back side
s and the above-mentioned conicity CT.

By definition, plysteer PS has a relationship expressed by the following equation.

LFDw = PS + CT ・−・・
...(11LFDs = PS - CT
・−・−・・(2)(+1, PS from equation (2),
The calculation of CT is as follows.

The relationships (11, (2), (3), and (4) above) can be represented in a diagram as shown in FIG.

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 rolls. Since this cause is primarily affected 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 considered substantially difficult to reduce it significantly unless the structure of the belt reinforcing layer itself is changed.

Now, the belt reinforcing layer can be taken out and represented as a two-layer laminate 50 of belt reinforcing layers 500 and 50d as shown in FIG. This two-layer laminate 50
When a tensile force is applied in the tire circumferential direction EE', 2
It is well known that the laminated board 50 deforms not only in the two-dimensional plane where the tension acts, but also three-dimensionally out of the plane, resulting in torsional deformation as shown in FIG. There is. The above-mentioned plysteer occurs due to such torsional deformation of the belt reinforcing layer.

In the past, many studies have been made to reduce this plysteer by adding a new belt reinforcing layer to the belt reinforcing layer, but adding such a new belt reinforcing layer is not suitable for radial tires. However, it was not very desirable, as it detracted from its characteristics such as low fuel consumption.

Therefore, the inventors of the present invention have studied to solve the above-mentioned problems, and have found that a pneumatic tire having the above-mentioned belt reinforcing layer structure and having a carcass cord layer composed of two 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 in contact with the carcass cord layer with respect to the tire circumferential direction is an acute angle, Angle α of the reinforcing cord of the car 2 cascord layer on the side in contact with the belt reinforcing layer
2 and the angle α of the reinforcing cord of the carcass cord layer below it
, the average value + (α1 + α2) is 96° to 108°, and the difference (α2 − α1) is 10° to 40°, so that He invented a pneumatic tire that greatly improved straight-line running performance, and filed a patent application. (Refer to the specification and drawings of Japanese Patent Application No. 55-188602.) However, as mentioned above, in order to improve straight running performance, the reinforcing cords of each carcass cord layer are made to intersect with each other at a predetermined angle with respect to the tire circumferential direction. In this case, there was a problem that the reinforcing cords of each carcass cord layer would break due to compression, especially when running at low internal pressure.

Therefore, an object of the present invention is to provide a pneumatic tire for a passenger car that can solve the above-mentioned problems, improve straight running performance, and significantly improve durability, especially when running at low internal pressure. .

Pneumatic tire q1 of the present invention that achieves the above objects: between the tread and the carcass cord layer, the angle of the reinforcing cord with respect to the tire circumferential direction is 15° to 30°, and the belt reinforcing layer is 150°A-165°. In a pneumatic tire in which at least two layers including a belt reinforcing layer are laminated, the carcass cord layer is composed of two upper and lower laminated carcass cord layers, and the tire circumferential direction of the reinforcing cord constituting each carcass cord layer is The angle of the reinforcing cord of the carcass cord layer on the side that is in contact with the belt reinforcing layer is measured from the side where the angle of the reinforcing cord of the reinforcing cord of the belt reinforcing layer on the side that is in contact with the carcass cord layer with respect to the tire circumferential direction is an acute angle. Average value of α2 and the angle α1 of the reinforcing cord of the carcass cord layer below - + (α, +α2)
is between 96° and 108°, and the difference (α2-α1) is 1
The total denier (TD) of the lower carcass cord layer is 0° to 40°.
D) is 1.1 to 1.5 times the total denier (TDU) per 50 pieces of the upper carcass cord layer.

The present invention will be specifically explained below with reference to embodiments shown in the drawings.

FIG. 4 is a half-sectional perspective view showing a pneumatic tire according to an embodiment of the present invention, and FIGS. FIG. 2 is a plan view developed explanatory diagram.

In FIGS. 4 to 8, 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. decrease. A carcass cord layer 4 is provided so as to wrap around the bead wires 6 that can be measured at both ends, and to run along the inner surfaces of the sidewall 2 and the tread 1. A belt reinforcing layer 5 made of steel cord is interposed therebetween. The carcass cord layer 4 has a two-layer laminated structure of an upper carcass cord layer 4u and a lower carcass cord layer 4d, and the belt reinforcing layer 5 also has an upper belt reinforcing layer 5u and a lower belt reinforcing layer. It has a two-layer laminated structure with layer 5d.

Of the two layers constituting the belt reinforcing layer 5, the upper belt reinforcing layer 5u has its reinforcing cord at an angle θ2 of 150° to 165° with respect to the tire circumferential direction EE', and the lower belt reinforcing layer 5d has an angle θ2 of 150° to 165°. The angle θ1 of the reinforcing cord with respect to the tire circumferential direction EE' is 15° to 30°, and the reinforcing cords of the upper and lower belt reinforcing layers 5u and 5d are arranged so as to cross each other. The structure of the reinforcing cords in this belt reinforcing layer 5 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, 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. The reinforcement cord of the side belt reinforcement layer 5d shall be measured from the side that is at an acute angle with respect to the tire circumferential direction, and the angle α of the reinforcement cord of the lower carcass cord layer 4d and the upper carcass cord layer 4u The average value β of the reinforcing cord angle α2 = + (
α1+α2. ) is within the range of 96° to 108°, and the difference between the inner angles (α, -α1) is 10” to 40°.
It is necessary to keep the temperature within the range of °. Angle α
1. α2 indicates that the reinforcing cord of the lower belt reinforcing layer 5d on the side in contact with the carcass cord layer 4 is in the tire circumferential direction EE'
6 and 8 to measure from the side that is at an acute angle to
As in the example shown in the figure, when the reinforcing cords of the lower 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.

In the present invention, as described above, the angle α of each reinforcing cord is
1. The average value β and difference (α2-α1) of α2 are each 9
Since the range is 6° to 108° and 10” to 40°, it is possible to reduce plysteer caused by torsional deformation of the belt reinforcing layer 5, and as a result, the straight running performance of the tire can be improved and the steering stability can be improved. improve; be able to do something;

However, if the average value β exceeds 108°, ride comfort, load durability, and tire molding/vulcanization workability will deteriorate, and if it is less than 96°, plysteer will not be reduced compared to conventional tires. Therefore, it is undesirable. In order to further improve riding comfort and load durability, it is more preferable to set the angle to 102° or less within the above range.

Furthermore, as mentioned above, the angle α1. The average value β of α2 is 96
Even if it is within the range of ° to 108 °, the difference (
It is necessary that α2-α1) be in the range of 10° to 40°, and in this way the value of the difference (α2-α1) must be within the range of 10° to 40°.
By setting it in the 0° range, plysteer can be reduced and straight-line running performance can be improved compared to a conventional radial tire in which the reinforcing cords of the upper and lower two carcass cord layers 4u and 4d are arranged in parallel in the meridian cross-section direction of the tire. Furthermore, the rigidity of the carcass cord layer can be improved, and good handling stability can be obtained.

However, if the above angle exceeds 40°, load durability will deteriorate, and if it is less than 10°, plysteer will not be reduced compared to conventional tires, and furthermore, carcass rigidity will be insufficient, leading to a decrease in handling stability. I don't like this because it can cause problems. In order to further improve steering stability, it is more preferable to set the angle to 25° or more within the above range, and to further improve load durability, it is more preferable to set the angle to 3° within the above range.
It is more preferable to set the angle to 5° or less.

Further, the present invention provides that the lower carcass cord layer 4d has a
Since the total denier (TDD) per % was set to 1.1 to 1.5 times the total denier (TDU) per 50 of the upper carcass cord layer 4u, in the molding and vulcanization process, the upper carcass The difference between the tension applied to the reinforcing cords of the cord layer 4u and the reinforcing cords of the lower carcass cord layer 4d can be reduced, and good durability can be enjoyed even when running at extremely low internal pressure. .

However, if the value of TDD/TDU is less than 1.1 times, the reinforcing cords of the lower carcass cord layer 4d are likely to be damaged along the reinforcing cords of the upper carcass cord layer 4u, and if the value is 1.5 times or more, On the other hand, this is not preferable because the reinforcing cords of the upper carcass cord layer 4u are likely to be damaged along the reinforcing cords of the lower carcass cord layer 4d. More preferably, it is 1.2 times to 1.4 times.

The total denier (TDD) per 501 of the lower carcass cord layer 4d is the denier of the strands of the TDD2 lower carcass cord layer x the number of strands x the number of cords per 50X, and The total denier (TDU) per 501 of the code layer 4u is TDU
- Denier number of strands of the upper carcass cord layer x number of strands x number of cords per 501. These measurements were taken at the center of the belt reinforcing layer (tire equatorial plane) and at the same position for both the upper and lower carcass cord layers, and the number of cords in the 50-9 cord layer was measured at right angles to the cord direction.

In the above-described embodiment, the belt reinforcing layer 5 is a two-layer laminate made of steel cord. It is possible to use conventionally commonly applied materials, such as aromatic polyamide fiber cords used as the belt reinforcing layer, or both textile cord layers used as the belt reinforcing layer. Naturally, the end portion of the belt reinforcing layer may be bent inward. Furthermore, it is also possible to apply a belt reinforcing layer made of another textile cord in addition to the above-mentioned two layers, if necessary.

The cords of each carcass cord layer are made of nylon, rayon, polyester, aromatic polyamide fiber cords, etc.

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, 5, and 7, and the cord angle difference (α2−α ,)
Various pneumatic tires were manufactured in which the angle β was kept constant at 30° and the average value β of the angle was varied. The angles of the cords in the upper and lower layers of the belt reinforcing layer with respect to the tire circumferential direction were 20° and 160°, respectively, and the specifications of each carcass cord layer were as follows. Tire size is 195/70HR14
.

Rim 5y2-JJX14. 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. 9 were obtained.

Each carcass cord layer indicated by a 0 mark in FIG. 9 is constructed as shown in FIGS. 4 and 5, and its specifications are as follows: Upper carcass cord layer: Nylon cord, 1260D/2.30 pieces 1150mm
Lower carcass cord layer: Nylon cord, 1260D/2.38 pieces 159mmT
DD/TDU is constant at 21.3. Each carcass cord layer indicated by a mark in FIG. 9 is constructed as shown in FIGS. 4 and 7, and its specifications are as follows.

Upper carcass cord layer: Nylon cord, 840D/2.37 pieces 1/so Lower carcass cord layer: Nylon cord, 1260D/2.34 pieces 150 total LTDD/TDU = 1.4 and constant.

In addition, the conventional tire indicated by a star in FIG. 9 has a cap angle α2=90° as shown in FIG. 3, and the specifications of each carcass cord layer are as follows: Upper carcass cord layer 1 Nylon cord, 1260D/2. Lower carcass cord layer: Nylon cord, 1260D/2.34 150 TD
D/TDU=1. Note that the number of cords is a value measured at the center of the belt reinforcing layer (tire equatorial plane).

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 plysteer PS of the above tires 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 had the configurations shown in FIGS. 4, 5, 4, and 7, and the average cord angle β of the upper and lower carcass cord layers was 102°.
Various pneumatic tires were manufactured in which the angle difference (α2−α,) was kept constant and the angle difference (α2−α,) was varied. The angles of the cords in the upper and lower layers of the belt reinforcing layer with respect to the tire circumferential direction were 20° and 160°, respectively. Tire size is 195/7
0HR14, rim 5-JJX14. For these pneumatic tires, Plysteer PS was used based on the uniformity test method for automobile tires JASOC607.
As a result of the measurement, the results shown in FIG. 10 were obtained.

The O marks, * marks, and ☆ marks in FIG. 10 are the same as those in Experimental Example 1 described above. As is clear from this figure, when the cord angle difference (α2-αl) of the carcass cord layer is 1o° or more, plysteer is smaller than that of conventional radial tires, and straight-line running performance is improved. Recognize.

Experimental Example 3 For each pneumatic tire with the following specifications in which the TDD/TDU was varied from 0.8 to 1.8, the durability during low internal pressure running was measured using an indoor drum tester with a diameter of 1707%.

Each tire has an air pressure of 1.3'F/, 4, and a speed of 80 Km/
hr, load 780. The vehicle was allowed to run until the tire broke under a load of 1.5 kg, and the distance at which the tire broke was plotted in FIG.

If the vehicle ran for 10,000 km without causing any damage, it was considered a completed race and the run was discontinued.

The pneumatic tire used in this experiment had the structure of the belt reinforcing layer and the carcass cord layer shown in FIGS. 4 and 5 or 7, and the angle of the upper and lower carcass cord layers. The difference (α2-α,) is 30°, the half-average value β of the angle is 100'', and the sum of TDU and TDD (7) is fixed at approximately 16 x 10.'dale 150 mm,
Tire size is 195/70HR14, rim is 5V2-
It was named JJxi4.

Each carcass cord layer indicated by a circle in FIG. 11 is a nylon cord of 1260D/2 for both the upper and lower carcass cord layers. (Example of changing the number of cords in the upper and lower carcass cord layers) -Each carcass cord layer indicated by a mark is a nylon cord with an 840D/2 upper carcass cord layer and a 1260D/2 lower carcass cord layer. It is a nylon cord. (Example of changing the number of cords and thickness of the upper and lower layers) Each carcass cord layer indicated by Δ is a polyester cord with an upper carcass cord layer of 100 OD/2 and a lower carcass cord layer of 15 o OD/2. It is a polyester cord. (Example of changing the number and thickness of cords in the upper and lower layers) These TDU and TDD are located at the center of the belt reinforcement layer (
Measured at the tire equatorial plane) position.

As is clear from the figure, the value of TDD/TDU is 1.1~
Good results are obtained when the value is in the range of 1.5, especially when the value is in the range of 1.
It can be seen that in the range of 2 to 1.4, it will not break even after running for 110,000K.

Also, if the TDD/TDU value is less than 1.1, the lower carcass cord will break along the upper carcass cord, and 1.
It was discovered that when the number exceeds 5, the upper carcass cord breaks along with the lower carcass cord.

As described above, the pneumatic tire of the present invention has a belt reinforcing layer in which the reinforcing cord has an angle of 15° to 30° with respect to the tire circumferential direction, and a belt reinforcing layer having an angle of 15° to 165° between the tread and the carcass cord layer. In a pneumatic tire having at least two layers laminated with a belt reinforcing layer of Reinforcement of the carcass cord layer on the side in contact with the belt reinforcement layer when the angle with respect to the tire circumferential direction is measured from the side where the angle of the reinforcement cord of the belt reinforcement 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 + (α1 + αi) - of the angle α2 of the cord and the angle α1 of the reinforcing cord of the carcass cord layer below it is 96° to 108°, and the difference (α2 - α1) is 10
50° to 40°, and the total denier TDD per 50% of the lower carcass cord layer is 1.1 to 1.5 of the total denier TDU per 50% of the upper carcass cord layer. Since the belt reinforcement layer is doubled, the plysteer caused by the belt reinforcement layer mentioned above can be reduced compared to conventional radial tires, improving straight-line stability. The difference between the tension applied and the tension applied to the reinforcing cord of the lower carcass cord layer can be reduced, and durability can be significantly improved, especially when running at low internal pressure.

By increasing the TDD/TDU ratio within the above range, straight-line stability can be further improved.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between the running distance of a radial tire and lateral force, Figures 2 and 3 are model diagrams showing the state of deformation of the belt reinforcing layer, and Figure 4 is from an example of the present invention. FIGS. 5 to 8 are perspective views showing a carcass cord layer and a belt reinforcing layer of a pneumatic tire according to each embodiment of the present invention; Figures 5 and 6 show examples in which the ratio of TDD/rDu is determined by mainly changing the number of cords in the carcass cord layer, and Figures 7 and 8 show examples in which the ratio of TDD/rDu is determined by changing the number of cords in the carcass cord layer. Figure 9 shows the relationship between plysteer and angle average value V2 (α1+α2), and Figure 10 shows the relationship between plysteer and angle difference. (α2-α,), Figure 11 shows the distance traveled and TI)D, /'rI)
It is a relationship diagram with U. 1... Tread, 4... Carcass cord layer, 4u.
...Upper carcass cord layer, 4d...Lower carcass cord layer, 5...Belt reinforcing layer, 5u...Upper side/L. 5d: Lower belt reinforcing layer. Agent Patent attorney Makoto Ogawa - Patent attorney Ken Noguchi Patent attorney Kazuhiko Saishita Figure 2 Figure 3 E' 41!1 r' Figure 9 Figure 10 and 2-dl Figure 11

Claims (1)

[Claims] At least two layers are laminated between the tread and the carcass code layer: a belt reinforcing layer in which the angle of the reinforcing cord with respect to the tire circumferential direction is 15° to 30°, and a belt reinforcing layer in which the angle is 150° to 165°. Arrangement In the pneumatic tire, the carcass cord layer is composed of two upper and lower laminated carcass cord layers, and the angle of the reinforcing cords constituting each carcass cord layer with respect to the tire circumferential direction is in contact with the carcass cord layer. Angle α2 of the reinforcing cord of the carcass cord layer on the side in contact with the belt reinforcing layer and the carcass cord layer below it when measured from the side where the reinforcing cord of the side belt reinforcing layer has an acute angle with respect to the tire circumferential direction. The average value of the reinforcing cord angle α1 + (α1+
α2) is between 96° and 108°, and the difference (α2−α1
) is 10° to 40°; A pneumatic tire characterized by being 1.1 to 1.5 times as large.