JPS592902A - Pneumatic tyre - Google Patents

Abstract

PURPOSE:To contrive to improve the durability especially at running under low inflation pressure by a structure wherein reinforcement cords of carcass cord layers laminated in two layers or an upper and a lower layers are crossed each other peripherally and symmetrically with a specified angle and yet the total 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 reinforcement cords of the upper carcass cord layer 5u and of the lower carcass cord layer 5d are rendered to intersect each other at an angle of 60-80 deg. with respect to the peripheral direction of the tyre and at the same time are arranged substantially symmetrical to the direction of the meridional cross section of the tyre. Due to the arrangement as described above, the rigidity of the carcass part is improved better than ever, resulting in obtaining excellent driving stability and improving the durability at high speed running by preventing the upper part of a side wall from being pushed up during high speed running. 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 cord layer 4u and that in the 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 particularly, to a pneumatic tire for a passenger car that has improved high-speed durability and handling stability, as well as significantly improved durability especially when running at low internal pressure. This relates to pneumatic tires.

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, wear resistance, etc. due to the effect of the belt reinforcing layer.

However, as the expressway network has become more complete, passenger car tires have recently come to be required to have higher high-speed durability and handling stability.In order to meet these demands, two upper and lower carcass cord layers are laminated. Additionally, a radial tire has been proposed in which reinforcing cords constituting the upper carcass cord layer and the lower carcass cord layer are arranged so as to intersect with each other symmetrically in the meridian cross-section direction of the tire.

However, as described above, when the reinforcing cords of the upper and lower carcass cord layers are arranged symmetrically and intersecting each other with respect to the tire meridional cross-sectional direction, the upper carcass cords are removed during the molding and vulcanization process.

The difference between the tension applied to the reinforcing cords of the upper and lower carcass cord layers becomes large and the tension applied to the reinforcing cords of the lower carcass cord layer becomes large, which causes the problem that the reinforcing cords of the upper and lower carcass cord layers break due to compression, especially when running at low internal pressure. there were.

Therefore, an object of the present invention is to provide a pneumatic tire for passenger cars that solves the above-mentioned problems, improves high-speed durability and handling stability, and significantly improves sailing resistance and labor requirements especially when running at low internal pressure. Our goal is to provide the following.

A pneumatic tire of the present invention that achieves the above object is a pneumatic tire in which a belt reinforcing layer is laminated between a tread and a carcass cord layer, and the carcass cord layer is laminated in two layers, an upper and a lower layer. The reinforcing cords constituting the upper carcass cord layer and the lower carcass cord layer are arranged at an angle of 60° to 8° with respect to the tire circumferential direction.
They intersect with each other at 0 degrees and are arranged substantially symmetrically in the tire meridional section direction, and furthermore, the total denier per 50 (TDD) of the lower carcass cord layer is
) 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. 1 is a half-sectional perspective view of a pneumatic tire according to an embodiment of the present invention, FIG. 2 is a plan view developed explanatory view of the belt reinforcing layer and carcass cord layer of the same tire, and FIG. 3 is another embodiment of the same tire. FIG. 2 is a plan view developed explanatory diagram according to an example.

In FIGS. 1 to 3, 1 is a tread, 2 is a sidewall provided to extend on both sides of the tread 1, and 6 is a bead wire embedded in the lower end of the sidewall 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 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 5d. It has a two-layer laminated structure.

Of the two layers constituting the belt reinforcing layer 5, the upper and lower belt reinforcing layers 5u and 5d are in such a relationship that their reinforcing cords intersect with each other at an angle of 15° to 30" with respect to the tire circumferential direction EE'. It is located.

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 reinforcing cords constituting the carcass cord layer 4 described above is an important component in improving the high-speed durability and stability of the tire. The reinforcing cords constituting the side carcass cord layer 4d intersect with each other at angles θ2 and θ1 with respect to the tire circumferential direction of 60° to 80°, and are arranged substantially symmetrically with respect to the meridional cross-sectional direction of the tire.

Here, "substantially symmetrical with respect to the meridional cross-sectional direction of the tire" mentioned above means that the angle θ2 of the reinforcing cords of the upper carcass cord layer 5u with respect to the tire circumferential direction is When the angle measured from the same direction as the angle θ1 with respect to the tire circumferential direction is θ2',
The angle 02' of the reinforcing cord of the upper carcass cord layer 5u with respect to the tire circumferential direction and the angle 02' of the reinforcing cord of the upper carcass cord layer 5u and the angle 02' of the lower carcass cord layer
This means that the average angle η-+(θ1+02') between the reinforcing cord of the layer 5d and the angle θ with respect to the tire circumferential direction is within 90°±4.

As described above, the present invention provides the upper carcass cord layer 5u.
and the reinforcing cords constituting the lower carcass cord layer 5d intersect with each other at 60° to 80° with respect to the tire circumferential direction, and are arranged substantially symmetrically with respect to the tire meridional cross-sectional direction. Each reinforcing cord of the upper and lower carcass cord layers is set at 90° to the tire circumferential direction,
In other words, compared to so-called conventional radial tires in which each reinforcing cord is arranged in parallel in the meridian cross-section direction of the tire, it is possible to improve the rigidity of the carcass part and obtain good handling stability while driving at high speeds. It is possible to effectively prevent the phenomenon that the upper part of the sidewall rises, thereby improving high-speed durability.

However, if the angle of the reinforcing cords of the upper and lower carcass cord layers 5u and 5d with respect to the seven circumferential direction of the tie is less than 60°, the load durability will deteriorate, which is not preferable.

Further, if the angle exceeds 80°, the above-mentioned steering stability and high-speed durability will deteriorate, which is not preferable.

Further, the present invention provides that the lower carcass cord layer 4d has a
Since the total denier (TDD) of the nine cords was set to 1.1 to 1.5 times the total denier (TDU) per 50X 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 will be damaged along the reinforcing cords of the upper carcass cord layer 4u, and if the value is 1.5 times or more, the opposite will occur. upper carcass cord layer 4
The reinforcing cord of u is damaged along the reinforcing cord of the lower carcass cord layer 4d. More preferably 1
．． More preferably, it is 2 times to 1.4 times.

The total denier (TDD) per 50% of the lower carcass cord layer 4d is: TDD = denier number of strands of the lower carcass cord layer x
The total denier (TDU) of the upper carcass cord layer 4u is as follows: Number of strands x 50 - number of cords per unit, and the total denier (TDU) of the upper carcass cord layer 4u is: TDU = denier of the strands of the upper carcass cord layer x number of strands x Number of codes per 50X. These measurements were taken at the center of the rubberized reinforcing layer (tire equatorial plane) and at the same position for both the upper and lower carcass cord layers, and the number of cords per 50 hits was measured at right angles to the cord direction.

In the above-described embodiment, the belt reinforcing layer 5 is a two-layer laminated structure made of steel cord. Conventionally commonly used materials can be used, such as a belt reinforcing layer made of aromatic polyamide fiber cord, or a belt reinforcing layer made of both textile cords. 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.

In addition, the cord of each carcass cord layer is made of nylon, rayo/
, polyester, aromatic polyamide fiber cord, etc.

Note that 6 in the figure is a bead filler.

Further details will be explained below using specific experimental examples.

For each pneumatic tire with the following specifications in which ``''/'rnu was varied from 0.8 to 1.8, the load durability during low internal pressure running was tested using an indoor drum tester using a drum with a diameter of 1707%. It was measured.

Each tire has an air pressure of 1.3'/! , speed 80K”!/h
The vehicle was run under a load of 675 r and a load of 9 until the tire broke, 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 configuration of the belt reinforcing layer and carcass cord layer shown in Figs. 1, 2, and 3, and the cord angle θ2-70 of the upper and lower carcass cord layers. “, θ is 75°, average angle η = 93°, and the sum of TDU and TDD at the tire equatorial plane is approximately 16
The X10' denier was fixed at 150, the tire size was 185/70HR13, and the tire size was 5JX13.

Each carcass cord layer indicated by a circle in FIG. 4 is a nylon cord of 1260D/2 for both the upper and lower carcass cord layers. (Example of changing the number of cords in each of the upper and lower carcass cord layers) ・Each carcass cord layer indicated by a mark is a nylon cord of 840 D/2 in the upper carcass cord layer, and a 1260 D/2 carcass cord layer in the lower carcass cord layer. 2 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 a 100OD/2 upper carcass cord layer, and a 1500D/2 lower carcass cord layer. It is a polyester cord. (Example of changing the number and thickness of cords in the upper and lower layers) The tires with TDD/TDU=1 marked with ○ are conventional tires.

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 no damage occurs in the range of 2 to 1.4.

If the value of i fc TDD/TDU is less than 1.1, the lower carcass cord will break along the upper carcass cord, and if it exceeds 1.5, the upper carcass cord will break along the lower carcass cord. I discovered that

As described above, the pneumatic tire of the present invention is a pneumatic tire in which a belt reinforcing layer is laminated between a tread and a carcass cord layer. The reinforcing cords constituting the upper carcass cord layer and the lower carcass cord layer have a width of 60" to 80" in the tire circumferential direction.
” and are arranged substantially symmetrically with respect to the tire meridional section direction, and furthermore, the total delta (TDD) per 50% of the lower carcass cord layer is determined by the upper carcass cord layer. Since it is 1.1 to 1.5 times the total denier (TDU) per 50%, it can improve high-speed durability and handling stability, while significantly improving durability when running at low internal pressure. be able to.

In other words, the durability of the carcass cord layer can be improved.

[Brief explanation of drawings]

FIG. 1 is a half-sectional perspective view of a pneumatic tire according to an embodiment of the present invention, and FIG. 2 shows the belt reinforcing layer and force of the same tire.
FIG. 3 is a planar view development explanatory diagram of the cascode layer, FIG. 3 is a planar view development explanatory diagram of another embodiment, and FIG.
DI)/TDU. 1... Tread, 4... 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 ε Procedural amendment 1. Case Description Sho #+57 (14 Patent Application No. 1099
50 No. 2, Name of the invention Pneumatic tire 3, Person making the amendment/1G (Relationship with 'I Patent applicant's address (
Address] 4. Agent Address: 105 Tokyo Minato 1〆゛Nishishinbashi 3-J 3
No. 3 Pelican Building 7, details of amendment (1) "90°±4" on page 6, line 17 of the specification is corrected to "90°±4°". (2) On page 13, lines 9 to 12, "Figure 2 is a plan view explanatory diagram" is corrected as follows. “Figure 2 shows TDD by adjusting the number of carcass cords.
/TDU ratio is determined. A planar view development explanatory diagram of the belt reinforcing layer and carcass cord layer of the same tire. Figure 3 shows another implementation in which the TDD/TDU ratio was determined by adjusting the thickness of the carcass cord. (3) Figure 3 of the drawing is corrected as shown in the attached sheet.

Claims (1)

[Claims] Between the tread and the carcass cord layer: 1. In a pneumatic tire in which belt reinforcing layers are laminated, the carcass cord layer is composed of 21 laminated carcass cord layers, and the reinforcing cords constituting the upper carcass cord layer and the lower carcass cord layer are provided. , intersect with each other at an angle of 160° to 80° with respect to the tire circumferential direction, and are arranged substantially symmetrically with respect to the tire meridional cross-sectional direction, and furthermore, the total denier (TDD) of the lower carcass cord layer is ) is 1.1 to 1.5 times the total denier (TDU) per 50% of the upper carcass cord layer.