JPS63106102A - Radial type for passenger car - Google Patents

Abstract

PURPOSE:To improve abrasion resistance and fuel consumption by specifying the ratio of radius of curvature at a tread face and the ratio of radius of curvature at a shoulder part of a carcass between standard inside pressure filling up and specified inside pressure filling up, respectively. CONSTITUTION:The radius of curvature of a tread face 12 at the time of filling up inside pressure by 10% is defined as R1 and the radius of curvature of a shoulder part 6A of a carcass is defined as RC1, where the carcass 6 passes by below the shoulder part 12B of a tread face 12. And the radius of curvature at the time of standard inside pressure is defined as RT2 and RC2 for the tread face 12 and the shoulder part 6A of the carcass, respectively. And the ratios of each radius of curvature between 10% inside pressure filling and standard inside pressure filling, that is, RT2/RT1 and RC2/RC1, are set between 1.10 and 1.40 and between 0.65 and 0.85 respectively. And the ratio between the radius of curvature of a tread face at the time of standard inside pressure and the outside diameter of a belt layer is set above 0.42. By this constitution, abrasion resistance and fuel consumption are improved.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention improves wear resistance and improves fuel efficiency by setting the amount of outward change of the shoulder portion to be large due to filling of internal pressure. The present invention relates to radial tires for passenger cars that can improve performance.

(Prior art) In recent years, tires with a radial structure in which carcass cords are arranged almost perpendicular to the tire equator plane have been widely used as they have excellent characteristics such as wear resistance and handling stability. A hoop effect is imparted to the tire by surrounding the outer surface of the carcass with a relatively rigid so-called belt layer in which organic or metal cords are arranged at a relatively small angle with respect to the tire's equatorial plane. Furthermore, the inner cavity shape of the mold for curing the tire is set so that the molded tire becomes a natural equilibrium type in which no deformation of the carcass occurs when a standard internal pressure is applied to the molded tire.

[Problem that the invention seeks to solve]

However, in such carcass-shaped radial tires, especially tires with a relatively high aspect ratio and a carcass shape that is close to circular, the relationship between the carcass A and the belt NB is small even when the standard internal pressure is filled, as shown in Figure 6. Because the bulging deformation of the shoulder part of the carcass A is small, especially near the end of the belt NB, the carcass A
The bonding force due to the pressing between the carcass A and the breaker B is not much larger than the bonding force when no internal pressure is filled, and is inferior to the binding force between the carcass A and the belt layer B.

Therefore, in the belt layer B, especially near the ends, the carcass A
It is difficult for the tension that acts on the belt layer B to act on the belt layer B, and the belt layer B cannot exhibit the necessary hoop effect. As a result, the shape of a portion of the shoulder of the trend tends to become uneven, and combined with the reduction in the restraining force of the belt layer B, uneven wear occurs when the tire runs, deteriorating the wear resistance. Furthermore, as the bending force acting on the belt JIH increases during rolling, the stress acting on the belt JIB increases, resulting in an increase in rolling resistance and a deterioration in fuel efficiency.

The present invention is based on the principle of deforming the trend surface so that the radius of curvature becomes large and increasing the amount of change in a part of the shoulder when filling with low internal pressure and standard internal pressure. The object of the present invention is to provide a radial tire for a passenger car that can improve wear resistance and improve fuel efficiency by smoothly acting on belt layer B and increasing the hoop effect of belt WIB.

[Means for solving problems]

The present invention has a curvature radius RT of the tread surface when the rim is assembled to a standard rim and 10% of the standard internal pressure is applied.
Tread surface curvature radius R when I and ti semi-internal pressures are added
Radius ratio RT2/RT1 with T2 is 1.10 or more and 1.
40 or less and is composed of at least one ply of organic fiber cord, the radius of curvature RCI when the 10% pressure is applied and the radius of curvature R when the standard internal pressure is applied is the shoulder part of the carcass where the carcass passes near the trend shoulder part.
The radius ratio RC2/RCI with C2 is 0.65 or more and 0.
This is a radial tire for passenger cars with a rating of 85 or less.

Further, in the present invention, the radius of curvature RT2 when the standard internal pressure is applied is a ratio RT2. Includes radial tires for passenger cars with /DB of 0.42 or more.

An embodiment of the present invention will be described below based on the drawings.

In FIG. 1, a radial tire l for a passenger car includes a bead portion 3.3 on both sides through which a bead core 2 passes, a sidewall portion 4.4 extending radially outward from the bead portion 3, and a trend portion 5 connecting both ends of the sidewall portion 4.4. In addition, the sidewall portion 4 and the tread portion 5 include a carcass 6 that is folded back around the bead core 2 from the inside to the outside.
The main body section of the In addition, in the trend part 5, a belt layer 7 is arranged on the outside of the carcass 6.
A bead apex 9 is provided between the main body portion and the folded portion thereof, while this radial tire 1 for a passenger car is
It is attached to the so-called standard rim 10 by fitting the bead 3 into the flange 11.11 of the rim 10.

The carcass 6 is a so-called radial cord arrangement body in which cords are arranged at an angle of about 80° to 90″ with respect to the tire equatorial plane C, and the cords are made of nylon, polyester, rayon, or aromatic polyamide mi. .

This carcass 6 is made of ply of 1 to 3N.

The bell) Fi7 has, for example, a two-layer structure of a first ply 7A disposed on the carcass 6 side and a second ply 7B above it, and both the first and second plies 7A and 7B are made of metal cords. Moreover, each tire is arranged at a relatively shallow angle with respect to the tire equatorial plane C and inclined in opposite directions. Also the first
The ply 7A is wider than the second ply 7B, and both ends of the first ply 7A extend below the edge a where the sidewall portion 4 and the tread portion 5 intersect.

Note that the radial tire 1 for passenger cars of this example is 1. The distance DT from the lower end of the bead portion 3 to the maximum height point of the tread surface 12, which is the upper surface of the tread portion 5, when filling with standard internal pressure;
It is formed in a slightly flat shape with a ratio to the tire width W of less than 1, for example about 0.9.

As shown in FIG. 2, in the passenger car radial tire 1, after the rim Mi, the radius of curvature RTI of the trend surface 12 when 10% of the standard internal pressure is applied is greater than the radius of curvature RTI of the tread surface 12 due to the addition of standard internal pressure. It is deformed so that the radius of curvature RT2 becomes large.

That is, the tire is deformed so that the difference DC-DS between the tire outer diameter DC at the maximum height point shown in FIG. 1 and the tire outer diameter DS at the edge a becomes smaller. As a result, the amount of change in the outward bulge of the shoulder portions 12B on both sides of the trend surface 12 is increased compared to the crown portion 12A of the midsection of the trend surface 12. As a result, as the internal pressure is filled, the carcass 6 pushes up the belt layer 7, especially near the edges, thereby increasing the bonding force between the carcass 6 and the belt layer 7, and reducing the tensile force acting on the carcass 6, especially the edges of the belt layer 7. The hoop effect of the belt layer 7 can be enhanced.

Also, the radius ratio RT2/RTI is 1.10 or more and 1.4
It is set to 0 or less. Here, the radius ratio RT2/R
When Tl is greater than 40, the overhang of the shoulder portion becomes excessive and excessive tensile force is applied to the carcass 3, impairing its durability and increasing the tension of the tread rubber, resulting in fatigue cracking and chipping. It comes with drawbacks such as making it easier. Also, the radius ratio is 1. When it is smaller than lO, the belt layer 7 is not pushed up enough by the carcass 6, and the above-mentioned effect cannot be exhibited.

Further, in the tire 1, the shoulder portion 6A of the carcass where the carcass 6 passes below the shoulder portion 12B of the tread surface 12 is deformed so that the radius of curvature is smaller when the pressure is at the standard internal pressure than when the pressure is 10%. This serves to push up the shoulder portion 12B by applying the standard internal pressure, thereby increasing the radius of curvature of the trend surface 12 due to the addition.

Also, the radius ratio RC2/RCI is 0.65 or more and 0.8
Set to 5 or less. When the radius ratio RC2/PCI is smaller than 0.65, the carcass 6 is bent excessively, the tensile force is excessive as described above, and the durability of the tire is impaired due to fatigue etc., or the radius ratio exceeds 0.85. In some cases, the amount by which the belt layer 7 is pushed up by the carcass 6 is reduced, making it impossible to achieve the above-mentioned effects. Note that the radii PCI and RC2 of the shoulder part of the carcass 6 are as shown in FIG.
Under each internal pressure condition, a point P1 where a perpendicular line d extending from the edge a and perpendicular to the tire axial direction intersects the carcass 6;
, a point P2 where a perpendicular line e passes through a position that bisects half of the tread width, that is, a position that bisects the distance between the maximum height point and the edge a, and the carcass, and a tire that passes through the maximum middle position of the tire. It is represented by the radius of a circle passing through three points, including a point P3 where a line f parallel to the axis intersects with the carcass 6. Further, in the case of a tread having a shape in which the tread end portion has a curvature, the position of the edge portion a is the intersection of the extension surface 12 of the tread surface and the extension surface of the surface of the sidewall portion 4.

With such a configuration, the tread surface 12 is deformed to increase the radius of curvature by filling with standard internal pressure, improving wear resistance, and reducing rolling resistance by improving the hoop effect, thereby improving fuel efficiency. Also carcass 6
Such deformation of the shoulder portion 6A due to internal pressure filling
It also serves to increase the tensile force acting on the belt layer 7.

Further, in the tire 1, the ratio RT2/DB of the radius of curvature RT2 when a standard internal pressure is applied to the outer diameter DB of the belt layer 7 arranged annularly on the outside of the carcass 6 is 0.42 or more.

By setting the radius of curvature of the trend surface 12 when the standard internal pressure is applied in this way, the trend surface 12 can take on a relatively large circular arc, and the shoulder portion 12B can be deformed outward.

The vulcanization mold (not shown) used to manufacture the radial tire for passenger cars of the present invention has a so-called natural equilibrium shape in order to cause the above-described deformation by applying standard internal pressure.
In particular, the inner cavity shape is formed into a shape that is removed at the shoulder portion. A natural equilibrium shape is a shape in which the carcass can maintain a constant tension even when internal pressure increases, and the radial tire for a passenger car of the present invention has a shape in which the shoulder portion 12L3 is specially shaped in advance in order to increase the amount of deformation of the shoulder portion 12L3. The shoulder portion 12B is set to a shape that is smaller than the natural equilibrium shape in the direction toward the center of the inner cavity of the tire, and is removed from the natural equilibrium shape.
The amount of deformation at B is increased and the shoulder portion 6A of the carcass 6 is
The tension can be increased.

In the present invention, the standard internal pressure refers to the internal pressure applied to the tire under standard conditions of use, or the pressure in the range of 10% below E, and the tire of the present invention includes a reinforcing layer (for reinforcing the bead part). Various modifications can be made, such as providing a bridle (not shown), changing the number of briars on the belt FJ7, and making the upper briai 7B wider.

Example 1 A tire with a tire size of 5.60R13 having the structure shown in FIG. 1 was prototyped according to the specifications shown in Example 1 in Table 1, and was mounted on a 4JX13 rim and measured.

The tire was compared and measured with a tire of the same size and specifications listed in Comparative Example 1 in Table 1. The standard internal pressure is 2゜0kg/ca.
! The 10% pressure is 0.2 kg/cj, and the rolling resistance index is the coasting rotation until the tire is pressed against a drum with a diameter of 1707 m and rotated at a predetermined speed (80 km/h) until it stops. Calculated from numbers. Comparative example 1
It is expressed as an index with 100.

Also, it was installed on a passenger car with an exhaust of 11,800cc, and the
Addition to kjI! ! The results of the wear test are shown in Figure 4. It can be seen that the amount of wear of the product of this example is reduced.

Furthermore, FIG. 5 shows the amount of wear, that is, the amount of shoulder drop at the edge a where the tread surface 12 and the sidewall portion 4 intersect. Similarly, the implementation product is excellent.

In the table, the numerical values in parentheses represent the dispersion of the data, and the average value is shown without the parentheses.

Example 2 A tire with a tire size of 6.40R14 was prototyped according to the specifications of Example 2 shown in Table 1, and compared with the tire of Comparative Example 2. As in Example 1, the tire of Example 2 had the following properties: Compared to the tire of Comparative Example 2, it was superior in rolling resistance and wear resistance.

〔Effect of the invention〕

As described above, in the radial tire for passenger cars of the present invention, the radius of curvature of the tread surface when filled with standard internal pressure is set to be larger within the required numerical range than when filled with low internal pressure. Basically, the amount of outward deformation in the radial direction of the shoulder part of the tire is greater than that of conventional tires, which increases the bonding force between the carcass and Bell II.
It is possible to improve the hoop effect of the belt a and also improve the grounding performance, and by making it possible to touch the ground over a wide range of trend surfaces, the amount of wear is reduced. It also stabilizes the shoulder area, prevents uneven wear such as shoulder drop wear, and increases the durability of the tire. Furthermore, increasing the rigidity of the shoulder section can reduce rolling resistance, improve fuel efficiency, increase cornering power, and improve handling stability, among other benefits.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing one embodiment of the present invention, Fig. 2 is a line diagram showing deformation of the tread portion due to standard internal pressure filling, Fig. 3 is a cross-sectional view showing the shoulder portion in detail, and Fig. 4-5 The figure is a diagram showing the results of an abrasion test, and FIG. 6 is a diagram showing a conventional tire structure with only a carcass and a belt layer. 2...-bead core, 3--bead section, 4--side wall section, 5--trend section, 6--carcass, 7-belt layer, 10...-rim,
12- Tread surface, 12A-... Crown portion of tread surface, 12B... Shoulder portion of trend surface, RTI・
...Tread surface curvature radius at 10% pressure, RT2--tread surface curvature radius at standard internal pressure, PCI...curvature radius of carcass shoulder section at 10% pressure, RC2... - The radius of curvature of the shoulder part of the carcass when the standard internal pressure is applied, DB - The outer diameter of the belt layer when the standard internal pressure is applied. Patent Applicant Sumitomo Rubber Industries Co., Ltd. Agent Patent Attorney Tadashi Naemura Figure 2 Figure 4I2! Acceleration Award Authenticity 1 Test Tire Size: 5.60F? 13 Old Man 5 Figure 1 = Iwo Y Gokei (no km) 3rd Wie Figure 6 June 26, 1986 3. Relationship with the person making the amendment case Patent applicant address Tsutsui-cho, Chuo-ku, Kobe City 1-1-1 Name: Katsura, Representative of Sumitomo Rubber Industrial Beast Company 1) Yario 4, Agent Address: 4-2-26 Nishinakajima, Yodoyou-ku, Osaka-Tenjin Dai 1
Building Telephone (06) 302-1177 Name (82
96) Patent attorney Tadashi Naemura 5, Number of inventions increased by amendment None 8, Catalog in order of 11,000 per cent (1) Figure 2 of the amended drawings
1i+! 1st 2nd! Y!

Claims (2)

[Claims] (1) Assemble the rim to the standard rim, and set the standard internal pressure to 1
The radius ratio RT2/RT1 of the radius of curvature RT1 of the tread surface when applying 0% pressure to the radius of curvature RT2 of the tread surface when applying standard internal pressure is 1.10 or more and 1.40 or less, and the organic fiber cord The radius of curvature RC1 when the above-mentioned 10% pressure is applied and the radius of curvature RC2 when the standard internal pressure is applied to the shoulder part of the carcass where the carcass consisting of at least one ply of the layer passes near the tread shoulder part.
The radius ratio RC2/RC1 is 0.65 or more and 0.85
The following radial tires for passenger cars. (2) The radius of curvature RT when the standard internal pressure is applied
2, the ratio RT2/DB of the radius of curvature RT2 and the outer diameter DB of the belt layer disposed annularly on the outside of the carcass inside the tread surface when a standard internal pressure is applied is 0.
The radial tire for a passenger car according to claim 1, characterized in that the tire has a diameter of 42 or more.