JPS60143110A - Radial tyre excellent in ride comfortableness - Google Patents

Abstract

PURPOSE:To improve ride comfortableness by arranging two different kinds of rubber each having its own specific coefficient of complex elasticity to the central part and the upper/lower end parts of the side wall of a tyre, respectively. CONSTITUTION:The side wall 6 of a tyre is divided into three parts: a central part 7 located in the vicinity of M corresponding to the maximum width of the tyre, an upper end part 8 connecting the central part 7 to a tread part 5, and a lower end part 9 connecting the central part 7 to a clinch-apecks 10. Rubber having a coefficient of complex elasticity of 30-50kg/cm<2> is used for the central part 7, while rubber having a coefficient of complex elasticity of 50-80kg/ cm<2> is used for both upper and lower parts 8 and 9. Height h1 of the lower end 7b of the central part 7 from the bead part 2 is set at 40-60% of the sectional height H of the tyre, while height h2 of the upper end 7a of the central part from said bead part 2 is set at 60-70% of H. With this contrivance, an intersecting angle formed by a carcass profile and the road surface becomes small, thereby enhancing absorbing/damping effect to deformation-related strain in a flex-zone so as to improve ride comfortableness.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a radial tire with improved riding comfort, particularly to a radial tire for passenger cars.

Generally, in a radial tire, a belt layer in which the cords are arranged at a relatively shallow angle to the tire equator is placed outside the crown of a toroidal carcass in which the cords are arranged in the radial direction, and the cords in the belt layer are made of steel, aramid, etc. A material with a high elastic modulus is used. Therefore, radial tires are highly effective depending on the belt layer, and while the tread rigidity is increased, it has excellent wear resistance and handling stability, while the tread part is difficult to deform when driving and going over bumps on the road surface. Without being absorbed by the sidewalls, the impact is transmitted from the bead to the wheel rim and then to the axle, causing vibrations that impair ride comfort. Therefore, in radial tires, wear resistance, handling stability, and ride comfort are in a conflicting relationship, and many proposals have been made to improve ride comfort, but most of them are based on the characteristics of the former two and the latter. This has been done from the perspective of how to balance the

The present invention maintains high rigidity of the tread portion to improve handling stability and
Riding comfort is advantageously improved by effectively absorbing and mitigating vibrations caused by shocks applied to the tread using Zidewall without sacrificing the basic characteristics of wear resistance.

The present invention comprises a pair of left and right bead cores, a toroidal carcass whose ends are folded back around the bead cores, a belt layer disposed outside the crown portion of the carcass, and an annular tread disposed above the belt layer. and a pair of zyde walls extending from both ends of the tread portion in the direction of the bead portion, the zyde walls being arranged at a center portion located near the two sides of the maximum width of the tire, and an upper end portion connecting the center portion and the tread portion. The central part is divided into three parts at the lower end connecting the clinch-pex, and the central part is made of rubber having a complex modulus of elasticity (E*) of 30 to 50 kg/cnl, and the upper and lower ends are made of rubber having a complex modulus of elasticity (E*) of 30 to 50 kg/cnl. Complex modulus of elasticity (E*) is 50
This is a radial tire with excellent riding comfort, characterized by the fact that each tire has a rubber of -80 kg/cn.

Embodiments of the radial tire of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing the right half of the radial tire of the present invention.

In the figure, a radial tire (1) includes a toroidal carcass (3) whose end is folded back around a bead core (2) and a belt layer (4) disposed outside the crown of the carcass. There is. The carcass has a so-called radial structure in which organic fiber cords of polyester, nylon, rayon, aramid, etc. are arranged in the radial direction of the tire. Further, the belt layer has cords having a high elastic modulus such as steel or aromatic polyamide arranged at a relatively shallow angle with respect to the tire equator, for example, at an angle of 10 to 30 degrees. Next, in the present invention, an annular 1-red portion (5) is arranged above the belt layer, and furthermore, Zide walls (6) extending from both ends of the tread portion (5) toward the bead portion are arranged. There is. The Zyde wall (6) includes a center portion (7) located near the upper side of the tire maximum width position, an upper end portion (8) connecting the center portion (7) and the tread portion, and the center portion (7). It is divided into three parts at the lower end (9) that connects the clincher pex (10), and the center part (7) has a complex modulus of elasticity (E*) of 30-5".
The upper end part (8) and the lower end part (9) are made of Okg/cot rubber and have a complex 1Uailability ratio (E*) of 50 to 80.
kg/cnJ rubber is used. And “C central part (7
) is located on the − side of the tire maximum width position (M),
The height hl) of the lower end (7b) of the center part from the bead part is 40 to 60% of the tire cross-sectional height 11), preferably 4
It is in the range of 8 to 55%, and furthermore, the height h2) of the upper end (7a) of the center part from the heat part is the tire cross-sectional height 11)
It is in the range of 60 to 70%.

In order to improve handling stability and wet grip during high-speed driving, it is necessary to widen the tread contact area, and for this purpose, the deformation behavior of the cross-sectional shape of the tire is shown in the unloaded state of curve △, as shown in Figure 2. In the transformation from the carcass profile of curve B to the carcass profile of the loaded state of curve B, the carcass profile of the loaded state changes to the road surface (
It is important to form a flex zone (F'R) that is largely deformed in the region close to G) and to expand the ground contact rl]. - In order to improve ride comfort, the carcass profile (curve B) must be at a shallow angle (θ) with the road surface (G).
) and the flex zone (FR
), it is necessary to use rubber that is highly effective in absorbing and attenuating deformation strain in order to effectively cushion the impact from the tread and improve riding comfort. In the present invention, the positions and rubber physical properties of each component of the Zydewall are defined as described above, and are also made from viewpoint A. Therefore, the complex elastic modulus (E*) of the rubber in the central portion located in the flex zone (FR) is 50 kg/cn? If it exceeds 30 kg/cut, the absorption of impact from the tread portion will not be sufficient, while if it is less than 30 kg/cut, the amount of deformation will be too large and cracks will easily occur, which is not preferable. Further, the upper end portion 8 is connected to the tread portion (5) having relatively high rigidity, and since no structural fault is formed between the two due to dissimilar rubber, the complex modulus of elasticity (E*) is 50-80. kg
/ clff rubber is used. - The crab end (9) is connected to the clincher pex (10) which has high hardness, and together with the bead apex (11), it increases the rigidity of the bead part and relatively increases the lateral rigidity, which is a drawback of radial tires. Hard Goto has a complex modulus of elasticity (E*) of 50 to 8.
A comb of 0 kg/c% is used.

Here, the complex elastic modulus (E*) was measured using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho Co., Ltd. at a strain of 2% and a humidity of 30°C.
, the results were measured at a frequency of 1011z. In the present invention, the comb in the central portion (7) has a large amount of deformation and is therefore susceptible to mechanical and chemical deterioration. Therefore, in order to sufficiently withstand these deteriorations, a comb composition based on carbon black is used. It will be done.

In this way, the present invention divides the Zydo λ-ru comb into three parts, places a flexible rubber in the flex zone above the tire's maximum IIJ position, and places comparatively hard combs on both sides below the tire. Based on the unique deformation behavior of the cross-sectional carcass, the tread contact period is widened, maintaining high steering stability and improving ride comfort.

Example tire size 195/70. Tires were prototyped using R1/I 89H radial tires for passenger cars according to the specifications shown in Table 1, and the handling stability and riding comfort of each tire were evaluated.

(1) Ride comfort evaluation method Rim: 5 1/2J Internal pressure: 2, Okg/ci! Load: 360kgf Drum: Smooth surface with a diameter of 1.59m.
Fix a 10mm x 10 square protrusion.

The above load was applied to the tire shaft, and the axial force applied to the tire shaft when the tire ran over a protrusion during drum rotation was recorded, and its fluctuations (maximum value and attenuation of the waveform) were measured.

(2) Steering stability A feeling test was conducted by driving an actual vehicle and evaluated using a 5-point system, with the higher the value, the better. The running conditions are as follows.

Internal pressure: 2. Okg/c vehicle Both Soarer (2000cc FR gasoline vehicle) Crew: 1 person Test course: JΔFze1 (Okm/h ~ 18 (lk)
m/h) Rim: 5]/2J It is clear from Table 1 that the tire of the present invention has improved ride comfort.

[Brief explanation of the drawing]

FIG. 1 shows the right half of the cross-sectional view of the tire of the present invention, and the second
The figure is a schematic diagram showing the deformation behavior of the cross-sectional shape of the tire. ■ Radial tire 8 Upper end 2 Bead core 9 Lower end 3 Carcass 10 Bead apex 4 Belt layer 5 Tread part 6 Zide wall 7 Central part Patent applicant Sumitomo Com Industries Co., Ltd. Agent Patent attorney Yoshihira Nakamura Figure 1 Figure 2

Claims (1)

[Claims] (1) A pair of left and right bead cores, a loid-shaped carcass whose ends are folded back around the bead cores, and a belt layer disposed outside the crown portion of the carcass and an annular-shaped carcass disposed above the belt layer. a tread portion and a pair of sidewalls extending from both ends of the tread portion toward the bead portion, the sidewalls having a center portion located near the upper side of the tire maximum width position, and an upper end connecting the center portion and the tread portion. The central part is divided into three parts, and a lower end part connecting the central part and the clincher pex, and the central part has a complex modulus of elasticity (E*) of 30 to 50 kg/c++! rubber, and the upper and lower ends have a complex modulus of elasticity (E*) of 50 to 80 kg/cn? A radial tire with excellent ride comfort characterized by the arrangement of different rubber parts.