JPS60116505A - Bias tire - Google Patents

Abstract

PURPOSE:To improve comfortableness to drive, flat spot or the like by forming the captioned tire, which has a carcass with fiber cords of predetermined extension arranged at a predetermined angle, through burying soft rubber of predetermined hardness between the carcass and the tread. CONSTITUTION:Soft rubber 15 of JIS hardness 40-50 deg. is buried covering the whole area of a tread part 2 between a carcass 5 and a tread 2 of a bias tire equipped with the carcass 5 formed by arranging the plural number of plies, formed by arranging fiber cords with a constant load extension 3-8% according to JIS L1017 provisions at angles of 40-50 deg. with respect to the circumferential direction of the tire, in such a manner as the cords cross with each other between plies. THe width WR of this soft rubber in this case is limited to 90- 110% of the width WT of the tread. Comfortableness to drive, flat spot or the like can be improved due to this structure.

Description

Detailed Description of the Invention The present invention uses a fiber cord with low elongation in the carcass, and embeds soft rubber in the lower part of the tread to improve riding comfort.
This article relates to bias tires with improved flat spots, etc.

In general, bias tires for small trucks and the like are set at an air pressure suitable for a constant load condition, regardless of the load of the cargo. Therefore, when the vehicle is traveling in an empty state, it is unable to absorb shocks caused by road joints, unevenness, etc., resulting in poor ride comfort. Recently, from the viewpoint of noise pollution prevention and flat spot vibration countermeasures, the carcass cord material has been shifting from conventional nylon fibers to low-elongation polyester fiber cords. However, fiber cords with low elongation have a high elastic modulus and poor vibration absorption, which impairs ride comfort.

Increasing the angle of the force chord in the tire circumferential direction reduces the tire's longitudinal spring constant and increases the so-called envelope effect, improving ride comfort, but it also reduces cornering power and increases the lateral spring constant. The constant also decreases, and the steering stability also deteriorates. As described above, ride comfort has characteristics that are contradictory to low noise, flat spots, cornering power, and steering stability, but the present invention aims to provide a bias tire that comprehensively balances these characteristics. purpose.

The present invention consists of a fiber cord consisting of an I/red part, both sidewall parts, and both bead parts, and has an elongation of 3 to 8% under constant load according to JIS L-1017 regulations, and is made of a fiber cord that is 40° to 50° with respect to the tire circumferential direction. In a bias tire equipped with a carcass in which a plurality of plies are arranged at an angle of 50°, the cords cross each other between the plies, and the entire tread area between the carcass and the tread has a JIS hardness of 40 to 58.
This is a bias tire with improved ride comfort, featuring embedded soft rubber.

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

FIG. 1 shows the right half of a cross-sectional view of the bias tire of the present invention.

In the figure, a bias tire 1 consists of a tread portion 2, a sidewall portion 3, and a bead portion 4, and a carcass 5.
consists of four inner plies 7.8.9.10 whose ends are folded back around the bead core 6 from the inside to the outside, and two outer plies II and 12 whose ends are folded back from the outside of the bead core 6 inward. It is equipped with

Both ends of the inner ply 7.8.9.10 are folded back around the bead core 6 and are stepped relative to each other to prevent overlapping stress concentration points. On the other hand, both ends of the outer plies 11 and 12 are terminated at the bead bottom without being wound around the bead core 6. The cords of each ply of the carcass are arranged at an angle of 40'' to 50'' in the tire circumferential direction in the tire equatorial plane, and the cords of adjacent plies are arranged so as to cross each other. If the cord angle is smaller than 40°, the envelope effect will be small and riding comfort will be reduced, which is undesirable. On the other hand, if it exceeds 50°, cornering power and lateral spring constant will be reduced, resulting in poor steering stability, which is undesirable.

A hard rubber, for example, JIS hardness 65°, extends radially outward from the upper side of the bead core 6 in a portion surrounded by the inner plies 7.8.9 and io and the outer ply 11.12.
~95° bead apex 13 has been installed to strengthen the bead Toden. Further, at least one reinforcing layer 14 is arranged to surround the bead core 6 and bead apex 13. This reinforcing layer 14 is composed of an organic fiber cord such as nylon, polyester, rayon, or aromatic polyamide fiber cord, or an inorganic fiber cord such as steel. This increases the rigidity of the sidewall portion, and its upper end 14a extends to near the tire maximum rp or ffp. The reinforcing layer is preferably composed of two plies, and in this case, one ply has its upper end fixed near the height of the bead apex 13.

In the present invention, soft rubber 15 is embedded in the lower part of the tread part and above the crown part of the carcass over the entire tread part. That is, the width WR of the soft rubber 15 is approximately equal to the width WT in the tread, that is, the width WR is in the range of 90 to 110% of the width WT. WRY (If WT is less than 90%, the impact absorption effect of the soft rubber cannot be expected. On the other hand, if it exceeds 110%, both ends of the soft rubber will be close to the surface of the buttress 16,
The deformation strain in this portion becomes severe, making it more susceptible to damage. In addition, soft rubber with a JIS hardness of 40 to 58 degrees is used, but if it is less than 40 degrees, the rigidity of the entire tread part will decrease, which will not only have a negative effect on wear resistance but also cause damage such as block chipping. Easy to accept, and JIS hardness is 58
This is because if the angle exceeds 100°, the rear guard effect of the unevenness will almost disappear. Furthermore, add 15 mm of soft rubber to the upper side of the carcass.
ta, is arranged with a thickness of ~1.0 s. It is preferable to arrange this soft rubber adjacent to the carcass, but it may also be buried inside the trend part away from the carcass as a deformable side. In this case, the boundary between the soft rubber and the tread part is in the tread groove. A small amount (3 cranes is required) from the bottom of the groove. In the present invention, abrasion-resistant rubber is used for the 1-red portion as in the past.

In the present invention, a fiber cord with low elongation, that is, a fiber cord with an elongation under constant load of 3 to 8% according to JIS L-1017 regulations, is used as the ply cord of the carcass. Here, for example, low molecular weight polyester, aromatic polyamide, etc. are preferably used as the fiber cord with low elongation, and in this case, it is extremely advantageous from the viewpoint of reducing tire noise, reducing flat spot vibration, and improving cornering power. be.

As described above, the present invention aims to reduce tire noise, flat spots, and improve cornering power by using a fiber cord with low elongation as the ply cord of the carcass, and also to solve the disadvantages caused by using a fiber cord with low elongation. By using a specific soft rubber, it is possible to improve ride comfort and provide a bias tire with excellent overall performance characteristics.

EXAMPLE Various types of tires were manufactured as trial tires with internal structures of rib type light trucks having tire sizes of 7.00 to 15.10 PR as shown in FIG. 1 and Table 1, and their tire characteristics were evaluated. In addition, the polyester t used in Table 1
The IIll fiber has an elongation of 5% under constant load according to JIS L-1017.

Tire noise was measured by placing a sound-collecting microphone directly next to the tire at a distance of 10 mm from the center of the tire RP under driving conditions of an internal pressure of 5.0 kgf/ci, a load of 1080 kgf, and a speed of 43 km/h.
Measurements were taken in an anechoic chamber with a distance of 0 cm and a height of 25 cm from the ground plane.

(Compliant with tire noise test method stipulated by JASOC606) Ride comfort and PJ longitudinal stability were evaluated by actual vehicle tests.
The IF value is calculated using the point system, and the larger the number, the better it is.

It is recognized from Table 1 that the present invention has comprehensively excellent properties.

[Brief explanation of drawings]

FIG. 1 shows the right half of a cross-sectional view of the bias tire of the present invention. ■・-・Tire, 2--Tread section, 3--Side wall section, 4--Bead section, 5--...
Carcass, 6--Bead core, 7.8.9, l〇-Inner ply, 11.12--Outer ply, 13-Bead apex, 14-Reinforcement layer, 15-Soft rubber. Patent applicant Sumitomo Rubber Industries Co., Ltd. Agent Patent attorney Tadashi Naemura

Claims (2)

[Claims] (1) A fiber cord consisting of the tread portion, both sidewall portions, and both bead portions and having an elongation of 3 to 8% under constant load according to JISL-1017 regulations is used to extend 40 to 50” in the circumferential direction of the tire. A bias tire with a carcass in which multiple plies are arranged at an angle so that the cords intersect each other between the briars, has a JIS hardness of 40 to 58° in the entire trend area between the carcass and the tread. Bias tires with improved ride comfort featuring embedded rubber. (2) The bias tire according to claim 1, wherein the mf4I cord is a polyester fiber cord.