JPS63203403A - Heavy-duty radial tire - Google Patents

Abstract

PURPOSE:To sharply reduce instability due to rolling, by setting up a carcass ply reinforced layer adjacently at least in the inner part of a carcass ply ranging from a bead part to the vicinity of both ends of a belt layer. CONSTITUTION:In a carcass ply 3, steel cords are disposed at a angle of 70 deg.-90 deg. to the circumferential direction of a tire, and both ends of it and turned up on the circumference of a bead core 2 and engaged therewith. And, in a belt layer 4, the steel cords are disposed at the outside of a crown part of the carcass ply 3 at a shallow angle in the tire circumferential direction. In addition, a bead apex 5 is gradually reduced of its thickness and extended toward a sidewall from an upper side of the bead cores 2 between the carcass ply 3 and the turnup part. In the above structure, at least in the inner part of the carcass ply 3, there is additionally provided with a carcass reinforced layer 6A. With this carcass reinforced layer, instability due to rolling is sharply reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high-load radial tire that can be suitably used for cargo handling vehicles such as industrial vehicles and construction vehicles, and has improved running stability and vibration damping performance.

[Prior art]

In the past, so-called bias tires were often used as tires on which heavy loads were applied, such as tires for industrial vehicles and tires for construction vehicles.However, in recent years, radial tires that use steel cord as the carcass layer have improved in longitudinal spring constant. It is becoming widely used because of its low ride comfort and excellent wear resistance.

[Problem that the invention seeks to solve]

However, this kind of radial tire is especially suitable for forklifts)
When used in an L-rack or the like, there are many opportunities for turning, starting and stopping, and rolling, pitching, etc. tend to occur each time. Furthermore, when driving over bumps on the road surface, the vehicle body will experience unstable lateral sway. This phenomenon is not a big problem when used as a tire for a passenger car, etc., but becomes a problem to be solved when used for an industrial vehicle such as a forklift truck.

An object of the present invention is to provide a high-load radial tire that can solve the above-mentioned problems by reducing lateral vibration and improving vibration damping properties when the radial tire turns, runs, climbs over protrusions, etc. It is said that

[Means for solving problems]

In the present invention, the steel cord is
A carcass ply arranged at an angle of 90° to 90° and folded at both ends around the bead core to be locked; a belt layer in which steel cords are arranged at a shallow angle in the circumferential direction of the tire on the outside of the crown portion of the carcass; A bead apex extends from the upper side of the bead core toward the sidewall with a gradually decreasing thickness between the ply and the folded portion thereof, and the bead apex extends along the inside of the carcass ply and faces across the carcass ply. This is a high-load radial tire characterized in that an inner carcass ply reinforcing layer extending from both ends of the belt layer to the bead portion is attached.

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

In FIG. 1, a radial tire 1 includes a carcass ply 3, a belt [4, a bead apex 5, and an inner carcass ply reinforcing layer 6A.

The carcass ply 3 is secured by arranging steel cords at an angle of 70'' to 90° with respect to the tire circumferential direction and folding both ends around the bead core 2, and the belt N4 is
Steel cords are arranged on the outside of the crown part of the carcass ply 3 at a shallow angle in the tire circumferential direction, and in this example, the first belt layer 4A,
It consists of a three-layer body in which a second belt layer 4B and a third belt layer 4C are stacked. Furthermore, the bead apex 5 extends between the carcass ply 3 and its folded portion with a gradually decreasing thickness from the upper side of the bead core 2 in the sidewall direction. is attached. Further, as shown in FIG. 2, an outer carcass ply reinforcing layer 6B can also be provided on the outer side of the carcass ply 3.

Further, in this example, a reinforcement jW7 that goes around the carcass ply 3 that is folded around the bead core 2, and another reinforcement layer 9 that passes through the outer part of the reinforcement layer 7 and extends upward along the bead apex 5 are provided. Note that only one of the reinforcing layer 7 and the reinforcing layer 9 can be used, or both can be omitted.

Here, the carcass ply reinforcements 16A and 6B are for reinforcing the lateral rigidity of the tire side parts, and highly elastic cords such as aramid fibers are preferably used, but organic fibers such as nylon, polyester, and rayon may also be used. I can do it. Further, the carcass ply reinforcing layers 6A and 6B have their cords arranged at an angle of 30° to 90° with respect to the radial direction of the tire, thereby reinforcing the lateral rigidity of the carcass 3 in which the cords are arranged in the radial direction.

As shown in FIG. 2, the upper end of the outer carcass ply reinforcing layer 6B is arranged to partially overlap the first belt layer 4A below both ends of the first belt layer 4A. In addition, the inner carcass ply reinforcement N6A partially overlaps both ends of the first belt N4A via the carcass ply 3, so that the inner carcass ply reinforcement N6A is formed of a belt layer 4 facing each other with the carcass ply 3 in between.
are placed at both ends of the

The lower end of the further outer carcass ply reinforcing layer 6B terminates above the bead core 2 without being locked around the bead core 2.

Further, the lower end of the inner carcass ply reinforcing layer 6A is interrupted above the bead core 2, and the lower part is sandwiched between the reinforcing layer 717 and the carcass ply 3. Note that the lower end portion can also be attached to the outer surface of the reinforcing layer, and in this case, when a steel cord or the like is used as the reinforcing layer, stress concentration in a part can be alleviated.

Furthermore, carcass ply reinforcement 1i6A, 6B is usually 11! when using aramid fibers! On the other hand, when using relatively low-rigidity fiber cords such as nylon, it is preferable to arrange two or more cords in an intersecting manner.

The outer carcass ply reinforcing layer 6B extends in contact with the outer surface of the carcass ply 3, so that on the lower outer surface,
The bead apex 5 is arranged adjacent to the bead apex 5, and the bead apex 5 has a JIS-A hardness of 75″ to 90°.
Hard rubber stiffener 53 and JIS-A hardness 45''~
Formed as a two-layer b4 body of 65° buffer 5B. Note that it may be a single layer of hard rubber, and its upper end extends to a range of 20 to 60% of the cross-sectional height of the tire, reinforcing the bead and side portions and increasing the lateral and longitudinal spring constants of the tire.

〔Example〕

A tire with a tire size of 7.00R12 having the structure shown in FIG. 1 was manufactured as a prototype according to the specifications shown in Table 1, and the tire characteristics such as lateral vibration, damping coefficient, and spring constant were evaluated.

Further, as comparative examples, conventional bias tires, steel textile tires, and steel radial tires were prototyped according to the specifications shown in Table 1.

The characteristics in Table 1 were measured at an air pressure of 7.0 kg f/d.
(bias tire) and 9.0 kg F/d (radial tire).

The tire of the present invention has the following characteristics: the number of lateral vibrations until convergence, the convergence time,
It can be seen that the damping coefficient etc. are superior to conventional tires.

〔Effect of the invention〕

Like a ridge, the present invention has a carcass ply reinforcing layer adjacent to the inside of the carcass ply, extending from the bead to the vicinity of both ends of the belt layer in a steel radial tire, which reduces instability due to lateral vibration compared to conventional steel radial tires. can be significantly reduced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the right half of one embodiment of the tire of the present invention, and FIG. 2 is a sectional view showing the right half of another embodiment of the tire. 1...Tire, 2...Bead core, 3...Carcass ply, 4...Belt layer, 5-Bead apex, 6A-Inner carcass ply reinforcement layer, 6B...Outer carcass Ply reinforcement layer. Patent Applicant Sumitomo Rubber Industries Co., Ltd. Agent Patent Attorney Tadashi Naemura Figure 1 Figure 2

Claims (3)

[Claims] (1) Steel cord at 80° to the tire circumferential direction
A carcass ply arranged at a 90° angle and folded at both ends around a bead core to be locked; a belt layer in which steel cords are arranged at a shallow angle in the tire circumferential direction on the outside of the crown portion of the carcass; and the carcass ply. The bead apex extends from the upper side of the bead core toward the sidewall between the folded portions with a gradually decreasing thickness, and the carcass ply is provided with the belt facing along the inside of the carcass ply and sandwiching the carcass ply. A high-load radial tire characterized by having an inner carcass ply reinforcing layer extending from both ends of the layer to the bead portion. (2) The carcass ply is characterized in that an outer carcass ply reinforcing layer is attached along the outer side of the carcass ply from both ends of the belt layer to the bead portion. radial tire for high loads. (3) The high-load radial tire according to claim 1 or 2, wherein the carcass ply reinforcing layer is made of fiber cord.