JPH01282003A - Pneumatic tyre - Google Patents

Abstract

PURPOSE:To improve uniformity and durability of a tyre by splitting the central part of the tyre crown of a belt layer and winding an organic fiber cord around the split part helically at a specific angle against the peripheral direction of the tyre. CONSTITUTION:Among a plural number of belt layers 51-53, for example, the first belt strengthening layer 51 counted from a carcass layer toward the tread direction is split from the central part of a crown. And in the central part of the crown, a reinforcing layer 50 is provided. That is, the reinforcing layer 5CL is wound helically with a reinforcing cord 5c made of at least one piece of organic fiber actually at the angle 0 deg. against the tyre peripheral direction. Accordingly, the end 5e of the reinforcing cord 5c is only positioned on the side of the reinforcing layer 5CL but does not form any spliced part, and consequently, deformation generated during processes of formation and/or vulcanization of the tyre caused by spliced parts can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a pneumatic tire with excellent tire uniformity and uniformity.

[Conventional technology]

In recent years, the performance required of tires has widened.
Accordingly, various types of tire belt structures have been adopted.

For example, in the case of a radial tire for a passenger car, as shown in FIG. A belt structure in which a belt tension layer 5' having a cord arrangement intersecting with the belt tension layer 5 on the tread 3 side is arranged with both ends thereof bent inward, as shown in FIG. 3B. 5. Belt tension layer having an arrangement of intersecting cords folded inwardly.
Belt structure in which 5゛ is combined and arranged, and furthermore, Fig. 3C
As shown in Figure 2, a belt structure has been proposed in which only the belt layer 5" on the Trend 3 side is separated at the center, and both ends of the belt tension layer 5.5" are wrapped with another reinforcing layer.

By adopting this structure, it is possible to prevent part of the shoulder of the belt layer from rising during high-speed driving, and by providing a separation part in the belt layer in the center of the tire, the rigidity of the center part is lowered, improving steering stability. is ensured. and,
In a tire with this type of structure, a reinforcing layer 6 made of organic fiber cords is arranged at an angle of approximately 0° with respect to the tire circumferential direction in order to maintain a certain degree of rigidity in the tire circumferential direction at the separated portions of the belt layers. is common.

In addition, for heavy-load tires that are subjected to particularly severe running conditions, as shown in FIG. A radial tire with a so-called split structure, in which the center part of the tire is separated and placed in two parts on both shoulders, and the second and third belt reinforcement layers 5□ and 5J are placed on the outer periphery. In order to improve the drawbacks of this tire, such as a decrease in the belt reinforcing effect at the center of the crown and separation at the end of the belt layer, organic fiber cords with a cord angle of 0° to 10° are added to the center of the tire. A radial tire in which a reinforcing layer 5CL is disposed has been proposed (for example, Japanese Patent Laid-Open No. 63-22702).

However, in all of these conventional radial tires, tire constituent materials such as a carcass layer, belt layer, and tread are sequentially laminated to form a green tire, which is then heated and pressurized in a vulcanization mold to form the tire. However, when producing the above-mentioned green tire, for example, the reinforcement N5cL shown in FIG. 4 described above is overlapped at its end portions to form a splice portion S, as shown in FIG.

Radial tires are generally made by making the outer circumference of the green tire smaller than the vulcanization mold before vulcanization, and pressurizing the green tire from the inside in the vulcanization mold to make the tire grow. It is molded and vulcanized by being brought into close contact with the inner peripheral surface of the vulcanization mold (called a lift). However, if this lift is applied, the fourth
In the figure, bell 1 - reinforcement layer 5I and belt tension layer 5□
, 53, the outer circumferential length can grow due to the arrangement structure of its constituent cords, whereas the outer circumferential length is 0'' in the tire circumferential direction.
The reinforcing layer 5ct in FIG. 4, which is arranged at an angle of
As long as overlapping code terminals are not shifted relative to each other,
unable to grow. In reality, the adhesive strength of the splice S is smaller than the tensile strength of the cord, so the growth during tire molding is due to the misalignment of the splice.

As a result, belt reinforcement layer 51 and belt tension layer 5□, 5. As a result, an uneven portion is formed at this splice portion on the circumference of the tire, which causes vibration of the vehicle during high-speed running and a decrease in durability. This phenomenon further increases the disorder of the cords in the belt reinforcing layer 51 in particular.
When tires are installed on a vehicle and a durability test is conducted,
This is supported by the fact that the vicinity of the splice part becomes a factor in deteriorating uniformity and promotes tread wear, and that most peeling failures occur from the splice part during indoor durability tests.

In order to solve this problem, the reinforcing layer 5CL is cut diagonally at a certain angle along its length in order to disperse the splices in the circumferential direction of the tire and improve the uniformity of the tire. One possible method is to distribute the splice parts in the circumferential direction of the tire by winding the tire around the tire, but in this case, the cutting angle with respect to the length direction should be made as small as possible.
It is preferable to have a long diagonal cant in order to disperse the splice portions in the tire circumferential direction.

However, as the cutting angle becomes smaller, it becomes more difficult to cut the reinforcing layer, and it is extremely difficult to stack and combine reinforcing layers canted at such a small angle with the same width (overlap). In addition to significantly worsening workability, deformation of the tire at the splice portion and deterioration of uniformity cannot be avoided, making it impractical.

This phenomenon also occurs in the belt structures of radial tires for passenger cars shown in FIGS. 3A, B, and C.

[Purpose of the invention]

An object of the present invention is to provide a pneumatic tire that prevents deterioration in uniformity and uniformity of the tire due to the splice portion of the reinforcing layer and improves durability.

[Structure of the invention]

The pneumatic tire of the present invention has a plurality of belt layers arranged between the tire tread and the carcass layer.
The tire crown center portions of at least one of the belt layers are spaced apart, and at least one organic fiber cord is spirally wound around the spaced apart crown center portion at a substantially 00 angle with respect to the tire circumferential direction. It is characterized by being rotated.

In the following, the present invention will be described in detail based on the embodiment of the heavy-duty tire shown in FIG. 4. In the case of the passenger car tire shown in FIG. 3, the belt reinforcement shown in FIG. Layer 5. They are essentially the same except that they are omitted.

As shown in FIG. 1A, in the present invention, the first
5th belt reinforcement layer. is spaced apart from the center of the crown, and a cord angle with respect to the tire circumferential direction is arranged at a part of both shoulders at a cord angle of 40" to 750", and at least one organic fiber cord is arranged in the crown center with a substantial angle with respect to the tire circumferential direction. A reinforcement N5cL without splices is arranged around the tire circumference, spirally wound at an angle of 0°.

That is, as shown in FIG. 1B, the reinforcing layer 5CL at the center of the crown includes a reinforcing cord 5 made of at least one organic fiber wound spirally at an angle substantially O'' with respect to the circumferential direction of the tire. Therefore, the terminal 5° is only located on the side surface of this wound reinforcing layer 5CL, and does not form a splice part like a conventional reinforcing layer, and the tire forming caused by the splice part mentioned above , no deformation was observed during vulcanization.

In the present invention, the reinforcing layer 5CL, which has no splice part and is constructed by spirally winding the organic fiber cord around the tire periphery, includes the carcass layer 4 and the second reinforcement layer 5CL as counted from the carcass layer 4 in the trend direction. Since it is provided between the belt tension layer 52 and the second belt tension layer 52, the above-mentioned lift during molding and vulcanization of the tire is prevented from being applied directly to the belt tension layer 52, and this lift is received by the reinforcing layer 5. This makes it possible to mold tires uniformly, that is, to manufacture tires with excellent uniformity.

In the embodiment shown in FIG. 4, the case where the belt tension layer is two layers is illustrated, but the present invention also includes a case where the belt tension layer is three or more layers.

The width of the crown center reinforcing layer 5cL of the present invention is determined by reducing the radial bending rigidity (improving flexibility) in the crown center region, which is susceptible to stress concentration, and by reducing the width of the first belt reinforcing layer 5I for the shoulder region. The selection may be made as appropriate, taking into account the uneven wear of a part of the shoulder due to a decline in the reinforcing effect of the
A range of χ to 45χ is preferable.

In addition, it is preferable for the angle of the organic fiber cord with respect to the tire circumferential direction to be as close to O'' as possible from the viewpoint of tire durability, but it does not have to be strictly θ°, and consideration should be given to improving productivity. However, it is sufficient if the code angle is substantially 00.

The terminal of the above-mentioned wound cord is also as shown in Figure 1.
They may be placed at corresponding positions across the wound cord layers, or may be placed at symmetrical positions (directly opposite positions) on the circumference of the tire.

In the tire of the present invention, the reinforcing layer 5 at the center of the crown
It is desirable that the organic fiber cord of CL is wound regularly along the outer circumference of the tire so that it has a constant width. However, the number of times the cord forming this reinforcing layer is wound around the tire outer periphery, the number of cords, etc. vary depending on the type and size of the tire, and can be selected as appropriate. For example, one of these organic fiber cords may be wound around the outer circumference of the tire, or several cords may be arranged in a band or tape shape and then spirally wound.

The organic fiber cords constituting the reinforcing layer 5CL at the center of the crown of the present invention include textile cords such as nylon 6, nylon 66, polyester fibers, and aromatic polyamide fibers (trade name "Kevlar"), but are not particularly limited. It's not something you can do.

Moreover, the cords of the first belt reinforcement layer 51 and the second and subsequent belt tension layers 5□, 53, etc. that constitute the tire of the present invention are not particularly limited;
It is usually best to use steel cord.

Hereinafter, the effects of the present invention will be specifically explained using Examples and Comparative Examples.

The uniformity of the tires is JASOC607.
In accordance with the Automobile Tire Uniformity Test Method,
Tires - Evaluated by radial run-ahead (RRO) and radial force variation (RPV), which measure tire unevenness as described above.

Examples and Comparative Examples The tire size is ]0OOI+2014pH, and the reinforcing layer is made by arranging nylon cords 5 in a strip shape in parallel to form a reinforcing cord.As shown in FIG. As shown in the tire of the present invention in which a reinforcing layer was formed by regularly winding the nylon cord at an angle of approximately 0° with respect to the tire circumferential direction so as to have a constant width of about 60 mm, and as shown in FIG. Reinforcement cord rubber seams embedded in rubber with a width of about 60 mm! For comparison tires using ・ as a reinforcing layer (circumferential length of the wrap portion at the time of tire molding: approximately 50 mm), RRO
and RFV were measured. The results are shown in the table. Also, R
A chart of RO measurement is shown in FIG.

Note that the cord arrangement angle of the belt layer with respect to the tire circumferential direction is 5. −60°, 5□−206,53=20°.

As mentioned above, the above explanation was based on the example of the heavy-duty tire shown in FIG.
Similarly, the reinforcing layer 6 of the passenger car tire shown in , B, and C is made of organic fiber cords that are substantially 0.6 mm in the circumferential direction of the tire.
By spirally winding at an angle of , it is possible to prevent the cords of the belt layer located on both sides of the separated position in the width direction from being disturbed, and it is possible to obtain a tire that is uniform and has excellent durability.

〔Effect of the invention〕

According to the present invention, the reinforcing cord is placed along the outer circumference of the tire.
By directly winding the tire circumferentially at a substantially 00 angle, a significantly smaller reinforcing layer is formed at the splice,
And since such a reinforcing layer was placed between the belt layers,
The uniformity and uniformity of the tire can be improved, and it can be made to have excellent durability, reduced vibration during high-speed running, and excellent comfort.

[Brief explanation of the drawing]

FIG. 1A is a developed plan view showing the laminated state of the belt layer and reinforcing layer of the tire of the present invention, FIG. 1B is a partial plan view of the reinforcing layer of the tire of the present invention developed in the circumferential direction of the tire, and FIG. A partial plan view showing the reinforcing layer of a conventional tire expanded in the tire circumferential direction.
FIGS. 3 and 4 are cross-sectional explanatory diagrams of essential parts showing trend parts of the radial tire of the present invention, and FIG. 5 is a chart of RRO measurement showing tire uniformity. 1... Tread portion, 4... Carcass layer, 5. ...
Belt reinforcement layer, 5□, 53... Belt tension layer, 5CL
... Reinforcement layer, 5C ... Reinforcement cord, 5Q ... Cord terminal, S ... Splice part. Agent Patent Attorney Nobuo Ogawa −

Claims (4)

[Claims] (1) In a tire in which a plurality of belt layers are arranged between the tread and the carcass layer, the center portion of the tire crown of at least one of the belt layers is separated, and at least one belt layer is provided in the center portion of the separated crown. 1. A pneumatic tire characterized in that an organic fiber cord is wound spirally at an angle of substantially 0° with respect to the circumferential direction of the tire. (2) The pneumatic tire according to claim 1, wherein the spaced apart belt layers are formed of a single ply with both ends bent inward, and the tire is for a passenger car. (3) The pneumatic tire according to claim 1, wherein the pneumatic tire is for use in a passenger car, and the belt layer is formed by combining two plies with one end bent inward. (4) The pneumatic tire according to claim 1, wherein the spaced apart belt layer is a belt reinforcement layer adjacent to the carcass layer, and the tire is for heavy loads.