JPH0741768B2 - Pneumatic tire - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pneumatic tire having a round tread surface used for aircraft tires and the like.

[Conventional technology and its problems]

In radial tires and belted bias tires, a breaker layer is provided inside the tread portion and outside the carcass to impart a hoop effect to the tread portion and improve the rigidity of the tread portion.

Conventionally, this breaker layer has a ply formed by connecting parallel quadrilateral cloth pieces obtained by obliquely cutting rubberized cloth of a tire cord sewn with a cut edge as a side edge on a tire forming drum. It is formed by winding in the circumferential direction and joining the edges by lap joints.

However, in this case, since the thickness varies due to the lap joint in the tire axial direction, the uniformity of the tire is impaired. Also, in this ply, cutting edges of the cord appear at both edges, and stress concentration is likely to occur at this end, and rubber peeling is likely to occur especially when used as the outermost ply.

Further, when such a ply is used, in the case of a tread surface having an arc shape in the tire meridional cross section, such as an aircraft tire, it becomes difficult to attach the ply, and rubber peeling easily occurs. Further, if the cord is largely tilted with respect to the tire equator in order to allow the carcass to expand due to the expansion of the carcass at the time of tire molding, the one-sided flow due to the price tear becomes significantly large.

On the other hand, for example, Japanese Patent Publication No. 44-17801 discloses that a breaker cord is spirally wound to facilitate the above-mentioned attachment and to form a breaker layer without lap joint. However, the one disclosed in this publication is intended for a flat tire of high speed, and is intended to equalize the stress of each part by changing the winding density at the tread central part and the shoulder part. From the to the other shoulder is continuously wound with a cord.

Therefore, the productivity is poor, and the cords are inclined at the same angle from one shoulder to the other shoulder, which contributes to the vehicle flow.

Further, JP-A-51-55505 discloses a strip (5 to 50 mm
Although it shows that the breaker layer is formed by spirally winding (width), this also continuously winds from one shoulder to the other shoulder with a cord, and has the same problem as the above proposal. .

Further, in Japanese Patent Laid-Open No. 54-126305, in order to increase the rigidity of the tread, a third layer of the metal cord is provided outside the two-layer belt layer made of the metal cord, and a central portion of the tread and portions on both sides of the tread edge. It is proposed that the strength of the portion on the tread edge side be greater than that of the central portion of the tread, by classifying into two parts, and providing a difference in the number of cords to be driven.

However, this one is intended only to make the strength uniform, and does not divide the ply into two parts in the tire axial direction by the gap of the tire equator, much less the direction of the spiral.

The present invention is based on using a plurality of plies formed by spiral winding as a breaker layer, and forming the plies of the outermost layer as ply pieces arranged with a gap on the tire equator and by spiral winding in the opposite direction. Another object of the present invention is to provide a pneumatic tire that can prevent productivity and vehicle flow and can optimize the rigidity distribution of the tread surface.

[Means for solving problems]

The present invention comprises a carcass that folds back the bead portion from the tread portion to the side wall portion, and a breaker layer that is arranged inside the tread portion and outside the carcass, and has an arc-shaped tread surface in the tire meridional section. In the pneumatic tire described above, the breaker layer is formed by spirally winding a rubberized breaker cord at an angle θ whose angle to the tire circumferential direction is substantially close to 0 °, and a plurality of the breaker layers overlap radially inward and outward. The outermost ply is composed of a pair of ply pieces that are symmetrically divided about the tire equator with a gap on the tire equator and that have an outer edge in the tire axial direction extending near the outer edge of the tread portion. In addition, each ply piece of the outermost ply has a rubberized breaker cord wound in the opposite spiral direction. It is a pneumatic tire characterized by being formed by

[Action]

Even with a pneumatic tire having a round tread surface where rubber peeling easily occurs, loosening occurs between the cords by winding the breaker cord at an angle θ substantially equal to 0 ° with respect to the tire circumferential direction. Can be wound without
As a result, the hoop effect in the tire circumferential direction is improved, the strength in the tread circumferential direction is effectively increased, and the cutting edge is substantially absent, so that rubber peeling at the end of the breaker layer can be prevented.

The outermost ply is divided symmetrically around the tire equator with a gap on the tire equator, and the tire outer edge consists of a pair of ply pieces extending in the vicinity of the outer edge of the tread portion. Reinforcement,
The productivity can be improved by preventing the lifting of the shoulder portion at the time of high speed rotation and simultaneously winding and forming each ply piece.

Furthermore, each ply piece is spirally wound at an angle θ substantially close to 0 ° with respect to the tire circumferential direction. Moreover, since the direction of the spiral is reversed in each ply piece, there is no vehicle flow and maneuverability is improved. sell.

〔Example〕

An embodiment of the pneumatic tire according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows only the carcass 1 and the breaker layer 2. The carcass 1 is a carcass ply made of a radial or biased carcass cord that is folded back from the tread portion (not shown) to the sidewall portion and folded back at the bead core of the bead portion. Is used.

Further, the breaker layer 2 is arranged inside the tread portion and outside the carcass, and the tread surface of the tread portion is curved in an arc shape in the meridional section of the tire to form, for example, an aircraft tire.

In the present embodiment, the breaker layer 2 is composed of upper and lower two plies 3 and 4, and the lower ply 3 on the carcass 1 side is
The tread portion is reinforced by providing a hoop effect over substantially the entire width of the tread portion.

Further, in this example, the ply 4 on the tread surface side is the outermost ply, and is a ply piece divided into two with the same width with the inner edge in the tire axial direction being located in the gap G on the tire equator C.
4A, 4B, and the tire axial outer edges of the ply pieces 4A, 4B are located near the tire axial outer edge of the tread portion, in this example, near the outer edge of the lower ply piece 3.

With this structure, the lower ply 3 imparts rigidity to the entire width of the tread, and the upper ply 4 imparts rigidity only to the shoulder portion where rigidity is required. Further, by providing the gap G near the tire equator C, the weight is reduced, the amount of cord used is reduced, and the cost is reduced.

The upper and lower plies 3 and 4 of the breaker layer 2 are formed by continuously spirally winding one breaker cord.

Furthermore, each ply piece 4A, 4B of the upper ply 4 should be spirally wound from the inner edge on the tire equator C side toward the outer edge on the shoulder side or from the outer edge on the shoulder side toward the inner edge on the tire equator C side. Formed by. Also, when winding, the spiral direction is reversed in the ply pieces 4A, 4B, which prevents the vehicle from flowing due to the price tear, and it becomes possible to spirally wind the ply pieces 4A, 4B at the same time. It is possible to wind and form the pieces at the same time, which can shorten the winding time and improve workability.

The angle of the cord with respect to the tire circumferential direction is set to an angle substantially close to 0 °.

Here, substantially 0 ° is an angle with respect to the tire circumferential direction of the cord when the cord is spirally wound while closely contacting the side edges of the cord, and the radius at the winding position, The angle θ can be obtained from the width of the cord, and this value determines the width of the cord so that the angle becomes substantially 0 °.

In addition, from the width W in the tire axial direction of the breaker layer and the winding diameter D, a spiral that makes one turn from one tread edge as a base point to the same point in the tire axial direction of the other tread edge as the base point. The angle θ is given by the following formula, and in the present invention, the code angle is sufficiently smaller than this angle θ.

θ = Tan ^-1 W / πD ... The breaker cord is made of rubber-coated steel cord or fiber cord, and nylon, polyester, rayon or the like is used as the fiber cord, and the material of this cord is appropriately known. You may use the thing of.

The method of spirally winding the breaker cord is the same as the conventional method.

Further, in order to prevent rubber peeling more reliably, a reinforcing layer (not shown) such as rubber or a nylon cord is arranged on the entire width of the ply piece of the breaker layer or a part thereof,
The taga effect can be enhanced.

In the breaker layer, plies other than the outermost ply may be formed by spirally winding a cord, or the ply of the above-mentioned Sudare weave may be used in combination.

When spirally winding, even when using a ply of a woven fabric, it is preferable to set the angle of each cord within the θ angle of the above formula to prevent the occurrence of price tear due to excessive inclination.

〔The invention's effect〕

As described above, in the pneumatic tire of the present invention, by winding the breaker cord at an angle θ whose angle to the tire circumferential direction is substantially close to 0 °, the breaker cord can be wound without causing looseness between cords. Improves the tire circumferential direction hoop effect, effectively increases the tread circumferential direction strength, and has substantially no cutting edge and has a round tread surface, but at the end of the breaker layer. It can prevent the rubber peeling.

The outermost ply is divided symmetrically around the tire equator with a gap on the tire equator, and the tire outer edge consists of a pair of ply pieces extending in the vicinity of the outer edge of the tread portion. Reinforcement,
Prevents lifting of the shoulder during high-speed rotation.

Further, each ply piece on both sides can be formed by winding at the same time, which can improve productivity, and each ply piece is spirally wound at an angle θ with respect to the tire circumferential direction being substantially close to 0 °, and By reversing the direction of the spiral in each ply piece, there is no vehicle flow and maneuverability can be improved.

[Brief description of drawings]

The drawings are cross-sectional views showing a carcass and a belt layer according to an embodiment of the present invention. 1 ... Carcass, 2 ... Breaker layer 3, 4 ... Ply, 4A, 4B ... Ply pieces.

Claims (1)

[Claims] 1. A carcass comprising a carcass folded from a tread portion to a side wall portion and folded back at a bead portion, and a breaker layer disposed inside the tread portion and outside the carcass, and a tread surface in a meridional section of a tire is arc-shaped. In the pneumatic tire described above, the breaker layer is formed by spirally winding a rubberized breaker cord at an angle θ whose angle to the tire circumferential direction is substantially close to 0 °, and overlaps radially inside and outside. In addition to multiple plies, the outermost ply is divided symmetrically around the tire equator with a gap on the tire equator, and consists of a pair of ply pieces whose axial outer edge extends in the vicinity of the outer edge of the tread portion. , And each of the ply pieces of the outermost ply has a single rubberized breaker cord wound in the opposite spiral direction. A pneumatic tire characterized by being formed by being.