JPH10157408A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance durability by preventing peeling of the end of the folded part of a carcass and to facilitate tire molding. SOLUTION: This tire includes a carcass including an involute carcass ply 7 provided with a ply part 7b where the periphery of a bead core 5 is plied from outside to inside along the direction of the tire axis, at a main body part 7a leading from a tread part 2 to a bead part 4 via a side wall part 3, and also includes a belt layer 9 consisting of two or more belt plies placed inside the tread part and radially outside the carcass, the involute carcass ply being formed of two ply pieces 10A, 10B split from each other along the direction of the tire axis at the tread part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire having improved durability of a bead portion and easy molding without reducing rigidity.

[0002]

2. Description of the Related Art Conventionally, pneumatic tires used for passenger cars, trucks, buses, and the like have a carcass ply e.
As shown in FIGS. 10 (A) and 10 (B), the bead core f is wound up from the inside in the tire axial direction to the outside at the bead portion f. In a tire used for a truck, a bus, or the like, a carcass ply has a bead portion f at an upper end of a winding portion h.
Above, to increase the rigidity of the bead part.

[0003]

In the tire formed as described above, during running, the compressive force repeatedly acts on the sidewall portion and the bead portion. Occurs.

In order to solve such a problem, it is conceivable to wind up the carcass ply from the outside in the axial direction of the tire to the inside, and cover the winding end where the peeling occurs at the main body of the carcass.

However, simply changing the direction of winding of the carcass ply from the outside to the inside can eliminate the peeling of the winding end, but at the time of forming the tire, using a molding machine used for forming a conventional tire. However, there is a problem in that the unit cannot be turned up, special equipment is required, and work efficiency is poor.

As a result of repeated research and experiments, the inventor has found that the carcass ply wound inward in the axial direction can be separated at the tread portion in the tire axial direction, thereby preventing peeling at the winding end of the carcass ply. They have found that a molding die for a tire can be used, and have completed the present invention.

[0007] The present invention prevents the end portion of the winding portion of the carcass ply from peeling, increases the durability of the bead portion,
It is intended to provide a pneumatic tire that can be easily formed.

[0008]

According to the present invention, there is provided a main body extending from a tread portion to a side wall portion and extending to a bead portion. A carcass including the provided inner winding carcass ply, and a belt layer comprising two or more belt plies disposed inside the tread portion and radially outside the carcass, and the inner winding carcass ply is provided with a tread. A pneumatic tire formed by two ply pieces divided in a tire axial direction at a portion.

The carcass ply is wound around the bead core from the outer end in the tire axial direction to the inner side. As a result, the compressive force acting on the sidewall portion and the bead portion, which acts repeatedly when the tire is running, is received by the main body passing through the outer wall of the tire, and the compressive force acting on the winding portion is greatly reduced. Therefore, even at the end of the winding portion, the durability of the bead portion can be improved without peeling.

The inner winding ply is formed of two ply pieces divided in the tire axial direction at the tread portion. By dividing the inner winding ply in this way, winding of the ply into the bead core at the time of molding is facilitated. On the other hand, the tread portion is provided with a belt layer composed of two or more belt plies outside the inner winding ply, so that the carcass is formed by two ply pieces disassembled in the tire axial direction. The tire frame can be formed in cooperation with the belt layer, the vertical rigidity of the tread portion and the lateral rigidity of the sidewall portion can be secured, and various running performance of the tire and durability of the tread portion can be maintained.

According to a second aspect of the present invention, each ply piece forming the inner winding carcass ply is brought into close contact with the belt layer, and an edge of the ply piece facing each other has a gap of 0.8 times or less the belt width b. It is preferable that they face each other as a.

Further, the inner carcass ply is provided with a gap a of not more than 0.8 times the belt width b between opposing edges of the ply pieces, and is provided outside the ply pieces. A splice ply that is at least 20 mm smaller than the belt width b and that is in close contact with the ply piece may be provided inside the belt layer.

Further, as described in claim 4, the inner winding carcass ply may be configured such that opposing ply pieces overlap each other at a tread portion.

According to a fifth aspect of the present invention, the bead portion may be provided with a bead reinforcing layer for winding the bead core along the outward surface of the carcass. The bead reinforcing layer can suppress the displacement of the winding portion of the carcass and more effectively suppress the occurrence of peeling at the edge of the winding portion.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 and 2, a pneumatic tire 1 is extended radially inward from a tread portion 2 and a pair of sidewall portions 3, 3 extending radially inward from both ends thereof, and from each sidewall portion 3, respectively. And a bead portion (4) having a bead core (5) and fitted to the rim (J).

The pneumatic tire 1 has a body portion 7a extending from the tread portion 2 to the vicinity of the outer side of the bead core 5 of the bead 4 in the tire axial direction from the tread portion 2 to the tire axial direction around the bead core 5. The carcass 6 is composed of one inner winding carcass ply 7 having a winding portion 7b that is turned up from the outside to the inside, winds the bead core 5 and rises radially outward, and the inside of the tread portion 2. And a belt layer 9 disposed radially outside of the carcass 6. The maximum width b of the belt layer 9 in the tire axial direction is set in a range of 0.8 to 1.0 times the tread width TW.

In this embodiment, a bead apex 8 having a triangular cross section using a hard rubber is formed between the main body portion 7a and the winding portion 7b of the inner winding carcass ply 7 and rises from the bead core 5 outward in the radial direction. Provided.

The inner winding carcass ply 7 is divided into two in the tread portion 2 in the tire axial direction, and is formed by two ply pieces 10A and 10B.

The ply pieces 10A and 10B are made of a carcass cord made of an organic fiber such as nylon, rayon, polyester, or aromatic polyamide or steel and arranged in a radial or semi-radial arrangement in which the carcass cord is inclined at an angle of 75 to 90 degrees with respect to the tire equator C. Ply pieces 10A and 10B facing each other
Of the belt width b with respect to the tire axial direction.
Are opposed to each other with a gap a of 0.8 times or less.

The belt layer 9 comprises a plurality of belt plies, in this example, two belt plies, each of which is made of nylon,
Belt cords made of organic fibers such as rayon, polyester, aromatic polyamide or steel or steel are arranged in a direction crossing each other between the plies. In this example, the crossing angle of the cord between the plies is set in a range of 16 to 25 degrees.

A band layer 15 (corresponding to a dashed line in FIG. 1) in which a cord made of an organic fiber such as polyamide or nylon or steel is disposed at an angle of approximately 0 ° with respect to the tire equator C outside the belt layer 9 in the radial direction. ) May be arranged over the entire width of the belt layer or covering only the edge of the belt layer.
By providing such a band layer, lifting of the belt layer 9 during traveling can be prevented, and the durability of the tread portion can be increased.

The ply pieces 10A and 10B are brought into close contact with each other without any gap on the inward surface of the belt ply 9A located on the innermost side of the belt layer 9 in the tread portion 2 in the radial direction.

Two divided ply pieces 10A, 10B
In the inside of the belt layer 9 of the tread portion 2, the stress in the axial direction of the carcass cord due to the filling air pressure is extremely small. Therefore, the two ply pieces 10A and 10B
The tire frame is formed integrally with the belt layer 9 having the above configuration. Such divided ply pieces 10A, 10A
The carcass 6 made of B can secure the vertical rigidity of the tread portion 2 and the lateral rigidity of the sidewall portion 3.

If the gap a becomes larger than 0.8 times the belt width b, the joining area where the carcass 6 and the belt layer 9 overlap becomes small, and the rigidity of the entire tire becomes insufficient. Peeling occurs from the edges F, F of 10A, 10B, and reduces durability.

In the tread portion 2, as shown in FIG. 3, two radially outer portions of the divided ply pieces 10 A and 10 B and an inner side of the belt layer 9, which are at least 20 mm smaller than the belt width b, Ply pieces 10A, 10B
And a splice ply 11 that is in close contact with each of the ply pieces 10A and 10B can be provided. The joining ply 11 is formed as a ply having substantially the same configuration as the ply pieces 10A and 10B. Ply 11
When the belt is formed to have a wide width, peeling is likely to occur at both end edges of the joint ply 11 in the axial direction of the tire during running, so the width must be at least 20 mm smaller than the belt width b.

Also, as shown in FIG.
A and 10B may be arranged so as to overlap each other on the inner side of the belt layer 9 of the tread portion 2 with the overlapping portion 16 provided. The overlapping portions do not necessarily need to be in close contact with each other, and may be in any state in which they are in close contact with each other without any gap.

As shown in FIGS. 5, 6, and 7, the carcass 6 is provided with two inner winding carcass plies 7 arranged inside and outside.
a, 7b. In this case, the gap a formed between the respective edges of the respective ply pieces 10A, 10A, 10B, 10B, including the inner and outer two carcass plies 7a, 7b. One is set to be 0.8 times or less the belt width b.

The inner winding carcass ply 7 is, as described above,
A winding portion 7b is provided around the bead core 5 from the outside toward the inside in the tire axial direction. The height h1 of the winding portion 7b from the bead base line L is 0.7 to 5.2 of the flange height H of the rim J in this example.
The range is doubled.

When the ratio h1 / H is less than 0.7, the inner winding carcass ply 7 cannot withstand the tensile force due to the internal pressure.
The running-in portion 7b is liable to slip off during running, and even if it exceeds 5.2 times, there is no change in the peeling resistance of the end portion and the weight increases.

The bead apex 8 is JIS in this example.
It is made of a hard rubber having an A hardness of 80 to 90 degrees and increases the rigidity of the bead portion 4. In this example, the height h4 of the bead apex 8 from the bead base line L is larger than the height h1 of the winding portion 7b of the inner winding carcass ply 7, so that the rigidity of the bead portion is further increased and the main body portion 7a And the winding part 7b.

The main body 7a at the leading edge P of the winding portion 7b
The distance A from is set to 2.5 mm or more in this example.
If it is less than 2.5 mm, the distortion generated at the leading edge P of the winding portion cannot be suppressed, and the distance A is preferably 2.5 to 18 mm. If the diameter is increased beyond 18 mm, the bead apex 8 in the bead portion 4 becomes thick, the lateral rigidity of the tire becomes excessive, and the maneuverability decreases.

Further, in this embodiment, a bead reinforcing layer 12 is provided along the outward surface of the carcass 6 in the bead portion 4. This bead reinforcing layer 12 is formed by the inner winding carcass ply 7.
And a cord made of strong organic fibers such as aromatic polyamide or steel, and covered with a topping rubber.

The bead reinforcing layer 12 is provided on the main body 7a.
A folded portion 12b is provided integrally with a base portion 12a along the outer side surface of the winding portion 7b so as to rise on the inner surface in the tire axial direction of the winding portion 7b. The height h2 of the tip of the base portion 12a from the bead base line L and the folded portion 12b are formed. The height h3 of the leading end from the bead base line L is set to be smaller than the height h1 of the winding portion 7b of the inner winding carcass ply 7, and the peeling from each leading end of the bead reinforcing layer 12 as a starting point. The occurrence of is prevented. It is not preferable that the heights h2 and h3 are close to the height h1 of the winding portion 7b because a large step is generated in the bending rigidity of the bead portion.

FIG. 8 shows an example of the structure of a bead portion 4 in a tire mounted on a 15 ° taper rim J 'used for a heavy-duty tire, for example. Also in this example, the heights H, h1, h2, h3, and h4 of the inner winding carcass ply 7 and the bead reinforcing layer 12 are formed in substantially the same relationship as that of the configuration shown in FIG.

Since the inner carcass ply is divided into two ply pieces 10A and 10B in the tire axial direction,
As shown in FIGS. 9 (A) to 9 (C), a single-stage type usually used for molding a tire can be used as it is.
However, since the ply is divided, it is difficult to maintain the regular contour of the carcass against the sheping pressure, so the molding ladder is reinforced with a cord of polyamide, steel or the like oriented in the tire axial direction. Preferably, Prada K is used.

[0036]

EXAMPLES Test 1 The tire size was 11 / 70R22.
5 14P. For the R truck bus tire, the tread portion 2 had the configuration shown in FIG. 1 and was prototyped according to the specifications shown in Table 1, and its performance was tested. In addition, the tires (comparative examples 1 to 3) other than the configuration of the present application were also tested together to compare the performance.

The test method is as follows. Driving test each test
Tires on a 7.5 × 22.5 rim and internal pressure
7.75kgf / cm ^TwoRuns on a table under a load of 2700 kgf
Using a row test machine, run continuously at a speed of 50 km / Hr
And the mileage when the tread is damaged
It was determined by Table 1 shows the test results.

[0038]

[Table 1]

[0039]

[Table 2]

Test 2 The tire size was 1000R20 14PR and 11 /
For each tire of 20R22.5 14PR, the tip height h1 of the winding portion 7b in the bead portion 4,
In addition, a prototype was manufactured by changing the heights h2 and h3 of the base portion 12a and the folded portion 12b of the bead reinforcing layer 12 (Examples 11 to 15, 21 to 25), and durability was confirmed. Tires of conventional configuration (conventional examples 11 and 21)
A test was also conducted to compare the performance. Tables 3 and 4 show the test conditions and test results.

[0041]

[Table 3]

[0042]

[Table 4]

[0043]

As described above, the pneumatic tire of the present invention has the following features.
A carcass ply including an inner winding carcass ply provided with a winding portion in which the carcass is wound inward from the outside in the tire axial direction around the bead core, and the inner winding carcass ply is divided in the tread in the tire axial direction. As a result, it is possible to prevent peeling of the folded end of the carcass, which tends to occur in the past, to increase durability, and to use a general tire mold without procuring a special mold, and to mold the tire. Easy to do.

[Brief description of the drawings]

FIG. 1 is a sectional view in the tire axial direction showing an example of an embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing the bead portion.

FIG. 3 is a diagram showing another example of the configuration of the tread portion of the inner winding carcass ply.

FIG. 4 is a diagram showing another example of the configuration of the tread portion of the inner winding carcass ply.

FIG. 5 is a diagram showing another example of the configuration of the tread portion of the inner winding carcass ply.

FIG. 6 is a diagram showing another example of the configuration of the tread portion of the inner winding carcass ply.

FIG. 7 is a diagram showing another example of the configuration of the tread portion of the inner winding carcass ply.

FIG. 8 is a sectional view showing another mode of the bead portion.

FIGS. 9A to 9C are diagrams illustrating an example of a molding process of the tire of the present invention.

FIGS. 10A and 10B are cross-sectional views of a bead portion showing a conventional technique.

[Explanation of symbols]

 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 7 Inner winding carcass ply 7a Main body part 7b Wound part 9 Belt layer 10, 10A, 10B Ply piece 11 Joint ply 12 Bead reinforcement layer a Gap b Belt width F end edge

Claims (5)

[Claims] An inner winding carcass ply having a winding portion wound around a bead core from the outside in the tire axial direction to the inside in the tire axial direction is provided on a main body portion extending from a tread portion to a sidewall portion to a bead portion. A carcass, and a belt layer including two or more belt plies disposed inside the tread portion and radially outside the carcass, and the inner winding carcass ply is divided in the tread portion in the tire axial direction. A pneumatic tire formed by the two ply pieces. 2. The inner winding carcass ply according to claim 1, wherein each of the ply pieces is brought into close contact with the belt layer, and edges of the facing ply pieces are opposed to each other with a gap a of 0.8 times or less the belt width b. The pneumatic tire according to claim 1, wherein: 3. The inner-wound carcass ply has a gap a of 0.8 times or less the belt width b between opposite edges of the ply piece, and the outer side of the ply piece and the inside of the belt layer have the above-mentioned carcass ply. 2. The pneumatic tire according to claim 1, wherein a joint ply having a width at least 20 mm smaller than the belt width b and closely contacting the ply piece is provided. 4. The pneumatic tire according to claim 1, wherein the ply pieces of the inner winding carcass ply overlap each other at a tread portion. 5. The pneumatic tire according to claim 1, wherein said bead portion is provided with a bead reinforcing layer for winding a bead core along an outward surface of a carcass.