JP2000085309A - Tubeless tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce weight while enhancing operation stability and riding comfortability with good balance. SOLUTION: Only a rubber inner space part 11i forming a tire inner space face HS is formed of butyl rubber containing 10 wt.pt. or more of butyl rubber or its derivative, in topping rubber 11 of an inner carcass ply 9i located in a tire inner space side. A belt layer 7 comprises at least two sheets of belt ply 7A, 7B in which monofilament codes are arranged with 10-40 degree of angle with respect to a circumferential direction of a tire.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tubeless tire capable of achieving a reduction in weight while improving steering stability and ride comfort in a well-balanced manner.

[0002]

2. Description of the Related Art In a tubeless tire, an inner liner made of butyl rubber having excellent air impermeability is generally adhered to an inner surface of a carcass facing a tire cavity in order to keep air under pressure. .

[0003] However, even in such tubeless tires from which tubes are eliminated, further reduction in weight is desired in response to recent demands for resource saving and fuel efficiency reduction. JP-A-156007 and JP-A-8-113007 disclose that in a carcass ply, only the tire cavity side portion of a topping rubber covering both surfaces of a carcass cord is formed of butyl rubber, or substantially the entirety of the topping rubber. Is formed from butyl rubber.

[0004] Since the carcass ply can serve the function of an inner liner, the carcass ply has the advantage that the conventional inner liner can be omitted altogether and the weight can be reduced.

[0005]

However, as is well known, butyl rubber has low rebound resilience and is inferior in characteristics as a rubber elastic body as compared with diene rubber usually used as a topping rubber. As a result, if this butyl rubber is actually used as a topping rubber, the elasticity and rigidity of the tire will be impaired, and the performance of actual vehicles will be degraded, such as deteriorating the balance between steering stability and ride comfort. Problems occur. If the carcass ply is increased or a diene rubber layer is added in order to maintain the actual vehicle performance, the advantage of weight reduction by adopting butyl rubber is lost.

Therefore, the present invention is based on the fact that the use of butyl rubber is limited only to the tire cavity side portion of the topping rubber and that a monofilament cord is used as a belt cord, thereby improving steering stability and ride comfort. It aims to provide a tubeless tire that can achieve weight reduction while increasing the balance.

[0007]

In order to achieve the above object, the invention of a tubeless tire according to claim 1 of the present application is directed to a carcass having a ply body portion extending from a tread portion to a sidewall portion to a bead core of a bead portion. A carcass comprising a ply, and a belt layer disposed inside the tread portion and outside the carcass, and the ply body portion of the carcass ply located inside the carcass ply on the tire lumen side has a tire cavity. While forming a surface, the carcass ply is composed of a code array body in which carcass cords are arranged in parallel with each other and a topping rubber covering both sides of the code array body, and the topping rubber of the carcass ply in the above is the Only the rubber cavity portion which is provided in the range forming the ply body and forms the tire cavity surface is butyl And a belt layer is formed of at least two belt plies in which monofilament cords are arranged at an angle of 10 to 40 degrees with respect to the tire circumferential direction. It is characterized by:

[0008] In the invention of claim 2, the rubber cavity has a coating thickness from the carcass cord to the tire cavity of 0.2 to 1.0 mm.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, a tubeless tire 1 (hereinafter referred to as a tire 1) is a radial tire for a passenger car in this example, and includes a tread portion 2, sidewall portions 3 extending inward in the tire radial direction from both ends thereof, and each sidewall. And a bead portion 4 located at an inner end of the portion 3. In addition, a carcass 6 extending along the tire lumen H is bridged between the bead portions 4 and 4 on the tire 1, and a radially outer side of the carcass 6 and a tread portion 2.
A belt layer 7 is wound inward in the circumferential direction.

The carcass 6 is formed of at least one carcass ply 9 having a ply body 9A extending from the tread portion 2 to the bead core 5 of the bead portion 4 through the sidewall portion 3. In the tire 1 of the present invention, by not holding the conventional inner liner, the ply main body 9A of the carcass ply 9i located on the side of the tire lumen H in the carcass ply 9 causes the tire lumen surface H
Form S.

In this embodiment, the carcass 6 is formed at one end of the ply main body 9A by a single carcass ply 9 having a ply turn-up portion 9B that turns the bead core 5 from inside to outside in the tire axial direction. The case of a so-called 1-0 structure is illustrated. Therefore, this one carcass ply 9 constitutes the carcass ply 9i.

If required, the carcass ply 9 may have an n-0 structure using a plurality (n) of the carcass plies. Further, as shown in FIG. A 0-1, 1-1, or n-1 structure using the carcass ply 9 having the portion 9C can also be adopted. Especially in the 0-1 structure, the carcass ply 9
The side wall rubber 3G forming the side wall portion 3 and the clinch / chafer rubber 4G forming the bead portion 4 can be vulcanized and adhered to the same type of diene rubber, and thus can be integrated with the conventional tire. The durability can be increased to the level. The bead portion 4 is provided with a bead apex rubber 8 extending radially outward from the bead core 5 passing between the ply body portion 9A and the ply turnover portion 9B or 9C.

As shown in FIGS. 2 and 3, the carcass ply 9 holds the carcass cord 10A with respect to the tire equator C.
It is formed of a cord array 10 arranged in parallel with each other at an angle of 5 to 90 degrees, and a topping rubber 11 covering both sides of the cord array 10. As the carcass cord 10A, nylon, rayon, polyester,
A so-called textile cord obtained by twisting a plurality of filaments made of an organic fiber material such as an aromatic polyamide can be suitably used.

[0014] The carcass ply 9i in the above is
In the topping rubber 11, the ply body 1
Only the rubber cavity 11i that is provided in the range where 0 is formed and forms the tire cavity surface HS is formed of butyl rubber.

Here, butyl rubber refers to raw rubber 10
It means a rubber composition containing 10 parts by weight or more of butyl rubber or a derivative thereof in 0 parts by weight. Butyl rubber (II
R) is a copolymer of isobutylene and a small amount of isoprene, and as a derivative thereof, for example, chlorinated butyl rubber obtained by reacting the butyl rubber with chlorine, bromine, or the like;
A halogenated butyl rubber such as a brominated butyl rubber is used.

The butyl rubber contains natural rubber (NR), butadiene rubber (BR), styrene
Diene rubbers such as butadiene rubber (SBR) can be compounded, and as raw rubber, reinforcing agents such as carbon black, vulcanizing agents, vulcanization accelerators, softeners, etc. Can be added.

On the other hand, in the topping rubber 11, a rubber portion 11o other than the rubber cavity portion 11i, or a topping used for a carcass ply 9 other than the inner carcass ply 9i when a plurality of carcass plies 9 are arranged. The rubber 11 contains the diene rubber in an amount of 90 parts by weight or more, preferably 10 parts by weight, based on 100 parts by weight of the raw rubber, as in the related art.
A non-butyl rubber containing 0 parts by weight is used.

As described above, the rubber cavity 11i of butyl rubber having high air permeability has a function of surrounding the tire cavity H, so that the carcass ply 9 can function as a conventional inner liner. Extensive weight reduction can be achieved by eliminating the inner liner.

Here, the carcass ply 9i in the above is
In order to exhibit the required internal pressure holding performance, the content of butyl rubber or a derivative thereof in the butyl rubber is required to be 10 parts by weight or more as described above, and more preferably 30 parts by weight or more. Preferred for nature.

The coating thickness Ti from the carcass cord 10A to the tire lumen surface HS in the rubber lumen portion 11i.
Is preferably in the range of 0.2 to 1.0 mm. When the coating thickness Ti is less than 0.2 mm, the internal pressure holding performance may be insufficient. In addition, butyl rubber has low rebound resilience and is inferior in characteristics as a rubber elastic body, so that the elasticity and rigidity of the tire are impaired, which causes a reduction in actual vehicle performance. Therefore, it is necessary to minimize its use. If the coating thickness Ti exceeds 1.0 mm, the balance between the steering stability and the riding comfort is maintained even with the improvement by the belt layer 7 described later. There is a risk that it will not be possible to
It also causes an unnecessary increase in tire weight. Therefore, the lower limit of the coating thickness Ti is 0.3 mm or more, and the upper limit is 0.8 m.
m is more preferable.

The critical surface E of the rubber inner cavity 11i is shown in FIG.
As shown in (A) to (C), in addition to passing through the code array body 10, for example, on the center line N of the code 10A,
It can also be formed deviating outside or inside the center line N. However, the upper limit of the rubber thickness T up to the critical surface E of the rubber cavity 11i is determined by the carcass cord diameter from the viewpoint of the balance between the steering stability and the ride comfort or the adhesiveness to the carcass cord 10A. D +, Ti +
It is preferable that the thickness be 0.5 D or less and 1.5 mm or less.

According to the present invention, in order to suppress the deterioration of the actual vehicle performance due to the butyl rubber, the belt layer 7 is formed by connecting the monofilament cord 20 to the tire circumferential direction by 10 mm.
It is characterized by being formed of at least two belt plies arranged at an angle of up to 40 degrees.

More specifically, in this example, the belt layer 7 is formed of two inner and outer belt plies 7A and 7B, and the plies 7A and 7B are oriented differently so that the monofilament cords 20 intersect between the plies. Are arranged.

As the monofilament cord 20, a metal wire such as a steel filament for forming a normal tire cord can be suitably used. As for the thickness,
Generally, a diameter D1 of 0.35 to 0.55 mm is used, but as shown in FIG.
The diameter D1 is such that the cross-sectional area 20S of 0 is 0.68 to 0.88 times the sum of the cross-sectional areas 31S of the filaments 31 of the steel cord 30 normally used for the belt layer 7 ベ ル ト 31S.
Are preferred. That is, in the tire for passenger cars, the twist structure is 1 × 3 / 0.27 (Σ31S = 0.1717 mm ² ).
Is widely used, so that the diameter D1
Is preferably 0.39 to 0.44 mm so that its cross-sectional area 20S is in the range of 0.117 to 0.151 mm ² .

The number of cords N (lines / 5 cm) of the monofilament cord 20 can be suitably employed in the range of 33 to 47 (lines / 5 cm) which is almost the same as that of the conventional belt layer.

Such a monofilament cord 20
Can greatly increase the bending rigidity while exhibiting the same tensile elasticity as the conventional twisted cord. As a result, the in-plane rigidity of the tread portion 2 can be increased without increasing the weight of the belt layer 7, and insufficient elasticity and rigidity of the tire due to the use of the butyl rubber in the carcass 6 can be intensively solved. In addition, it is possible to maintain or improve the steering stability. Further, the decrease in ride comfort due to the increase in in-plane rigidity is prevented by the decrease in sidewall rigidity due to the use of the butyl rubber.

As described above, the configuration in which the butyl rubber is used for the carcass 6 and the configuration in which the monofilament cord 20 is used for the belt layer 7 are optimally matched. In order to solve the problem, it is possible to improve the steering stability and the riding comfort of the tire as a whole in a well-balanced manner, and to achieve a reduction in weight. Such an effect is most effectively exhibited in a tire in which the carcass 6 is formed by one carcass ply 9.

As the monofilament cord 20,
In this example, a metal wire is illustrated, but for example, an organic fiber material such as nylon, rayon, or polyester may be employed as required.

The tire of the present invention is not limited to a passenger car, but can be changed to various modes such as a motorcycle or a heavy load.

[0030]

FIG. 1 shows a tire having a size of 195 / 65R14.
A tubeless tire for a passenger car having the above configuration was manufactured on a trial basis based on the specifications in Table 1, and the tire weight, air permeability, productivity, and actual vehicle performance of each test tire were tested. The results are shown in Table 1. Table 2 shows the rubber composition at that time. The test conditions are as follows.

(1) Tire Weight The weight per tire was measured, and was shown as an index with the conventional product as 100. The smaller the value, the lighter. (2) Air permeation resistance: Tires are stipulated in rims (6JJ x 1)
4) After assembling the rim, filling it with the specified internal pressure (200 kpa) and leaving it in an oven at 80 ° C. for 15 days, measure the rate of decrease in the internal pressure of the tire. Was. The larger the value, the better the air permeation resistance. (3) Productivity: The process time required to form a green tire was represented by an index with the conventional product being 100. The smaller the value, the better the productivity. (4) Actual vehicle performance: Tires with specified rim (6JJ x 14)
And mounted on all wheels of a passenger car (2000 cc / FF) at a specified internal pressure (200 kpa) and ran on a test course. The characteristics relating to the steering wheel responsiveness, rigidity, grip and the like at that time were indicated as a steering stability by a ten-point evaluation by a sensory evaluation by a driver. The larger the value, the better the steering stability.・ Similar to the above, 10 points according to driver's sensory evaluation on bumpy road, Beljasso road (cobblestone road surface), Bitzmann road (pebble-paved road surface), etc. It was shown by evaluation. The larger the value, the better the ride comfort.

[0032]

[Table 1]

[0033]

[Table 2]

As a result of the test, in Example 1, the same air permeation resistance as that of the conventional product can be exhibited, and the tire weight can be reduced and the productivity can be improved by eliminating the inner liner. In addition, since the monofilament cord was used for the belt layer, it was confirmed that both the steering stability and the riding comfort, which are contradictory performances, could be improved by 0.5 point compared with the conventional tire.

On the other hand, in Comparative Example 1, the use of the butyl rubber in the carcass reduced the rigidity of the sidewalls and increased the ride comfort, but impaired the balance, such as reduced steering stability. Decreases performance. Further, in Comparative Example 2, the employment of the monofilament cord increases only the belt stiffness. As a result, the steering stability is increased, but the riding comfort is lowered, thereby deteriorating the balance and deteriorating the actual vehicle performance.

[0036]

As described above, in the tubeless tire of the present invention, the use of butyl rubber is stopped only in the tire cavity side portion of the carcass topping rubber, and the monofilament cord is used as the belt cord, so that the steering stability is improved. It is possible to achieve a reduction in weight while enhancing the performance and ride comfort in a well-balanced manner.

[Brief description of the drawings]

FIG. 1 is a sectional view of a tire showing one embodiment of the present invention.

FIG. 2 is a perspective view showing a structure of a carcass ply.

FIG. 3 is an enlarged partial sectional view showing a bead portion.

FIGS. 4A to 4C are cross-sectional views showing a state of a critical surface of a rubber cavity in a topping rubber.

FIG. 5 is a sectional view illustrating a monofilament cord.

FIG. 6 is a cross-sectional view showing another example of the folded structure of the carcass ply.

[Explanation of symbols]

 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 7 Belt layer 7A, 7B Belt ply 9 Carcass ply 9A Carcass ply in ply main body 9i Carcass ply 10 Cord arrangement 10A Carcass cord 11 Topping rubber 11i Rubber cavity 20 Monofilament cord H Tire lumen HS Tire lumen surface Ti coating thickness

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] December 16, 1999 (1999.12.
16)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

[0008] Further, in the invention of claim 1, the rubber inner cavity has a coating thickness of 0.2 to 0.8 mm from the carcass cord to the tire inner surface , and the rubber inner cavity has a critical thickness.
The upper limit of the rubber thickness T to the surface is D, where the carcass cord diameter is D
In this case, it is set to Ti + 0.5D or less.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

[0012] Before Symbol Ki the carcass ply 9 multiple (n) Like n-0 structure and also de be used were also the bead portion 4, between the ply main body portion 9A and the ply turnup portion 9B or 9C A bead apex rubber 8 extending radially outward from the bead core 5 is disposed therethrough.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction contents]

The coating thickness Ti from the carcass cord 10A to the tire lumen surface HS in the rubber lumen portion 11i.
Is preferably in the range of 0.2 to 0.8 mm. When the coating thickness Ti is less than 0.2 mm, the internal pressure holding performance may be insufficient. In addition, butyl rubber has low rebound resilience and is inferior in characteristics as a rubber elastic body, so that the elasticity and rigidity of the tire are impaired, which causes a reduction in actual vehicle performance. Therefore, its use is Ru need der be stopped and to a minimum. What
If it is Kutsugaeatsu of Ti exceeds 1.0 mm, even by improvement due to the belt layer 7 to be described later, driving stability riding comfort and balance occurs a possibility that it becomes impossible to maintain the, also the tire weight not Invites the necessary increase. Therefore, the lower limit of the coating thickness Ti is 0.3 mm or more, and the upper limit is 0.1 mm.
It is necessary to be 8 mm or less , in the present invention
The coating thickness Ti is set to 0.2 to 0.8 mm.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of the drawings]

FIG. 1 is a sectional view of a tire showing one embodiment of the present invention.

FIG. 2 is a perspective view showing a structure of a carcass ply.

FIG. 3 is an enlarged partial sectional view showing a bead portion.

FIGS. 4A to 4C are cross-sectional views showing a state of a critical surface of a rubber cavity in a topping rubber.

FIG. 5 is a sectional view illustrating a monofilament cord.
You.

[Description of Signs] 2 Tread section 3 Side wall section 4 Bead section 5 Bead core 6 Carcass 7 Belt layer 7A, 7B Belt ply 9 Carcass ply 9A Carcass ply in ply body 9i Car code 10A Carcass cord 11A Carcass cord 11 Topping rubber 11i Rubber lumen 20 Monofilament cord H Tire lumen HS Tire lumen surface Ti coating thickness

[Procedure amendment 6]

[Document name to be amended] Drawing

[Correction target item name] Fig. 1

[Correction method] Change

[Correction contents]

FIG.

[Procedure amendment 7]

[Document name to be amended] Drawing

[Correction target item name] Fig. 6

[Correction method] Deleted

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) // B60C 15/00 B60C 15/00 F

Claims (2)

[Claims] 1. A carcass comprising a carcass ply having a ply body portion extending from a tread portion to a bead core of a bead portion through a sidewall portion, and a belt layer disposed inside the tread portion and outside the carcass. The carcass ply has a tire cavity surface formed by the ply main body portion of the carcass ply located on the tire cavity side in the carcass ply, and the carcass ply has a cord array body in which carcass cords are arranged in parallel with each other. Topping rubber for covering both sides of the cord array body, and the topping rubber of the carcass ply in the inside is provided only in the rubber cavity portion forming the ply body portion and forming the tire cavity surface. Is formed from a butyl rubber containing 10 parts by weight or more of butyl rubber or a derivative thereof, and Layer is at least arranged at an angle of 10 to 40 degrees monofilament cord with respect to the tire circumferential direction 2
A tubeless tire comprising a plurality of belt plies. 2. The tubeless tire according to claim 1, wherein said rubber cavity has a coating thickness from a carcass cord to a tire cavity surface of 0.2 to 1.0 mm.