JPH085285B2 - Safety tire - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a safety tire capable of improving run-flat performance while improving rim assembling performance on a rim for a 15 ° taper tubeless tire and reducing weight increase. .

[Conventional technology]

There is a demand for a so-called run-flat tire that can continue to run even when the tire is deflated due to a flat tire or the like.

On the other hand, as such a tire, conventionally, for example, a core-shaped support body made of an elastic body or the like is attached to the rim by being mounted inside the tire, and a tire load acting at the time of puncture or the like is supported by the support body, and It has been proposed to form a rubber layer of high hardness inside the side wall portion of a tire to reduce vertical flexure of the tire at the time of puncture and to prevent structural damage of the tire case.

However, in the case of a tubeless tire with a 15 ° taper, it is originally difficult to assemble the rim because it is used by mounting it on a so-called one-piece rim, and in addition, a high hardness rubber layer is formed inside the sidewall part. 15 °
Safety tires for tapered rims make rim assembly work even more difficult.

Therefore, the most important performance requirements for a safety tire for a 15 ° taper rim are as follows.

(1) The rim assembly work for the one-piece 15 ° taper rim should be easy.

(2) It is possible to reliably prevent the tire bead portion from coming off the bead base of the rim during run-flat traveling.

(3) To be able to maintain the required load capacity during run-flat traveling.

[Problems to be Solved by the Invention]

However, in the case of using a support in a conventional tire, the tire weight is increased due to the increase in the number of parts, the product cost is increased, and particularly the rim assembly performance is significantly reduced. There is a problem.

Also, in the case of forming a reinforcing rubber layer inside the sidewall, in order to reduce the above-mentioned vertical deflection and obtain run-flat performance, the rubber layer extends from the shoulder portion to the bead portion, and usually has a maximum rubber thickness of 15 mm or more. Therefore, this also cannot avoid a great increase in weight of the tire, and the bead rigidity is excessively increased, and the rim assembly performance is deteriorated. In addition, the rubber layer is prone to flexural fatigue due to repeated deformation at the time of puncture or the like and, in combination with the temperature rise due to the large rubber thickness, induces rubber breakage during run-flat running for a relatively short distance.

The present invention provides a low-elasticity rubber layer made of soft rubber continuous inward in the radial direction of a sidewall reinforcement layer, which comprises a rubber reinforcement body made of elastic rubber on the inner surface of a sidewall portion and a cord reinforcement body having a reinforcement cord, and Basically, a toe part for fixing the rim made of hard rubber is provided continuously on the inner side in the radial direction to improve the rim assembly property of the one-piece rim with a 15 ° taper and to reduce the weight increase of the tire while the run flat It is an object of the present invention to provide a safety tire that can improve performance and solve the above problems.

[Means for solving the problem]

In order to solve the above-mentioned problems, the safety tire of the present invention has a bead portion that a bead core passes through and sits on a rim, a side wall portion that extends radially outward from each bead portion, and a tread that joins the side wall portion. And a carcass having a carcass cord which has a toroidal shape and which is locked by folding both ends around the bead core of the bead part through the tread part and the side wall part, and the carcass inside the tread part and the carcass. A belt layer having a belt cord located outside of the tire and arranged at a relatively small cord angle with respect to the tire equator, while at the inner surface of the carcass of the sidewall portion, a radial direction of a thick central portion is provided. The outer and inner parts of the taper taper so that the thickness decreases radially outward and inward, respectively. -Shaped rubber reinforcing member made of elastic rubber, and at least one reinforcing ply arranged on the inner surface of the rubber reinforcing member and inclining the reinforcing cord at an angle of 25 to 55 ° with respect to the radial direction. 100% modulus is 10 to 20kg / in the area from the inner side in the radial direction of the side wall reinforcing layer to the bead heel line passing through the inner side in the axial direction of the bead portion.
It has a low elastic rubber layer made of rubber of cm ² and consists of a hard rubber with JIS A hardness of 70 to 90 ° that protrudes radially inward from the radially inner side of this low elastic rubber layer at the radially innermost side of the bead part. A safety tire for 15 ° taper tube reslims that has a toe part for fixing the rim.

[Action]

In this way, the sidewall reinforcing layer reinforced by the cord reinforcing body having the rubber reinforcing body made of elastic rubber on the inner surface thereof restrains both sides of the rubber reinforcing body with the carcass and the cord reinforcing body, and therefore has a load supporting ability. It can be greatly increased, the vertical deflection at the time of puncture, etc. can be reduced, the bending fatigue of the rubber reinforcement can be reduced, and the load capacity during run-flat traveling can be reliably maintained. Further, the cord of the cord reinforcing body is arranged at an angle of 25 to 55 ° with respect to the radial direction, and as a result, it is possible to prevent the rigidity difference from the rubber reinforcing body from becoming excessive and prevent separation between the two. .

In addition, this makes it possible to reduce the thickness of the rubber reinforcement body with a maximum rubber thickness of 12.0 mm or less, and as a result, it is possible to reduce the tire weight and suppress the heat generation of the rubber, which is combined with the effect of reducing the bending fatigue. The durability can be greatly improved.

Further, on the inner side in the radial direction of the sidewall portion reinforcing layer,
By disposing a low-elasticity rubber layer having a 100% modulus of 10 to 20 kg / cm ² , it is possible to suppress an excessive increase in bead rigidity and improve the rim assembly performance by elastic deformation of this rubber layer. JIS A hardness of the toe part made of hard rubber continuous to the inner side in the radial direction of the elastic rubber layer is firmly fitted to the recess of the rim, and it is securely prevented from coming off from the rim even while running the run flat .

In order to effectively exert the load supporting ability of the sidewall reinforcing layer, the length of the outer edge of the rubber reinforcement and the outer edge of the belt layer should be 0.07 times or more and 2.0 times or less the belt width. Is good.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a safety tire 1 assembled on a so-called one-piece rim R for a so-called 15 ° taper tubeless tire in which a bead bend of the rim has a taper of α = 15 °.

In the figure, a safety tire 1 has a toroidal shape including a bead portion 3 through which a bead core 2 passes, a side wall portion 4 extending outward from the bead portion 3 in a radial direction, and a tread portion 5 joining an upper end of the toroidal shape. While passing through the wall portion 4 and the tread portion 5, a carcass 6 having a main body portion with respect to the bead core 2 is arranged in the bead portion 3, while the tread portion 5 is provided with a belt layer 7 positioned on the outer surface in the radial direction of the carcass 6, A sidewall reinforcement layer 10 is provided on the inner surface of the sidewall portion 4.

The carcass 6 has a rewinding portion that is rewound from the inside of the tire to the outside. In this example, the carcass 6 is composed of two layers of carcass plies 6A and 6B. Carcass ply
6A, 6B has a carcass cord with a radial structure that inclines at an angle of 60 to 90 ° with respect to the tire equator, and the carcass cord includes steel cords, rayon, polyester,
Organic fiber cords such as nylon and aromatic polyamide may be used.

Further, the belt layer 7 disposed in the tread portion 5 is composed of a wide inner belt ply 7A on the carcass 6 side and a slightly narrow outer belt ply 7B provided in contact with the upper surface thereof. Both 7A and 7B have belt cords that are inclined at a relatively small angle of, for example, 35 ° or less with respect to the tire equator.

In this embodiment, steel cords can be preferably used as the belt cords, but high elastic organic cords such as aromatic polyamide and those having relatively low elastic modulus such as nylon, polyester and rayon can also be used. When the belt cord is formed by using an organic fiber cord having a relatively small elastic modulus, it can be useful for keeping the hoop effect of the carcass 6 at the time of deformation and following the deformation of the carcass 6.

Further, a band layer 8 is provided on the outer surface in the radial direction of the belt layer 7.

In this example, the band layer 8 is composed of an inner band ply 8A, an inner band ply 8B, and an outer band ply 8C,
The inner band ply 8A extends toward the shoulder side beyond the outer edge in the tire axial direction beyond the outer edge of the outer belt ply 7B, and the inner edge forms a strip shape that is interrupted in the tread. The outer band plies 8B and 8C have outer edges substantially aligned with the inner band plies 8A and cover the belt layer 7 over the entire tread portion 5. Band ply 8A, 8B, 8C
Both use an organic fiber cord such as rayon, nylon, polyester, etc. to alleviate the shear strain acting between the outer surface of the belt layer 7 and the tread rubber when the tire is deformed, and the rubber generated at the end of the belt layer 7 To prevent peeling. A breaker cushion 9 made of soft rubber is interposed between the carcass 6 and the inside of the band layer 8 at the end of the belt layer 7.

The sidewall reinforcing layer 10 includes a rubber reinforcing member 11 arranged on the inner surface of the carcass 6 and a cord reinforcing member 12 provided adjacently along the inner surface of the rubber reinforcing member 11.

In the present embodiment, the rubber reinforcing member 11 has an outer portion 11 that is formed by tapering the rubber thickness outwardly in the tire radial direction of a thick central portion 11A having a maximum thickness portion Q near the tire maximum width position.
B has a substantially crescent shape with B and a similar inner portion 11C provided inside, and in this example, JIS A hardness is 70 to 90 °, and 100% modulus is formed from hard rubber of 30 to 70 kg / cm ^2. It

Further, the rubber reinforcing member 11 extends the outer portion 11B from the side wall portion 4 to the tread portion 5 in order to effectively support the tire load at the time of puncture or the like, and the tire axial direction thereof. The tire axial length S1 between the inner edge and the tire axial outer edge of the belt layer 7 is the belt width of the belt layer 7.
It is set to 0.07 times or more and 0.2 times or less of BW. When the length S1 is less than 0.07 times the belt width BW, the tire load does not properly act on the rubber reinforcing member 11 and the longitudinal deflection amount is increased to impair the run flat performance and the durability thereof is reduced. To do. As for the vertical deflection amount, the length S1 is the belt width.
Beyond 0.2 times BW, it is almost constant, and if it exceeds 0.2 times, it not only wastes material but also increases tire weight.

Similarly, the lower portion 11C of the rubber reinforcement 11 extends from the side wall portion 4 to the upper portion of the bead portion 3 and has a radial length S3 between the tire radial lower edge and the center of the bead core 2. , From the heel point P of the bead portion 3 to the rim R
Is twice the flange height F, which is the length in the tire radial direction up to the upper edge of the rim flange Ra. The heel point is an aerial point where the inner side surface of the rim flange portion Ra and the bottom surface of the bead intersect, and when the length S3 is less than twice the flange height F, the rigidity of the bead portion 3 is unnecessarily increased. It tends to lower the assembly performance.

If it exceeds 2.0 times the flange height F, the rigidity in the upper portion of the bead portion 5 becomes insufficient, the amount of vertical deflection is increased, the run flat performance is impaired, and stress concentrates on the portion, which lowers the durability. It is easy to let them do it.

Further, in this example, a low elastic rubber layer LM made of rubber having a 100% modulus of 10 to 20 kg / cm ² is provided in a region from the height twice the flange height F to the bead heel line through the inner side in the axial direction of the bead portion. To reduce the lateral rigidity of the bead. Ten
When the 0% modulus is 10 kg / cm ² or less, the toe part that locks to the rim is greatly deformed, resulting in necking, and the bead part is easier to separate from the rim. If it is 20 kg / cm ² or more, the lateral rigidity of the bead portion becomes too large and the workability of assembling the rim deteriorates. Further, the cord reinforcing body 12 is, for example, a reinforcing cord made of an organic fiber cord having a low elastic modulus such as nylon, rayon, polyester, etc. at 25 ° or more in the tire radial direction.
In this example, one reinforcing ply 12 arranged at an angle of 55 ° or less.
It is formed of A and is arranged on the inner surface of the rubber reinforcing body 11 almost all over. Thus, by inclining the cord reinforcement, the difference in rigidity with the rubber reinforcement 11 can be alleviated and peeling of the ply can be prevented.

Therefore, the rubber reinforcing member 11 is reinforced by the cord reinforcing member 12 and relaxes the local compressive strain generated on the inner surface thereof to prevent the occurrence of cracks or the like, while the inner and outer parts thereof are the reinforcing ply 12A and the carcass ply 6A, 6B. Since it is restrained by, the load supporting ability can be greatly increased, the vertical deflection amount can be reduced, the run flat performance can be greatly improved, and the bending fatigue of the rubber reinforcement 11 can be reduced. In addition, this improves the run-flat performance while also increasing the maximum rubber thickness T in the maximum thickness portion Q to 12.0 mm or less.
As a result, it is possible to reduce the weight of the tire, while suppressing the heat generation of the rubber of the rubber reinforcement 11, and in combination with the reduction of the bending fatigue, the durability at the time of run flat is greatly improved. sell. When the reinforcing cord is less than 25 °, the difference in rigidity in the radial direction between the rubber reinforcing member 11 and the reinforcing ply 12A becomes too large, which easily causes ply separation, and when it exceeds 55 °, the load supporting ability becomes insufficient. Become. Therefore, the reinforcing cord is more preferably 35 ° or more and 48 ° or less with respect to the tire radial direction. If the maximum rubber thickness T is less than 3.0 mm, it becomes difficult to obtain runflat performance.

Further, in the tire 1 of this example, the bead core 2 is used.
A bead apex (13) made of rubber is provided in the upper part of the carcass in a region surrounded by the carcass body and its folded-back portion and extends outward in the tire radial direction in a tapered shape.

Further, the bead portion 3 is provided with an inwardly facing piece made of hard rubber, which is substantially triangular and has a lower end protruding radially inward from a bead base line L along the bead bottom, on the inner side in the tire axial direction of the carcass 6. Thus, the lower end portion of the inwardly facing piece forms a toe portion 14 that projects inward at the tire axially inner end of the bead portion 3. Further, a concave hump groove 15 is formed on the lower surface of the bead portion 3 outside the toe portion 14 in the axial direction of the tire, and a concave hump groove 15 is formed so as to be continuous with the toe portion 14.
14. A chainer 19 is provided so as to cover the pump groove 15 and prevent the bead portion 3 and the rim R from being displaced from each other. Further, in this bead portion 3, the toe portion 14 is fitted in the annular groove 16 provided in the rim R, the hump 17 formed in the rim R is fitted in the hump groove 15, and the bead portion 3 is seated in the rim R. This prevents the rim from coming off when air escapes due to a flat tire or the like. The toe part 14 and the hump groove 15 are the bead parts 3 of both sides.
It may be provided on one side or only on one side.

The JIS A hardness of the rubber of the toe part is 70 to 90 _HS , and if it is 70 _HS or less, it is easily separated from the annular groove 16 during runflat running.
Also, if it exceeds 90 _HS, it becomes difficult to fit the rim assembly.

〔Concrete example〕

The tire size of the structure shown in Fig. 1 is 215 / 50R14.5.
While making a prototype of the tires of the specifications shown in Table 1,
The trial tire was mounted on a rim having a rim size of 6.00 to 14.5 SW, and the rim assembly performance and run flat performance of each tire were compared and evaluated.

It should be noted that the rim assembling performance is indicated by a five-point method for the feeling evaluation by the operator, and the larger the value, the better. In addition, the run-flat performance is shown as an index with the running distance until the tire is destroyed when the tire loaded with a load of 700 kg is run in a punctured state as an index with Comparative Example 2 being 100, and the larger the value, the better.

[Advantages of the Invention] As described above, the safety tire of the present invention has a sidewall reinforcing layer including a rubber reinforcing body made of hard rubber and a cord reinforcing body having a reinforcing cord on the inner surface of the side wall portion in the radial direction thereof. Since the low elastic rubber layer is provided on the inside to reduce the lateral rigidity of the bead portion, the run-flat performance can be significantly improved without impairing the rim assembly performance and reducing the increase in weight.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention. 2 ... bead core, 3 ... bead part, 4 ... sidewall part, 5 ... tread part, 6 ... carcass, 7 ... belt layer, 10 ... sidewall reinforcing layer, 11 ... rubber reinforcing body, 11A …… central part, 11B …… outer part, 11C …… inner part, 1
2 …… Cord reinforcement, 12A …… Reinforcement ply, 14 …… Toe part.

Claims (4)

[Claims] 1. A toroidal shape having a bead portion through which a bead core passes and which is seated on a rim, a side wall portion extending outward in the radial direction from each bead portion, and a tread portion connecting the side wall portion, and A carcass having a carcass cord that is locked by folding both ends around the bead core of the bead part through the tread part, the side wall part, and is located inside the tread part and outside the carcass and with respect to the tire equator. And a belt layer having belt cords arranged at a relatively small cord angle, while the carcass inner surface of the side wall portion has a radial outer portion and an inner portion in a radial direction of a thick central portion. A rubber reinforced body made of elastic rubber having a substantially crescent-shaped cross section by tapering the thickness decreasing outward and inward. A side wall reinforcement layer comprising a cord reinforcement body which is disposed on the inner surface of the rubber reinforcement body and which comprises at least one reinforcement ply in which reinforcement cords are inclined at an angle of 25 to 55 ° with respect to the radial direction. In addition to being provided, the area from the inner side in the radial direction of this sidewall reinforcement layer to the bead heel line passing through the inner side in the axial direction of the bead portion is 10
A low elastic rubber layer made of soft rubber with a 0% modulus of 10 to 20 kg / cm ² is provided. JISA hardness that protrudes radially inward from the radially inner side of the low elastic rubber layer to the radially innermost side of the bead 70 to 90 °
Safety tire for 15 ° taper tubeless rims, which is made of hard rubber and has a toe part for rim fixing. 2. The safety tire according to claim 1, wherein the rubber reinforcing body has a maximum rubber thickness T in a portion having a maximum thickness of 3.0 mm or more and 12.0 mm or less. 3. The rubber reinforcing body has a tire axial direction length S1 between a tire axial direction inner edge of the outer portion and a tire axial direction outer edge of the belt layer between the outer edge of the belt layer. The safety tire according to claim 1, wherein the belt width BW, which is the length, is 0.07 times or more and 0.2 times or less. 4. The rubber reinforcement has a radial length S3 from the center of the bead core to a lower edge of the inner portion of the tire in a radial direction of the tire from a heel point of the bead portion to an upper edge of a rim flange of the rim. 2. The safety tire according to claim 1, wherein the flange height F is 2.0 times the radial length of the tire.