JP2011079481A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire for a small-sized truck of which the durability can be improved while reducing its weight. <P>SOLUTION: A carcass ply 18 is constituted of two carcass plies, i.e. a first carcass ply 32 and a second carcass ply 34. The inner carcass ply 32 and the second carcass ply 34 have main bodies 32A, 34A and wound-up portions 32B, 34B, respectively. A wind-up end 32C of the wound-up portion 32B of the first carcass ply 32 is arranged at either an inner diameter side or an outer diameter side of the inner-most belt ply 22. A crossing angle θ at the tread part 12 formed of a steel cord 2202 of the inner-most belt ply 22 and a carcass cord 3202 comprised of an organic fiber of the wound-up portion 32B of the first carcass ply 32 is set to be within a range from 0° to 45°. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire for a light truck.

Pneumatic tires for light trucks are used under conditions of higher internal pressure and higher load than passenger car tires. Nevertheless, in order to reduce weight and simplify manufacturing, organic fiber cords are generally used for the carcass cord of the carcass layer, and the structure around the bead portion is also simple. .
However, since it must be strong enough to withstand the harsh usage environment, it is possible to use higher strength steel cords for the belt layer or increase the number of belt plies to three compared to conventional passenger car tires. is doing.

JP 2004-352174 A JP 59-2908

In recent years, many passenger car tires have adopted a structure in which the winding end of the carcass layer is disposed under the belt layer in order to improve the durability while reducing the weight.
If this structure can be diverted to a pneumatic tire for a small truck, the tire rigidity can be secured by the rolled-up portion of the carcass layer, so that the durability of the tire can be improved. It is possible to reduce the weight.
However, since pneumatic tires for light trucks are used under conditions of high internal pressure and high load, when this structure is diverted, separation occurs between the rolled-up portion of the carcass layer and the belt layer, resulting in durability. The problem of deterioration occurs.
The present invention has been devised in view of the above circumstances, and an object of the present invention is to provide a pneumatic tire capable of improving durability while reducing the weight of a pneumatic tire for a small truck. .

  In order to achieve the above object, a pneumatic tire according to the present invention includes a carcass layer extending from a tread portion through a sidewall portion to a bead core of the bead portion, and a belt layer disposed inside the tread portion and outside the carcass layer. The carcass layer is composed of one or a plurality of carcass plies using an organic fiber cord, the belt layer is composed of a plurality of belt plies using a steel cord, and at least one carcass ply is An innermost belt ply having a winding portion wound around the bead core from the inside to the outside of the tire, and a winding end that is a tip of the winding portion is located on the innermost diameter side of the tire among the plurality of belt plies Disposed on the inner diameter side or outer diameter side of the inner fiber layer and the organic fiber cord of the winding portion in the tread portion and the innermost layer base Crossing angle between the steel cord Topurai is in the range 0 and 45 degrees.

According to the present invention, since the occurrence of separation between the carcass layer and the belt layer can be efficiently suppressed, the structure in which the winding end of the carcass layer is disposed under the belt layer, which is employed in passenger car tires, is compact. It can be diverted to pneumatic tires for trucks.
Therefore, the durability of the pneumatic tire for a small truck can be improved while reducing the weight.

1 is a half sectional view of a pneumatic tire according to a first embodiment. It is explanatory drawing of the crossing angle (theta) which the steel cord of an innermost layer belt ply and the carcass cord of the winding-up part of a 1st carcass ply make in the tread part of the pneumatic tire of 1st Embodiment. It is half part sectional drawing of the pneumatic tire of 2nd Embodiment. It is explanatory drawing of crossing angle (theta) which the steel cord of an innermost layer belt ply and the carcass cord of the winding-up part of a 1st carcass ply make in the tread part of the pneumatic tire of 3rd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the first embodiment will be described.
As shown in FIG. 1, the pneumatic tire 10 includes a tread portion 12, a pair of sidewall portions 14 extending inward in the tire radial direction from both side portions of the tread portion 12, and an inner peripheral side of each sidewall portion 14. And a pair of continuous bead portions 16.
A carcass layer 18 is stretched between a pair of bead portions 16, and a belt layer 20 is disposed inside the tread portion 12 and outside the carcass layer 18.

The belt layer 20 is composed of three belt plies, an innermost layer belt ply 22 located on the innermost side, an intermediate layer belt ply 24 located on the outer side thereof, and an outermost layer belt ply 26 located on the outer side thereof. .
Each belt ply 22, 24, 26 is composed of a number of steel cords and a topping rubber that covers the cords.
Both side portions of the belt layer 20 are covered with a pair of edge bands 28.
As shown in FIG. 2, the steel cords of the intermediate layer belt ply 24 and the outermost layer belt ply 26 are inclined with a relatively small constant angle with respect to the tire equatorial plane 30. In the intermediate layer belt ply 24 and the outermost layer belt ply 26, those steel cords are inclined in the opposite direction, so that a so-called cross ply is formed so as to exert a tagging effect.
The steel cord of the innermost layer belt ply 22 is inclined with a large angle with respect to the tire equatorial plane 30, constitutes a so-called high angle belt ply, and functions as a strength member.

The carcass layer 18 is composed of two carcass plies, a first carcass ply 32 and a second carcass ply 34.
The first and second carcass plies 32 and 34 are configured by covering a large number of carcass cords that intersect the tire equatorial plane 30 (or tire circumferential direction) at approximately 80 to 90 degrees with a topping rubber. It has a radial structure.
The carcass cord is made of an organic fiber cord such as polyester, nylon, or rayon.
The first and second carcass plies 32 and 34 include main body portions 32A and 34A and winding portions 32B and 34B, respectively. The main body portions 32A, 34A pass from the tread portion 12 through the sidewall portion 14 to the bead core 38. The winding portions 32B and 34B are wound around the bead core 38 from the inner side to the outer side in the tire width direction following the main body portions 32A and 34A.

A belt cushion 40 is provided outside the winding portion 32B of the first carcass ply 32 extending from the sidewall portion 14 to the tread portion 12. The end of the belt cushion 40 on the inner side in the tire width direction is interposed between the winding portion 32 </ b> B of the first carcass ply 32 and the belt layer 20.
The belt cushion 40 is made of a low heat-generating rubber having a loss tangent tan δ at 60 ° C. in the range of 0.03 to 0.08, suppresses the occurrence of separation between the carcass layer 18 and the belt layer 20, and has durability. Improvements are being made.

The winding end 34C of the winding part 34B of the second carcass ply 34 is located at a position beyond the tire maximum width position outward in the tire radial direction.
Further, the winding end 32C of the winding portion 32B of the first carcass ply 32 is disposed on the inner diameter side or outer diameter side of the innermost layer belt ply 22 and has a so-called high turn-up structure, and the winding portion 32B is reinforced with the carcass. It functions as a layer to ensure tire rigidity.
Here, if the winding end 32C is close to the outer end of the adjacent belt layer 20, in the present embodiment, if it is close to or coincides with the outer end 22C of the innermost belt ply 22, separation is likely to occur. Become. Therefore, it is necessary to secure a distance W between the winding end 32C of the winding portion 32B and the outer end 22C of the innermost layer belt ply 22 that are overlapped with each other via the belt cushion 40. However, if the distance W is too large, the weight of the tire increases.
For this reason, the distance W is set to 10 mm to 20 mm, and the occurrence of separation is suppressed and the durability is improved while reducing the weight of the tire. In other words, the winding end 32 </ b> C of the winding portion 32 </ b> B of the first carcass ply 32 is positioned at a position of 10 mm to 20 mm on the inner side in the tire width direction from the outer end of the adjacent belt layer 20. In this embodiment, the innermost belt ply 22 is positioned 10 mm to 20 mm inward in the tire width direction from the outer end of the innermost layer belt ply 22, and the occurrence of separation is suppressed and the durability is improved while reducing the weight of the tire. Yes.
Further, the outer end 22C of the innermost layer belt ply 22 in the tire width direction is set to be more than the outer end of the belt ply adjacent to the outer diameter side of the innermost layer belt ply 22, that is, the outer end 24C of the intermediate layer belt ply 24. It is located at a position of 6 mm to 14 mm inside the tire width direction.

As shown in FIG. 2, in the tread portion 12, the crossing angle θ formed by the steel cord 2202 of the innermost belt ply 22 and the carcass cord 3202 of the winding portion 32B of the first carcass ply 32 is 0 to 45 degrees. It is set to fall within the range of degrees.
Thereby, in the tread part 12, generation | occurrence | production of the separation between the carcass layer 18 and the belt layer 20 can be suppressed efficiently, and it is advantageous when aiming at the improvement of durability.
Preferably, the lower the crossing angle θ is, the lower the occurrence of separation between the carcass layer 18 and the belt layer 20 and the more advantageous the durability.
Further, when the crossing angle θ is 45 degrees or more, there is a problem that the shearing force between the carcass layer 18 and the belt layer 20 is increased, and separation between the carcass layer 18 and the belt layer 20 is easily generated.
For this reason, the crossing angle θ is preferably in the range of 0 to 45 degrees.
On the other hand, for example, in the tread portion 12, the carcass cord 3202 of the winding portion 32B intersects the tire equator plane 30 at 90 degrees, and the steel cord 2202 of the innermost belt ply 22 starts from 80 degrees with respect to the tire equator plane 30. When intersecting at 90 degrees, the intersecting angle θ is in the range of 0 to 10 degrees, but there is a slight disadvantage from the viewpoint of securing rigidity in the tire cross-sectional direction.
Therefore, the crossing angle θ is more preferably in the range of 10 degrees to 45 degrees.

According to the first embodiment, since the occurrence of separation between the carcass layer 18 and the belt layer 20 can be efficiently suppressed, the winding end of the carcass layer used in passenger car tires is placed under the belt layer. Can be diverted to pneumatic tires for small trucks.
Accordingly, the tire rigidity can be ensured by the rolled-up portion 32B of the carcass layer 18 so that the durability of the tire can be improved. For example, the number of carcass plies can be reduced from three to two or from two to one. Alternatively, the weight can be reduced by reducing the number of belt plies from three to two.
That is, the durability of the pneumatic tire for a light truck can be improved while reducing the weight.

Next, a second embodiment will be described with reference to FIG.
The same portions and members as those in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and only portions different from those in the first embodiment will be described.
In the second embodiment, the carcass layer 18 is constituted by a single carcass ply 40 to improve the durability while reducing the weight.
The carcass ply 40 has a radial structure configured by embedding carcass cords made of a large number of organic fiber cords that intersect the tire equatorial plane 30 at approximately 80 to 90 degrees in a topping rubber.
The carcass ply 40 has a main body portion 40A and a winding portion 40B, and the winding end 40C of the winding portion 40B is on the inner diameter side or outer diameter side of the innermost belt ply 22 as in the first embodiment. Has been placed.
The winding end 40C is positioned at a position 10 mm to 20 mm inward in the tire width direction from the outer end 22C of the innermost layer belt ply 22 in this embodiment, rather than the outer end of the adjacent belt layer 20, thereby reducing the weight of the tire. In order to improve the durability, the occurrence of separation is suppressed while improving the durability.
Further, the outer end 22C of the innermost layer belt ply 22 in the tire width direction is positioned at a position of 6 mm to 14 mm inside the outer end 24C of the intermediate layer belt ply 24 in the tire width direction, thereby reducing the weight while ensuring rigidity. I am trying.

In the tread portion 12, the crossing angle θ formed by the steel cord of the innermost belt ply 22 and the carcass cord of the winding portion 40B is set to fall within a range of 0 to 45 degrees. Thereby, in the tread part 12, generation | occurrence | production of the separation between the carcass layer 18 and the belt layer 20 can be suppressed efficiently, and it is advantageous when aiming at the improvement of durability.
The intersection angle θ is preferably in the range of 0 degree to 45 degrees, and more preferably in the range of 10 degrees to 45 degrees.
According to the second embodiment, similar to the first embodiment, a structure in which a carcass winding end is disposed under a belt layer, which is employed in a passenger car tire, is used as a pneumatic tire for a small truck. It can be diverted, and the durability of the pneumatic tire for light trucks can be improved while reducing the weight.

Next, a third embodiment will be described with reference to FIG.
The third embodiment is a modification of the first and second embodiments, and the same portions and members as those in the first and second embodiments are denoted by the same reference numerals and description thereof is omitted. Only the points different from the first and second embodiments will be described.
In the third embodiment, the belt layer 20 is constituted by two belt plies of an innermost layer belt ply 52 located on the innermost side and an outermost layer belt ply 54 located on the outer side, thereby reducing the weight. It is intended to improve durability.
Each belt ply 52, 54 is composed of a number of steel cords and a topping rubber that covers the cords.
The steel cords 5202 and 5402 of the innermost layer belt ply 52 and the outermost layer belt ply 54 are inclined in a reverse direction with a large angle with respect to the tire equatorial plane 30, and each constitutes a high angle belt ply.
The carcass ply 40 includes a main body portion and a winding portion 40B, and the winding end 40C of the winding portion 40B is disposed on the inner diameter side or the outer diameter side of the innermost layer belt ply 52, as in the first embodiment. Has been.
In this embodiment, the winding end 40C is 10 mm to 20 mm (distance W is 10 mm to 20 mm) on the inner side in the tire width direction than the outer end 52C of the innermost layer belt ply 52 than the outer end of the adjacent belt layer 20. It is positioned at a location to reduce the occurrence of separation while improving the durability while reducing the weight of the tire.

Further, in the tread portion 12, the crossing angle θ formed by the steel cord 5202 of the innermost layer belt ply 52 and the carcass cord 4002 of the winding-up portion 40B is set to fall within the range of 0 degree to 45 degrees. Thereby, in the tread part 12, generation | occurrence | production of the separation between the carcass layer 18 and the belt layer 20 can be suppressed efficiently, and it is advantageous when aiming at the improvement of durability.
The intersection angle θ is preferably in the range of 0 degree to 45 degrees, and more preferably in the range of 10 degrees to 45 degrees.
According to the third embodiment, as in the first and second embodiments, the structure used for passenger car tires in which the carcass winding end is disposed under the belt layer is used for air for small trucks. It can be diverted to a tire, and its durability can be improved while reducing the weight of a pneumatic tire for a small truck.

Examples of the present invention will be described below in comparison with comparative examples.
About the comparative example and the example, an evaluation test was performed for the durability performance and the weight performance of the pneumatic tire having the configuration shown in Table 1.
In Comparative Examples and Examples, pneumatic tires having a tire size of 195 / 85R16 114 / 112L were used.
In Comparative Examples 1 and 3, the carcass layer 18 is composed of a carcass ply made of two organic fiber cords. In Comparative Examples 2 and Examples 1 to 5, the carcass layer 18 is made of a single organic fiber cord. Consists of.
In Comparative Examples 1 and 2 and Example 1, the belt layer 20 is constituted by a belt ply made of two steel cords. In Comparative Example 3 and Examples 2 to 5, the belt layer 20 is made of three steel cords. It consisted of a belt ply consisting of
In Table 1, “belt layer and carcass layer intersection angle” is an intersection angle θ formed by the steel cord of the innermost layer belt ply and the carcass cord of the carcass ply winding portion in the tread portion.
In Table 1, “the distance between the carcass winding end and the belt end” is the distance between the winding end of the carcass ply and the outer end of the adjacent belt ply where the carcass ply and the belt ply overlap.
About durability performance, it runs to the drum under the drum durability test conditions described in JIS D4230, and the mileage is indexed. The standard example is set to 100, and the larger the value, the better the performance. Yes.
The weight performance is indicated by an index with the standard example being 100, and the larger the value, the lighter the weight.

As is clear from Table 1, Comparative Example 1 and Example 1 in which the carcass ply is reduced compared to Comparative Example 1 are equivalent in terms of durability, and Example 1 maintains durability compared to Comparative Example 1. It is clear that the weight performance can be improved.
Moreover, although Example 1 and Comparative Example 2 in which the number of carcass plies and the number of belt plies are the same in terms of weight performance, it is clear that Example 1 can improve durability performance compared to Comparative Example 2.
Further, Comparative Example 3 and Example 2 with a reduced carcass ply than Comparative Example 3 are equivalent in terms of durability performance, and Example 2 can improve weight performance while maintaining durability performance compared to Comparative Example 3. Is clear.
Moreover, when the comparative example 3 and the examples 3-5 which reduced the carcass ply compared with the comparative example 3 are compared, it is clear in those examples that both durability performance and weight performance can be improved from the comparative example 3. .

  DESCRIPTION OF SYMBOLS 10 ... Pneumatic tire, 12 ... Tread part, 14 ... Side wall part, 16 ... Bead part, 18 ... Carcass layer, 20 ... Belt layer, 22 ... Innermost layer belt ply, 24 ... Middle Layer belt ply, 26... Outermost layer belt ply, 32... First carcass ply, 34... Second carcass ply, 32B, 34B.

Claims (5)

A carcass layer from the tread part through the sidewall part to the bead core of the bead part,
A belt layer disposed inside the tread portion and outside the carcass layer,
The carcass layer is composed of one or a plurality of carcass plies using an organic fiber cord,
The belt layer is composed of a plurality of belt plies using steel cords,
At least one of the carcass plies has a winding portion wound around the bead core from the inside to the outside of the tire, and a winding end that is a leading end of the winding portion is the most of the plurality of belt plies of the tire. Arranged on the inner diameter side or outer diameter side of the innermost layer belt ply located on the inner diameter side,
In the tread portion, the crossing angle between the organic fiber cord of the rolled-up portion and the steel cord of the innermost belt ply is in the range of 0 to 45 degrees.
Pneumatic tire. The winding end is located 10 mm to 20 mm inside in the tire width direction with respect to the outer end of the belt ply of the adjacent belt layer.
The pneumatic tire according to claim 1. The belt layer is composed of three sheets of the innermost layer belt ply, an intermediate layer belt ply located on the outer side, and an outermost layer belt ply located on the outer side.
The intermediate layer belt ply and the outermost layer belt ply are cross plies in which steel cords constituting them are inclined in opposite directions with a relatively small constant angle with respect to the tire equatorial plane,
The innermost layer belt ply is a high angle belt ply inclined with a large angle with respect to the tire equatorial plane.
The pneumatic tire according to claim 1 or 2. A belt cushion having a loss tangent tan δ at 60 ° C. in the range of 0.03 to 0.08 is provided on the outer side of the rolled-up portion extending from the sidewall portion to the tread portion,
The end portion of the belt cushion is interposed between the wound-up portion and the belt layer,
The pneumatic tire according to any one of claims 1 to 3. The outer end of the innermost layer belt ply in the tire width direction is located at a position of 6 mm to 14 mm on the inner side in the tire width direction from the outer end of the belt ply adjacent to the outer diameter side of the innermost layer belt ply.
The pneumatic tire according to any one of claims 1 to 4.

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