JPH04260803A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve the cut resistance at a side wall part without lowering the tire running performance. CONSTITUTION:A ring of a rib body 8 protruding out is provided at a side wall part 4 of a tire base body 6. A reinforcement layer 7 comprising organic fibers is provided at the rib body 8.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is particularly suitable for use in heavy-load vehicles, and improves the service life of tires by facilitating tire retreading and increasing cut resistance at the sidewall portion when driving on rough roads. Regarding Uru pneumatic tires.

0002

[Prior Art] For example, pneumatic tires for heavy loads used on rough roads such as civil engineering/construction sites, quarry sites, etc.
Sharp rocks, stones, etc. that rise from the road surface tend to cause cut-like crack damage to the tread as well as to the side region extending from the tread to the sidewall portion of the tire at its maximum width.

[0003] Therefore, in order to improve the cut resistance particularly in such side regions, a protective ply made of steel cords is conventionally buried outside the carcass and inside the tire base, or as disclosed in Japanese Patent Application Laid-Open No. 1-160711. As shown in the publication, it has been proposed to provide an annular projection on the sidewall portion and cover the annular projection with a plurality of side protectors made of rigid bodies.

0004

[Problems to be Solved by the Invention] However, when such a protective ply is used, shearing force tends to concentrate at the upper and lower ends of the protective ply when the tire deforms during contact/non-contact. Cords tend to become corroded by rust due to moisture, etc., which can lead to cord looseness, separation, etc. at a relatively early stage. Moreover, since the protective ply needs to be buried within the tire base over almost the entire width of the side area, it is difficult to replace it during tire retreading, and the overall service life of the tire cannot be sufficiently extended. There's a problem.

[0005] Furthermore, in the device disclosed in JP-A-1-160711, since the side protector is made of a rigid body such as a metal plate or plastic, it has poor followability against tire deformation and is prone to peeling or falling off from the tire base. Likely to happen. Moreover, even though this tire is divided into a plurality of parts, it is a rigid body, so the tire rigidity, especially the longitudinal rigidity, is excessively increased, which significantly impairs steering stability, ride comfort, etc., and leads to a decrease in driving performance.

[0006] The present invention is based on the fact that a reinforcing layer using organic fiber is integrally provided on the annular rib-like body protruding from the sidewall portion, thereby improving cut resistance in the side region without impairing running performance. The purpose of the present invention is to provide a pneumatic tire which can greatly improve the tire service life by making tire retreading convenient.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the pneumatic tire of the present invention has a toroidal shape in which a tread part connects each outer end of a sidewall part extending outward in the tire radial direction from a pair of bead parts. A rib-like body protruding outward from the base body and continuous in an annular manner is provided in the sidewall portion of the tire base body and between the outer end and the tire maximum width position, and A reinforcing layer using organic fibers is provided along the outer surface.

[0008]

[Operation] As described above, the present invention provides a sidewall portion of a tire base constituting a normal tire with a rib-shaped body projecting outward, and covers the rib-shaped body with a reinforcing layer. Therefore, when driving on rough roads, avoid rocks etc. that protrude from the road surface.
can be received by the rib-like body before other areas,
While reducing the rib width of the rib-like body, it is possible to suppress the occurrence of cuts in other areas. In addition, the reinforcing layer covering the rib-shaped body contains organic fibers, so it has relatively high cut penetration resistance, and the protrusion of the rib-shaped body increases the tire thickness from the carcass, making it difficult to use with conventional steel cord plies. It can exhibit puncture resistance that is approximately the same as or better than that of a type that is buried. Furthermore, by employing organic fibers, the reinforcing layer can improve its followability to the tire base, maintain tire running performance, and prevent separation from the rib-shaped body. In addition, since the rib-like bodies locally protrude from the tire base, they can be easily replaced during tire retreading, and the service life of the tire can be improved overall.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings, taking as an example a radial tire for heavy loads. In the figure, a pneumatic tire 1 includes a pair of bead portions 3 through which a bead core 2 passes, a sidewall portion 4 extending outward in the tire radial direction from each bead portion 3, and the sidewall portion 4.
The tire has a toroidal tire base 6 having a tread portion 5 connecting each outer end thereof, and a rib-like body 8 having a reinforcing layer 7 protrudes from the tire base 6.

The tire base 6 includes a carcass 9 whose both ends extending from the tread portion 5 through the sidewall portion 4 to the bead portion 3 are folded back around the bead core 2, and a carcass 9 which extends from the tread portion 5 through the sidewall portion 4 to the bead portion 3 and which is folded back around the bead core 2. It is reinforced by the belt layer 10 disposed inside the portion 5 and provides necessary tire strength and tire rigidity.

In this example, the carcass 9 has a radial or semi-radial structure consisting of one or more carcass plies with carcass cords arranged at an angle of 70 to 90 degrees with respect to the tire equator. Ru. As the carcass cord, organic fiber cords such as aromatic polyamide, nylon, polyester, etc., and inorganic fiber cords, such as steel, are used.

The belt layer 10 includes at least one belt ply 10, in this example, first, second, third, and fourth belt plies 10, which are arranged in order from the carcass side toward the tread surface.
It has a four-layer structure consisting of a, 10b, 10c, and 10d. The second belt ply 10b has a larger ply width in the tire axial direction than the other belt plies 10a, 10c, and 10d, and the belt layer 1 has a maximum width.
0 width WB, that is, in this example, the second belt ply 10
The ply width of b is 0.80 times or more of the tread width WT and 0.
．． By making it 99 times or less, the belt layer 10 reinforces the tread portion 5 with a hoop effect over almost its entire width. Note that the belt plies 10a, 10b, 10c, 10d
In this example, the belt cord is 10~10 to the tire equator.
It is a cord arrangement body arranged at an angle of 70 degrees, and in this example, by using a high-strength steel belt cord as the belt cord, the hoop effect is enhanced, and the cut resistance of the tread portion 5 is improved. There is.

[0013] Such a carcass 9, belt layer 1
A rib-shaped body 8 is provided on the sidewall portion 4 of the tire base body 6 in which the tire rubber is embedded in the tire rubber.

As shown in an enlarged view in FIG. 2, the rib-shaped body 8 is
It is made of the same rubber composition as the sidewall rubber constituting the sidewall portion 4, has a substantially trapezoidal cross-sectional shape, and is formed integrally with the sidewall portion 4. Also rib-like body 8
is the tire maximum width position P where the sidewall portion 4 extends most in the tire axial direction from the outer end e1 of the sidewall portion 4
In the side region Y leading to, in this example, in particular the buttress portion 12
It is located and protrudes between the lower end of and the maximum width position P. Note that the buttress portion 12 is similar to the sidewall portion 4.
This is a heat dissipation recess that is recessed in an arc shape from the outer end e1 to the side of the belt layer 10, and by providing the rib-like body 8 below the buttress portion 12, the temperature at the shoulder portion can be reduced. This suppresses the rise and prevents belt edge peeling.

Furthermore, the rib-like body 8 has an upper point Q1 and a lower point Q2 that rise outward from the outer surface of the sidewall portion 4 in an arc shape in this example.
It has an outer surface 8S that is substantially parallel to the straight line K passing between the outer surfaces 8S and 8S.
The rib width L, which is the length between the upper and lower edges, is set to 10 mm or more, and the reinforcing layer 7 is provided on the outer surface 8S.

In this example, the reinforcing layer 7 is formed of a reinforcing rubber material in which short organic fibers 14a are mixed substantially uniformly in a rubber base material 13 that is substantially the same as the rubber composition forming the rib-shaped body 8. ,
The outer surface 8S has a thickness t1 of at least 1 mm or more.
It is attached to the entire surface of.

As the organic short fibers 14a, for example, in addition to nylon, polyester, vinylon, high modulus aromatic polyamide fibers, aromatic polyester fibers, etc. can be used. In addition, it is preferable that the reinforcing layer 7 includes 5 to 20 parts by weight of organic short fibers 14a mixed randomly with no directionality based on 100 parts by weight of the rubber base material.
Moreover, as the organic short fibers 14a, those having a length of 0.3 mm to 3.0 mm can be used. Note that when the thickness t1 is 1 mm or less and the short fiber length is less than 0.3 mm, the effect of improving cut resistance becomes insufficient and the life of the tire is reduced. In addition, when the content of the short fibers exceeds 20 parts by weight, the reinforcing layer 7
The rigidity of the rib-shaped body 8 becomes excessive, and separation between the rib-shaped body 8 and the rib-like body 8 is likely to occur. Moreover, when the length exceeds 3.0 mm, workability is poor. Also, from the straight line K to the outer surface 7 of the reinforcing layer 7
The protrusion height h leading to S is set to be 2 mm or more. Note that when the rib width 7L is less than 10 mm and the protrusion height h is less than 2 mm, collision with a rock or the like before other areas becomes uncertain, leading to occurrence of cuts outside the other areas. .

Further, in this example, a vinyl rubber layer 15 is attached to the outside of the reinforcing layer 7, covering the entire outer surface thereof and extending to the surface of the sidewall portion 4, so as to cover the reinforcing layer 7 together with the rib-shaped body 8. . The vinyl rubber layer 15 can prevent the reinforcing layer 7 from deteriorating due to ozone, moisture, etc. and reduce its cut resistance and cut growth resistance. 8 and the vinyl rubber layer 15, a three-layer structure can be constructed, and thereby the overall cut penetration resistance etc. can be greatly improved. The vinyl rubber layer 15 also helps improve appearance. Furthermore, vinyl rubber layer 1
5 is preferably provided with a thickness of 1 mm or less,
Such vinyl rubber layer 15, reinforcing layer 7 and rib-shaped body 8
are integrally separated by heating during tire vulcanization, and the reinforcing layer 7 can be easily replaced together with the rib-shaped body 8 during tire retreading. Note that it is possible to further improve the appearance by forming a stamp such as a pictograph pattern on the outer surface of the vinyl rubber layer 15. At this time, the stamp is formed by recessing the vinyl rubber layer 15, the reinforcing layer 7, and the rib-shaped body 8. It is desirable to keep the thickness of each layer constant.

Another implementation of the reinforcing layer 7 is disclosed in FIG. In FIG. 3, the reinforcing layer 7 is formed of two inner and outer reinforcing plies 7a and 7b in this example using an organic fiber cord made by twisting organic long fibers together. Each of the reinforcing plies 7a and 7b is in the form of a sheet in which a cord arrangement body in which the organic fiber cords are arranged at an angle of 30 to 90 degrees with respect to the circumferential direction of the tire is embedded with topping rubber, and each of the organic fiber cords is formed of a ply. They are arranged in a direction that intersects each other.

In this example, the rib-shaped body 8 is formed via a step 16 extending inward from the outer surface of the sidewall portion 4, and the reinforcing layer 7 is formed on the main portion 7A that covers the outer surface 8S of the rib-shaped body 8. Wing portions 7B are provided above and below, along the upper and lower surfaces of the rib-like body 8, and whose ends are interrupted at the step 16. Note that the step 16 has a step height H that is at least greater than the thickness of the reinforcing layer 7, and in this example, approximately equal to the sum T of the thickness of the vinyl rubber layer 15, thereby covering and protecting the end portion of the reinforcing layer 7. While preventing peeling from the end portion, the outer surface of the vinyl rubber layer 15 and the outer surface of the sidewall portion are aligned to improve appearance.

(Specific example) A tire having the structure shown in FIG. 1 and a tire size of 10.00
A heavy-load tire R2014PR was prototyped based on the specifications shown in Table 1, and the cut resistance of the prototype tire was compared with a conventional tire by a sidewall impact test.

[0022]

[Table 1]

[0023]In the sidewall impact test, a pendulum is collided with the sidewall of a tire mounted on a regular rim and filled with the regular internal pressure, and the cut energy at which the tire becomes punctured is measured. can be,
It is shown as an index with the conventional tire set as 100. Note that the larger the index value, the better the cut resistance.

[0024]

[Effects of the Invention] As described above, since the pneumatic tire of the present invention has the structure, the cut resistance in the sidewall portion can be increased without impairing the tire running performance, and the service life of the tire can be greatly extended. It can be improved.

[Brief explanation of the drawing]

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

FIG. 2 is an enlarged partial cross-sectional view showing a rib-like body together with a reinforcing layer.

FIG. 3 is an enlarged partial cross-sectional view of another embodiment of the reinforcing layer.

[Explanation of symbols]

3 Tread part 4 Sidewall part 5 Tread section 6 Tire base 7 Reinforcement layer 8 Ribbed body e1 Outer end of sidewall part P Tire maximum width position

Claims (1)

[Claims] Claims: 1. Said sidewall portion of a toroidal tire base in which a tread portion connects each outer end of a sidewall portion extending outward in the radial direction of the tire from a pair of bead portions, and also connects said outer end with a tire maximum width position. A rib-like body protruding outward from the base body and continuous in an annular manner is provided between the base body and
A pneumatic tire in which the rib-like body is provided with a reinforcing layer using organic fibers along the outer surface of the rib-like body.