JPH06316206A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To enhance the endurance of a pneumatic tire against external damage, maneuvering stability, and sustainability for rim slipping off while lightweight constructing of the tire is promoted, by furnishing the outer wall surface of the side wall part with a protector made from a rubber compound protruding from the outer wall surface and extending in the circumferential direction, and also furnishing a void confined by the protector. CONSTITUTION:The outer wall surface 3A of the side wall part 3 is furnished with a protector or protectors 6 which protrude at the outer wall surface 3A and extend in the tire circumferential directfion. Its section shape in the radial direction is semicircular, and a void 7 is provided approx. in the center thereof which continues in the circumferential direction and shut from the outside. The void 7 should have a capacity V being 0.3 to 0.7 times as large as the whole volume V of the protector 6. This allows the protector 6 to maintain its rigidity and also be achieved in a further lightweight construction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire having a high external damage resistance and a rim detachment resistance property against puncture.

[0002]

2. Description of the Related Art Recently, due to environmental problems and energy problems,
There is a great demand for improved fuel economy performance for vehicles. The same applies to tires, which require smaller rolling resistance and lighter weight. In particular, the reduction of the tire weight can improve both the rolling resistance of the tire and the low fuel consumption performance of the vehicle.

To reduce the weight of a pneumatic tire, the thickness of the tread rubber is reduced. Reduce the rubber thickness of the sidewall part. Reduce the diameter of the carcass cord that makes up the carcass. Lower the hoisting height of the carcass. Aim to reduce the volume of bead apex.
Reduce the tread width. Although the method has been considered from the past, the tire formed by the method,
In that case, the wear resistance is poor and the steering stability is reduced. Further, in the case of the tire, when the tire comes into contact with the road shoulder, the outer wall is inferior in external damage resistance such as cracking. Further, in the case of the tire, the basic tire performance is deteriorated such that steering stability is deteriorated.

On the other hand, when the tire is flat, as shown in FIG.
As shown in FIG. 8, the bead b moves from the rim j, and there is a risk of rim detachment. To prevent this rim detachment, as shown in FIG. There is also a proposal to attach a thick rubber a, and a projection c is provided on the bottom surface of the bead portion b as shown in FIG. 9, and the projection c is fitted into the groove portion d formed in the rim j together with the rim assembly. Has been done.

[0005]

However, in the former case, the weight of the tire increases, which causes an increase in rolling resistance.
In the latter case, a special rim is required in addition to an increase in rolling resistance, and there is a problem that the marketability is poor.

The inventor has found that the above-mentioned problems can be solved by providing a protector made of a rubber composition and having a closed space inside thereof on the outer wall surface of the sidewall portion in a circumferential direction. It was.

The present invention improves the safety of driving by increasing the resistance to external damage of the sidewall portion and preventing the rim from coming off even when air leaks due to external damage, and the rigidity in the lateral direction is increased, so that steering stability is improved. The purpose of the present invention is to provide a pneumatic tire that can improve the tire's performance, promote the weight reduction of the tire, and reduce the rolling resistance.

[0008]

SUMMARY OF THE INVENTION The present invention is a toroidal tire base body in which a tread portion joins between outer ends of sidewall portions extending outward in the tire radial direction from a pair of bead portions to which rims are fitted. And a protector made of a rubber composition protruding from the outer wall surface and extending in the circumferential direction on the outer wall surface of the sidewall portion, and a closed space provided in the protector. It is a pneumatic tire characterized by.

The vacant space is 0.3 of the total volume of the protector.
It is preferable to have a volume not less than twice and not more than 0.7 times.

It is more preferable that the space is filled with a resin having a specific gravity of 1.0 or less, or a resin, a foam material, or a mixture thereof.

The protector preferably contains 0.1 to 0.5 weight ratio of short fibers in its rubber composition, oriented in the tire circumferential direction.

[0012]

[Function] A protector is provided on the outer wall surface of the sidewall portion so as to project from the outer wall surface and extend in the circumferential direction.
As a result, when the tire comes into contact with the road shoulder as shown in FIG. 4 during traveling, the protector collides with the road shoulder, prevents damage to the outer wall of the sidewall, and prevents accidents such as air leakage.

Further, by providing such a protector, the rubber thickness of the sidewall portion can be reduced, the weight of the tire can be reduced, and the rolling resistance can be reduced.

Further, by providing the protector having the above-mentioned structure on the outer wall surface of the side wall portion, the lateral spring constant is increased and the lateral rigidity is larger than that of the conventional tire, so that the steering stability is improved.

In addition, even if the vehicle is in a run-flat state due to air leakage due to puncture during traveling,
As shown in FIG. 7, the presence of the protector increases the bending rigidity of the sidewall portion and prevents local deformation of the sidewall portion, thereby preventing the sidewall portion from cracking. Further, by increasing the rigidity in the lateral direction, it is possible to prevent the rim from being detached from the bead portion at the time of the run flat, and it is possible to enhance the safety during traveling.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 to 4, a pneumatic tire 1 (hereinafter referred to as tire 1) has a pair of bead portions 2 and 2 to which a rim J is fitted.
And a toroidal tire base body 5 including sidewall portions 3 and 3 extending outward from the bead portions 2 and 2 in the tire radial direction, and a tread portion 4 connecting the outer ends of the sidewall portions 3 and 3, respectively. Have.

In the tire base 5, the bead core 3 of the bead portion 2 passes from the tread portion 4 to the sidewall portion 3.
A carcass 13 that folds back around, and a belt layer 14 inside the tread portion 4 and radially outward of the carcass 13,
The bead portion 2 is provided with a bead apex 15 having a triangular cross section that rises radially outward from the bead core 12 between the main body portion and the folded portion of the carcass 13.

The carcass 13 is a carcass cord made of an organic fiber such as nylon, rayon or aromatic polyamide, and in this embodiment, it is 70 to 90 with respect to the tire equator C.
A carcass ply of a radial or semi-radial arrangement that is inclined and arranged is formed by one or more layers, in this example, one layer.

The belt layer 14 comprises one or a plurality of belt cords made of organic fiber cords such as nylon, rayon and aromatic polyamide or steel cords arranged parallel or inclined with respect to the tire equator, and in this example, two. Formed by the belt ply.

In the side wall portion 3, a side wall rubber is attached to the outside of the carcass 13 in the tire axial direction, and the side wall rubber 16 forms an outer wall surface 3A. As the sidewall rubber, a rubber softer than the tread rubber forming the tread surface 4A is used. The outer wall surface 3
A has one or a plurality of protectors 6 protruding from the outer wall surface 3A and extending in the tire circumferential direction.
This is wound.

In this embodiment, as shown in FIG. 2, one protector 6 is arranged near the tire maximum width point B, which is a point on the outer wall surface 3A in the tire maximum width BW, and the protector 6 has no end on the outer wall surface 3A. Orbit around. Further, its radial cross-section has a semicircular shape, and has a cavity 7 continuous in the circumferential direction at its substantially central portion and closed from the outside. The cross-sectional shape of the protector may be a rectangular or triangular contour shape other than the above-mentioned configuration, and the space 7
May have a discontinuity in the circumferential direction and be intermittent. Further, the protector 6 has a maximum tire width point B as shown in FIG.
It is also possible to dispose a plurality of, in this example, three inward and outward in the radial direction with respect to the center, and further to extend a long strip-shaped protector around the tire maximum width point B in a spiral shape. . By increasing the number of protectors 6 or the number of laps, it is possible to improve the scratch resistance and the rim removal resistance performance, but if it is too large, it becomes difficult to achieve weight reduction. It is preferable to arrange 1 to 5 tires on one side of the tire.

The empty space 7 is the total volume V of the protector 6.
The volume v is preferably 0.3 times or more and 0.7 times or less. By providing such a space 7, the protector 6 can further reduce its weight while maintaining its rigidity.

When the volume ratio v / V of the space 7 is less than 0.3, the weight reduction effect is small, and when it exceeds 0.7, the protector 6 has too low rigidity, and the damage resistance and rim detachment resistance are low. Hard to achieve improvement.

The protector 6 is made of a rubber composition which is harder than the side wall rubber. In this embodiment, the rubber composition contains short fibers of 10 to 50 PHR and the short fibers are arranged in the tire circumferential direction. It is arranged for.
As the short fiber material, nylon, rayon, polyester, aromatic polyamide, cellulose resin, crystalline polybutadiene, organic fiber such as cotton thread, carbon fiber, metal fiber, boron and glass fiber can be used. As the short fiber material, organic fiber, especially nylon, can be preferably used.

This is because if the content of the short fibers is less than 10 PHR, the effect of the rigidity of the protector 6 is poor, and if it exceeds 50 PHR, poor adhesion between the rubber and the fibers may occur.

The short fibers preferably have a diameter of 1 μmm to 0.1 mm and a length of 20 μmm to 2 mm. If the thickness and the length are smaller than the above values, the cut resistance is inferior, while if it exceeds the above values, the fatigue resistance of the rubber layer may be deteriorated. The short fibers have an inclination of 0 to 20 with respect to the circumferential direction, and thus are substantially oriented in the circumferential direction.

The protector 6 has a complex elastic modulus E * measured by a viscoelastic spectrum meter of 50 to 450 kg /
It is set to cm ² , preferably 80 to 400 kg / cm ² .
This is because even if the value is higher or lower than the above value, sufficient cut resistance and fatigue resistance, which are maintained in harmony with the sidewall rubber, cannot be obtained.

As described above, the protector 6 is kneaded by using a Banbury or calender roll to improve the kneading of rubber, and is further molded or extruded by a calender roll to align the orientation of the short fibers in the direction of extrusion. It is possible to form a long rubber body.
Then, this rubber body is attached to the outer surface of the sidewall rubber in the tire molding step prior to vulcanization, and is integrally attached to the sidewall rubber by vulcanization.

In this embodiment, the void 7 is filled with fibers. As the fiber, a lightweight organic fiber having a specific gravity of 1.0 or less is used. In addition to the above-mentioned fibers, a resin or a foam material having a specific gravity of 1.0 or less may be used to fill the voids 7, and a mixture thereof may be used. By loading the fibers or the like into the space 7 in this manner, the rigidity of the protector 6 in the circumferential direction can be further increased as compared with the case where the space 7 is not filled at all.

Next, the operation of the protector 6 when the tire is running will be described. Outer wall surface 3 of the sidewall part 3
By providing the protector 6 having the above-described configuration in A,
When a curb protruding from the road surface L or a road shoulder W approaches and comes into contact with the curbstone, the protector 6 prevents the outer wall surface 3A of the sidewall portion 3 from contacting the road shoulder W, as shown in FIG. Prevents contact with the shoulder W of the wall surface 3A,
It is possible to protect the sidewall portion 3 from external damage, which makes it possible to reduce the rubber thickness of the sidewall rubber and reduce the weight of the tire.

When short fibers arranged in the tire circumferential direction are mixed in the rubber composition forming the protector 6, the protector 6 maintains a high rigidity in the circumferential direction, whereby the internal pressure is increased. The tire shape in the tire axial cross section at the time of filling can be maintained in a special shape.

In FIG. 5, the pneumatic tire provided with the protector 6 according to the configuration of the present application is shown by a solid line, the conventional tire t not provided with a protector is shown by a chain line, and each of the tires 1 and t has the same size. In addition, the tire bases are configured the same and the respective tire cross-sectional shapes in a state where the tire pressure is filled are shown.

When both tires 1 and t are filled with the internal pressure, the sidewall portion 3 rises outward in the radial direction. However, by arranging the protector 6 on the outer wall surface 3A of the sidewall portion 3, the amount of rise is suppressed. As a result, as shown in FIG. 5, the tire 1 provided with the protector 6 having the configuration of the present application is
It has a shape that bulges inward in the radial direction compared to.

That is, in FIG. 5, the outer wall surface 3A of the sidewall portion 3 has a radius of curvature radially outward in the tire 1 of the present application.
Is R1 and the conventional tire t is R1 ', then R1>R1'. On the other hand, when the radius of curvature of the outer wall surface 3A radially inward is R2 for the tire 1 of the present application and R2 ′ for the conventional tire t, R2 <R2 ′.

As a result, in the tire 1 having the configuration of the present application, the radius of curvature of the outer wall surface 3A radially outward from the maximum width point B can be increased, and as a result, the lateral force is counteracted when the tire is running. The steering stability can be improved by increasing the contribution rate of the internal pressure and increasing the lateral rigidity of the tire.

Further, when a load P is applied to the tire 1 in the radial direction, a bending moment M with the rim flange JF as a fulcrum acts as shown in FIG. 6, and a force F for lifting the rim base JB acts. This phenomenon is remarkable when a run-flat state is caused by a puncture as shown in FIG. When the protector 6 is provided to reduce the radius of curvature R2 inward in the radial direction as in the tire 1 having the configuration of the present application, the bending moment M is reduced and therefore the force F is reduced. As a result, it is possible to prevent the rim from coming off during puncture, and it is possible to improve the safety of traveling.

[0037]

SPECIFIC EXAMPLES Tires (Examples 1 to 3) each having a tire size of 185 / 60R14 and having the configuration shown in FIG. 1 were prototyped and their performances were tested.
A tire having a conventional structure without a protector (comparative example) was also tested and the performance was compared. The tires of Examples 1 to 3 were made thinner by reducing the thickness of the sidewall rubber than the tires of Comparative Example. The test specifications are as follows.

A) Lateral spring constant For each test tire, the maximum internal pressure specified in JIS standard,
It is calculated from the magnitude of the lateral force and the displacement when a lateral force is applied to the tire under the condition of maximum load, and is represented by an index with the comparative example being 100. The larger the value, the higher the lateral spring constant.

B) Rim resistance performance A low internal pressure of 0.5 kg / cm ² was applied to each test tire and a lateral force was applied in a flat pressing state to measure the lateral force at the moment of rim disengagement. Is shown as an index. The larger the value, the better the anti-rim removal performance. The test results are shown in Table 1.

[0040]

[Table 1]

As a result of the test, it was confirmed that the embodiment had improved lateral spring constant and rim detachment resistance even though the weight was reduced as compared with the prior art.

[0042]

As described above, the pneumatic tire of the present invention is
The outline is to provide a protector that is continuous in the circumferential direction on the outer wall surface of the sidewall portion, and to provide a void inside the protector. The detachability can be improved.

[Brief description of drawings]

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

FIG. 2 is an enlarged cross-sectional view showing a sidewall portion thereof.

FIG. 3 is a cross-sectional view showing another example of the protector.

FIG. 4 is a cross-sectional view showing a state where the tire is in contact with the side wall.

FIG. 5 is a cross-sectional view showing the operation.

FIG. 6 is a sectional view showing the operation.

FIG. 7 is a cross-sectional view showing a run-flat state.

FIG. 8 is a cross-sectional view schematically showing a conventional tire.

FIG. 9 is a cross-sectional view schematically showing a conventional tire.

FIG. 10 is a cross-sectional view showing a run-flat state of a conventional tire.

[Explanation of symbols]

 2 bead part 3 sidewall part 3A outer wall surface 4 tread part 5 tire base 6 protector 7 void J rim

Claims (4)

[Claims] 1. A pneumatic tire having a toroidal tire base body in which a tread portion connects between outer ends of sidewall portions extending outward in the tire radial direction from a pair of bead portions to which rims are fitted. A pneumatic tire characterized in that a protector made of a rubber composition that projects from the outer wall surface and extends in the circumferential direction is provided on the outer wall surface of the sidewall portion, and a closed space is provided in the protector. 2. The empty space has a total volume of 0.
The pneumatic tire according to claim 1, which has a volume of 3 times or more and 0.7 times or less. 3. The pneumatic chamber according to claim 1, wherein the void is filled with any one of fibers, resins and foams having a specific gravity of 1.0 or less, or a mixture thereof. tire. 4. The protector contains short fibers of 10 to 50 PHR in its rubber composition, and the short fibers are oriented in the tire circumferential direction.
Alternatively, the pneumatic tire according to item 3.