JP2000071723A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire with a rim protector that facilitates controllability during turning without deteriorating riding comfort. SOLUTION: In a pneumatic tire, a bead portion 4 is provided with an annular rim protector 9 projecting outwards in the axial direction of the tire and continuously formed along the periphery thereof. The rim protector 9 is provided with a plurality of slits 12 formed at the angle θ ranging from 45 deg. to 80 deg. relative to carcass chords 6c from the side view of the tire and tilted in the same direction as that of rotation of the tire, which are arranged at intervals to the center of the axis of the tire circumferentially. The width of the slit 12 is set to 0.5 mm or greater and the distance from the bottom of the slit to the carcass is set to 2.0 mm or greater.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pneumatic tire provided with a rim protector for protecting a rim flange.

[0002]

2. Description of the Related Art In recent years, flattening of tires has been advanced in order to improve lateral stiffness of the tires and improve athletic performance.
Various tires with a percentage of less than 10% have also appeared. As the flattening of the tire progresses, the cross-sectional height of the tire becomes relatively small, so that the rim flange of the rim and the like pass relatively close to the road surface. Therefore, for example, if the vehicle is brought too close to the road shoulder, the rim flange may come into contact with the curb and damage it.

In order to prevent such damage to the rim flange, for example, as shown in FIG. 8, a bead portion b is formed so as to protrude outward in the tire axial direction so as to cover the rim flange jf and to be continuous in the tire circumferential direction. It has been proposed to provide a rim protector d. As a result, the rim protector d is brought into contact with the curb on the road shoulder before the rim flange jf to prevent the rim flange jf from being damaged.

By the way, such a rim protector d
Is generally formed by increasing the rubber gauge, so that the bending region such as the sidewall portion is reduced, and the longitudinal spring of the tire tends to be increased, thereby deteriorating the riding comfort and increasing the load burden on the bead portion b. The durability may be reduced.

In general, during normal running, such a rim protector d has a certain gap between an inward surface i facing inward in the tire radial direction and a rim flange jf. However, at the time of turning, etc., as shown by a dashed line in the figure, the inward surface i of the rim protector comes into contact with the rim flange jf in a wide range so as to rest on the rim flange jf, thereby rapidly increasing the tire rigidity. However, there is a problem that it is very difficult to control the vehicle at the time of turning.

The present invention has been devised in view of such a problem. In the rim protector, a notch which is inclined at a predetermined angle with a radially arranged carcass cord as viewed from the side of the tire is provided. It is an object of the present invention to provide a pneumatic tire with a rim protector that can easily control the vehicle during turning without compromising ride comfort.

[0007]

According to a first aspect of the present invention, there is provided a carcass having carcass cords arranged in a radial direction from both sides of a tread portion to a bead core of a bead portion via sidewalls and a sidewall portion. A pneumatic tire provided with an annular rim protector that protrudes outward in the tire axial direction and is continuous in the tire circumferential direction at the bead portion. A plurality of cuts inclined at an angle of 45 to 80 ° with respect to the carcass cord and in the same direction with respect to the rotation direction of the tire are spaced in the circumferential direction around the tire axis, and the width of the cut is set to 0. The distance D from the bottom of the cut to the carcass is 5 mm or more and the distance D is 2.0 mm or more.

According to a second aspect of the present invention, the tread portion has a directional tread pattern in which a rotation direction is specified, the rim protectors are formed in bead portions on both sides, and the cuts are formed by: The pneumatic tire according to claim 1, wherein the rim protectors on both sides of the tire are inclined in the same direction with respect to the rotation direction of the tire.

According to a third aspect of the present invention, the tread portion has a non-directional tread pattern in which a rotation direction is not specified, the rim protectors are formed in bead portions on both sides, and the cuts are The pneumatic tire according to claim 1, wherein the rim protectors on both sides of the tire are inclined in opposite directions to the rotation direction of the tire.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 illustrates an assembly of a normal rim J and a pneumatic tire in a standard state in which the rim is assembled to a normal rim J, is filled with a normal internal pressure, and has no load. Appears symmetrically with the right half.

[0010] The "regular rim" is a rim defined for each tire in the standard system including the standard on which the tire is based.
"Standard rim", "Measuring Rim" for TRA, or "Measuring Rim" for ETRTO.

[0011] The "normal internal pressure" is the air pressure that is defined for each tire in the standard system including the standard on which the tire is based. Table "TIRE LOAD LIMITS AT
VARIOUS COLD INFLATION PRESSURES "
EINFTO means "INFLATION PRESSURE",
When the tire is for a passenger car, the pressure is 300 kPa.

Further, the "regular load" is a load defined by each standard in each standard in a standard system including a standard on which the tire is based. Ba Table "TIRE LOAD LIMITS A
The maximum value described in "T VARIOUS COLD INFLATION PRESSURES", or "LOAD CAPACITY" for ETRTO.

In FIG. 1, a pneumatic tire according to the present embodiment includes a carcass 6 extending from a tread portion 2 to a bead core 5 of a bead portion 4 through a sidewall portion 3, and a tire radius inside the tread portion 2 and the carcass 6. A flat tire having a belt layer 7 disposed on the outer side in the direction and having a flatness of 50% or less, and a flattening ratio of 45% in this example, is illustrated as an example.

The carcass 6 has a carcass cord 6C (shown in FIG. 2) of, for example, 75.degree.
One or more radial structures arranged at an angle of 0 °, preferably 80 to 90 °, and one carcass ply 6A that intersects the tire equator C at almost 90 ° is illustrated in this example. . In the present embodiment, the carcass ply 6A includes a toroidal main body 6a extending from the tread portion 2 to the bead core 5 of the bead portion 4 via the sidewall portion 3;
A folded portion 6b is formed integrally with the body portion 6a and is folded around the bead core 5 from the inside to the outside in the tire axial direction. As the carcass cord, an organic fiber cord such as polyester, nylon, rayon or the like is preferably adopted, but a steel cord may be adopted depending on the tire.

The main body 6a of the carcass ply 6A
A bead apex 8 that extends from the bead core 5 in the tire radial direction and is made of hard rubber is disposed between the bead portion 5 and the folded portion 6b to reinforce the bead portion 4.

The belt layer 7 is formed by forming a high elastic cord such as a metal cord by 10 to 40 ° with respect to the tire equator.
At least two, in this example, inner and outer belt plies 7A and 7B, which are arranged at a small angle, are superposed in a direction in which the cords cross each other. Although not shown, a so-called band layer or the like in which a low elasticity organic fiber cord is substantially arranged in the tire circumferential direction may be appropriately arranged on the outer side of the belt layer 7 in the tire radial direction.

Further, the pneumatic tire includes the bead portion 4.
Further, an annular rim protector 9 protruding outward in the tire axial direction and continuing in the tire circumferential direction is formed. Such a bead protector 9 has a further larger tire profile than a standard tire bead profile N that smoothly connects a sidewall portion 3 and a separation point P at which the bead portion 4 is separated from the rim J, as shown in an enlarged view in FIG. It protrudes axially outward. The rim protector 9 extends so as to cover a radially outer portion of the flange arc portion JF1 which is an arc-shaped portion of the rim flange JF and with a small gap therebetween, and extends the rim flange JF from a curb on a road shoulder. Protect.

In the present embodiment, the surface of the rim protector 9 has a convex top 9a, which is the portion most protruding outward in the tire axial direction from the bead profile N of the standard tire.
And hem portions 14 and 15 smoothly extending inward and outward in the tire radial direction from both ends of the top portion 9a and smoothly continuing to the bead profile N of the standard tire. The raised one is illustrated.

The skirt portion 14 on the inner side in the radial direction of the tire.
Indicates that, in the standard state, the flange arc portion JF2 of the rim flange JF is separated from the tire outermost point M in the tire radial direction. In addition, such a rim protector 9
Is preferably formed from a rubber having excellent wear resistance and trauma resistance using, for example, a hard clinch rubber which is in contact with the vertical portion JF1 of the rim flange.

In this embodiment, as shown in FIG. 2 (A) which is a side view of the tire and FIG. 2 (B) which is a schematic view of the intersection of the cord and the cut, the tire is attached to the rim protector 9. When viewed from the side, the carcass cord 6C of the carcass 6 has an angle θ of 45 to 80 ° (measured on the acute angle side) with respect to the carcass cord 6C and a plurality of cuts 12 inclined in the same direction with respect to the rotation direction of the tire. They are spaced in the circumferential direction with the center at the center. Note that the carcass cord 6C is compared with a portion of the bead portion 4 closest to the cut, in this example, a folded portion 6b of the carcass ply.

By forming such notches 12 in the rim protector 9, deformation of the rim protector 9 can be promoted when a vertical load is applied to the tire. As a result, the bending area can be increased, the riding comfort can be improved, and the bead can be improved. Part 4
Can be improved in durability.

Further, when turning, a lateral force acts on the tire, so that the tire is deformed as shown in FIGS. 4 (A) to 4 (B), and the rim protector 9 comes into contact with the flange circular arc portion JF2. The notch 12 can be opened, or as shown in FIG. 4C, a further lateral force acts to narrow the notch 12 again to allow further deformation of the rim protector 9. Therefore, a sharp change in tire stiffness is prevented even at the time of turning, so that the controllability of the vehicle is facilitated. Further, such a plurality of cuts 12 enhance the heat radiation effect of the rim protector 9 that easily accumulates heat due to the large rubber gauge, and serve to further improve the durability of the bead portion 4.

The notch 12 regulates the angle of intersection with the carcass cord 6C as viewed from the side of the tire, thereby promoting deformation of the rim protector 9 and increasing strength or rigidity in the notch direction, for example. Of the rim protector 9 can have the strength directionality. Then, the strength direction is set to the carcass cord 6.
By intersecting with C at a specific angle, the bead portion 4 can be suitably reinforced and steering stability can be improved. This has the same effect as, for example, arranging a cord chain in which cords are arranged obliquely in the bead portion.

The cut 12 and the carcass cord 6
If the angle of intersection with C is less than 45 °, the angle of intersection is too small to obtain a deformation promoting effect on the rim protector 9, and if it exceeds 80 °, on the other hand, the radial structure carcass has As a result, the inclination of the cut becomes too large, and the strength directionality cannot be obtained, and therefore, the steering stability tends to decrease. From such a viewpoint, the angle at which the cut 12 intersects the carcass cord 6C is:
It is desirably 45 to 70 °.

In the present embodiment, the cuts 12 are spaced at a uniform rotation angle pitch in the circumferential direction around the tire axis. This cut 12 is formed on one side of the tire, for example, at least 5 and preferably at least 10
It is particularly preferable to arrange more than 20 pieces, more preferably more than 20 pieces at a uniform rotation angle pitch. In this example, as shown in FIG. 5, which is a cross section taken along line XX of FIG. 2, the cut 12 is formed from the outer skirt 15 of the rim protector to the inner skirt 14 via the top 9a. An example is shown. In addition,
Such a cross-sectional shape of the cut 12 can be variously deformed, and can be formed by various methods such as a vulcanization mold or a knife cut after vulcanization.

The cut 12 has a width of 0.5
mm and the distance D (shown in FIGS. 3 and 5) from the bottom portion 12B of the cut 12 to the carcass is 2.0 mm
It is necessary to do the above. The width of the cut is 0.
When the distance D is less than 5 mm, the effect of promoting the deformation of the rim protector 9 tends to be relatively reduced.
If the diameter is less than mm, cracks that reach the carcass from the bottom portion 12B of the cut 12 are likely to occur due to stress concentration or the like, and the durability of the tire is reduced.

From such a viewpoint, the width of the cut is, for example, 0.5 to 3.0 mm, preferably 0.5 to 2.0 mm.
The distance D is desirably 0 mm, more preferably 0.5 to 1.5 mm, and the distance D is desirably 2.0 to 5.0 mm.

The radius of curvature of the bottom portion 12B of the notch 12 is, for example, 0.5 to 0.5 to prevent stress concentration.
Provision of a small arc portion of 1.0 mm may be preferably implemented. Further, the groove depth of the circumferential groove 12 may be determined in consideration of the reason for limiting the groove bottom position.
It can be set to about 10 mm, and in this example, about 7 mm is illustrated.

As shown in FIG. 6 in which the tire is developed,
Rim protectors 9, 9 on bead portions 4, 4 on both sides, respectively
And the notches 12 are made to be in the same direction with respect to the rotation direction of the tire at the rim protectors 9 on both side surfaces of the tire, and also, as shown in FIG. Can also.

FIG. 6 exemplifies a tire having a directional tread pattern T1 in which the tread portion 2 has a specified direction in which the rotation direction is marked on a sidewall portion or the like because the action of the lateral groove 20 differs depending on the rotation direction. ing. In this case, it is preferable that the cuts 12 are formed in the rim protectors 9 on both sides of the tire in the same direction with respect to the rotation direction of the tire. That is, when the tire is deployed, the cuts 12 are arranged substantially symmetrically with respect to the tire equator C.

In the present embodiment, the notch 12 is inclined toward the first arrival side in the tire rotation direction with respect to the bead side. By tilting in this direction, the bead reinforcing effect by the rim protector 9 can be easily obtained. Also, in the tire having such a directional tread pattern T1, the inclination of the cut 12 with respect to the rotation direction is the same at the bead portions 4 on both sides of the tire, so that the right and left rigidity balance is improved. Excellent steering stability is demonstrated.

FIG. 7 illustrates a tire provided with a non-directional tread pattern T2 in which the rotation direction is not specified because the operation of the lateral groove 21 is the same regardless of the rotation direction. ing. In this case, it is preferable that the cuts 12 are formed in the rim protectors 9 on both sides of the tire so as to be inclined in a direction opposite to the rotation direction of the tire. That is, when the tire is deployed, the cuts 12 are arranged substantially point-symmetrically with respect to some arbitrary points on the tire equator C. Therefore, the operation of the rim protector 9 can be the same regardless of the rotation direction of the tire.

Although the embodiment of the present invention has been described in detail, the cut 12 is formed as shown in FIGS.
When the tire is deployed, it can be tilted in the same direction as the tilt direction of the lateral groove 20 or 21, and can also be tilted in the opposite direction. It is also possible to make the cut or to make the cut itself bend smoothly. Further, the present invention can be modified in various modes such that a plurality of cuts adjacent in the tire circumferential direction may overlap each other in the tire radial direction or may be separated from each other.

[0034]

EXAMPLE A pneumatic tire having a tire size of 215 / 45R17, having the basic structure shown in FIG. 1 and having the specifications shown in Table 1 was prototyped (Examples 1 and 2), riding comfort and steering stability. , Bead durability and the like were measured and evaluated.
Tests were also performed on a conventional tire having no cut (conventional example) and a tire (Comparative Examples 1 and 2) in which the cut width and the inclination angle with respect to the carcass cord did not satisfy the requirements of the present invention, and the performance was compared. The carcass cord was set at 90 degrees with respect to the tire equator C. The test method is as follows.

(1) Riding comfort Four test tires are mounted on a test vehicle, and the tires feel rough on a dry asphalt road surface of a tire test course.
The sensory evaluation of the driver regarding the thrust-up and the damping was performed, and the result was indicated by an index with the conventional example being 100. The higher the value, the better.

(2) Steering stability On a dry asphalt road surface of a tire test course,
Various test runs were performed, and the results were indicated by an index with the conventional example being 100 based on the sensory evaluation of the driver. The higher the value, the better.

(3) Bead Durability The test tire was mounted on a regular rim (17 × 7.0 JJ), filled with an internal pressure of 300 kPa, and was run on a drum at a load of 10.07 kN and a speed of 60 km / h. When the damage that can be confirmed visually is generated, the driving ends.
The running time was measured and evaluated by an index using the conventional example as 100. The higher the value, the better.

[0038]

[Table 1]

As a result of the test, it is understood that the tires of the examples are excellent in ride comfort, steering stability, bead durability and the like.

[0040]

As described above, according to the first aspect of the present invention, a notch is formed in the rim protector at a predetermined angle with respect to the carcass cord, so that when the tire is subjected to a vertical load, In addition to opening and closing the notch, the relative displacement of the rubber portion along the notch and the like can promote deformation of the rim protector, thereby increasing the bending area and improving ride comfort, and improving the bead portion. Durability can be improved. In addition, the notch enhances the heat radiation effect of the rim protector that easily accumulates heat due to the large rubber gauge, which helps to further improve the durability of the bead portion.

Further, the cuts are formed by restricting the intersection angle with the carcass cord as viewed from the side of the tire, thereby promoting the deformation of the rim protector and increasing the strength or rigidity in the cut direction, for example. Strength directionality. By intersecting the strength direction with the carcass cord at a specific angle, the bead portion can be suitably reinforced and the steering stability can be further improved.

According to the second aspect of the present invention, in a tire having a directional tread pattern in which a rotation direction is specified, the action of rim protectors formed on both sides of the bead portion is the same on both sides of the bead of the tire. Therefore, it is possible to improve the left-right rigidity balance of the tire and improve the steering stability.

According to the third aspect of the invention, it is possible to make the action of the rim protector the same irrespective of the rotation direction of the tire, which is particularly preferable for a tire having a non-directional tread pattern, and is easy to use. Versatility increases.

[Brief description of the drawings]

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

FIG. 2 is a partial side view of a bead portion as viewed from the side.

FIG. 3 is a partially enlarged sectional view of a bead portion.

FIGS. 4A to 4C are schematic diagrams showing deformed states of a bead portion.

FIG. 5 is a sectional view taken along line XX of FIG. 2;

FIG. 6 is a development view of a tire showing one embodiment of the present invention.

FIG. 7 is a development view of a tire showing another embodiment of the present invention.

FIG. 8 is a sectional view of a bead portion for explaining a conventional rim protector.

[Explanation of symbols]

 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 6A Carcass ply 6a Carcass ply body 6b Carcass ply turnback 9 Rim protector 12 Cut 12B Cut bottom

Claims (3)

[Claims] 1. A pneumatic tire having a carcass having carcass cords arranged in a radial direction from both sides of a tread portion through sidewall portions to a bead core of a bead portion, wherein the bead portion has a tire shaft. An annular rim protector that protrudes outward in the tire circumferential direction and is continuous with the tire circumferential direction. The rim protector has an angle of 45 to 80 ° with respect to the carcass cord of the carcass when the tire is viewed from the side and the rotation of the tire. A plurality of cuts inclined in the same direction with respect to the direction are spaced apart in the circumferential direction around the tire axis, and the width of the cut is 0.5 mm or more, and the distance D from the bottom of the cut to the carcass is 2. A pneumatic tire having a thickness of 0 mm or more. 2. The tire according to claim 1, wherein the tread portion has a directional tread pattern in which a rotation direction is designated, and the rim protectors are formed in bead portions on both sides, respectively, and the cuts are formed on rim protectors on both side surfaces of the tire. The pneumatic tire according to claim 1, wherein the tire is inclined in the same direction with respect to the rotation direction of the tire. 3. The tread portion has a non-directional tread pattern in which the direction of rotation is not specified, and the rim protectors are formed on bead portions on both sides, respectively, and the cuts are formed on rim protectors on both side surfaces of the tire. 2. The pneumatic tire according to claim 1, wherein the tire is inclined in a direction opposite to the rotation direction of the tire.