JPH11227410A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the lateral rigidity, cornering power, and the riding confortableness. SOLUTION: A pneumatic tire is provided with a carcass extending from a tread part 2 to a bead core of a bead part through a side wall part, and a belt layer arranged outside the carcass. In the tire, between a 5%-internal pressure state where the tire is assembled in a normal rim J and the internal pressure is 5% of a normal pressure, and a normal internal pressure state where a normal internal pressure is filled, a point E in the neighborhood of a belt edge is protrudably deformed from the 5%-internal pressure state toward the outside of the tire, and a profile outside region Q1 includes an inwardly deformed part 9 deformed from the 5%-internal pressure state toward the inside of the tire. A profile inside region Q2 includes a protrudlably deformed part 10 protruding from the 5%-internal pressure state toward the outside of the tire.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire capable of improving tire rigidity, cornering power and riding comfort.

[0002]

2. Description of the Related Art In recent years, from the viewpoint of energy saving, tires have been strongly required to have low fuel consumption. In order to improve the low fuel consumption of tires, the weight of tires has been reduced. . Such weight reduction is achieved by reducing the thickness of the rubber portion and reducing the number of plies forming the tire.

[0003]

Such a reduction in the weight of the tire can lead to low fuel consumption, but has a problem in that the rigidity and cornering power of the tire are reduced. The inventors of the present invention have conducted intensive studies in view of the above problems, and found that, even in a light-weight tire, by optimizing the tension of a cord constituting a belt layer and a carcass, the tire stiffness and cornering power were improved. And improved ride comfort.

That is, in order to improve the rigidity of the side portion of the tire, the carcass profile is set between a normal internal pressure state in which the tire is assembled to a normal rim and the normal internal pressure is filled from 5% of the normal internal pressure. Of the bead portion side, to protrude and deform the carcass rigidity by providing a protruding deformed portion in the inner region, and to improve the cornering power, for the belt layer that most affects the cornering power, at least two sheets To increase the apparent belt stiffness of this part by protruding and deforming the ply overlapping end where the ply overlaps, furthermore, in order to improve the riding comfort, in the carcass profile outside the tread side profile, Provide an inwardly deformed portion that deforms inside the tire to reduce the apparent rigidity of this portion. There have thus completed the present invention obtained a finding that it is effective.

As a prior art, Japanese Patent Publication No. Sho 61-2
Japanese Patent Application Laid-Open No. 8521, Japanese Patent Publication No. 61-28522 (Prior Art A), Japanese Patent Application Laid-Open No. 7-112602 (Prior Art B), and Japanese Patent Publication No. 7-75922 (Prior Art C) have already been proposed. .

[0006] In particular, with regard to the prior art A, it has been proposed to optimize the tension of the carcass cord by specifying the shape of the carcass profile, but these proposals include the provision of a tire outside the profile. There is no disclosure of providing an inwardly deforming portion that deforms inward. Therefore, the improvement of the ride comfort is still insufficient. Further, in the prior art B, it is described that the carcass cord tension in the shoulder region of the tire is reduced, but it is not related to the improvement of the cornering power and the tire rigidity. Further, with respect to the known technique C, although an improvement in cornering power by improvement of a carcass line is disclosed, an improvement in ride comfort and rigidity of a tire side portion is not disclosed.

[0007] As described above, an object of the present invention is to provide a pneumatic tire capable of simultaneously improving tire rigidity, cornering power and ride comfort.

[0008]

According to a first aspect of the present invention, there is provided a carcass extending from a tread portion through a sidewall portion to a bead core of a bead portion, and a carcass extending radially outward of the carcass and inward of the tread portion. And a belt layer having a ply overlap portion in which at least two belt plies overlap in the tire radial direction, wherein the ply overlap portion of the belt layer in a tire meridional section at a normal internal pressure state. A point E near the belt edge where the tire radial direction line passing through the outer end point in the tire axial direction intersects with the carcass profile, and the profile outer point where the tire radial direction line passing through the tire axial direction outer end point of the belt layer intersects the carcass profile P0 and the maximum width point P1 of the carcass, which is the outermost carcass profile in the tire axial direction. Profile outer region Q1 and a profile inner region Q2 between the carcass maximum width point P1 and a profile inner point P2 at which a tire axial direction line passing through the tire radial outer end of the bead core intersects with the carcass profile. When the tire is rim-assembled on a normal rim and the normal internal pressure state where the normal internal pressure is charged from the internal pressure state of 5% of the normal internal pressure, the point E near the belt edge is set.
Is deformed to protrude from the 5% internal pressure state toward the outside of the tire, and the profile outer region Q
1 includes an inwardly deformed portion that is deformed from the 5% internal pressure state toward the inside of the tire, and includes the profile inner region Q2.
Is characterized by including a protruding deformation portion protruding from the 5% internal pressure state toward the outside of the tire.

[0009] In this specification, "normal internal pressure" is an air pressure defined for each tire in a standard system including the standard on which the tire is based.
Maximum air pressure for TMA, table "TIRE L for TRA
The maximum value described in "OAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", or "INFLATION PRESSU" for ETRTO
RE ", or 180 if the tire is for a passenger car.
KPa.

The "regular rim" is a rim defined for each tire in a standard system including the standard on which the tire is based. For example, a standard rim for JATMA and a "Design Rim" for TRA Or ETRTO
Then "Measuring Rim".

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 illustrates a pneumatic tire for a passenger car. A carcass 6 extends from a tread portion 2 to a bead core 5 of a bead portion 4 through a sidewall portion 3.
And a belt layer 7 disposed outside the carcass 6 in the tire radial direction and inside the tread portion 2.

The carcass 6 has at least one carcass cord having a radial structure in which carcass cords are arranged at an angle of 75 ° to 90 ° with respect to the tire equator C, in this embodiment, one carcass ply 6.
A. Thereby, the weight of the tire is reduced. The carcass cord is an organic fiber cord. In this embodiment, polyester is used, but cords such as nylon, rayon, and aramid can also be used.

The carcass ply 6A has a main body 6a extending from the tread portion 2 to the bead core 5 of the bead portion 4 via the side wall portion 3, and is folded back around the bead core 5 from the main body portion 6a. One having a folded portion 6b to be locked is exemplified. Carcass 6
A bead apex 8 extending from the bead core 5 in the tire radial direction and made of hard rubber is disposed between the main body portion 6a and the folded portion 6b to reinforce the bead portion 4.

In the present embodiment, the belt layer 7 forms a ply overlapping portion K by overlapping two belt plies 7A and 7B in the tire radial direction. The width of the ply overlap portion in the tire axial direction can be appropriately determined according to a customary manner, but is preferably, for example, 0.8 to 1.1 times the tread width.

The belt plies 7A and 7B are arranged such that the cords are inclined at a small angle of 10 to 40 ° with respect to the equator of the tire, and the cords are overlapped with each other in a direction in which the cords cross each other. The belt ply 7A in the radial direction is
This shows a belt ply formed wider than the outer belt ply 7B. In the present embodiment, a steel cord is used for the belt cord, but a high elastic organic fiber cord such as aramid or rayon may be used if necessary.

In the present invention, the tire is mounted on the regular rim J
In a meridional section of the tire in a normal internal pressure state (no load) filled with a rim and filled with a normal internal pressure (in this example, 180 KPa), a carcass profile 6c (shown in FIG. 2) which is a center line of the carcass 6 has a normal internal pressure. It is characterized in that a specific deformation is made between the 5% internal pressure state and the normal internal pressure state filled with the normal internal pressure. The carcass ply has a folded portion 6b in the carcass ply.
Is not included.

First, in the present invention, a position and a region to be described below are specified in a carcass profile 6c in a meridional section of a tire in a normal internal pressure state in which a tire is mounted on a normal rim J and filled with a normal internal pressure.

First, a point where the tire radial direction line a passing through the outer end point Be in the tire axial direction of the ply overlap portion K of the belt layer 7 intersects the carcass profile 6c is determined as a point E near the belt edge.

Further, the point where the tire radial direction line b passing through the outer end point of the belt layer 7 in the tire axial direction, in this example, the outer end point of the inner belt ply 7A in the tire axial direction intersects with the carcass profile 6c is defined as the profile outer side. Let it be point P0.
In addition, the carcass maximum width point that is the outermost in the tire axial direction of the carcass profile 6c is defined as P1, and the area between the profile outside point P0 and the carcass maximum width point P1 is defined as the profile outside area Q1.

A point at which the tire axial line c passing through the tire radial outer end of the bead core 5 intersects the carcass profile 6c is defined as a profile inner point P2, and the profile inner point P2 and the carcass maximum width point P1 Is defined as the profile inner region Q2.

In the present invention, the point E in the vicinity of the belt edge is set at the 5% internal pressure between the normal internal pressure state where the tire is assembled to the normal rim J and the internal pressure is filled from 5% of the normal internal pressure. One of the features is that it protrudes from the state toward the outside of the tire and deforms.

By protruding and deforming the point E near the belt edge of the carcass profile 6c, the edge of the belt layer 7, that is, the end portion of the belt ply 7A located outside the ply overlapping portion K in the axial direction. Can be suitably protruded and deformed. As a result, the belt cord tension can be increased at the edge of the belt layer 7, the apparent rigidity of the belt can be increased, and thus the tire strongly resists lateral deformation when a slip angle is given to the tire. The cornering power can be obtained.

It is particularly preferable that the entire profile edge region Q0, which is the profile of the carcass between the point E near the belt edge and the point P0 outside the profile, is protruded and deformed toward the outside of the tire. Is significantly increased.

In the tire of the present invention, between the 5% internal pressure state and the normal internal pressure state, the profile outer region Q1 includes an inwardly deforming portion 9 that deforms from the 5% internal pressure state toward the inside of the tire. The profile inner region Q2 is also characterized in that it includes a projecting deformation portion 10 projecting from the 5% internal pressure state toward the outside of the tire.

Thus, the carcass profile 6c
By providing an inwardly deforming portion 9 that deforms inward of the tire in the profile outer region Q1 on the tread portion side, the carcass cord tension in the inwardly deforming portion 9 can be reduced as compared with other portions. Therefore, the apparent rigidity of the carcass 6 at such a portion can be reduced, so that when going over a projection or the like, the outer region Q1 of the profile can be flexibly deformed to absorb an impact and enhance ride comfort. be able to.

In the carcass profile 6c, since the protruding and deforming portion 10 is provided in the profile inner region Q2 on the bead portion 4 side, the carcass cord tension of this portion can be increased, and the apparent carcass rigidity can be increased. Can be increased. Therefore, not only the edge of the belt layer 7 but also the bead portion 4 has increased rigidity against lateral deformation, so that the rigidity of the side portion of the tire is improved, and the steering stability is further improved in conjunction with the improved rigidity of the belt layer 7. Can improve.

The carcass profile 6c is
It can be easily specified by using an imaging device such as a CT scan. The inward deformation and the protruding deformation of the carcass profile 6c are as follows.
It is preferable to secure a deformation amount of not less than mm, preferably not less than 2 mm, and in particular, it is preferable to set such that the amount of overhang deformation in the inner region Q2 of the profile is maximized.

[0028]

EXAMPLES Various types of radial tires for passenger cars having a tire size of 205 / 65R15 were manufactured, and the effects of the present invention were tested on the cornering power, the lateral spring constant, the riding comfort, and the stress distribution of the cords of each part of each tire. In addition, FIG.
FIG. 7 shows the carcass profile of each tire in a 5% internal pressure state (dotted line) and a normal internal pressure state (solid line) captured by the CT scan.

With respect to the cornering power, the lateral force at a slip angle of 1 ° of the rim-assembled tire was measured using an indoor testing machine, and was expressed as an index when the conventional tire was set to 100. In addition, the horizontal spring is 50 kgf in a load state in which a vertical load of 480 kgf is applied to the tire.
The lateral spring constant was determined from the amount of lateral deflection when the lateral load was applied, and was expressed as an index with the conventional example being 100. Furthermore, with regard to ride comfort, the test tire was mounted on the four wheels of the test vehicle and the vehicle was run.
It was indicated by an index of 00. In each case, the larger the index, the better. Table 1 shows the test results.

[0030]

[Table 1]

As a result of the test, those of the embodiment are the conventional ones,
It can be confirmed that all of the cornering power, the lateral spring, and the riding comfort are improved as compared with the comparative example.

Next, the distribution of the stress acting on the belt cord and the carcass cord under the normal internal pressure state for each of the tires of the embodiment and the conventional example is shown in FIGS. 8A and 8B.
Shown in As is apparent from these figures, in the embodiment, the stress of the belt cord is increased in the profile edge area Q0, while the stress of the carcass cord is reduced in the outer area Q1 and the carcass cord is reduced in the inner area Q2 of the profile. It can be confirmed that the stress is increased.

[0033]

As described above, according to the first aspect of the present invention, the tire is rim-assembled to the normal rim and 5% of the normal internal pressure.
Between the internal pressure state and the normal internal pressure state where the normal internal pressure is charged, the inner area of the bead side profile of the carcass profile has a protruding deformation portion to increase the carcass cord tension, and a point near the belt edge protrudes and deforms. To increase the tension of the belt cord on the edge side of the belt layer, and to provide an inwardly deformed portion that deforms toward the inside of the tire in the outer region of the tread side profile of the carcass profile to positively increase the carcass cord tension With such a reduction, tire stiffness, cornering power and ride comfort can be simultaneously improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a right half of a tire according to an embodiment of the present invention.

FIG. 2 is a diagram showing a profile of the carcass.

FIG. 3 is a diagram showing a carcass profile of a conventional tire.

FIG. 4 is a diagram showing a profile of a carcass of the tire of Comparative Example 1.

FIG. 5 is a diagram showing a profile of a carcass of the tire of Comparative Example 2.

FIG. 6 is a diagram showing a profile of a carcass of the tire of Comparative Example 3.

FIG. 7 is a diagram showing a profile of a carcass of a tire of Comparative Example 4.

8A is a graph showing a stress distribution of a belt cord in a normal internal pressure state, and FIG. 8B is a graph showing a stress distribution of a carcass cord in a normal internal pressure state.

[Explanation of symbols]

 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 6c Carcass profile 7 Belt layer 9 Inward deformation part 10 Overhang deformation part

Claims (1)

[Claims] 1. A carcass extending from a tread portion to a bead core of a bead portion via a sidewall portion, and at least two belt plies arranged radially outward of the carcass and inward of the tread portion, and at least two belt plies overlap in the tire radial direction. A pneumatic tire comprising a belt layer having a ply overlap portion, wherein a tire radial direction line passing through a tire axial direction outer end point of the ply overlap portion of the belt layer is a carcass profile in a tire meridional section in a normal internal pressure state. A point E near the belt edge, which intersects with the profile, and a carcass maximum width at which the tire radial direction line passing through the outer end point in the tire axial direction of the belt layer intersects with the profile of the carcass, and the outermost point P0 of the profile of the carcass. The profile outer region Q1 between the point P1 and the carcass maximum When the tire axial direction line passing through the tire radial direction outer end of the bead core and the width point P1 is defined as a profile inner region Q2 between the profile inner point P2 intersecting with the carcass profile, the tire is assembled to the regular rim. In addition, during a period from the 5% internal pressure state of the normal internal pressure to the normal internal pressure state filled with the normal internal pressure, the point E near the belt edge is protruded from the 5% internal pressure state toward the outside of the tire, and is deformed.
The profile outer region Q1 includes an inward deforming portion that deforms from the 5% internal pressure state toward the tire inner side, and the profile inner region Q2 protrudes from the 5% internal pressure state toward the tire outer side. A pneumatic tire comprising: