JP2544528B2 - High speed heavy duty tire - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-speed heavy-duty tire capable of improving the durability by reducing the internal strain of the tire and making the contact pressure uniform.

[0002]

2. Description of the Related Art Generally, a pneumatic tire is vulcanized and molded under an internal pressure of about 20 kg / cm2.
At that time, the carcass case is constrained by the vulcanization mold together with the tire outer shape, and the carcass extends under the constrained shape so that the cord tension becomes uniform and is integrated with the tire rubber.

On the other hand, high-speed heavy-duty tires, especially aircraft tires, are used under severe conditions such as heavy loads and high-speed running, so their proper internal pressure, that is, normal internal pressure, is 1
This is 5 to 16 kg / cm2, which is extremely large compared to general vehicle tires.

[0004]

Therefore, in such an aircraft tire, the tire inner cavity expands into a substantially circular shape close to a natural equilibrium state due to the large normal internal pressure during use. As a result, there is a problem that the tread portion largely bulges outward in the radial direction of the tire, the internal strain is increased by locally increasing the tension of the carcass cord, and the tire durability is impaired.

Therefore, the present inventors have made extensive studies to suppress such internal strain. As a result, in the conventional tire, as shown in FIG. 6, the radius of curvature ra during vulcanization molding of the carcass A in the tread crown region Y on the tire equator side is extremely large, that is, flat. , The radius of curvature ra is remarkably reduced to the radius of curvature rb in the normal internal pressure state shown by the alternate long and short dash line, and the change in the radius of curvature ra, rb in the crown region Y is the main cause of the local internal strain. It was determined that the durability is reduced.

Moreover, since the carcass A expands toward one natural equilibrium shape, the radius of curvature rb is 0.5 kg / cm when the normal internal pressure is large like an aircraft tire.
2 It was confirmed that the radius of curvature ra under internal pressure was not so affected.

That is, the present invention is based on the fact that the radius of curvature of the carcass in the crown region during vulcanization molding is set small in advance, and the radius ratio to the radius of curvature under normal internal pressure is restricted to a low level. The purpose is to provide a high-speed heavy-duty tire that can improve durability.

[0008]

In order to achieve the above object, a high speed heavy load tire of the present invention comprises a carcass folded around a bead core of a bead part from a tread part to a sidewall part, The carcass inner line formed by the inner surface of the carcass facing the tire inner cavity in the tire cross section including the tire shaft has a carcass inner line of 0.5 kg / cm2 in which the tire is mounted on a regular rim and is filled with an inner pressure of 0.5 kg / cm2.
A carcass equator point C where the carcass inner line intersects the tire equatorial plane when in an internal pressure state, and a carcass which is the distance from the carcass equator point C to the tire axially outermost point Q1 on the carcass inner line in the tire axial direction. Inner line width W 1
A first point P1 on the carcass inner line that is separated from the carcass equator point C by a distance of two times on both sides in the tire axial direction,
A radius of curvature R1A of a first arc C1A passing through P1 and the first point P1 and a distance L2 that is ⅙ times the line width W in the carcass from the first point P1 are separated from each other in the tire axial direction outside. The second point P2 on the line in the carcass and the second point P2
Second arc C passing through the third point P3 on the in-carcass line further separated from the distance L2 by 2 in the tire axial direction outside
A radius of curvature R2A of 2A and a distance L3 of 0.16 times the carcass height H, which is the distance from the bottom surface of the bead portion to the carcass equator point C in the tire radial direction, are set to the outermost point Q.
In the radius of curvature R3A of the third arc C3A passing through the upper and lower side wall points Q2 and Q3 vertically separated from the tire radial direction and the outermost point Q1, the second arc C2A
Has a radius of curvature R2A smaller than the radius of curvature R1A of the first circular arc and is equal to or larger than the radius of curvature R3A of the third circular arc, and the inside of the carcass when the tire is mounted on the regular rim and is filled with the regular internal pressure. First arc C1B of the line
The radius of curvature R1B of the second arc C2B, the radius of curvature R2B of the second arc C2B, and the radius of curvature R3B of the third arc C3B,
The radius of curvature R2B of the arc C2B is smaller than the radius of curvature R1B of the first arc C1B and the radius of curvature R3 of the third arc C3B.
The radius ratio R1A / R1B, which is the ratio of the radius of curvature R1B to the radius of curvature R1A, is 1.0 or more and 3.0 or less.

[0009]

As described above, the tire of the present invention is
Formed by increasing the curvature of the carcass in the crown area in advance,
Radius ratio R1A / R between the radius of curvature R1A of the first arc C1A of the carcass line in the 0.5 kg / cm2 internal pressure state and the radius of curvature R1B of the first arc C1B in the normal internal pressure state
1B is restricted to 1.0 or more and 3.0 or less. That is, since the amount of change in the radius of curvature of the carcass at the time of internal pressure filling is reduced, local deformation of the tire at the time of internal pressure filling can be suppressed, and the carcass cord tension can be made uniform. , Reduce the occurrence of internal strain of the tire,
The durability can be improved.

Further, by reducing the change amount of the radius of curvature and equalizing the tension of the carcass cord, it is possible to reduce the local outer diameter growth of the tread portion due to the high speed rotation, particularly the outer diameter growth in the tread shoulder region. It is possible to equalize the ground contact pressure, improve the friction life, and suppress the occurrence of ply peeling due to an increase in tire heat generation.

In a tire having a radial structure, when the belt rigidity is excessively large and the belt width is excessively small, the carcass at the time of normal internal pressure filling is locally outwardly curved and deformed at the belt end, and the second arc C2B The radius of curvature R2B is the third
The effect of reducing the internal strain cannot be exhibited, for example, the curvature radius becomes smaller than the radius of curvature R3B of the arc C3B.

Therefore, in the present invention, in order to obtain the effect of reducing the internal strain, the radius of curvature R2A, R2B of the second arc is the radius of curvature R3A of the third arc in both the 0.5 kg / cm2 internal pressure state and the normal internal pressure state. , R3B or higher.

[0013]

EXAMPLE One example of the present invention is tire size 46 ×.
An example of a 17R20 radial tire for an aircraft will be described with reference to the drawings.

In FIG. 1, which shows a normal internal pressure state in which the normal rim R is attached and the normal internal pressure is filled, a high-speed heavy load tire 1 includes a bead portion 3 through which a bead core 2 passes, and a bead portion 3 which is continuous with the bead portion 3 and is radially outside the tire. It is provided with a side wall portion 4 extending in the direction and a tread portion 5 connecting the outer ends of the side wall portion 4.

Further, in the tire 1, a plurality of bead cores 2 each having a substantially circular cross section are folded back from the inside of the tire to the outside,
For example, an inner layer 7A composed of four carcass plies 7a ...
And a plurality of carcass plies 7b, for example, two carcass plies 7b surrounding the folded-back portion of the inner layer 7A and folded back from the outside of the tire.
A carcass 7 having an outer layer 7B made of 7b is provided. Further, the carcass cords of the carcass plies 7a and 7b are arranged in a radial direction having an inclination of 70 degrees to 90 degrees with respect to the tire equatorial plane CO, and in this example, the carcass 7 is arranged between adjacent carcass plies. The carcass cord or the tire is alternately crossed and inclined with respect to the circumferential direction of the tire.

A bead apex 9 made of a tapered rubber extending in the tire radial direction is provided above the bead core 2 to enhance rigidity and disperse the stress due to the bending of the carcass folded portion. A chefer (not shown) for preventing rim displacement can be provided on the outer surface of the bead portion 3.

Further, the tread portion 5 is located inside the tread portion 5 and is located outside in the radial direction of the carcass 7.
A belt layer 10 arranged at a cord angle of -20 degrees, preferably 0-5 degrees is provided, and in this example, between the belt layer 10 and the carcass 7 is 5 with respect to the tire equatorial plane. One or more layers of cut breakers 14 arranged at a cord angle of -40 degrees are interposed, and the cut breakers 14 improve cornering force performance. By providing the cut breaker ply 14 on the outside of the belt layer 10, it is possible to improve the cornering force and also function as a protective layer for the belt layer 10. It can also be provided inside and outside.

Further, the belt layer 10 is composed of a plurality of, for example, 6 to 10 belt plies 10a, and the belt ply 10a is gradually narrowed outward in the radial direction, whereby the belt layer 10 is formed into a tire. It has a trapezoidal shape in a tire cross-section including an axis, and its side surface 10b is an inclined surface substantially along the outer surface SB of the tire buttress portion. Further, the width WS of the belt layer 10, that is, the maximum width of the belt layer 10, that is, the width of the innermost ply 10a in this example, is 75 to the total tire width.
The range is about 85%.

In the present invention, the tire is assembled on the rim and the internal pressure is 0.5 kg / cm ² to the normal internal pressure (15.5 kg / cm ² ).
Carcass 7 in the crown area Y when filled up with air
3 is shown in FIG. 3 with the curvature R1 and the curvature in the case of the conventional tire as a broken line r1. In the present invention, the curvature of the crown region is preset by the shape of the tire die, and the amount of change to the curvature at the time of normal internal pressure is reduced to suppress the occurrence of internal strain of the tire.

That is, the radius of curvature R1 of the first arc C1A of the line LA in the carcass under an internal pressure of 0.5 kg / cm2.
A is 1.0 times or more the radius of curvature R1B of the first arc C1B of the carcass inner line LB in the normal internal pressure state, and 3.
It is set to 0 times or less.

Here, the carcass inner line L (the carcass inner lines LA and LB are collectively referred to as the carcass inner line L)
Is a line formed by the inner surface of the carcass 7 facing the tire lumen O in the tire cross-section, and the carcass inner line LA is defined by the first arc C1A located in the tread crown region and the tread shoulder region as shown in FIG. Second arc C2 located
A and a third arc C3A in the vicinity of the outermost point of the tire where the tire deformation at the ground contact / specific ground contact is significant. The first arc C1A is a carcass equator point C at which the in-carcass line LA intersects the tire equatorial plane CO, and the carcass equator point C to the outermost point Q1 in the tire axial direction on the in-carcass line LA. A distance L1 that is 1/2 times the line width W in the carcass, which is the distance in the tire axial direction, is set to the carcass equator point C.
Is a circular arc that passes through the first points P1 and P1 on the carcass in-line LA that is separated from both sides in the tire axial direction, and in the present invention, the radius of curvature R1A of the first circular arc C1A is the outside of the tire in the normal internal pressure state. It is set to be smaller than 1.5 times the diameter D. The radius of curvature R1A is preferably 1.0 times or less the tire outer diameter D, and more preferably 0.6 times or less.

The second arc C2A is defined by the first point P
1, a second point P2 on the in-carcass line LA that is separated from the first point P1 by a distance L2 that is 1/6 times the in-carcass line width W outward in the tire axial direction, and the second point. It is an arc passing through P3 and a third point P3 on the in-carcass line LA further distant from the P2 by the distance L2 in the axial direction of the tire.

The third arc C3A has a distance L3 which is 0.16 times the carcass height H, which is the distance from the bottom surface E of the bead portion 3 to the carcass equator point C in the tire radial direction, and is the outermost point Q1. Is an arc passing through upper and lower sidewall points Q2 and Q3 separated from each other in the tire radial direction and the outermost point Q1.

The line LA in the carcass has the second line
The radius of curvature R2A of the circular arc C2A is smaller than the radius of curvature R1A of the first circular arc C1A and is equal to or larger than the radius of curvature R3A of the third circular arc C3A, and is flat and smoothly continuous. The radius of curvature R3A is 0.5 of the total width of the tire in a normal internal pressure state.
It is preferably not more than double.

The carcass inner line LB in the normal internal pressure state is a smoothly continuous curve including the first arc C1B, the second arc C2B and the third arc C3B which are defined in the same manner as the carcass inner line LA and are the same. In a tire with a strong and structured carcass and belt of
The radius of curvature R1B of the arc C1B is as shown in FIG.
0.5kg / cm2 The value decreases toward an almost constant value without being affected by the value at the internal pressure state.

The present invention was completed by finding the characteristics of the radius of curvature R1B as described above.
The radius of curvature R1A under an internal pressure of 0.5 kg / cm2 can be freely set when forming a raw tire.

However, in order to exert the effect of reducing the internal strain by regulating the radius ratio R1A / R1B, it is necessary to use the belt layer 10 having an appropriate elastic strength to smoothly connect the carcass inner line LB. Therefore, for this reason, the radius of curvature R2B of the second arc C2B is smaller than the radius of curvature R1B of the first arc C1B and is smaller than the third arc C3.
The radius of curvature of B is R3B or more. 0.5kg / cm
² The carcass inner lines LA and LB in the internal pressure state and the normal internal pressure state can be derived by measuring the carcass of the tire filled with the predetermined internal pressure air with a CT scanner or the like, and the state before the internal pressure air is filled. The line in the carcass of the tire can be measured by cutting the tire and shaping the tire with plaster.

In this way, by restricting the amount of change in the radius of curvature of the carcass inner line L, it is possible to suppress local deformation of the tire and to make the cord tension uniform when filling the inner pressure, and to make the cord tension uniform. As shown in FIG. 4, lifting of the tread portion 5 is reduced, which helps to make the ground pressure uniform. FIG. 5 shows an optimum ground contact surface shape T that can be adopted in the present invention. The ground contact surface shape T is a footprint when a normal load is applied in a normal internal pressure state, and is a shoulder position separated from the tire equatorial plane CO by a distance W2 that is ⅓ times the maximum ground contact width W1 in the tire axial direction. The contact length Ls at U is the tire equatorial plane CO
It is preferable that the contact length Lc is 0.7 to 1.0 times, and the maximum contact width W1 is 0.7 to 1.0 times the contact length Lc. When the contact length Ls is larger than 1.0Lc, the contact pressure of the shoulder portion becomes excessive and induces uneven wear and belt end separation. Further, when the maximum ground contact width W1 is smaller than 0.7 Lc, bead deformation increases and the bead durability is impaired. When the ground contact length Ls is less than 0.7Lc and the maximum ground contact width W1 is 1.0Lc
If it exceeds, it will be difficult to manufacture tires.

[0029]

Since the tire of the present invention is constructed as described above, it is useful for reducing the internal strain of the tire and making the contact pressure uniform, thereby improving the durability of the tire.

[Brief description of drawings]

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

FIG. 2 is a schematic diagram illustrating an in-carcass line.

FIG. 3 is a schematic diagram showing an example of a change in the radius of curvature of the first arc due to the filling internal pressure.

FIG. 4 is a schematic diagram showing an example of a ground pressure distribution of the present invention.

FIG. 5 is a schematic diagram showing an optimum ground contact surface shape that can be adopted in the tire of the present invention.

FIG. 6 is a diagram showing a tire deformation for explaining a conventional technique.

[Explanation of symbols]

 2 bead core 3 bead part 4 sidewall part 5 tread part 7 carcass L, LA, LB carcass inner line

 ─────────────────────────────────────────────────── --Continued front page (56) Reference JP-A-2-225105 (JP, A) JP-A-55-51605 (JP, A) JP-A-63-34203 (JP, A) JP-A-55- 8903 (JP, A) JP 63-179708 (JP, A) JP 63-106102 (JP, A) JP 1-309805 (JP, A)

Claims (2)

(57) [Claims] 1. A carcass comprising a carcass folded from a tread portion to a sidewall portion around a bead core of a bead portion, and having a carcass formed by an inner surface of the carcass facing a tire bore in a tire cross-section including a tire shaft. In the inner line, the tire is attached to the regular rim and 0.5kg / cm2
When the internal pressure is 0.5 kg / cm @ 2, the carcass equator point C where the carcass inner line intersects the tire equator plane, and the outermost point Q1 in the tire axial direction on the carcass inner line from the carcass equator point C To the first point P1, P1 on the carcass inner line that is separated from the carcass equator point C on both sides in the tire axial direction by a distance L1 that is 1/2 times the carcass inner line width W that is the distance in the tire axial direction. The radius of curvature R1A of the passing first circular arc C1A, the first point P1 and the first point P1
From the point P1 to a second point P2 on the carcass inner line that is separated by a distance L2 that is 1/6 times the carcass inner line width W to the outside in the tire axial direction, and the second point P2 to the distance L2 from the tire. The radius of curvature R2 of the second arc C2A that passes through the third point P3 on the carcass line that is further separated axially outside
A, and the carcass equator point C from the bottom of the bead portion
A distance L3 which is 0.16 times the carcass height H which is the distance in the tire radial direction from the outermost point Q1 to the upper and lower sides in the tire radial direction.
And the radius of curvature R3A of the third arc C3A passing through the outermost point Q1 and the radius of curvature R2A of the second arc C2A.
Is smaller than the radius of curvature R1A of the first circular arc and is equal to or larger than the radius of curvature R3A of the third circular arc, and further, the first line of the carcass in the normal state where the tire is mounted on the regular rim and the regular internal pressure is filled. Radius of curvature R1 of arc C1B
B, radius of curvature R2B of second arc C2B and third arc C3
In the radius of curvature R3B of B, the radius of curvature R2B of the second arc C2B is smaller than the radius of curvature R1B of the first arc C1B and is equal to or larger than the radius of curvature R3B of the third arc C3B, and the radius of curvature with respect to the radius of curvature R1A. R1
A high-speed heavy-duty tire having a radius ratio R1A / R1B, which is a ratio of B, of 1.0 or more and 3.0 or less. 2. The first device under an internal pressure of 0.5 kg / cm2.
The high-speed heavy-duty tire according to claim 1, wherein the radius of curvature R1A of the arc C1A is smaller than 1.5 times the outer diameter D of the tire in the normal internal pressure state.