JPH08142602A - Radial tire - Google Patents

Abstract

PURPOSE: To provide a radial tire suitable for an automobile capable of improving the riding comfort performance by the vibration. CONSTITUTION: In a radial tire provided with a carcass 6 where the cord is arranged in the radial direction and a belt layer 7 to be arranged on the outer side in the radial direction of this carcass 6, the carcass profile 9 which is fitted to a wide rim which is wider than the standard rim by 0.5 inch and when the regular inner pressure is filled therein satisfies the inequalities of 0.69<=R1/rc<=1.39, and 0.99<R2/R3<1.17, where R1 is the radius of curvature of the first semi-circle C1 connecting the first point (b) and the second point (c), R2 is the radius of curvature of the second semi-circle C2 connecting the third point (d) and the fourth point (e), and R3 is the radius of curvature of the third semi-circle C3 connecting the fourth point (e) and the sixth point (f).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radial tire suitable for passenger cars which can improve vibration riding comfort.

[0002]

2. Description of the Related Art A radial force variation (hereinafter referred to as "RFV") is a factor that influences the vibration and riding comfort performance of a vehicle. RFV
Is a force of load fluctuation that appears vertically on the tire rotation axis when the tire is rotated by applying a load.
Is transmitted to the vehicle via the axle, reducing the riding comfort.

Generally, RFV has a deep relationship with a radial runout (hereinafter referred to as "RRO") which is a vertical vibration when a tire having an unbalanced shape is rotated, and it has been found that the RFV can be reduced by reducing the value. are doing.

As a means for reducing the RRO, for example, polishing the tread surface with a perfect circular buff is effective in the case of a new tire, but the root cause has been investigated and removed. In many cases, the deterioration of the RFV is surfaced such that uneven wear occurs or the tire profile changes as the tire is used for running.

It has also been attempted to reduce the RRO by dispersing the seams of tire constituent members such as tread rubber and belt ply in the tire circumferential direction. It is not something that will be lost, and its effect is not yet sufficient.

[0006]

As described above, the RFV
When the tire is new, even if the tire is within a predetermined standard, it may increase due to running of the tire even if uneven wear does not occur in the tread portion. Therefore, the RFV must be considered not only when new tires are used, but also at a constant level at all times when it is actually mounted and used in a vehicle, but a proposal that can realize this is presently made. Absent.

By the way, in a tire used for running, the wear condition of the tread portion, the tire internal pressure, and the like change every moment during running, and in particular, if the carcass profile changes due to the latter change in the internal pressure, the RRO in the tire circumferential direction. In recent years, it has been found that the RFV also greatly changes and the RFV is increased. Therefore, if the shape change of the carcass profile is small even if the tire internal pressure changes, the RFV
Can be expected to be suppressed.

In view of such circumstances, the present invention was devised from the viewpoint of minimizing the shape change of the carcass profile even when the tire internal pressure changes, and not only when the tire is new, but also when the tire is in use. It is an object of the present invention to provide a radial tire that suppresses RFV, improves vibration riding comfort of a vehicle, and can maintain the improved performance for a long period of time.

[0009]

DISCLOSURE OF THE INVENTION The present invention has a turn-back portion that turns back around the bead core of the bead portion from the tread portion to the side wall portion from the inner side to the outer side in the tire axial direction, and the cord in the radial direction. With the arranged carcass,
A radial tire comprising a belt layer arranged radially outside of the carcass and inside the tread portion,
The carcass profile in the meridian section of the tire when mounted on a wide rim wider by 0.5 inch than the rim width of the standard rim and filled with the normal internal pressure is a point a at which the carcass profile intersects with the tire equatorial plane, and from this point a The first point on the tread portion of the carcass profile that separates in the tire axial direction a distance (0.7 × BW / 2) obtained by multiplying 1/2 of the tire axial width of the layer (BW / 2) by 0.7 b, the second point c on the tread portion of the carcass profile that separates the half length (BW / 2) of the belt layer from the point a, the maximum width position of the carcass profile to the carcass profile cross-sectional height (H ), The height (h) from the bead base line up to the maximum width position (H)
-H) multiplied by 0.7, a distance {0.7 x (H-h)} is separated to the outside in the tire radial direction by a third point d on the side wall portion of the carcass profile and the maximum width position by the fourth point. Point e, the distance from this fourth point e {0.7 × (H−h)}
Is the fifth point f on the side wall of the carcass profile that is separated inward in the tire radial direction, and the radial length from the tire rotation axis to the second point c is rc, the first point b and the second point c, a first arc C1 having a radius of curvature R1 smoothly connecting with c, a second arc C2 having a radius of curvature R2 smoothly connecting between the third point d and the fourth point e;
The third arc C3 having a radius of curvature R3 that smoothly connects between the point e and the fifth point f is 0.69 ≦ R1 / rc ≦ 1.39,
The radial tire is characterized by satisfying the relationship of 0.99 <R2 / R3 <1.17.

The carcass profile is mounted on a wide rim that is 0.5 inches wider than the rim width of the standard rim, and is filled with 5% of the normal internal pressure to 1 of the normal internal pressure.
It is preferable that the amount of protrusion at the time of performing the internal pressure changing process for changing the internal pressure to 00% is 1 mm or less at the maximum, and the amount of protrusion of the buttress portion is larger than that of the bead portion.

[0011]

FIG. 1 shows a carcass profile 9 of the radial tire of the present invention in a meridional section of the tire when mounted on a wide rim wider by 0.5 inch than the rim width of the standard rim and filled with the normal internal pressure. .

In the figure, the following points are defined on the carcass profile 9. First, the point where the carcass profile 9 intersects with the tire equator C is defined as a, and from this point a, a distance (0) obtained by multiplying 1/2 length (BW / 2) of the tire axial width BW of the belt layer 7 by 0.7. The point that separates 0.7 × BW / 2) in the tire axial direction is referred to as a first point b.

Next, from the point a, the 1 /
The bead base from the position of the maximum width W of the carcass profile 9 to the maximum width position from the carcass profile cross-sectional height (H) to the second point c, which is the point on the tread portion separating the two lengths (BW / 2). Height from line BL (h)
Distance obtained by multiplying the length (H−h) minus 0.7 by 0.7
A point on the sidewall portion that separates x (H−h)} on the outer side in the tire radial direction is defined as a third point d.

Further, the maximum width position of the carcass profile is defined as a fourth point e, and the distance {0.
A point on the sidewall that is separated by 7 × (H−h)} inward in the tire radial direction is defined as a fifth point f. Also tire rotation axis CL
Let rc be the radius length from to the second point c.

After defining each point in this way, a first arc C1 having a radius of curvature R1 that smoothly connects between the first point b and the second point c, the third point d and the fourth point C1. The second arc C2 having a radius of curvature R2 smoothly connecting with e and the third arc C3 having a radius of curvature R3 smoothly connecting between the fourth point e and the fifth point f have the following relationship. Is satisfied.

First, the ratio (R1 / rc) of the radius of curvature R1 and the radius length rc from the tire rotation axis CL to the second point c is set to 0.69 or more and 1.39 or less. . Second, the ratio of the radii of curvature R2 and R3 (R2 / R
3) is larger than 0.99 and smaller than 1.17.

Here, it is known from various experimental results how the carcass profile 9 is deformed by the internal pressure filling process for changing the internal pressure from 5% of the normal internal pressure to 100%. 5 (A) to (C) show the carcass profile 9 of the tire mounted on the standard rim,
The change state when the internal pressure filling process is performed for each shape is shown by a solid line at 5% normal internal pressure and a dotted line at 100% normal internal pressure.

When the carcass profile 9 shown in FIG. 5 (A) is the above-mentioned otafuku type with a downward bulge, the buttress portion 10 radially outside of the carcass maximum width position.
However, it protrudes larger than the bead portion 4.

The carcass profile 9 shown in FIG.
Is based on the natural equilibrium shape theory, the carcass as a whole is approximately similar to the protruding shape, and the carcass profile 9 in FIG. It was found that the bead portion 4 protrudes larger than the buttress portion 10.

Similarly, FIGS. 6A to 6C show changes in the shape of the carcass profile 9 due to the internal pressure filling process when the rim width is appropriately changed. For example, the profile in the vulcanization mold is shown. Is indicated by a one-dot chain line, a normal internal pressure of 5% when mounted on the standard rim is indicated by a solid line, and a normal internal pressure at 100% is indicated by a dotted line.

In the case where the space between the beads is narrowed when the bead is mounted on the standard rim as compared with the case of the vulcanization mold shown in FIG. When the protrusion is larger than the portion 10 and the width between the beads in the front mold and the standard rim is substantially the same as shown in FIG. 7B, the entire carcass profile 9 protrudes in a substantially similar shape. It has been found that the buttress portion 10 is larger than the bead portion 4 when the bead spaces are widened when mounted on the standard rim as compared with the inside of the vulcanization mold in FIG.

Based on the above, when the wide rim is mounted, the ratio (R1 / rc) is less than 0.69 and the ratio (R2 / R) is less than
In 3), when set to 0.99 or less, the carcass profile 9 has an upwardly bulging squid shape in which the buttress portion projects. Therefore, when the bead portion is mounted on a standard rim and the internal pressure filling process is performed, the shape of the bead portion can be largely protruded.

On the contrary, when the ratio (R1 / rc) is larger than 1.39 and the ratio (R2 / R3) is set to 1.17 or more, the carcass profile 9 is projected to the inside of the sidewall portion. Ottafuku type with a clear downward bulge. Therefore, in this case, if the buttress portion is mounted on a standard rim and subjected to the internal pressure filling process, the buttress portion is largely protruded. By narrowing the gap between the beads, the protrusion of the bead portion can be suppressed to some extent by the protrusion of the bead portion.

That is, such a carcass profile has a shape change in which the carcass profile largely protrudes when the tire is mounted on the standard rim and filled with the normal internal pressure. That is, it was found from various experiments that the RRO in the tire circumferential direction was large.

On the other hand, the radial tire of the present invention is
Since the carcass profile regulates the respective ratios (R1 / rc) and (R2 / R3), the carcass profile is slightly Otahuku-shaped compared to the natural equilibrium shape. In this case, when mounted on the standard rim and subjected to internal pressure filling change processing from 5% to 100% of the normal internal pressure, the interval between the bead portions is narrowed by 0.5 inch.

Therefore, the carcass profile 9 is
As described in FIG. 4 and FIG. 5, the protrusion of the bead portion due to the narrowing of the bead portion by 0.5 inch and the protrusion of the buttress portion based on the Otafuku shape cancel each other, so that the both protrusions are mutually offset. It is possible to find an equilibrium point that is uniform and has an extremely small absolute value of 1 mm or less.

That is, in the radial tire, the carcass profile 9 is R depending on the change of the internal pressure during use of the tire.
As a result of only a small and uniform shape change that hardly affects RO and suppressing the RFV, the vibration riding comfort performance of the vehicle can be greatly improved and this performance can be maintained for a long period of time.

The carcass profile 9 preferably has a slightly larger amount of protrusion of the buttress portion 10 than the bead portion 4 when the internal pressure filling process is performed with the carcass profile 9 mounted on the wide rim. The reason for this will be described later.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. As shown in FIGS. 2 and 3, a radial tire 1 includes a carcass 6 folded back from a tread portion 2 to a sidewall portion 3 at a bead core 5 of a bead portion 4 from an inner side to an outer side in a tire axial direction, and the carcass. 6 is provided on the outer side in the radial direction and on the inner side of the tread portion, and the main body portion 6a of the carcass 6 and the folded portion 6 are provided.
A bead apex 8 made of rubber having a tapered shape extending from the bead core 5 and being harder than the surrounding rubber composition is provided between the above and b.

The carcass 6 has one or more cord plies in which a carcass cord made of an organic fiber such as aromatic polyamide, rayon, nylon or polyester is arranged in the radial direction of 70 to 90 degrees with respect to the tire equator C. It is formed by using.

The belt layer 7 is formed of a belt cord preferably made of steel, for example, 1 with respect to the tire equator C.
The inner and outer two layers of belt plies 7A and 7B arranged at small angles of 0 to 30 degrees are formed by overlapping in a direction in which the cords intersect with each other, so that the tread portion 3 can be strongly provided with a hoop effect.

Both ends of the inner belt ply 7A are formed wider than the outer belt ply 7B. The belt cord may be made of various cord materials such as organic fiber other than steel.

The points a to f described in the section of action are defined on the carcass profile, and then the first point b is defined.
And a second arc c having a radius of curvature R1 smoothly connecting the second point c, a second arc C2 having a radius of curvature R2 smoothly connecting the third point d and the fourth point e, and The fourth point e
The third circular arc C3 having a radius of curvature R3 that smoothly connects between the fifth radius and the fifth point f is the radius of curvature R1 and the tire rotation axis CL.
To the second point c to the radius length rc (R1 / r
It has already been stated that c) is set to 0.69 or more and 1.39 or less, and the ratio (R2 / R3) of the radii of curvature R2 and R3 is larger than 0.99 and smaller than 1.17. It is as follows.

As shown in FIG. 2, this radial tire has a wide rim JA that is 0.5 inch wider than the standard rim width RW.
Mounted on the vehicle and subjected to internal pressure change processing for changing the internal pressure from 5% of the normal internal pressure to 100% of the normal internal pressure, the protrusion amount F of the carcass profile 9A in the tire meridional section is larger than that of the bead portion 4. Also, the buttress portion 10 is set to be slightly larger.

Further, such a radial tire is a standard rim J having a rim width narrower by 0.5 inch than the rim width of the wide rim JA.
When the carcass profile 9C is mounted on the carcass and the carcass profile 9C is subjected to the internal pressure change process, the buttress portion 10 and the bead portion 4 cancel each other out so that the carcass profile 9C and the bead portion 4 are equal to each other and the absolute amount thereof is small. You can find points.

If the change in the shape of the carcass profile 9C due to the change in the internal pressure is small, the carcass profile has almost no effect on the RRO even if the internal pressure changes while the tire is in use, and the RFV is suppressed to improve the ride comfort performance of the vehicle. As mentioned above, it can be greatly improved.

Here, the standard rim J is JATMA.
Refers to the standard rim in the standard, and the regular internal pressure is JATMA
Refers to the air pressure specified in the standard. The carcass profile is shown as the thickness center line of the body portion 6a of the carcass 6, and the second point c and the third point d on the carcass profile are smoothly connected by an arc. .

Next, a manufacturing method suitable for manufacturing the radial tire 1 will be described as follows. First, in the vulcanization step of vulcanizing the raw tire cover 1A in the vulcanization mold as shown in FIG. 3, the distance between the bead portion outer surfaces 4a is set to be larger than the rim width RW of the standard rim to be mounted. It is important to use a vulcanizing mold 12 having a bead molding surface 11 having a clip width CW that can be molded. In this embodiment, the clip width CW is 0.8 inches added to the standard rim width RW. The width is illustrated.

From FIGS. 5 and 6 described above, in order to minimize the change in shape of the carcass profile 9 due to internal pressure filling, the shape of the carcass profile in the vulcanization mold should be a natural equilibrium shape, and the clip width CW should be set. Clearly, it is important to match the standard rim width RW.

However, if the clip width CW is matched with the standard rim width RW, the spacing between the bead portions 4 and 4 tends to be narrowed, and the bladder BD (which can expand and contract toward the tire inner cavity during vulcanization). (Shown in FIG. 3) is difficult, and when the tire rim is assembled, a sufficient contact state between the bead portion and the rim flange cannot be ensured and the workability of the rim assembly is deteriorated. Therefore, the clip width CW of the vulcanization mold is the standard rim width R so as not to deteriorate the productivity of such tires.
It is premised to be larger than W.

On the other hand, the vulcanization mold 12 is an Otafuku mold in which the carcass profile 9 during vulcanization is slightly downwardly bulged from the carcass maximum width position to the profile based on the natural equilibrium shape theory. It is preferable to form the molding surface so that

Next, the vulcanized tire 1B obtained by vulcanizing the green cover 1A is subjected to a post-cure inflation process (hereinafter referred to as "injection") in which an internal pressure larger than atmospheric pressure is applied and the vulcanized tire 1B is held for a certain time.
It is important to perform the "PCI process").

In the PCI process, as shown in FIG. 4, the vulcanized tire 1B which has undergone the vulcanization process has a rim width PW larger than the standard rim width RW and 1.5 inches added to the standard rim width RW. The figure shows that the mounting is performed on the rim body 13 having an increase width of 1.5 inches or less and a clip width CW or less.

Generally, in the vulcanization step, due to the presence of the molding surface of the vulcanization mold 12, sufficient tension cannot be applied to the carcass cord in the carcass ply, and the carcass cord is not in a fully extended state. Therefore, by performing the PCI process, the carcass profile can be fixed in a sufficiently extended state under a situation in which the carcass cord can be freely deformed, and the cord path elongation of the carcass due to the internal pressure filling is small, and by extension, the carcass profile 9 The change in shape can be made smaller.

Further, in the PCI process, the bead portion 4 is formed in the clip width after vulcanization by using the rim body 13 having the rim width PW larger than the standard rim width RW and less than or equal to the clip width CW. The width of the bead portion can be made equal or narrower, but the bead portion is held in a shape wider than the standard rim width RW. Therefore, after the PCI process, by mounting the tire on the standard rim J, the interval between the bead portions 4 is narrowed.

As is clear from the above, the vulcanization, PC
In the radial tire 1 that has gone through the process I, the carcass profile 9 has a slightly otafuku shape based on the natural equilibrium shape of the downward bulge, and the bead portions 4 are widened,
When the rim is assembled to the standard rim J and the internal pressure filling process is performed, the carcass profile 9 has a protrusion of the buttress portion 10 based on the otaku shape and the bead portion 4 as shown in FIGS.
The protrusions of the bead portion 4 due to the narrowing of the distance between the two offset each other, so that the two protrusions are uniform with respect to each other and find an equilibrium point at which the absolute amount is small.

In addition, as a result of the PCI step, the carcass cord is held in a stretched state due to uniform tension, and as a result, the elongation due to internal pressure filling is extremely small and can be neglected. 9
The absolute amount of protrusion can be made small, for example, 1 mm or less.

It is well known that the above-mentioned natural equilibrium shape theory is proposed as a carcass profile which is less likely to change shape due to internal pressure filling. This natural equilibrium shape theory means that when the axial end point of the belt layer and the bead portion fixed position point are given (under the assumption that these two points do not move).
This is a theory in which the carcass profile can be uniquely obtained by defining either the carcass code path or the carcass maximum width.

The feature of this natural equilibrium shape theory is that the tension acting on the carcass cord is constant. Therefore, if it is considered that the carcass cord is stretched, it can be said that the carcass profile based on this theory can be expanded and deformed substantially uniformly from the original shape and the deformation amount can be kept small.

Regarding the natural equilibrium shape theory, see W. H
offerberth, Kautsch. Gummi
(8-1955, 124-130) for details.

Since the carcass profile based on the natural equilibrium shape theory is applicable to the film area theory, for example, the side wall region between the end portion of the belt layer 7 in the tire axial direction and the tip of the bead apex 8 can be applied. Although the natural equilibrium shape theory can be adopted, the following modifications are made to the crown region located on the tire radial inner side of the belt layer 7 of the carcass 6 and the bead portion region on the tire axial inner side of the bead apex.

The crown region is between DP on the coordinate system having the y axis on the tire rotation axis and the z axis in the radial direction passing through the tire equator position as shown in FIG. It is considered that this region shares the tire internal pressure with the carcass cord of the carcass 6 and the belt cord of the belt layer 7.

Here, the belt internal pressure distribution rate in which the belt layer 7 shares the tire internal pressure is expressed by the equation 1 as a function of z, Tb.
Can be approximated and expressed.

[0054]

[Equation 1]

However, a is optional depending on the belt layer,
The belt internal pressure sharing rate Tb has a parabolic shape in which when a = 0, the uniform pressure sharing of τo is achieved over the entire area of the belt layer 7, and when a = τo, the pressure sharing is 0 at both ends of the belt layer and τo is on the equator. . rp and rd are coordinate values.

Next, the bead apex 8 of the bead portion 4
Te is the bead internal pressure sharing ratio in which the tire internal pressure is shared by r
It can be approximately expressed as a function of
Rb is the r coordinate at the inner end of the bead apex, r
e is the r coordinate at the tip of the bead apex, and τe is the pressure sharing rate at the inner end of the bead apex.

[0057]

[Equation 2]

In such a case, from the balance condition between the cord tension tc acting on the carcass cord and the tire internal pressure p, if the number of carcass cords around the tire is N between the radius of curvature Rs of the cross section at the point of radius r, then N The relational expression 3 holds.

[0059]

(Equation 3)

Note that Tc is the internal pressure share of the carcass 6, r
And Tc = 1−Tb in the crown region.
(Tb: belt internal pressure share), T in the bead area
c = 1-Te (Te: bead internal pressure sharing rate), and otherwise Tc = 1. Further, the Rs can be expressed as in Equation 4 from the geometrical relation.

[0061]

[Equation 4]

By substituting the equation 4 and the carcass internal pressure sharing rate Tc into the equation 3, the crown region (between D and P), the sidewall region (between E and D) and the bead region (E and B) are substituted.
5) to form a carcass shape by integrating
It can be given as 7.

[0063]

(Equation 5)

[0064]

(Equation 6)

[0065]

(Equation 7)

However, B in the equations 5 to 7 is as shown in the equation 8.

[0067]

(Equation 8)

The carcass profile 9 at the time of mounting the standard rim, which is based on the natural equilibrium shape, can be drawn by using the formulas expressed by the above-mentioned equations 5 to 7. As for the above-mentioned formulas 5 to 7, as shown in FIG. 8, carcass diameter: rp, carcass width: W, rim width: RW, belt width: BW, bead portion thickness: CT, bead apex height: BH
The carcass profile can be drawn by appropriately giving (from the bead base line BL), belt internal pressure sharing ratio Tb, and bead internal pressure sharing ratio Te.

The carcass diameter: rp, the carcass width: W, and the rim width: RW can be appropriately determined by giving standards such as JATMA and JIS and various rubber gauges, and the belt width: BW can be determined by the carcass width. : Smaller than W and carcass width: W, {1.25-
It is set to be larger than the coefficient multiplied by 0.01 × (flatness ratio)}.

In this embodiment, the bead internal pressure sharing ratio Te
Is 0.7, and the belt internal pressure share Tb is a value when the tread portion 2 of the carcass profile 9 is the flattest.

By giving appropriate numerical values in this way,
The carcass profile 9 when the tire is mounted on the standard rim can be drawn, and the code path of the carcass 6 can be calculated from this. The calculated code path of the carcass 6 is fixed and vulcanized in the vulcanization mold. The carcass profile 9 in the inside may be widened to the rim width: RW to the clip width CW, and an appropriate numerical value may be given based on the molding surface of the mold.

In this way, the clip width CW of the vulcanization mold 12
When the width is wider than the standard rim width RW, when the standard rim J is mounted on the standard rim J, the bead portion interval is narrowed as described above, and the bead portion 4 is protruded by the internal pressure filling process. Therefore, the carcass profile 9 has the same code path as the theoretical curve of the above-mentioned mathematical expressions 5 to 7 in FIG. 8, and as shown by the dotted line, the maximum width position rm is shifted to the bead side, and the tire radial direction is changed. The inside is an Otafuku type with a slightly downward bulge from this theoretical curve,
By the protrusion of the buttress portion 10 due to the internal pressure filling process, the protrusion of the bead portion 4 and the protrusion of the bead portion 4 can be canceled each other, and the protrusion itself can be made uniform and small.

The clip width CW varies depending on the tire size. For example, the tire size is 205 / 65R.
In case of 15, it is preferably 0.5 than the rim width of the standard rim.
Greater than one inch and less than or equal to 1.5 inches, preferably 0.
It is about 8 inches (20.32 mm). In other words, it is about 6 to 20% of the nominal tire size (205 mm).

When the increase width is 0.5 inch or less, the bead 4 is formed.
On the contrary, if it exceeds 1.5 inches, the change of the carcass profile is too large to achieve the purpose.

Next, in the PCI step, as shown in FIG. 4, the vulcanized tire 1B which has been subjected to the vulcanization step has a rim width PW larger than the standard rim width RW and a standard rim width RW of 1.5 inches. Is added to the rim body 13 having a width of 1.5 inches or less and a clip width CW of the vulcanization die 12 or less. In this embodiment, the standard rim width RW is 0.5. It has been increased by an inch (12.55 mm).

As described above, the PCI process is performed by using the rim body B satisfying the relationship that the rim width PW is larger than the standard rim width RW and is equal to or smaller than the clip width CW of the vulcanizing die, preferably smaller than the clip width. , The carcass cord can be stretched while maintaining or narrowing the space between the bead portions 4 that are widened during the vulcanization process, and the shape of the carcass profile can be maintained, and the deformation of the bead portion 4 when the standard rim is attached can be prevented. Can be moderated.

In the PCI process, it is necessary to pay attention to the following three points. First of all, the vulcanized tire 1B has at least 90 to 100%, preferably 100% of the normal internal pressure.
That is, the tire is allowed to freely deform by filling the inner pressure of No. 2 and holding only the bead portion 4 in such a state.

If the load of the internal pressure cannot be applied sufficiently and the free deformation of the tire cannot be allowed, the carcass profile 9 cannot be maintained in the equilibrium state in which the carcass cord is extended, and the carcass is filled at the time of the normal internal pressure filling. While the cord path is changed to adversely affect the shape change of the carcass profile 9, conversely, when it exceeds 100% of the normal internal pressure, an excessive load is applied to the carcass cord and durability is deteriorated, which is not preferable.

Second, in the PCI process, the temperature of the tire is controlled to about 80 to 160 degrees Celsius while utilizing the residual heat during vulcanization. If the temperature exceeds 160 ° C., rubber burning or the like will occur and the product value will be impaired, whereas if it falls below 80 ° C., the carcass cord will tend to contract, which is not preferable.

Thirdly, the PCI process is to maintain the internal pressure filling state and temperature control for about 10 to 20 minutes. The lower limit of 10 minutes is the minimum time for achieving the original effect of the PCI process, and if it is less than this, sufficient elongation cannot be imparted to the carcass cord. Because it is inferior in sex.

The radial tire that has undergone the vulcanization process and PCI process as described above is mounted on a wide rim that is 0.5 inch wider than the rim width of the standard rim. The protrusion amount of the carcass profile when the internal pressure change process to change to 100% internal pressure is larger in the buttress part than in the bead part, and conversely it is mounted on a narrow rim that is 0.5 inch narrower than the rim width of the standard rim. Then, when the internal pressure changing process is performed, it is possible to set a carcass profile in which the bead portion protrudes more than the buttress portion, and in this example, each protrusion amount can be stopped to about 1 mm or less. That is, it is possible to manufacture a radial tire capable of changing the shape of the carcass profile as described in claim 1.

[0082]

[Specific example] Tire size 205 / 65R15 (standard rim rim width RW: 6 inches), vulcanization mold clip width 6.8 inches, PCI process rim body rim width 7 inches, 6.5 Three types of inches and 6 inches are set, and a tire according to the manufacturing method of the example is prototyped based on the specifications of Table 1 (example), and a tire manufactured by a manufacturing method other than the example (conventional example and comparative example). Examples 1 to 5) were also prototyped and tested. In the conventional tire, the carcass profile in the vulcanization mold is an arc type having a substantially single arc as a basis. The test procedure is as follows.

A) Shape change of carcass profile The tire is mounted on a wide rim which is 0.5 inch larger than the rim width of the standard rim, the inner pressure filling process is performed, and the shape change of the carcass profile before and after the change is measured by X-ray CT. It recorded using the measuring device and confirmed the amount of protrusion and the state.

(B) Vibration Ride Comfort Performance For each tire, the force variation (FV) was measured when the tire was new and after running for 12,800 km, and displayed as an index with the conventional example being 100. The smaller the value,
It shows that the FV is small and the vibration riding comfort is excellent. In addition, as for the traveling condition, while using the FV measuring machine,
Load 468kgf, regular internal pressure 2.0KSC, standard rim 6.
It was carried out under the condition that the positive and negative slip angles were changed every 1600 km at 0JJ × 15 and a slip angle of 1 degree. The test results are shown in Table 1.

[0085]

[Table 1]

As a result of the test, the tires of the examples have small FVs both when new and after running, and especially after running.
Was confirmed to be small.

[0087]

As described above, according to the present invention, the RFV can be suppressed not only when the tire is new, but also after the tire is used, the vibration riding comfort performance of the vehicle can be improved, and it can be maintained for a long time. Radial tires may be provided.

[Brief description of drawings]

FIG. 1 is a conceptual diagram illustrating a carcass profile of a radial tire of the present invention.

FIG. 2 is a conceptual diagram showing a change in shape of a carcass profile of the radial tire of the present invention.

FIG. 3 is a cross-sectional view illustrating the vulcanization of a radial tire.

FIG. 4 is a cross-sectional view for explaining a PCI process.

5 (A) to (C) are diagrams for explaining the shape change of the carcass profile due to the internal pressure filling process.

6A to 6C are diagrams for explaining the change in shape of the carcass profile due to the internal pressure filling process.

FIG. 7 is a diagram for explaining a carcass profile.

FIG. 8 is a diagram for explaining a carcass profile.

[Explanation of symbols]

 2 tread part 3 sidewall part 4 bead part 5 bead core 6 carcass 7 belt layer 8 bead apex 9 carcass profile 10 buttress part

Claims (2)

[Claims] Claims: 1. A carcass having a turn-back part that goes from the tread part to the side wall part and turns back around the bead core of the bead part from the inner side to the outer side in the tire axial direction, and a cord arranged in the radial direction. A radial tire having a belt layer arranged radially outside and inside the tread portion, the tire being mounted on a wide rim wider by 0.5 inch than the rim width of a standard rim and being filled with a normal internal pressure. The carcass profile in the meridional section of the tire is a point a where the carcass profile intersects with the tire equatorial plane, and a distance obtained by multiplying ½ length (BW / 2) of the axial width of the belt layer by 0.7 from this point a. (0.7 x BW /
2) the first point b on the tread portion of the carcass profile separating the tire axial direction, and the half length (BW / 2) of the belt layer to the point a.
Second on the tread part of the carcass profile separating from
Point c, from the maximum width position of the carcass profile, the height (H−) obtained by subtracting the height (h) from the bead base line from the carcass profile cross-sectional height (H) to the maximum width position.
h) multiplied by 0.7, a distance {0.7 × (H−h)}, which is a third point d on the sidewall portion of the carcass profile, which is separated outward in the tire radial direction, and the maximum width position is the fourth point. e, the fifth point f on the sidewall of the carcass profile, which is separated from the fourth point e by the distance {0.7 × (H−h)} inward in the tire radial direction, and the second point from the tire rotation axis. When the radius length up to c is rc, a first arc C1 having a radius of curvature R1 that smoothly connects between the first point b and the second point c, and the third point d and the fourth point e. And a second arc C2 having a radius of curvature R2 that smoothly joins between and, and a radius of curvature R that smoothly joins between the fourth point e and the fifth point f.
The third circular arc C3 of No. 3 is 0.69 ≦ R1 / rc ≦ 1.
Radial tire characterized by satisfying the relationship of 39 and 0.99 <R2 / R3 <1.17. 2. The carcass profile is mounted on a wide rim that is 0.5 inch wider than the rim width of a standard rim, and is filled with an internal pressure of 5% of the normal internal pressure to a normal internal pressure of 100.
The radial tire according to claim 1, wherein the amount of protrusion when the internal pressure change processing for changing to the% internal pressure is performed is 1 mm or less at the maximum, and the amount of protrusion of the buttress portion is larger than that of the bead portion.