JPH01202502A - Heavy duty radial tire - Google Patents

Abstract

PURPOSE:To improve the durability of a tire for bus and the like by mounting the tire onto a rim having narrower width than that of a standard rim and filling inner pressure of predetermined % that of regular level thereby specifying carcass profile of cross-section in radial direction under no-load state. CONSTITUTION:In a tire to be mounted on a rim narrower than a standard rim and filled inner pressure of 5% that of regular level while having maximum height H of carcass line C (hereafter, referred to carcass C) under no-load and rim width W, a balanced curve N passing through a contact point A be tween tangential lines m, m' at the widest point of the carcass C and cross points B, D between the carcass C and normals p, p' at points separated by a distance 0.45W (W represents rim width) from an equator face M is obtained. The profile of the carcass is set such that the distance (u) between the contact points E and A of the curve N and the tangential lines m, m', intervals (s), (t) between the curve N and the carcass C in the upper and lower regions of the sidewall satisfy the formulae I-III respectively. By such arrangement, durabil ity can be improved.

Description

Detailed Description of the Invention (Industrial Application Field) In connection with improving the durability of pneumatic radial tires, especially heavy-duty radial tires such as those for trucks or buses, the present invention provides a belt for reinforcing the tread. The edges,
This paper attempts to propose a heavy-duty radial tire that prevents separation that tends to occur at the ply end of the carcass, which provides the main reinforcement of the tire.

Generally, in order to improve the durability of the bead part of pneumatic radial tires, we carefully examine the carcass ply folding method.
The materials and structure of reinforcement members such as stiffeners and stiffeners have been studied. but,
Although each method may be effective for a certain size, it may be difficult to adapt to other sizes, or there may be disadvantages that lead to a significant increase in costs, so no fundamental solution has been reached. not present.

This invention is novel in that it is possible to obtain a strain distribution inside a tire suitable for improving tire durability by introducing a novel and outstanding method for controlling the change in shape of a tire when filling the tire with internal pressure. Utilizing this knowledge, we have achieved useful improvements to the above-mentioned heavy-duty radial tires.

(Prior Art) In order to obtain various tire performances, the carcass shape of a tire has generally taken a so-called natural equilibrium shape in which changes in the tire shape before and after filling with internal pressure exhibit uniform bulging deformation. On the other hand, the following disclosure can be cited as a conventional technique related to controlling the change in tire shape when the tire is filled with internal pressure.

That is, according to the illustration in FIG. 3 of the specification of U.S. Pat. No. 4,155,392, by lowering the maximum width of the tire toward the inside in the radial direction of the tire while filling with internal pressure, the tensile strain generated particularly in the sidewall is reduced. It is discussed that the tire life expectancy can be improved by reducing the tire life. However, in this case, when the internal pressure is filled, part of the shoulder of the tire also moves inward in the axial and radial directions of the tire, lowering the initial tension applied to the belt, which reduces the dynamic performance of the tire and the durability of the end of the belt. becomes worse.

In addition, JP-A-55-83604 also discloses a concept similar to the above-mentioned one, and in this case as well, the portion from the end of the belt to a part of the shoulder is filled with normal internal pressure in the axial direction and radial direction of the tire. As a result, the initial tension of the belt is lowered, which also deteriorates performance.

Furthermore, JP-A-58-1616 and JP-A-59-482
Each publication No. 04 discloses a technology that reduces the rolling resistance of a tire by changing the tire shape, but when the tire shape changes, the upper area of the sidewall bulges and deforms due to filling with the normal internal pressure. As a result, the amount of bulging deformation of the bead and tread portions is insufficient, and the strain distribution inside the tire due to deformation is not appropriate, making it impossible to obtain sufficient durability as a tire for heavy loads.

(Problems to be Solved by the Invention) The present invention aims to more advantageously and stably improve the durability of the bead portion and belt portion of a heavy-duty pneumatic tire.

(Means for Solving the Problems) The present invention includes at least one radial carcass using a non-stretchable cord extending from one bead to the other, and reinforcing the tread on the carcass. For pneumatic radial tires equipped with a belt, the internal pressure is filled from the free-standing state of the tire before filling to the officially specified internal pressure under no load, mounted on a standard rim or a rim narrower than the standard rim among applicable rims. When you do,
The tire profile in the radial cross section of the tire extends outward in the radial direction of the tire over the entire crown area from one end of the tire's contact width (tread edge) through the crown center to the other end of the tire's contact width. On the other hand, in the upper region of the sidewall section from the end of the tire ground contact width to the tire maximum width position after filling with the normal internal pressure, at least a portion of the sidewall, that is, the internal pressure filler extends onto the tire contour, which is the self-supporting state of the tire. When the tire contours after being filled with the normal internal pressure are superimposed, there is a dent in the axial direction of the tire at the part that spans between the two points of contact and/or intersection that appear, and the rim flange is indented from the maximum width position of the tire after being filled with the above-mentioned normal internal pressure. This is a radial tire for heavy loads that extends outward in the axial direction of the tire in the lower region of the sidewall section up to the point of contact with the tire, and optimizes the strain distribution that occurs inside the tire under the deformation of each part.

Here, the following embodiment is preferred.

A pneumatic tire that is mounted on a specified rim, in which the bead base of the rim that engages with the bead part has an angle of about 5 degrees with respect to the tire rotation axis, and is a standard rim or a standard rim among applicable rims. The profile of the radial carcass in the radial cross section of the tire when mounted on a narrow rim and filled with an internal pressure of 5% of the normal internal pressure under no load is the maximum of the carcass line C from the rim diameter line RL. Height is H1 Rim flange spacing is rim width W, radial tangent mm' at maximum width position of carcass line C
The contact point is A, and the rim diameter line R is 0.45 times the rim width W from the tire's equatorial plane M to the outside in the axial direction of the tire.
The intersection of the carcass line C with the perpendicular line pp' set at L is sequentially B, D, and then the above tangent mm' of the equilibrium shape curve N that passes through the intersection B and the radial direction tangent mm'.
The following relationship is established for the radially outward separation distance U of the contact point A from the contact point E. ■ The maximum distance S of the carcass line C that separates inwardly from the equilibrium shape curve N in the lower sidewall area. Similarly, for the maximum height H, the following relationship points B, A, and D are connected smoothly in the same way for the maximum distance t of the carcass line C that is spaced outward from the equilibrium shape curve N in the upper region of the sidewall. A pneumatic tire characterized by having a compound curve, and which is mounted on a specified rim, in which the bead base of the rim that engages with the bead portion has an angle of approximately 15° with respect to the axis of rotation of the tire. , Standard 11J or the profile of the radial carcass in the radial cross section of the tire under no load, mounted on a rim narrower than the standard rim among applicable rims and filled with an internal pressure of 5% of the normal internal pressure. However, the maximum height of the carcass line C from the rim diameter line RL is H1, the flange spacing of the rim is the rim width W, the intersection with the radial direction tangent mm' at the maximum width position of the carcass line C is A, and the equator of the tire is The intersection of the carcass line C with the perpendicular line pp' drawn from the surface M to the rim diameter line RL at a distance of 0.45 times the rim width from the surface M to the axially outward side of the tire is sequentially passed through B, D, and then the intersection B and the radial line. The tangent mm' of the equilibrium shape curve N that is tangent to the direction tangent mm'
The following relationship is established for the radially outward separation distance U of the contact point A from the contact point E, and the maximum distance S of the carcass line C separating inwardly from the equilibrium shape curve N in the lower region of the sidewall. Similarly, the following related points B, E and D are connected smoothly for the maximum distance t of the carcass line C which is spaced inwardly from the equilibrium shape curve N in the upper region of the sidewall in the upper region of the sidewall for the maximum height H. A tire consisting of compound curves.

A pneumatic tire that is mounted on a specified rim, in which the bead base of the rim that engages with the bead part has an angle of approximately 5° with respect to the tire rotation axis, and is a standard rim or a standard rim among applicable rims. The profile of the radial carcass in the radial cross-section of the tire when mounted on a rim narrower than that and filled with an internal pressure of 5% of the standard internal pressure under no load is the carcass line C from the rim diameter line RL. Assuming the maximum height is H, the maximum width position of the carcass line C and a straight line jj' parallel to the axis of rotation of the tire that separates the distance L) I from the rim diameter line RL to the outside in the radial direction, which is equal to 0.55 times the maximum height H. The carcass line C with respect to the perpendicular line Rl' drawn from the equatorial plane M of the tire to the rim diameter line RL at a distance of 0.5 times the rim width from the tire's equatorial plane M to the outside in the axial direction of the tire. F and G at the intersection
For each maximum distance V of the carcass line C that is outside of the line segment FI connecting the intersection point F and the intersection point I and separated from it, the following relational intersection point G is passed through the intersection point I for the maximum height H. Similarly, the following relationship holds true for the maximum ratio #W of the carcass line C which is spaced apart from the arc GI on the outside of the arc GI that is in contact with the tangent line rom'.Furthermore, the distance between the carcass line C and the tangent line mm' The intersection point of contact point A with the following relationship for distance X
A tire consisting of a compound curve that smoothly connects the following related points F, A, and G with respect to the distance X to the outside in the radial direction.

A pneumatic tire that is mounted on a specified rim, in which the bead base of the rim that engages with the bead part has an angle of about 15 degrees with respect to the tire rotation axis, and is a standard rim or a standard rim among applicable rims. The profile of the radial carcass in the radial cross-section of the tire when mounted on a rim narrower than that and filled with an internal pressure of 5% of the standard internal pressure under no load is the carcass line C from the rim diameter line RL. The maximum height is H, and the radial line at the maximum width position of the carcass line C and a straight line jj' parallel to the axis of rotation of the tire that separates a distance LH corresponding to 0.55 times the maximum height H from the rim diameter line RL to the outside in the radial direction. The intersection point with the direction tangent mm' is I, and the intersection of the carcass line C with l', a perpendicular line l set on the rim diameter line RL at a distance of 0.5 times the rim width from the tire's equatorial plane M to the outside in the axial direction of the tire. in order F, G
, and for the maximum distance V of the carcass line C that is outside of the line segment Fl connecting the intersection F and the intersection Regarding the maximum distance W of the carcass line C which is also outside of the arc Gl which is in contact with the tangent line mrn' and is separated from the arc Gl, the following relationship also holds: A tire consisting of a compound curve that smoothly connects the following related points F, A, and G with respect to the radially outward separation distance X from the intersection ■.

A pneumatic tire that is mounted on a specified rim, in which the bead base of the rim that engages with the bead part has an angle of approximately 5° with respect to the tire rotation axis, and is a standard rim or a standard rim among applicable rims. The profile of the radial carcass in the radial cross-section of the tire when mounted on a rim narrower than that and filled with an internal pressure of 5% of the standard internal pressure under no load is the carcass line C from the rim diameter line RL. The maximum height is H, and the radial line at the maximum width position of the carcass line C and a straight line jj' parallel to the axis of rotation of the tire that is separated from the rim diameter line RL by a distance LH corresponding to 0.55 times the maximum height H from the rim diameter line RL to the outside in the radial direction. The intersection with the direction tangent mm' is 1
, and a point where a straight line kk' that is in equilibrium with the rim diameter line RL intersects with the carcass line C in the lower region of the sidewall, separated from the rim diameter line RL by a distance MH corresponding to 0.3 times the maximum height H in the radial direction. R1 Furthermore, the point where a perpendicular line L l' drawn from the tire's equatorial plane M to the rim diameter line RL at a distance of 0.5 times the rim width from the tire's axial direction outward intersects with the carcass line C in the upper area of the sidewall is G. A circular arc passing through point R and touching the above tangent line mm' at point I [For the maximum distance y of the carcass line C separating inwardly from H, the following related personnel points for the maximum height H An arc GI that passes through G and touches the above tangent mm' at point I
Maximum distance W of carcass line C separating outward from
Similarly, the following relationship is established for the separation distance X of the contact point A between the carcass line C and the tangent line mm' to the outside in the radial direction from the point I. From a compound curve that smoothly connects points R, I, and G, A tire.

A pneumatic tire that is mounted on a specified rim, in which the bead base of the rim that engages with the bead part has an angle of about 15 degrees with respect to the tire rotation axis, and is a standard rim or a standard rim among applicable rims. The profile of the radial carcass in the radial cross-section of the tire when mounted on a rim narrower than that and filled with an internal pressure of 5% of the standard internal pressure under no load is the carcass line C from the rim diameter line RL. The maximum height is H, and the radial line Jj' parallel to the axis of rotation of the tire is separated from the rim diameter line RL by a distance LH corresponding to 0.55 times the maximum height H from the rim diameter line RL to the outside in the radial direction at the maximum width position of the carcass line C. The point of intersection with the direction tangent mm' is ■, and a straight line kk' parallel to the rim diameter line RL is separated from the rim diameter line RL by a distance M)l corresponding to 0.3 times the maximum height H in the radial direction. The point where it intersects with the carcass line C in the lower sidewall area is R1, and the perpendicular line β l' is drawn from the tire's equatorial plane M to the outside in the axial direction of the tire on the rim diameter RL at a distance of 0.5 times the rim width. Determine the points that intersect with the carcass line C in the upper area of the sidewall as G, and create an arc RI that passes through point R and touches the tangent line mm' above at point I.
Maximum distance y of carcass line C separating inwardly from
, the maximum path 111 of the carcass line C that passes through the following related point G for the maximum height H and separates outward from the arc GI that touches the tangent mm' at point
Similarly, for each 1w, the following relationship: The separation ratio nx of the contact point A between the carcass line C and the tangent line mm' to the outside in the radial direction with respect to the point ■, the following relationship: a complex that smoothly connects points R, I, and G. The tire shall consist of a curved line, and the radially outward bulge g of the tire over the entire crown portion shall be 0.5 to 4.
．． A tire that is 0mm.

A tire in which the bulge in the entire region of the crown portion causes an increase in tension at least at the axial end of the belt having the maximum width among the belt layers.

A tire in which the length C of the tire surface of the portion extending between the contact point F and/or the intersection point G in the upper sidewall region is at least 20 mm.

The radial distance of the tire measured from the tire maximum width position after filling the normal internal pressure in the area between the contact point F and/or the intersection 6 in the upper sidewall area is 0 of the tire maximum height SH after filling the normal internal pressure. .15
Tires that are less than double.

A tire in which the maximum indentation d in the axial direction of the tire in the upper region of the sidewall portion is 0.5 to 4 mm or less.

A tire in which the maximum axially outward expansion f of the tire in the lower region of the sidewall is 3 to 12 mm.

The lower part of the sidewall extending between two points: foot n of the perpendicular line drawn down onto the carcass from the maximum width position of the tire after filling with the regular internal pressure, and foot n' of the perpendicular line drawn down onto the carcass from the point where the tire surface touches the rim flange. A tire whose carcass shape is a curve or straight line with the center of curvature on the inside of the tire when the internal pressure is filled to 5% of the normal internal pressure.

A tire in which the height (HE) of the carcass ply end from the bead base after filling with the regular internal pressure is 10 to 35% of the tire maximum height SH.

Furthermore, the radial carcass in the self-supporting state of the tire when mounted on a standard rim or an applicable rim that is narrower than the standard rim, and filled with an internal pressure of 5% of the officially specified internal pressure, with no load. The shape extends axially outward from the tire's equatorial plane M by 0.4 of the rim width W.
Equilibrium shape curve N that passes through intersections B and D of carcass line C with perpendicular pp' drawn to rim diameter line RL five times apart and touches radial tangent mm' of carcass line C.
In comparison, in the area above the sidewall from the point of contact of the carcass line C with the radial direction tangent mm' to the point of intersection, the carcass line C has a curvature greater than the curvature of the equilibrium shape curve N, and is located on the outside of the tire. In the area below the sidewall from A to the intersection, the carcass line C is larger than the equilibrium shape curve N and is located on the inside of the tire.

Now, Fig. 1 and Fig. 2 show heavy-duty radial tires according to the present invention of different sizes, with solid lines showing the tires in their standard condition after rim assembly and filled with a pressure equivalent to 5% of the normal internal pressure. A carcass path line 1 and a tire contour 2 defined by the carcass path line 1 are shown in a radial cross section of the tire.

Regarding the belts that serve to reinforce the tread on the scum, we have omitted the illustrations because it would be complicated to illustrate them under the deformation behavior of the tire, which will be discussed later. The arrangement is almost the same as in conventional tires.

Here, the standard state of the tire is defined as the state of micro-pressure encapsulation prior to the shape change as described above.In this invention, when assembling the rim, the bead is molded and vulcanized with a slightly wider bead foot width in the mold. By narrowing the width of the tire and mounting it on a standard rim among the applicable rims according to the tire size or a narrow rim, the shape of the tire is maintained in a self-supporting state that is uniform throughout each cross section over the entire circumference of the tire. This is for the purpose of

If the tire is difficult to fit when assembling the rim, or if the tire is severely deformed due to loading and storage, please seal it with the officially specified internal pressure and leave it for more than 24 hours, especially if the layer deformation is severe. If the curl still cannot be removed, run the tire for several tens of times more and then release the pressure again to equal 5% or 7% of the normal internal pressure.The self-supporting state is the standard state. be able to.

In FIGS. 1 and 2, broken lines indicate the carcass pass line 1' and the tire contour 2' in a state where the tire is filled with the normal internal pressure. This characteristic is clear, especially in this respect, the third section shows similar deformation in a comparative tire with a so-called natural equilibrium shape according to a conventional design.
It is even clearer when compared with FIG.

In other words, in this invention, one end of the tire ground contact width (
The other end of the tread is from the track shown in the diagram) to the tread center 3.
On the tread 5 extending through the tire to the other end 4 of the tire ground contact width, an approximately --like bulge g is generated outward in the radial direction of the tire. In the sidewall upper region 7 up to the tire maximum width position 6, at least a part thereof, the part indicated by C in the figure, is indented d in the axial direction of the tire, and further from the above position 6, the rim flange and In the region below the sidewall up to the contact point 8, the tire also protrudes outward in the axial direction f.

The shape change peculiar to this invention that causes the concave deformation in the upper region of the sidewall portion, the bulge of the tread portion 5, and the overhanging deformation in the lower region of the sidewall before and after filling with the normal internal pressure is due to the filling of the internal pressure. As a whole, it tries to swell.

■The carcass shape tries to approach the natural equilibrium shape.

■If you use a virtually non-stretchable cord for the carcass cord,
The carcass does not grow very well.

■Deformation due to internal pressure filling of the carcass occurs in a chain from the bead section to the tread section to the bead section, and deformation never occurs only in one part.

This method utilizes the film properties as they are.

More specifically, in order to realize this invention, when the rim is assembled and filled with an internal pressure of 5% of the normal internal pressure, each carcass takes the shape described above, thereby creating a shape unique to this invention. It becomes easier to obtain changes.

Regarding the carcass shape regulation, which corresponds to 5% of the regular internal pressure, tires with wide flat bottom rims in which the bead base of the rim that engages with the bead of the tire forms an angle of approximately 5° with the axis of rotation are used; The difference between tires that use 15° deep rims and those that use rims is simply that the radial heights of the flanges on both rims are different. This originates from the fact that the real values of the distances are different, but the essence of the invention idea is the same.

In addition, the equilibrium shape curve N is defined by the following equation according to the so-called equilibrium shape theory. From FIGS. 5 and 6, φ is parallel to the rotation axis with a distance R between the tangent of the curve N and the tire rotation axis. The angle formed by the straight line, RE is the distance from the point where the curve N takes the maximum distance in the axial direction to the rotation axis, and R is the distance from the point S where the tangent of the extension line of the above curve N is parallel to the rotation axis. Among the equilibrium shape curves drawn at a distance of The reference line is shown in FIG. 5 as a broken line. In this case, the height of point B is (0,15 to 0.30) ·H, and the height of point D is (0,82 to 0.98) ·H.

Figures 7 and 8 show the carcass profile (solid line) in the radial cross section of a conventional tire with a natural equilibrium shape when the rim is assembled and filled with 5% of the normal internal pressure, and point B.
The equilibrium shape curve (dashed line) passing through D and tangent to the radial tangent mm' of the carcass line is shown. The solid line and the broken line match well, and it can be seen that the shape of conventional tires is designed based on the equilibrium shape curve.

For tires using a 5° wide flat bottom rim, remove the carcass path line from the above equilibrium shape curve with reference to Figure 5, and in the area above the sidewall, set the maximum distance t between the carcass and the equilibrium shape curve to the equilibrium shape curve. Passing through the N tires,
Furthermore, in order to obtain a larger curvature in the upper sidewall area than in conventional tires, the distance U between the maximum width and height A of the carcass profile and the maximum width and height E of the equilibrium shape is such that point A is on the outside of point E in the tire radial direction. .

This makes it possible to indent deformation in the legal area above the sidewall when the normal internal pressure is filled and to cause sufficient expansion and protrusion deformation between the crown part and the lower area of the sidewall when filling the normal internal pressure, and also allows for sufficient expansion and protrusion deformation in the area below the sidewall. By setting the maximum distance S between the line and the equilibrium shape so that the carcass line passes inside the tire of the equilibrium shape, sufficient deformation to approach the equilibrium shape is obtained when the tire is filled with the normal internal pressure, resulting in improved durability.

For tires that use a 15° deep rim, remove the carcass path line from the above equilibrium shape curve with reference to Figure 6, and in the upper sidewall area, set the maximum distance t between the carcass and the equilibrium shape to the equilibrium shape. In order to obtain a larger curvature than conventional tires in the area above the sidewall of the tire, the distance U between the maximum width height A of the carcass profile and the maximum width height E of the equilibrium shape is such that point A becomes point C. Located radially outward.

This enables sufficient bulging deformation of the lower sidewall region when filling with the normal internal pressure, and also allows for the maximum distance S between the carcass line and the equilibrium shape in the lower sidewall region.
By allowing the carcass line to pass inside the tire with an equilibrium shape, sufficient deformation to approach the equilibrium shape can be obtained when the tire is filled with the normal internal pressure, resulting in improved durability.

If the values deviate from the respective minimum values in the above-mentioned ranges of t, S, and u, no improvement in durability can be expected because a sufficient change in shape cannot be obtained when filling with normal internal pressure, as will be described later. Furthermore, if the values deviate from the maximum of 1 shift in the range of t, S, and u, the deformation during normal internal pressure filling will be too large, increasing shear strain at the ends of the ply, and reducing the durability.

11th. Fig. 12 shows a cross section of a tire of the same size as Fig. 9 and Fig. 10, in which the carcass line of a conventional tire is applied to the carcass line of the present invention.

Here, in the area above the sidewall, the difference between the carcass line of the conventional tire and the reference line (arc GI) is small, and it can be seen that this reference line approximately represents the carcass shape of the conventional tire.

In addition, the carcass shape from the lower area of the sidewall to the bead is as shown in Figure 11 for a conventional tire.
The shape is deviated significantly from the reference line (straight line Fl).

As a preferred range of the present invention, in a tire to which a wide flat bottom rim is applied, the carcass line of a conventional tire is 5° from the reference line (arc Gl) which approximately expresses the area above the sidewall, and passes through the outside of the tire at a depth of 15°. In a tire that uses the bottom rim as the applicable rim, the distinctive feature that runs along the outside of the tire is clear from the comparison of the drawings.

In order to selectively cause large overhang and deformation in the lower sidewall region when filling with the regularly specified internal pressure, it is necessary to set the carcass line in this part to the inner side of the tire than the natural equilibrium shape. The carcass line is determined to be close to the reference line (straight line Fl) for tires with a 5° wide flat bottom rim, and for tires with a 15° deep bottom rim. It is preferable that (2) be satisfied.

Furthermore, for tires with a wide flat bottom rim as the applicable rim, the height to the maximum width position of the carcass is 5 degrees from the reference intersection I, and for tires with a 15 degree deep bottom rim as the applicable rim, radially outward. It is preferable to locate the

This is to obtain a curvature larger than that of the carcass line of a conventional tire in the upper sidewall region.

If the values deviate from the minimum values in the ranges of w and x described above and the maximum value in the range of V, a sufficient change in shape cannot be obtained when filling the normal internal pressure as described later. Also, W,
If the value deviates from the maximum value in the range of X, the deformation during normal internal pressure filling will be too large, shear strain will increase, and durability will actually decrease.

Figures 115 and 16 show tire cross sections of the same size as Figures 11 and 14, in which the carcass line of a conventional tire is applied to the carcass line regulations of the present invention.

Here, in the area above the sidewall, as mentioned above, the difference between the carcass line of the conventional tire and the reference line (arc GI) is small, and it can be seen that this reference line almost represents the carcass shape of the conventional tire.

Furthermore, the carcass shape from the lower area of the sidewall to the bead portion is also far away from the reference line (arc IR) as is clear from the comparison in FIGS. 13 and 14.

In order to selectively cause large overhang and deformation in the lower region of the sidewall when filling with the officially specified internal pressure, it is necessary to set the carcass line in this area to the inside of the tire from the reference line (straight line IR). The carcass line in the lower area is 5 degrees from the reference line (arc IR) in the case of a tire with a wide flat bottom rim, and 15 degrees from the reference line (arc IR) in the case of a tire with a deep bottom rim. ) is preferable.

In this way, after assembling the rim, the carcass pass line is set to the inner side of the tire from the carcass pass line after internal pressure filling in the natural equilibrium shape in the tread portion 5, and in the upper sidewall area 7, in the standard state with 5% internal pressure filling. In addition, the carcass shape from the lower sidewall area 9 to the bead is set on the inner side of the tire to have a larger curvature than the curvature after filling with internal pressure, which is a natural equilibrium shape. By using virtually non-stretchable cords such as steel cords or aromatic polyamides for the carcass braai, when filling with internal pressure, the carcass is dented in the area above the sidewalls, causing a chain reaction that causes a large bulge in the crown area. Additionally, the lower area of the sidewall can also be greatly expanded and deformed.

For example, if the upper region of the sidewall approximates a natural equilibrium shape, the carcass in that region will bulge out or remain essentially unchanged, resulting in the required amount of bulge in the crown region and a large bulge in the lower sidewall region. Therefore, it is not possible to achieve the strain distribution necessary for improving durability.

(Function) In general, most tire failures occur frequently at the ply end of the carcass, that is, at the bead.

In order to improve the failure that occurs at the carcass ply end of the bead part, by filling the end of the ply with moderate compressive stress and applying it under internal pressure, failure at the ply end is prevented and the durability of the bead part is improved. It has been clarified what can be obtained.

In other words, when the normal internal pressure is filled to cause the axially outward protrusion f in the lower region of the sidewall as described above, as shown in Fig. 17, the ply end e of the carcass will be approximately ±10 to 20 mm in the radial direction. Within the range of
By moving outward in the axial direction and inward in the radial direction and causing at least the vicinity of the carcass ply end e to extend radially inward as shown by the broken line, a radially inward compressive force can be applied to the carcass ply end e. It becomes possible.

Furthermore, in order to apply an appropriate compression force, when the tire is assembled on a rim and filled with an internal pressure of 5% of the standard internal pressure,
It is recommended that the center of the radius of curvature of the carcass shape corresponding to the lower region of the sidewall be on the inside of the tire, or that the carcass shape be close to a straight line.

The belt tension is increased by filling the crown region, particularly from the equator to the end of the maximum ground contact width, by filling the crown region with internal pressure.

This increase in belt tension greatly contributes to improving the durability of the belt ends, as it reduces the strain between the belt layers that occurs when the tire is loaded; This is effective in preventing separation at the ends of the belt.

In other words, when the initial tension of the belt is large, the deformation behavior of the belt that occurs when a load is applied to the tire is shown by the solid line arc in Fig. 18. The center 0 occupies a higher position than the belt, and therefore the amount of deformation in the deformation region R of the belt on the ground contact side is small, which reduces the shear strain between the cord cross layers of the belt, leading to improved durability of the belt end. It will be destroyed.

The above-mentioned tire strain distribution is achieved by a unique chain deformation behavior caused by normal internal pressure filling of the tire, resulting in improved durability of the crown and bead portions.

(Example) Example 1 Tire size: 10.0OR20 Rim size +7.50 V 20 (5° wide flat bottom rim) Regular internal pressure: 7.25 kg/cm 2 Carcass maximum height H: 240 mm Truck/bus tire As shown in Fig. 5, the height of point B is 53.2 m (0,22·H),
The relationship to the carcass line C set at point D height 226.2 mm (0,94 H) is s = 10.0 mm5
t = 7.8 mm.

Ll"23.9 mm, and in the place shown in Figure 1, d=1.3 mm, f=6.7
mm, g=1.9mm, h=26.5mm,
Steel c = 75mm, HE = 67.2mm -
We made a prototype of a Luradial tire.

-xu! -iz;t and so are within the range of b -;tb.

Comparative Example 1 Tire size: 10.0OR20 Rim size Near, 50V20 (5° wide flat bottom rim) Regular internal pressure: 7.25 kg/cm 2 Maximum carcass height H: 240 m+n As shown in Figure 7, the tires are for trucks and buses. The height of point B is 49.0+++m (0,20・H
), the relationship with the carcass line C' set at point D height 224.2 m (0,91·H) is s = 1.6.
For comparison, a steel radial tire of mm, t=0.3 mmz u=0.2 mm, and exhibiting uniform bulging deformation in a conventional natural equilibrium shape as shown in FIG. 3, was used.

In this case -X S # 1.5 <5.0- X t
#0.3<2.0-xu''-;0.2<5, and the carcass line C according to the present invention is far away from the cross line.

Example 2 Tire size near, 50 R16 Rim size: 600 GS 16 (5' wide flat rim) Regular internal pressure near, Okg/cm2 Carcass maximum height H = 178 mm Truck and bus tires shown in Figure 5 By the way, the height of point B is 41.6 mm (0,23・H)
, the relationship to the carcass line C determined at point D height 166 n++n (0,93・H) is s = 4.6 mm5
t = 2.8 mm.

When u=3.5mm and as shown in Fig. 1,
d = 0.8 mm, f = 5. (] nu++,
A steel radial tire with g = 1.0 mm was prototyped.

Comparative Example 2 Tire size +7.50 R16 Rim size N600 GS 16 (5° wide flat bottom rim) Regular internal pressure near, 0 kg/cm2 Maximum carcass height: 178 mm As shown in Figure 7, this is a truck/bus tire. , B point height 41.0mm (0,23・H)
, the relationship with the carcass line C' set at point D height 166.0 mm (0,91·H) is s = 1.2.
mm5t ==Q mm.

A steel radial tire with u=0.5 mm and a conventional natural equilibrium shape as shown in FIG. 3 was used for comparison.

Example 3 Tire size: 10.0OR20 Rim size Near, 50 V 20 (5-layer wide flat bottom rim) Regular internal pressure: 7.25 kg/cm" Maximum carcass height H: 5th tire for trucks and buses with a height of 241" In the place shown in the figure, the height of point B is 50.(bnm (0,21・H
), relation to the carcass line C determined in the order of D point height 229.7 (0,95 H), s = 7.0 mm,
t = 5.9 mm, u: = 16.7 mm, and in the place shown in Figure 1, d - 1.5 mm,
A steel radial tire with f = 5.0 mm and g = 1.8 mm was prototyped.

Comparative Example 3 Tire size: 10. O-OR20 rim size near, 50 V 20 (5 layer wide flat bottom rim) Regular internal pressure
: 7.25kg/cm2 carcass maximum height H=24
As shown in Figure 7, for a 0 mm truck/bus tire, the height of point B is 50.0 mm (0,20 H).
, the relationship with the carcass line C', which is set at the height of point D, 229.5 nun (0,94·H), is S = 3.0.
city, t=0.9mm, u=2.5 a+m,
A conventional steel radial tire with a natural equilibrium shape as shown in Figure 3 was used as a control for comparison.

FIG. 19 shows the distribution of the initial belt tension in the radial cross section of the tire of Example 1 and Comparative Example 1, which were determined by the finite element method. Each tire has four belt layers, starting from the inside in the radial direction.
The belt layer, the second belt layer, the third belt layer, and the fourth belt layer were used, and the tension distribution of the second belt layer and the third belt layer was determined.

In this case, the conditions for measuring the belt tension distribution were, of course, normal internal pressure filling and no load.

As is clear from FIG. 19, the tire of the present invention had a higher circumferential tension than the comparative example, and this tendency was also the same in the relationship between Example 2.3 and Comparative Example 2.3. .

The results of a comparative test to determine how much the above-described increase in belt tension affects the durability of the belt ends are as follows.

Test Conditions In the Nislip angle drum test, a slip angle of 3° was applied at a normal internal pressure and a load twice the normal load, and the speed was 5 Qkm/hr.

Results: Example 1: 895km1, Example 2: 802km
, Example 3 completed a distance of 840 km.

Separation occurred at the end of the belt at each running point: 630 km in Comparative Example 1, 625 km in Comparative Example 2, and 592 km in Comparative Example 3.

Next, to examine the durability of the bead, a test was conducted using a drum testing machine.

Test conditions: normal internal pressure, twice the normal load, speed 60kn+/h Results: Example 1 completed 2000 km without any abnormalities, but Examples 2 and 3 each covered 19800 km.

A slight separation occurred at the braai end after driving 19,500 km.

Comparative example 1 is 14,500 km, Comparative example 2 is 14,450 km
In addition, separation occurred in 3rd model after driving for 15,000 km.

Example 4 Tire size: 11/70 R22,5 rim size
: 8.25 X22.5 (15° deep rim) Regular internal pressure: 8. Okg/cm2 carcass maximum height H
: As a 166 m+n truck/bus tire,
In the place shown in Figure 6, the height of point B is 30.5 mm.
(0,18・H), D point height 157.2 ml11 (
The relationship to the carcass line C defined in 0.94 H) is s = 5.8 mm, t = 1.7111111
%u = 9.0 mm, and in the place shown in Figure 2, d = 1.1 mm, f = 4.211111
．． g=1.7111111゜h=13.2nun,
A steel radial tire with c = 41 nim and HE = 19 mm was prototyped.

In this case, -x s =6.17, which falls within the range H of 3.0 to 9.0.

Comparative example 4 Tire size: 11/70 R22,5 rim size
: 8.25X22.5 (15° deep rim) Regular internal pressure +8.0 kg/cm2 Maximum carcass height H: 166 mm As a truck/bus tire, the height at point B is 30. 5+nm (0,18・H)
, the relationship with the carcass line C' set at point D height 157.2 mm (0,94·H) is s = 1.2 m
A conventional steel radial tire with natural equilibrium shape as shown in FIG. 4, with m and t=0.5 mm and u--1, Q mm, was used as Control 1 for comparison.

In this case, the equation is □×Sζ1.52, which is extremely far from the pass line of the carcass line C according to the present invention.

Example 5 Tire size: 285/75 R24.5 Rim size: 8.25 As shown in Figure 6, the height of point B is 38.8 mm (0,21・H)
, the relationship with the carcass line C determined at point D height 172.5 mm (0,94·H) is s=5. Omm,
t = 2.5 mm, u = 9.0 mm, and as shown in Figure 2, d = 2.5 mm5f = 7
．． A steel radial tire with a weight of 3 mm 5 g = 1.8 mm was prototyped.

Comparative example 5 Tire size: 285/75 R24,5 rim size
: 8.25 x 24.5 (15' deep rim) Regular internal pressure: 8.2 kg/cm2 Maximum carcass height:
As shown in Figure 4, for a truck/bus tire of 183+nm, the height of point B is 39.0+nm (0,21・H
), D point height 172.2 + nm The relationship with the carcass line C' set at (0,94・H) is s = 1.5
A steel radial tire with a conventional natural equilibrium shape of mm, t=0.0 mm, and u=0.0 mm as shown in FIGS. 3 and 4 was controlled and used for comparison.

Example 6 Tire size: 11 R22.5 Rim size: 8.25X22.5 (15" deep rim) Regular internal pressure near, Okg/cm2 Maximum carcass height H: 210 mΩ As shown in Figure 6, the tire size is for trucks and buses. In the place shown, the height of point B is 40.5 mm (0,19・H)
, s = 7.0 mm5t = 3.5 for carcass line C set at point D height 190 mm (0,90 H)
mm, u = 12.5 mm, and as shown in Figure 2, d = 1.2 w, f = 7.5 f
A steel radial tire with f1ffl, g = 1.8 was prototyped.

Comparative Example 6 Tire size: 11 R22.5 Rim size: 8.25 X22.5 (15° deep rim) Regular internal pressure: 7. As shown in Figure 8, for a truck/bus tire with a carcass maximum height of 210 mm, the height of point B is 40.5 mm (0,19 H), and the height of D is
The relationship with the carcass line C' set at a point height of 190.0 + nm (0,90·H) is in the order of S = 0.8, t
=0.5 mm-, u=1.8 +n[Il, and a conventional steel radial tire with a natural equilibrium shape as shown in FIG. 4 was controlled and used for comparison.

The results of a comparative test to determine how much an increase in belt tension affects the durability of the belt end are as follows.

Test Conditions: In the Nislip angle drum test, a slip angle of 3° was applied at a normal internal pressure, a load twice the normal load, and a speed was 60 km/hr.

Results: Example 4 traveled 806 km, Example 5 traveled 818 km, and Example 6 traveled 828 km.

Separation occurred at the end of the belt in Comparative Example 4 at 605 km, Comparative Example 5 at 640 km, and Comparative Example 6 at 603 km.

Next, to examine the durability of the bead, a test was conducted using a drum testing machine.

Test conditions: Normal internal pressure, twice the normal load, speed 60 km/h Results: Example 4 was run at 19,050 km, Examples 5 and 6 were run at 19,300 km and 19,750 km, respectively, and there was a slight problem at the ply end. A separation occurred.

Comparative example 4 is 14,500 km, Comparative example 5 is 15,700 km
In addition, Separation occurred in the same car after driving 16,400 km.

Example 7 Tire size: io, oo R20 Rim size Near, 50 V 20 (5° wide flat bottom rim) Regular internal pressure: 7.25 kg/cm" Maximum carcass height H: 240 +++ m As a tire for trucks and buses, Fig. 9 In the place shown in , the height of one point is 132 mm (0,55 H),
The relationship to the carcass line C, which is set at F point height 68.5 + nm (0,29-H) and G point height 221 mm (0,92 H), is v = Q mm, w = 7.8
aonSx = 23.9 mm, and as shown in Figure 1, d = 1.3 mm.

f=6.7mm, g=2.0mm5h=27n+m,
c=75.8mm.

A steel radial tire with HIE = 67mm was prototyped.

It is settled in.

Comparative Example 7 Tire size: 10.0OR20 Rim size Near, 50 V 20 (5° wide flat bottom rim) Regular internal pressure: 7.25 kg/cm" Maximum carcass height H: 240 [No. 11 as a tire for trucks and buses of 11111 1 point height 1 at the location shown in the figure
32mm (0.55・H), F point height 68.5mm
(0,27・H), G point height 221.0mm (0,9
The relationship to the carcass line C' defined in 0.H) is 5.
=4J mm, w=3.0 mm5x=9.3 ++
For comparison, a steel radial tie opening which exhibits uniform bulging deformation with a conventional natural equilibrium shape as shown in FIG. 3 was used.

Therefore, the carcass line C according to the present invention is far away from the pass line.

Example 8 Tire size near, 50 R16 Rim size: 6,00 GS 16 (5° wide flat bottom rim) Regular internal pressure near, Okg/am2 Maximum carcass height H = 178 mm For truck and bus tires, shown in Figure 9. As shown, the height of one point is 97.9mm (0.55・H)
, the relationship with the carcass line C determined at F point height 55.0 mm (0,31・H) and G point height 161.0 mm (0,9・H) is v = Omm5x = 9.4
mmSx = 16.8 mm, and in the place shown in Fig. 1, d = 0.8 w, f = 5.5 + nm,
A steel radial tire with g=1.2 mm was prototyped.

Comparative Example 8 Tire size near, 50 R16 Rim size: 6.00 GS 16 (5° wide flat bottom rim) Regular internal pressure: 7. As shown in Fig. 11, as a truck/bus tire with a carcass maximum height of 178 mm, the height at one point is 97.9 mm (0.55 H
), the relationship with the carcass line C' set at F point height 55.2 mm (0,28・H) and G point height 161.0 mm (0,85・H) is v=4,8 n+m, w=
A steel radial tire with a conventional natural equilibrium shape of 0.9 mmSx = 4.8 mm as shown in FIG. 3 was controlled and used for comparison.

Example 9 Tire size: 10.0OR20 Rim size near, 50V20 (5° wide flat bottom rim) Regular internal pressure: 7.25 kg/cm2 Maximum carcass height H: 241.5 mm As a truck/bus tire, Fig. 9 In the place shown in , 1 point height 1
32.8 m+n (0,55・H), F point height 57.5
mm (0,24・H), G point height 224 mm (0
, 93・H), v =
O++unSw = 7.5 mm, x = 28.5
mm, and as shown in FIG. 1, d =
1.5 mm, f = 6.5 mm, g = 1.8
We prototyped a steel radial tire with a diameter of mm.

Comparative Example 9 Tire size: 10.0OR20 Rim size = 7.50v20 (5° wide flat bottom rim) Regular internal pressure: 7.25 kg/cm2 Carcass maximum height H: 241.5 mm No. 11 as a truck/bus tire In the place shown in the figure, 1 point height 1
32.8 n+m (0,55・H), F point height 57.5
mm (0,24・H), G point height 224.0 +n
The relationship with the carcass line C' set at +n(0,93・H) is v=4.5 +nm, w=3.8 +n
+n, x=3.8 mm, and a conventional steel radial tire with a natural equilibrium shape as shown in FIG. 3 was used as a control for comparison.

The results of a comparative test to determine how much an increase in belt tension affects the durability of the belt end are as follows.

Test Conditions: In the Nislip angle drum test, a slip angle of 3° was applied at a normal internal pressure, a load twice the normal load, and a speed of 60 km/hr.

Results: Example 7: 865km, Example 8: 812km
In Example 9, the belt ran for 840 km and there was a slight separation at the end of the belt.

Comparative Example 7 ran 630 km, Comparative Example 8 ran 673 km, and Comparative Example 9 ran 600 km. Separation damage occurred at the Tehert end. Next, to examine the durability of the bead, a test was performed using a drum testing machine.

Test conditions: Normal internal pressure, twice the normal load, speed 60 km/h Results: Example 7 and Example 8 are 19450 km,
A slight separation occurred at the ply end after running for 19,000 km, but in Example 9, no abnormality occurred after running for 20,000 km.

Comparative example 7 is 14,500 km, Comparative example 8 is 15,700 km
In addition, Separation occurred in the same 9 after driving for 15,000 km.

Example 10 Tire size: 11/70 R22,5 rim size
: 8.25 X22.5 (15° deep rim) Regular internal pressure: 8. Okg/cm2 Maximum carcass height H: 167, 2 mm track
As a bus tire, as shown in Figure 10, the height at one point is 92.1 mm (0,55・H), the height at F point is 44.3 mm (0,26・H), and the height at G point is 146 mm.
The relationship to the carcass line C set at mm (0,88 H) is v=2.5 mmSw=3.0 mm5x=1
5.4 mm, and in the place shown in Figure 2, d-1, 1 ml, f = 4.2 mm, g
= 1.7 mm, h = 13.2 mm.

A steel radial tire with c = 41 mm and HfE = 19 mm was prototyped.

in this case, It is settled in.

Comparative example 10 Tire size: 11/70 R22,5 rim size
: 8.25 X22.5 (15° deep rim) Regular internal pressure: 8. Okg/cm2 carcass maximum height H
: As a truck/bus tire of 166,0 +na+, one point height is 91 in the Tato colony shown in Figure 12.
．． 3mm (0.55・H), F point height 44.0++u
n (0,27・H), G point height 146.4 mm (0
, 88・H) is v=6.3 mm5x=2.2 mm5x=2.8
A conventional steel radial tire with a natural equilibrium shape as shown in FIG. 4 was used as a control l for comparison.

Therefore, the carcass line C according to the present invention is far away from the pass line.

Example 11 Tire size: 285/75 R24,5 rim size
: 8.25 x 24.5 (15° deep rim) Regular internal pressure: 8.2 kg/cm2 For truck and bus tires with carcass maximum height H = 183 mm, one point higher as shown in Figure 10. length 100.7 mm (0,55
・H), F point height 49.0mm (0,27・H)
, the relationship with the carcass line C set at G point height 165.5wm (0,91・H) is v=2.0mm, w=
3.7 mm, x=18. on+m.

Also, in the place shown in Figure 2, d-"2.5mm
.

A steel radial tire with f = 8.0 mm and g = 1.8 + nm was prototyped.

Comparative Example 11 Tire size: 285/75 R24.5 Rim size: 8.25 , wipe the area shown in Figure 12 and place a point with a height of 100.7 mm (0.55 mm).
H), F point height 49.0mm (0,27・H), G
The relationship to the carcass line C', which is set at a point height of 166.8 mm (0,91 H), is v = 5.0 mm,
A steel radial tire with w=0.8 mm, x=4.0 mm, and a conventional natural equilibrium shape as shown in FIG. 4 was controlled and used for comparison.

Example 12 Tire size: lI R22.5 Rim size: 8.25 In the place shown in , the height of one point is 115.5 mm (0.55 mm).
H), F point height 54.5mm (0,30・H), G
V = 2.9w, w = 3.8 mm for carcass line C set at point height 181.0 mm (0.86 H)
, x = 16.7 mm, and as shown in Figure 2, d = 1.2 mm, f = 7.5 mm5
A steel radial tire with g = 1.7 mm was prototyped.

Comparative Example 12 Tire size: 11 R22.5 Rim size: 8.25 In the place shown in , the height of one point is 115.5 mm (0.55 mm).
H), F point height 54.5mm (0,26・H), G
The relationship to the carcass line C', which is set at a point height of 180.7 ml 1 l (0.86 H), is V = 5.8 mm,
w=1.2 mm, x=5.0 mm, and the fourth
A conventional steel radial tire with a natural equilibrium shape shown on the right as shown in the figure was used as a control for comparison.

The results of a comparative test to determine how much an increase in belt tension affects the durability of the belt end are as follows.

Test Conditions In the Nislip angle drum test, a slip angle of 3° was applied at a normal internal pressure and a load twice the normal load, and the speed was 5 Qkm/hr.

Results: Example 10: 803km, Example 11: 815km
m and Example 12, a slight separation occurred at the belt end at 833 km.

Comparative example 10 is 605km, comparative example 11 is 645km
.

In Comparative Example 12, separation occurred at the end of the belt at each point in time when the belt ran for 592 km.Next, the durability of the bead portion was examined using a drum testing machine.

Test conditions: normal internal pressure, twice the normal load, speed 60 km/h Results: Example 1O and Example 11, 18500 km,
A slight separation occurred at the end of the ply after running for 19,200 km, but in Example 12, no abnormality occurred after running for 20,000 km.

Comparative example 10 is 14,200 km, Comparative example 11 is 16,500 km
Also, separation occurred at 15,900 k+n in 12 km.

Example 13 Tire size: 10.0OR20 Rim size near, 50 V 20 (5° wide flat bottom rim) Regular internal pressure: 7.25 kg/cm2 Carcass maximum height H: 242 mark As a truck/bus tire, shown in Figure 13. In the area shown, the height of one point is 133.1 mm (0°55-
H), F point height 72.6mm (0,30・H),
The relationship with the carcass line C determined at the G point height 22On++n (0,91・H) is v=10.0mmSw=
7.8 mm5x=23.9 mm, and in the place shown in FIG. 1, d=1.3 mm, f=5.
7 mm, g = 2.0 mm5h = 27.0 + n
A steel radial tire with m, C = 75.0 mm, and HE = 67.1 mm was prototyped.

in this case, It is settled in.

Comparative Example 13 Tire size: 10.0OR20 Rim size near, 50 V 20 (5° wide flat bottom rim) Regular internal pressure: 7.25 kg/cm2 Maximum carcass height H: 242 mm As shown in Figure 15, this is a truck/bus tire. 1 point height 133.1mm (0.55・H)
, the relationship to the carcass line C', which is set at F point height 72.4 mm (0,30·H) and G point height 219 mm (0,90·H), is v=4.4 mm, w=3. 9
A steel radial tire with m+n, x=9.3 mm and a conventional natural equilibrium shape as shown in FIG. 3 was used as a control l for comparison.

In this case, the carcass line C according to the present invention is far away from the pass line.

Example 14 Tire size near, 50 R16 Rim size: 600 GS 16 Regular internal pressure: 7. Okg/cm2 For a truck/bus tire with a carcass maximum height H = 178 mm, the height at one point is 97.9 mm (0.55 H) as shown in Figure 13.
), F point height 53.4+yun (0,30・H),
The relationship to the carcass line C set at G point height 162; 5 mm (0,91 H) is y = 5.5 ffllll
lSw=3.4 mff1. x=16.8 mm, and as shown in FIG. 1, d=2.8 mm.

A steel radial tire with f = 5.1 mm and g = 1.0 mm was prototyped.

Comparative Example 14 Tire size near, 50 R16 Rim size: 600 GS 16 (5° wide flat bottom rim) Regular internal pressure: 7. As shown in Fig. 15, as a truck/bus tire with carcass maximum height: 178n+m, the height at one point is 97.9++un (0,55.
H), F point height 53.4mm (0,30・H), G
The relationship to the carcass line C', which is set at a point height of 162.5 n+m (0,91·H), is y=0.8mm, w=
A conventional steel radial tire with a natural equilibrium shape of 0.9 mm and x=4.8 mm as shown in FIG. 3 was controlled and used for comparison.

Example 15 Tire size: 10.0OR20 Rim size Near, 50 V 20 (5' wide flat bottom rim) Regular internal pressure: 7.25 kg/cm2 Maximum carcass height H: 241 As shown in Figure 13 as a truck/bus tire In the area shown, the height of one point is 132.6 mm (0.55 mm).
H), F point height 72.3+nm (0,30・H),
For carcass line C set at G point height 226 mm (0.94 H), y=9.8 mmSw=6.5
mm5x = 23.5 mm, and in the place shown in Figure 1, d = 1.5 mm, f = 5.0 m
A steel radial tire with m and g = 1.8 mm was prototyped.

Comparative Example 15 Tire size: 10.0OR20 Rim size near, 50 V 20 (5° wide flat bottom rim) Regular internal pressure: 7.25 kg/cm2 Maximum carcass height H = 241 mm As a truck/bus tire, shown in Figure 15 In the area shown, the height of one point is 132.6 mm (0.55 mm).
H), the relationship to the carcass line C', which is set at F point height 72.0 mm (0,3・H) and G point height 226.5 mm (0,94・H), is y=3.6 mIIIS
A steel radial tire with w=3.3 mm, x=3.8 mm, and a conventional natural equilibrium shape as shown in FIG. 3 was used as a control for comparison.

The results of a comparative test to determine how much an increase in belt tension affects the durability of the belt end are as follows.

Test Conditions In the Nislip angle drum test, a slip angle of 3'' was applied at a normal internal pressure, a load twice the normal load, and a speed of 59 km/hr.

Results: Example 13: 890km, Example 14: 802km
In Example 15 and M, slight separation occurred at the belt end at 851 km.

Separation occurred at the end of the belt at each running point: 585 km for Comparative Example 13, 640 km for Comparative Example 14, and 612 km for Comparative Example 15.Next, in order to examine the durability of the bead portion, a test was performed using a drum testing machine.

Test conditions: Normal internal pressure, twice the normal load, speed 60 km/h Results: Example 13 and Example 15 were tested at 18,500 km,
A slight separation occurred at the ply end after running for 19,000 km, but in Example 14, no abnormality occurred after running for 20,000 km.

Comparative example 13 is 14,900 km, Comparative example 14 is 16,000 km
Separation occurred on the same 15 when running at 15,550 ka+.

Example 16 Tire size: 11/To R22,5 rim size
: 8.25 X22.5 (15° deep rim) Regular internal pressure: 8. As shown in Fig. 14, as a truck/bus tire with carcass maximum height H: 168.2 mm,
1 point height 92.5mm (0,55・H), R point height 5
0.5mm (0,30・H), G point height 148m5
The relationship to the carcass line C defined at (0,88・H) is y=4.8mm, w=30.7mm5x=15.4
mm, and in the place shown in Figure 2, (1
"1.1mm.

f = 4.2 mm, g = 1.7 mm, h = 13
．． 2w, c=41mm, HE! We prototyped a steel radial tire with a length of 19m.

in this case, It is settled in.

Comparative Example 16 Tire size: 11/70 R22,5 rim size
: 8.25 X22.5 (15° deep rim) Regular internal pressure: 8. Okg/cm2 Maximum carcass height H: 167, 5 mm track
As shown in Figure 16, as a bus tire, the height at one point is 92.1+nm (0,55・H), the height at R point is 50.3mm (0,3・H), and the height at G point is 147.8.
Carcass line C' set to n++n (0,9・H)
The relationship to y=2.0ff1llll, w=1.
2 + nm, X: 2.8 mm, and a conventional steel radial tire with a natural equilibrium shape as shown in FIG. 4 was used as a control for comparison.

Therefore, the carcass line C according to the present invention is far away from the pass line.

Example 17 Tire size: 285/75 R24.5 rim size
: 8.25 x 24.5 (15° deep rim) Regular internal pressure: 8.2 kg/cm2 For truck and bus tires with carcass maximum height H = 183 mm, one point higher as shown in Figure 14. 100.7 m+n (0,5
5・H), R point height 54.9mm (0,30・H)
, the relationship to the carcass line C determined at point G height 165.5 mm (0,90 H) is y = 5.1 mm,
w=3.7 n++n, x=18.3mm, and as shown in Figure 2, (1"2.5mm.

A steel radial tire with f = 7.3 mm x g = 1.8 mm was prototyped.

Comparative Example 17 Tire size: 285/75 R24.5 Rim size: 8.25X24.5 (15° deep rim) Regular internal pressure: 8.2 kg/cm2 Maximum carcass height: 183111 [D as a truck/bus tire , the height of one point is 100.7 mm (0.55 mm) as shown in Figure 16.
・H), R point height 54.9 mun (0,30・H)
, the relationship with respect to the carcass line C' defined at G point height 165.1 mm (0,90-) () is y = 1.9111
mSw=0.8111m, x=4.91m,
A conventional steel radial tire with a natural equilibrium shape as shown in FIG. 34 was controlled and used for comparison.

Example 18 Tire size: 11R22.5 Rim size: 8.25 X22.5 (15° deep rim) Regular internal pressure: 8. Okg/cm2 Carcass maximum height H: 210 As shown in Figure 14, as a city truck/bus tire, the height at one point is 115.5 mm (0.55 mm).
・H), R point height 54.9mm (0,3O-H),
G point height 181. y=4,9 ramSw=3 for carcass line C set at offlm(0,86・H)
．． 8 mm, x=16.7 mm, and as shown in FIG. 2, d=1.2 mm, f=7.
A steel radial tire with a weight of 51M11g = 1.7 mm was prototyped.

Comparative Example 18 Tire size: 11 R22.5 Rim size: 8.25 X22.5 (15° deep rim) Regular internal pressure: 8. Okg/cm2 As shown in Figure 16, for a truck/bus tire with a carcass maximum height H = 210 mm, the height at one point is 115.5 mm (0.55 mm).
・H), R point height 54.5mm (0,3l-H),
The relationship to the carcass line C', which is set at a height of point G of 181.4 mm (0.86 H), is y-=1.8 mf.
A steel radial tire with flSw=1.2 mm, x=4.4 aun, and a conventional natural equilibrium shape as shown in FIG. 4 was used as a control for comparison.

The results of a comparative test to determine how much an increase in belt tension affects the durability of the belt end are as follows.

Test Conditions: In the Nislip angle drum test, a slip angle of 3° was applied at a normal internal pressure, a load twice the normal load, and a speed of 60 km/hr.

Results: Example 16: 865km, Example 17: 802km
M and Example 18 had a slight separation at the end of the belt at 845 km.

Separation occurred at the end of the belt at each running point: 620 km for Comparative Example 16, 629 km for Comparative Example 17, and 598 km for Comparative Example 18.Next, in order to examine the durability of the bead portion, a test was performed using a drum testing machine.

Test conditions: Normal internal pressure, twice the normal load, speed 60 km/h Results: Example 16 and Example 17 were tested at 18,500 km,
A slight separation occurred at the end of the ply after running for 18,550 km, but in Example 18, no abnormality occurred after running for 20,000 km.

Comparative example 16 is 14,200 km, Comparative example 17 is 15,950 km
Separation occurred on the same 18 after driving for 16,050 km.

(Effects of the Invention) The heavy-duty radial tire according to the present invention has significantly improved durability at the bead and belt ends.

[Brief explanation of the drawing]

Figures 1 and 2 are cross-sectional views showing the specific shape changes that occur in the tire of the present invention; Figures 3 and 4 are similar cross-sectional views of conventional tires; Figures 5 and 6 are similar cross-sectional views of conventional tires; 7 and 8 are cross-sectional views showing an embodiment of the present invention, and FIGS. 9 and 1 are cross-sectional views of conventional tires.
Figure O is a cross-sectional view showing another embodiment, Figures 11 and 12 are cross-sectional views of comparative tires, Figures 13 and 14 are cross-sectional views showing different embodiments, and Figures 15 and 16 are cross-sectional views of a comparative tire. Figure 17 is a cross-sectional view of a comparison tire; Figure 17 is an explanatory diagram of the deformation behavior of the tire due to internal pressure filling, Figure 18 is an illustration of the deformation behavior of the tire due to loading, and Figure 19 is a comparison diagram of the belt tension distribution across the width of the tread portion. be. 1.1'... Carcass line 2.2'... Tire outer contour 4... Tread edge 5... Tread 6...
Maximum position 7... Sidewall upper area 9... Sidewall lower area Patent applicant Brideston Co., Ltd. Figure 1 Figure 2 Figure 3 Figure 4 Figure 6 Hole G > 1 Helmet lO diagram, Figure 2112 Gohi B57 171st 181st

Claims (1)

[Claims] 1. An air pump comprising at least one radial carcass using a non-stretchable cord extending from one bead part to the other bead part, and a belt reinforcing the tread on the carcass. For radial tires, when the tire is installed on a standard rim or a rim that is narrower than the standard rim among applicable rims and is unloaded, the tire's internal pressure is filled from the self-standing state before internal pressure filling to the officially specified internal pressure. The tire profile in the directional cross section is at one end of the tire contact width (
The entire crown area from the tread edge through the crown center to the other end of the tire contact width bulges outward in the radial direction of the tire, while In the area above the sidewall part up to the wide position, at least part of it, that is, the tire for internal pressure filling, has contact points that appear at two points when the tire contour after normal internal pressure filling is superimposed on the freestanding tire contour. and/or the tire is dented axially inward in the area between the intersection points, and further axially outward in the lower area of the sidewall from the tire maximum width position to the point of contact with the rim flange after filling with the normal internal pressure. A radial tire for heavy loads, which is characterized by optimizing the strain distribution that occurs inside the tire under the deformation of different parts of the tire. 2. A pneumatic tire that is mounted on a specified rim, in which the bead base of the rim that engages with the bead part has an angle of approximately 5° with respect to the tire rotation axis, and is a standard rim or a standard applicable rim. The profile of the radial carcass in the radial cross section of the tire when mounted on a rim narrower than the rim and filled with an internal pressure of 5% of the normal internal pressure under no load is the carcass line C from the rim diameter line RL. The maximum height of the rim is H, the rim width is the rim width W, the point of contact with the radial tangent mm' at the maximum width position of the carcass line C is A, and the rim is moved from the equatorial plane M of the tire to the outside in the axial direction of the tire. Carcass line C relative to the perpendicular line pp' set on the rim diameter line RL at a distance of 0.45 times the width W
The intersection points of the above are defined in order as B, D, and the contact point E of the equilibrium shape curve N that passes through the intersections B and D and touches the radial tangent mm', and the contact point A is radially outward with respect to the contact point E. The following relationship 5<(240/H)×u<25 is satisfied for the separation distance u, and the maximum height is The following relationship 5.0<(240/H)×s<13.0 is satisfied for H, and
In the upper region of the sidewall, the point B satisfies the following relationship 2.0<(240/H)×t<10.0 for the maximum distance t of the carcass line C that is spaced outward from the equilibrium shape curve N.
, A and D are smoothly connected to each other in a compound curve. 3. A pneumatic tire that is mounted on a specified rim, in which the bead base of the rim that engages with the bead part has an angle of about 15° with respect to the tire rotation axis, and is a standard rim or an applicable rim. The profile of the radial carcass in the radial cross section of the tire when mounted on a rim narrower than the standard rim and filled with an internal pressure of 5% of the standard internal pressure under no load is the carcass line from the rim diameter line RL. C
The maximum height of the rim is H, the rim width is the rim width W, the intersection of the carcass line C with the radial tangent mm' at the maximum width position is A, and the rim is moved from the equatorial plane M of the tire to the outside in the axial direction of the tire. The intersections of the carcass line C with the perpendicular line pp' drawn to the rim diameter line RL at a distance of 0.45 times the width are sequentially B and D, and then the equilibrium shape curve N passes through the intersections B and D and touches the radial direction tangent mm'. The contact point E with respect to the tangent line mm' of For the maximum distance s of the carcass line C separating inwardly from the equilibrium shape curve N in the area, the following relationship 3.0<(240/H)×s<9.0 is satisfied for the maximum height H, and Similarly, the point B satisfies the following relationship 1.0<(210/H)×t<5.0 for the maximum distance t of the carcass line C separating inwardly from the equilibrium shape curve N in the upper sidewall region.
, E, and D are smoothly connected to each other in a compound curve. 4. A pneumatic tire that is mounted on a specified rim, in which the bead base of the rim that engages with the bead part has an angle of about 5° with respect to the tire rotation axis, and is a standard rim or an applicable rim. The profile of the radial carcass in the radial cross section of the tire when mounted on a rim narrower than the standard rim and filled with an internal pressure of 5% of the standard internal pressure under no load is the carcass line from the rim diameter line RL. The maximum width position of the carcass line C and a straight line jj' parallel to the axis of rotation of the tire that separates the rim diameter line RL from the rim diameter line RL to the outside in the radial direction by a distance LH corresponding to 0.55 times the maximum height H. The intersection point with the radial direction tangent mm' is I, and the carcass line C with respect to the perpendicular line ll' drawn from the equatorial plane M of the tire to the rim diameter line RL at a distance of 0.5 times the rim width from the tire's axial direction outward. F the intersection points in order
, G, respectively, and the line segment F connecting the intersection F with the intersection I
For the maximum distance v of the carcass line C outside of I and away from it, the following relationship 0<(240/H)×v<3.5 is satisfied with respect to the maximum height H, and the intersection point G
Similarly, the following relationship 4.0<(240/H)×w< 9.5 is satisfied, and further, the distance x between the carcass line C and the tangent line mm' is as follows; and the distance x between the contact point A and the intersection I in the radial direction is as follows: Points F and A that satisfy 15<(240/H)×x<35
The tire according to claim 1, characterized in that it is composed of a compound curve in which G and G are smoothly connected. 5. A pneumatic tire that is mounted on a specified rim, in which the bead base of the rim that engages with the bead part has an angle of approximately 15° with respect to the tire rotation axis, and is a standard rim or an applicable rim. The profile of the radial carcass in the radial cross section of the tire when mounted on a rim narrower than the standard rim and filled with an internal pressure of 5% of the standard internal pressure under no load is the carcass line from the rim diameter line RL. C
At the maximum width position of the carcass line C and a straight line jj' parallel to the axis of rotation of the tire, which is separated from the rim diameter line RL by a distance LH corresponding to 0.55 times the maximum height H from the rim diameter line RL to the outside in the radial direction. The intersection point with the radial direction tangent line mm' is I, and the intersection point of the carcass line C with the perpendicular line ll', which is erected on the rim diameter line RL at a distance of 0.5 times the rim width from the tire's equatorial plane M to the axially outer side of the tire. are defined as F and G in order, and the line segment F connecting the intersection F with the intersection I
For the maximum distance v of the carcass line C outside of I and away from it, the following relationship 0<(210/H)×v<5.0 is satisfied with respect to the maximum height H, and the intersection point G
Similarly, the following relationship 2.0<(210/H)×w< 8.0, and furthermore, the following relationship 6.0<(210/H) x Point F that satisfies <30.0
, A, and G smoothly connect to each other in a compound curve. 6. A pneumatic tire that is mounted on a specified rim, in which the bead base of the rim that engages with the bead part has an angle of approximately 5° with respect to the tire rotation axis, and is a standard rim or an applicable rim. The profile of the radial carcass in the radial cross section of the tire when mounted on a rim narrower than the standard rim and filled with an internal pressure of 5% of the standard internal pressure under no load is the carcass line from the rim diameter line RL. The maximum width position of the carcass line C and a straight line jj' parallel to the axis of rotation of the tire that separates the rim diameter line RL from the rim diameter line RL to the outside in the radial direction by a distance LH corresponding to 0.55 times the maximum height H. The intersection point with the radial direction tangent mm' is I, and a straight line kk' which is in equilibrium with the rim diameter line RL is also separated from the rim diameter line RL by a distance MH corresponding to 0.3 times the maximum height H in the radial direction. R at the point where it intersects with the carcass line C in the lower sidewall area, and further 0.5 of the rim width from the tire's equatorial plane M to the outside in the axial direction of the tire.
The points at which the perpendicular line ll' drawn to the rim diameter line RL intersects with the carcass line C in the upper region of the sidewall are defined as G, and the arc IR passes through point R and touches the tangent line mm' at point I. The maximum distance y of the carcass line C separating inwardly from the carcass line C satisfies the following relationship 6.0<(210/H)×y<11.5 with respect to the maximum height H, and
Similarly, for the maximum distance w of the carcass line C separating outward from the arc GI passing through point G and touching the tangent mm' at point I, the following relationship 4.0<(210/H)×w<9 Furthermore, the following relationship 15<(210/H)×x<35 is satisfied for the distance x of the contact point A between the carcass line C and the tangent line mm' to the outside in the radial direction from the point I. Satisfied, points R, I
The tire according to claim 1, characterized in that it is composed of a compound curve in which G and G are smoothly connected. 7. A pneumatic tire that is mounted on a specified rim, in which the bead base of the rim that engages with the bead part has an angle of approximately 15° with respect to the tire rotation axis, and is a standard rim or an applicable rim. The profile of the radial carcass in the radial cross section of the tire when mounted on a rim narrower than the standard rim and filled with an internal pressure of 5% of the standard internal pressure under no load is the carcass line from the rim diameter line RL. C
At the maximum width position of the carcass line C and a straight line jj' parallel to the axis of rotation of the tire, which is separated from the rim diameter line RL by a distance LH corresponding to 0.55 times the maximum height H from the rim diameter line RL to the outside in the radial direction. The intersection point with the radial direction tangent mm' is I, and a straight line kk' parallel to the rim diameter line RL is on the side, separated by a distance MH corresponding to 0.3 times the maximum height H from the rim diameter line RL in the radial direction. The point where it intersects with the carcass line C in the lower wall area is R, and the rim width is 0.0 mm from the tire's equatorial plane M to the axially outer side of the tire.
The point where the perpendicular line ll' drawn on the rim diameter line RL with a distance of 5 times intersects with the carcass line C in the upper region of the sidewall is defined as G, and the tangent line mm' is passed through point R at point I.
For the maximum distance y of the carcass line C that is separated inwardly from the arc RI that is in contact with Similarly, for the maximum distance w of the carcass line C separating outward from the arc GI passing through G and touching the tangent mm' at point I, the following relationship 2.0<(210/H)×w<8. 0, and furthermore, the following relationship 6.0<(210/H)×x<30 regarding the distance x of the contact point A between the carcass line C and the tangent line mm' to the outside in the radial direction from the point I. The tire according to claim 1, characterized in that the tire is composed of a compound curve that smoothly connects points R, I, and G, satisfying .0. 8. Claim 1, wherein the radially outward bulge g of the tire in the entire region of the crown portion is 0.5 to 4.0 mm.
, 2, 3, 4, 5, 6, and 7. 9. Claims 1, 2, 3, and 4, wherein the bulge in the entire region of the crown portion causes an increase in tension at least at the axial end of the belt having the maximum width among the belt layers.
, 5, 6, or 7. 10. Claims 1 and 2, wherein the tire surface length c of the portion extending between the contact point F and/or the intersection point G in the upper sidewall region is at least 20 mm.
Or the tires described in 3. 11. The radial distance h of the tire measured from the tire maximum width position after filling the area between the above-mentioned contact point F and/or intersection G in the upper sidewall area with the normal internal pressure
However, the tire maximum height SH after filling with the regular internal pressure is 0
．． The tire according to claim 1, 2, 3 or 4, which is 15 times or less. 12. The tire according to claim 1, 2, 3, 4, or 5, wherein the maximum indentation d in the axial direction of the tire in the upper region of the sidewall portion is 0.5 to 4 mm or less. 13. The tire according to claim 1, 2, 3, 4, 5, or 6, wherein the maximum axially outward expansion f of the tire in the lower region of the sidewall is 3 to 12 mm. 14. Sidewall extending between two points: foot n of a perpendicular line drawn down onto the carcass from the maximum width position of the tire after filling with the regular internal pressure, and foot n' of a perpendicular line drawn down onto the carcass from the point where the tire surface touches the rim flange. Claims 1, 2, 3, 4, 5, 6, or 7, wherein the carcass shape of the lower region is a curved line or a straight line with the center of curvature inside the tire when the internal pressure is filled to 5% of the normal internal pressure. tires. 15. Claims 1, 2, 3, wherein the height (HE) of the end of the carcass ply from the bead base after filling with the normal internal pressure is 10 to 35% of the tire maximum height SH.
The tire described in 4, 5, 6, 7 or 8. 16. The radial carcass in the free-standing state of the tire when installed on a standard rim or an applicable rim that is narrower than the standard rim, and filled with an internal pressure of 5% of the officially specified internal pressure, with no load. The shape is from the equatorial plane M of the tire,
An equilibrium shape curve that passes through the intersections B and D of the carcass line C with respect to the perpendicular line pp' set on the rim diameter line RL at a distance of 0.45 times the rim width W outward in the axial direction, and touches the radial tangent line mm' of the carcass line C. In comparison with N, in the upper sidewall area from the point of contact A of the carcass line C with the radial direction tangent mm' to the point of intersection D, the carcass line C has a curvature greater than the curvature of the equilibrium shape curve N and is located on the outside of the tire. The tire according to claim 1, in which the carcass line C is located further inside the tire than the equilibrium shape curve N in the region below the sidewall from the contact point A to the intersection point B.