JP2015202819A - Pneumatic radial tire for heavy load - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance side-cut resistance of a pneumatic radial tire for a heavy load.SOLUTION: In a pneumatic radial tire 10 for a heavy load, a thickness AW1 on the tire mounting outside is set 1.2-3.0 times greater than a thickness AW2 on the tire mounting inside, in a side line part 14A in a position of a side part 14 corresponding to a point D1 on the outermost side in a tire width direction of a carcass body part 18A in the unloaded condition of being assembled to a normal rim and filled with normal internal pressure.

Description

  The present invention relates to a heavy duty pneumatic radial tire.

  In heavy duty pneumatic radial tires, the maximum width of the tire is increased without changing the carcass line and the maximum width position is decorated on the side to eliminate the possibility of side cut resistance deterioration due to protrusions such as stones. The thing transferred to the buttress part from the line is disclosed (refer patent document 1).

  In the above-described conventional example, for the purpose of reducing the deep vertical cut received on the side portion from the tread surface direction, the aim is to verticalize the side-shaped road surface under load, and the reduction effect has been confirmed.

  However, an underground mine vehicle LHD, an underground mine HAULAGE, a heavy loader vehicle, and the like are often overloaded when loaded. When the amount of deflection increases due to overload, the vicinity of the folded end of the carcass ply (the maximum width portion of the carcass main body) protrudes outward in the tire width direction and may have the maximum width. Even if the scratches received in this region are shallow, they may develop by repeated load input and may penetrate into the tire inner surface, so further measures are required.

JP 2011-111003 A

  The present invention has been made in consideration of the above facts, and an object thereof is to improve the side cut resistance in a heavy duty pneumatic radial tire.

  A heavy-duty pneumatic radial tire according to claim 1 includes a pair of bead portions in which bead cores are embedded, side portions that are continuous to the outside in the tire radial direction of the bead portions, and outer ends in the tire radial direction of the respective side portions. A tread portion that connects the portions in the tire width direction, a carcass body portion that straddles between the bead portions and is positioned between the bead cores, and a folded portion that is folded back from the inside in the tire width direction of the bead core. Carcass ply, and when the outermost side in the tire width direction of the carcass main body portion in an unloaded state assembled with a normal rim and filled with a normal internal pressure is defined as D point, the side portion in the tire width direction passing through the D point The thickness is 1.2 times to 3.0 times the tire wearing outer side than the tire wearing inner side.

  The side cut resistance can be improved by increasing the thickness of the tire side part. However, simply increasing the thickness increases the tire mass and material cost, and further increases the tire width. There is a high possibility that the inner wall of the tunnel will be damaged by contact with the inner wall. On the other hand, it has been clarified from experience that the tire side portions are overwhelmed on the outside of the tire.

  Therefore, in the heavy-duty pneumatic radial tire according to claim 1, in the side portion corresponding to the outermost point D in the tire width direction of the carcass main body portion, the thickness outside the tire mounting is 1.2 of the thickness inside the tire mounting. Double to 3.0 times. In general, the point D is a portion that largely bends outward in the tire width direction at the time of load input. However, by making the outer thickness of the tire mounting larger than the inner thickness of the tire mounting, The distortion at the time of a deformation | transformation can be suppressed rather than an inner side. Thereby, the side cut-proof property of the pneumatic radial tire for heavy loads can be improved efficiently.

  If the thickness on the outer side of the tire is less than 1.2 times the thickness on the inner side of the tire, the effect of suppressing the progress of damage is reduced due to the deflection of the tire when the load is input. If the thickness on the outer side of the tire mounting exceeds 3.0 times the thickness on the inner side of the tire mounting, the amount of deflection on the inner side of the tire mounting becomes too large, the tread portion tilts, and it becomes difficult to ensure running stability.

  In the heavy-duty pneumatic radial tire according to claim 2, when the position of the tire outer surface obtained by extending the point D outward in the tire width direction is defined as the point A, the point A on the tire mounting outer side from the tire equatorial plane in the tire width direction. The outer side width that is the distance to the inner side width is 1.05 to 1.15 times the inner side width that is the distance from the tire equatorial plane to the point A inside the tire.

  When the width of the side portion from the tire equator plane is large between the tire wearing outer side (outer side width) and the tire wearing inner side (inner side width), the running stability decreases. Therefore, the outer side width is preferably 1.05 to 1.15 times the inner side width.

  In the heavy-duty pneumatic radial tire according to the third aspect, the tire maximum width position is located on the outer side in the tire radial direction from the point D in a no-load state in which a normal rim is assembled and a normal internal pressure is filled.

  In the heavy duty pneumatic radial tire according to the third aspect, the tire maximum width position is located at a so-called buttress portion on the outer side in the tire radial direction from the point D of the carcass main body portion. In general, since the rubber gauge is thick in the buttress part, the surface distortion at the time of tire deformation is small. By arranging the maximum tire width position in the buttress portion that easily contacts an obstacle on the road surface, the side cut can be prevented from progressing.

  The pneumatic radial tire for heavy loads according to claim 4 is configured such that, in the cross section in the tire width direction, when the maximum tire width position is B point and the tread center of the tread portion is C point, the B point is based on the C point. The distance h1 in the tire radial direction is 0.20SH to 0.40SH with respect to the tire cross-section height SH.

  When the distance h1 is less than 0.20SH, the amount of rubber at the so-called buttress portion of the tire (outside in the tire radial direction from the point D) increases, and the heat generation amount increases. On the other hand, when it exceeds 0.40SH, desired side cut resistance cannot be obtained.

  In the heavy-duty pneumatic radial tire according to claim 5, when the tread end of the tread portion is a T point in the tire width direction cross section, the tire radial direction cross-section with respect to the line segment in the tire radial direction passing through the B point in the tire width direction cross section. The angle α on the acute angle side of the tire outer surface between the point B and the point T is 0 <α ≦ 30 °.

  If the angle α is 30 ° or more, the side cut resistance may not be improved, so it is preferable to set the angle α within the above range.

  The heavy-duty pneumatic radial tire according to claim 6 has the point A1 as the tire wearing outer side of the point A, the point A2 as the tire wearing inner side, the point B1 as the tire wearing outer side of the point B, and the point B2 as the tire wearing inner side. Then, in the cross section in the tire width direction, the angle β1 on the acute angle side of the outer surface of the tire between the point B1 and the point A1 with respect to a line segment in the tire radial direction passing through the point A1 is 0 <β1 ≦ 30 °. In the cross section in the width direction, the angle β2 on the acute angle side of the tire outer surface between the point B2 and the point A2 with respect to a line segment in the tire radial direction passing through the point A2 is 0 ≦ β2 ≦ 30 °, and β1> β2 is there.

  If the angles β1 and β2 exceed 30 °, the amount of rubber in the buttress portion increases, and the amount of heat generated in that region may increase. Therefore, it is preferable to set the angle within the above range.

  As described above, according to the heavy-duty pneumatic radial tire according to claim 1 of the present invention, an excellent effect that the side cut resistance in the heavy-duty pneumatic radial tire can be improved is obtained. .

1 is a sectional view showing a heavy-duty pneumatic radial tire according to an embodiment, cut along a tire axis.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. As shown in FIG. 1, the heavy-duty pneumatic radial tire 10 according to the present embodiment includes a pair of bead parts 12, a side part 14, a tread part 16, and a carcass ply 18. In the drawing, the tire width direction is indicated by an arrow W, and the tire radial direction is indicated by an arrow R. The tire width direction is a direction parallel to the tire axial direction and including the tire axial direction.

  In addition, an arrow IN in the drawing indicates an inner side when the tire is mounted on the vehicle (hereinafter referred to as “tire mounting inner side”), and an arrow OUT indicates an outer side when the tire is mounted (hereinafter referred to as “tire mounting outer side”). Show. In the heavy-duty pneumatic radial tire 10 according to this embodiment, the inner side and the outer side of the tire at the time of mounting on the vehicle are designated. The alternate long and short dash line CL indicates the tire equator plane.

  The pair of bead portions 12 are portions that are fitted into a rim (not shown). A bead core 24 is embedded in each bead portion 12.

  The carcass ply 18 includes a carcass main body portion 18 </ b> A that straddles the bead portions 12 and is positioned between the bead cores 24, and a folded portion 18 </ b> B that is folded outward from the inside in the tire width direction of the bead core 24. For the cord of the carcass ply 18, steel, organic fiber, or the like is used. The outermost position in the tire width direction of 18A of the carcass main body portion in the no-load state assembled with the regular rim and filled with the regular internal pressure is defined as a point D (the point D1 is the outer side of the tire and the point D2 is the inner side of the tire). Point D is the portion that deforms most outward in the tire width direction when a load is applied to the tire. A plurality of belt layers 21 are arranged on the outer peripheral side of the crown region of the carcass ply 18.

  The side portion 14 is connected to the outer side of the bead portion 12 in the tire radial direction, and is attached to the normal rim and filled with the normal internal pressure. In the unloaded state, the tire maximum width position B point (the tire mounting outer side B1 point, the tire mounting inner side (B2 point) is located on the outer side in the tire radial direction from the maximum width position D point of the carcass main body 18A. That is, the tire maximum width position B is located at a so-called buttress portion 38 on the outer side in the tire radial direction from the maximum width position D of the carcass main body portion 18A.

  Here, the position of the side part 14 in the tire width direction corresponding to the point D1 and the point D2 is defined as a side line part 14A. Further, the outer surface of the side line portion 14A on the outer side of the tire is set as A1 point, and the inner surface is set as I1 point. Further, the outer surface of the side line portion 14A on the inner side of the tire is A2, and the inner surface is the point I2. In the side line portion 14A, the tire mounting outer thickness AW1 (distance between A1 and I1) is in the range of 1.2 to 3.0 times the tire mounting inner thickness AW2 (distance between A2 and I2). Is set.

  In addition, in the side line portion 14A, the thickness on the inner side in the tire width direction than the carcass main body portion 18A is the thickness DW1 (the distance between D1 and I1) on the outer side of the tire mounting, and the thickness DW2 on the inner side of the tire mounting (between D2 and I2). The distance is preferably set within a range of 1.2 times to 4.0 times of (distance).

  In the tire width direction cross section, the tire radial direction height h2 of the rim separation point F with respect to the rim base line BL of the bead portion 12 is in the range of 0.20SH to 0.40SH with respect to the tire cross section height SH. Is set.

  In the cross section in the tire width direction, the height h3 in the tire radial direction at the points A1 and A2 with respect to the rim base line BL of the bead portion 12 is within the range of 0.40SH to 0.45SH with respect to the tire cross section height SH. Is set.

  Further, in the tire width direction, the distance (outer side width SW1) from the tire equatorial plane CL to the tire wearing outer outer surface A1 point of the side line portion 14A is the tire wearing inner outer surface A2 point of the side line portion 14A from the tire equatorial plane CL. Is set within a range of 1.05 to 1.15 times the distance (inner side width SW2).

  A step portion 15 is formed on the outer surface of the side portion 14 on the tire mounting outer side. The step portion 15 is a step provided to increase the tire width on the outer side in the tire radial direction, and is located on the inner side in the tire radial direction with respect to the maximum width position D1 of the carcass main body portion 18A. The position of the tire radial direction outer end portion G point of the step portion 15 in the tire width direction is within the range of the outer side width SW1 × (0.9 to 1.0) with respect to the tire equatorial plane CL. Further, the position of the point G in the tire radial direction is in a range of h2 × (0.9 to 1.0) with respect to the rim base line BL. The side portion 14 is convexly curved outward in the tire width direction.

  The tread portion 16 is a portion that connects the outer ends in the tire radial direction of the side portions 14 in the tire width direction. Assuming that the tread center of the tread portion 16 is a C point in the cross section in the tire width direction, the distance h1 in the tire radial direction to the B point with respect to the C point is, for example, 0.20SH to the tire cross section height SH. It is preferably set within the range of 0.40SH. When the distance h1 is less than 0.20SH, the side-cut resistance is improved, but the rubber amount of the buttress portion 38 is excessive, so that the rubber volume is increased and the heat generation amount is increased. On the other hand, if it exceeds 0.40SH, desired side-cut resistance cannot be obtained, so it is preferable to be within the above range.

  Assuming that the end of the tread portion 16 is a tread end T point (T1 point on the outer side of the tire and T2 point on the inner side of the tire), between the points B1 and T1 with respect to the line segment in the tire radial direction in the tire width direction cross section The angle α1 on the acute angle side of the tire outer surface 38B1 is preferably set within a range of 0 <α1 ≦ 30 °, for example. In the cross section in the tire width direction, the angle α2 on the acute angle side of the tire outer surface 38B2 between the point B2 and the point T2 with respect to the line segment in the tire radial direction may be set within a range of 0 <α2 ≦ 30 °, for example. preferable. If the angles α1 and α2 exceed 30 °, the cut damage frequency and the cut depth increase, and the side cut resistance may not be improved. These angles α1 and α2 are ground angles, and are desirably as small as possible.

  In the cross section in the tire width direction, the angle β1 on the acute angle side of the tire outer surface between the points B1 and A1 with respect to the line segment in the tire radial direction passing through the point A1 is set within a range of 0 <β1 ≦ 30 °, for example. It is preferable. In the tire width direction cross section, the angle β2 on the acute angle side of the tire outer surface between the points B2 and A2 with respect to the line segment in the tire radial direction passing through the point A2 is set within a range of 0 <β2 ≦ 30 °, for example. It is preferred that If the angles β1 and β2 exceed 30 °, the amount of rubber in the buttress portion 38 increases, which may increase the amount of heat generated in that region. When a normal load (standard maximum load) is applied to the heavy-duty pneumatic radial tire 10, the road surface and the outer surface of the tire between points B and A (points A1, A2) are formed. It is desirable that the angle be 90 ° or more. Further, even when an overload of, for example, 120 to 130% of the normal load is applied to the heavy-duty pneumatic radial tire 10, the road surface and the distance between the B point and the A point are set so that the vicinity of the A point does not become the maximum width. It is desirable that the angle formed with the outer surface of the tire be 90 ° or more.

  In the present embodiment, “regular rim” refers to, for example, a standard rim in an applicable size defined in the 2014 YEAR BOOK issued by JATMA, and “regular internal pressure” similarly refers to the 2014 edition issued by JATMA. The air pressure for the maximum load at the applicable size and ply rating specified in YEAR BOOK.

  “Grounding end” means pneumatic pressure tire corresponding to the maximum load capacity (bold load in the internal pressure-load capacity correspondence table) for the applicable size and ply rating in JATMA YEAR BOOK with the heavy-duty pneumatic radial tire 10 attached to the regular rim. It is the outermost end portion in the tire width direction in the contact area when the internal pressure of 100% of (maximum air pressure) is filled and the maximum load capacity is applied.

  The “tread width” is a “tread width” defined in JATMA YEAR BOOK.

  When the TRA standard or ETRTO standard is applied at the place of use or manufacturing, the respective standards are followed.

  The two-dot chain line in FIG. 1 indicates the shape of a conventional tire (Patent Document 1). Compared with the conventional tire, in the present embodiment, the outer and inner rubber volumes in the tire width direction are increased in the side portion 14 on the tire mounting outer side (the portion where the hatched portion is increased). In addition, in the side portion 14 on the tire mounting inner side, the rubber volume on the outer side and the inner side in the tire width direction is reduced (the portion where the hatched portion is reduced).

(Function)

  This embodiment is configured as described above, and the operation thereof will be described below. In the heavy-duty pneumatic radial tire 10 according to the present embodiment, in the side line portion 14A, the thickness on the tire mounting outer side is set to 1.2 to 3.0 times the thickness on the tire mounting inner side. In this way, by making the thickness of the side line portion 14A on the tire mounting outer side thicker than the thickness on the tire mounting inner side, distortion of the portion on the tire mounting outer side due to load input can be suppressed. Therefore, the progress of the damage can be suppressed on the outer side of the tire wearing where the damage is often caused, and the side cut resistance can be improved.

  Further, since the thickness on the tire inner side is thinner than that on the tire mounting outer side, the side cut resistance can be improved efficiently without an unnecessary increase in the rubber volume.

  Further, in the present embodiment, the outer side width SW1 is set to 1.05 to 1.15 times the inner side width SW2, so the difference in width from the tire equatorial plane of the side portion is the tire mounting outer side. It is possible to maintain running stability without becoming too large between the tire and the inside of the tire.

  Further, in the present embodiment, the tire maximum width position (point B) that easily contacts an obstacle on the road surface is located on the buttress portion 38 on the outer side in the tire radial direction from the point D of the carcass main body portion. Progress can be effectively suppressed.

  In this embodiment, since the distance h1 in the tire radial direction from the tread center (point C) of the tread portion 16 to the tire maximum width position (point B) is appropriately set, the side cut resistance of the tire can be reduced. It is possible to achieve both suppression of heat generation.

  In the present embodiment, since the angles α1 and α2 are appropriately set, it is difficult to receive a side cut on the bead portion 12 side from the tire maximum width position (point B). For this reason, the side cut resistance of the tire can be improved.

  Furthermore, in the present embodiment, the angle β (β1, β2) on the acute angle side of the tire outer surface between the point B (point B1, point B2) and the point A (point A1, point A2) is appropriately set. The increase in the rubber amount of the buttress portion 38 can be suppressed, and the amount of heat generated by the tire can be suppressed.

  In order to confirm the effect of the present invention, each of the heavy-duty pneumatic radial tires suitable for the underground mine loader shown in Comparative Examples 1 to 4 and Examples 1 to 3 (FIG. 1) of the specifications shown in Table 1 is used. Using 20 pieces each, a test was conducted on the waste product rate by side cut. The tire size is 26.5R25. The relationship between the outer side width SW1 and the inner side width SW2, the ratio of the tire mounting outer thickness AW1 to the tire mounting inner thickness AW2 in the side line portion 14A, (AW1 / AW2), the tire on the inner surface side of the side line portion 14A The ratio of the outer thickness DW1 to the inner tire thickness DW2 (DW1 / DW2), angles α1, α2, and β1, β2 are set as shown in Table 1, and the waste rate by each side cut is obtained. It was. The waste product rate is indicated by an index. When the index of Comparative Example 1 is 100, the lower the index, the lower the waste product rate due to side cuts. Further, the running stability of each heavy load pneumatic radial tire was determined. The running stability is also indicated by an index. The index of Comparative Example 1 is set to 100, and the higher the index, the higher the running stability.

  As Table 1 shows, the waste product rate of Examples 1-3 was smaller than Comparative Examples 1-3, and it was a favorable result. When the side gauge ratio AW1 / AW2 is less than 1.2, as shown in Comparative Example 3, the side cut has a small effect of reducing the waste product rate, and when the side gauge ratio AW1 / AW2 exceeds 3.0, the comparison is made. As shown in Example 4, it can be seen that the running stability is greatly reduced. In Examples 1-3, it turns out that the waste product rate can be reduced significantly, maintaining driving stability by comparison with a comparative example.

DESCRIPTION OF SYMBOLS 10 Heavy load pneumatic radial tire 12 Bead part 14 Side part 14A Side line part 16 Tread part 18 Carcass ply 18A Carcass main body part 18B Turn-up part B1, B2 Tire maximum width position CL Tire equatorial plane D Tire width direction of carcass main body part Outermost AW1 Tire wearing outer thickness AW2 Tire wearing inner thickness SW1 Outside side width SW2 Inside side width α1 Angle α2 Angle β1 Angle β2 Angle

Claims (6)

A pair of bead portions with embedded bead cores;
Side portions that respectively continue to the outside in the tire radial direction of the bead portion,
A tread portion that connects tire radial direction outer end portions of each side portion in the tire width direction; and
A carcass ply having a carcass main body portion that straddles between the bead portions and is located between the bead cores, and a folded portion that is folded back from the inside in the tire width direction of the bead core;
With
When the outermost side in the tire width direction of the carcass main body portion in a no-load state assembled with a normal rim and filled with a normal internal pressure is defined as D point, the thickness in the tire width direction of the side portion passing through the D point is the tire mounting outer side. Is a pneumatic radial tire for heavy loads, which is 1.2 to 3.0 times the inside of the tire.   Assuming that the position of the outer surface of the tire extending from the point D outward in the tire width direction is the point A, the outer side width, which is the distance from the tire equatorial plane to the point A outside the tire mounting in the tire width direction, is the tire equatorial plane. 2. The heavy-duty pneumatic radial tire according to claim 1, which is 1.05 to 1.15 times an inner side width which is a distance from a point A to a point A inside the tire.   3. The heavy-duty pneumatic radial according to claim 1, wherein a tire maximum width position is located on the outer side in the tire radial direction from the point D in a no-load state in which a normal rim is assembled and a normal internal pressure is filled. tire. In the tire width direction cross section, assuming that the tire maximum width position is point B, and the tread center of the tread portion is point C,
The heavy-duty pneumatic radial tire according to claim 3, wherein a distance h1 in the tire radial direction from the point C to the point B is 0.20SH to 0.40SH with respect to the tire cross-section height SH. In the tire width direction cross section, when the tread end of the tread portion is a T point,
The heavy-duty load according to claim 4, wherein an angle α on the acute angle side of the tire outer surface between the point B and the point T with respect to a line segment in the tire radial direction passing through the point B is 0 <α ≦ 30 °. Pneumatic radial tire. The point A1 is the outer side of the tire wearing point A, the point A2 is the inner side of the tire, the point B1 is the outer side of the tire, and the point B2 is the inner side of the tire.
In the cross section in the tire width direction, an angle β1 on the acute angle side of the tire outer surface between the point B1 and the point A1 with respect to a line segment in the tire radial direction passing through the point A1 is 0 <β1 ≦ 30 °.
In the cross section in the tire width direction, an angle β2 on the acute angle side of the tire outer surface between the point B2 and the point A2 with respect to a line segment in the tire radial direction passing through the point A2 is 0 ≦ β2 ≦ 30 °,
The heavy-duty pneumatic radial tire according to claim 4 or 5, wherein β1> β2.

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