WO2016051685A1 - Pneumatic tire for heavy loads - Google Patents

Pneumatic tire for heavy loads Download PDF

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Publication number
WO2016051685A1
WO2016051685A1 PCT/JP2015/004594 JP2015004594W WO2016051685A1 WO 2016051685 A1 WO2016051685 A1 WO 2016051685A1 JP 2015004594 W JP2015004594 W JP 2015004594W WO 2016051685 A1 WO2016051685 A1 WO 2016051685A1
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Prior art keywords
tire
belt
belt layer
width direction
tire width
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PCT/JP2015/004594
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French (fr)
Japanese (ja)
Inventor
高史 大野
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株式会社ブリヂストン
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Publication of WO2016051685A1 publication Critical patent/WO2016051685A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
    • B60C9/02—Carcasses
    • B60C9/04—Carcasses the reinforcing cords of each carcass ply arranged in a substantially parallel relationship
    • B60C9/08—Carcasses the reinforcing cords of each carcass ply arranged in a substantially parallel relationship the cords extend transversely from bead to bead, i.e. radial ply
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
    • B60C9/02—Carcasses
    • B60C9/0292—Carcass ply curvature
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
    • B60C9/18—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
    • B60C9/18—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers
    • B60C9/20—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel

Definitions

  • the present invention relates to a heavy-duty pneumatic tire, and more particularly to a heavy-duty pneumatic tire with improved uneven wear resistance without reducing durability.
  • Patent Document 1 In heavy-duty pneumatic tires with heavy loads such as those used in heavy vehicles such as buses and trucks, uneven wear tends to occur in the shoulder portion of the tire tread.
  • Various techniques for improving uneven wear resistance by improving uneven wear generated in the shoulder portion have been proposed (for example, Patent Document 1).
  • the uneven wear generated in the shoulder portion of the tread portion may not be sufficiently reduced or the uneven wear resistance is improved. Even if it is possible, there are cases where it is difficult to achieve a balance between uneven wear resistance and other performances, such as a decrease in durability due to separation of the belt end portion, for example.
  • an object of the present invention is to provide a heavy duty pneumatic tire capable of improving uneven wear resistance without reducing durability.
  • a heavy-duty pneumatic tire according to the present invention is a belt ply including a carcass and a belt layer disposed at a tread portion on the outer side in the tire radial direction of the carcass and including a belt cord extending along a tire circumferential direction.
  • a heavy-duty pneumatic tire having no circumferential belt layer, wherein the belt layer is formed by laminating a pair of belt plies, and the belt cords of the belt plies are connected to the tire equator.
  • the angle theta 1 with respect to the tire equatorial plane, and, the belt cords of the belt plies constituting the angled belt layer, with respect to the tire equatorial plane The degree ⁇ 2, 10 ° ⁇ 1 ⁇ 25 ° and 15 ° ⁇ 2 ⁇ 1 ⁇ 25 °
  • the shape of the carcass in the cross section in the tire width direction has two different curvature radii having a center of curvature on the tire lumen side from the outermost position in the tire radial direction to the outermost position in the tire width direction of the carcass.
  • the “range where the belt plies of the crossing belt layers overlap” refers to a range where the belt plies of the crossing belt layers overlap in the tire radial direction.
  • the curvature radii R 1 and R 2 are R 1 / R 2 ⁇ 9.5 It is preferable that According to this, since the amount of radial growth in the tire radial direction in the vicinity of the shoulder portion of the carcass can be further reduced, it is possible to more reliably suppress a decrease in tire durability.
  • the angle and dimensions for example, the angle of the belt cord of the belt layer with respect to the tire equatorial plane, the distance from the tire equatorial plane in the overlapping range, etc., unless otherwise specified, are applied to the tire assembled on the applicable rim. It refers to the angle and dimensions in a no-load state filled with a specified air pressure.
  • “applicable rim” is an industrial standard that is effective in the area where tires are produced and used. In Japan, JATMA (Japan Automobile Tire Association) YEAR BOOK is used, and in Europe, ETRTO (European Tire and Rim Technical Organization) is used.
  • STANDARDDS MANUAL in the United States, refers to standard rims (or “Applied Rim” or “Recommended Rim”) in applicable sizes, as described in TRA (The Tire and Rim Association, Inc.) YEAR BOOK, etc.
  • the state that “the tire mounted on the applicable rim is filled with the prescribed air pressure” means that the tire is mounted on the applicable rim and the maximum size of the single wheel in the applicable size / ply rating described in JATMA, etc.
  • the air pressure maximum air pressure
  • the air can be replaced with an inert gas such as nitrogen gas or the like.
  • a space rubber disposed between tire width direction ends of the pair of belt plies constituting the crossing belt layer, a carcass tire outer side in the tire radial direction, A cushion rubber disposed on the inner side in the tire radial direction of the end portion in the tire width direction of the belt layer, and a tread rubber disposed on the outer side in the tire radial direction of the belt layer at the tread portion and forming a tread surface.
  • “elastic modulus” refers to “100% modulus”
  • “100% modulus” refers to a JIS dumbbell-shaped No. 3 sample prepared, at a temperature of 30 ° C. in accordance with JIS K6251. The tensile stress at 100% elongation measured by performing a tensile test under the condition of speed 500 ⁇ 25 mm / min.
  • FIG. 2 is a development view showing a belt layer of a tread portion of the heavy duty pneumatic tire of FIG. 1 together with a carcass.
  • FIG. 1 is a tire width direction showing a tread portion (half portion) periphery of a heavy-duty pneumatic tire (hereinafter also referred to as a tire) according to the present invention in a no-load state in which a tire mounted on an applicable rim is filled with a prescribed air pressure.
  • FIG. 1 is a tire width direction showing a tread portion (half portion) periphery of a heavy-duty pneumatic tire (hereinafter also referred to as a tire) according to the present invention in a no-load state in which a tire mounted on an applicable rim is filled with a prescribed air pressure.
  • the heavy-duty pneumatic tire 1 shown in FIG. 1 is a tire to be mounted on a bus or a truck, and a part of the pneumatic tire 1 is omitted, but a tread portion 2 and a pair of sides connected to both sides of the tread portion 2. A wall portion and a bead portion (not shown) connected to each sidewall portion are provided. Furthermore, the heavy-duty pneumatic tire 1 has a carcass 3 extending in a toroidal shape between a bead core embedded in each bead portion over the tread portion 2, the sidewall portion, and the bead portion. Although the carcass 3 shown in FIG. 1 is composed of one ply, in the tire 1 of the present invention, the number of plies can be changed to two or more if necessary.
  • a tread rubber 21 that forms a tread surface is disposed on the outer side in the tire radial direction of the carcass 3 of the tread portion 2 and more specifically on the outer side in the tire radial direction of the belt layer 4 described later.
  • a circumferential groove 22 extending in the tire circumferential direction is formed on the tread surface.
  • the circumferential groove 22 is shown, but a width direction groove or the like extending in the tire width direction can also be formed, and any tread pattern, for example, a rib-like pattern or a block-like pattern can be used. be able to.
  • a belt layer 4 is provided.
  • the tire 1 of this embodiment does not have the circumferential belt layer comprised by the belt ply which consists of a belt cord extended along a tire circumferential direction.
  • “extending along the tire circumferential direction” means that the angle ⁇ is substantially 0 ° with respect to the tire equator plane E and is slightly inclined with respect to the tire equator plane E (for example, within 5 °). Means allowed.
  • the belt layer 4 is configured by laminating a pair of belt plies 4a, and a cross belt layer 41 in which the belt cords of the belt plies 4a intersect each other across the tire equatorial plane E.
  • the belt cords of the respective belt plies 4a constituting the crossing belt layer 41 have an angle ⁇ 1 with respect to the tire equatorial plane E and are arranged substantially symmetrically. In addition, as long as it cross
  • the angled belt layer 42 made up of one belt ply 4a and the cross belt layer 41 made up of a pair of belt plies 4a from the inside in the tire radial direction to the outside in the tire radial direction.
  • the layers are stacked in order, the stacking order can be arbitrarily changed.
  • the tension of the belt layer arranged in the tread portion becomes the largest in the center portion of the tread portion when the tire rolls, and the tire portion extends toward the shoulder portion on the outer side in the tire width direction of the tread portion. Since the contact pressure on the road surface of the shoulder portion decreases and the tire rolls and kicks the road surface, the shoulder portion may slide against the road surface, resulting in uneven wear on the shoulder portion. It was. Therefore, the heavy duty pneumatic tire 1 of the present invention includes the belt layer 4 having the crossing belt layer 41 and the angled belt layer 42, and does not have the circumferential belt layer, and each of the crossing belt layers 41 constituting the crossing belt layer 41.
  • the angle ⁇ 1 of the belt cord of the belt ply 4a with respect to the tire equatorial plane E, and the angle ⁇ 2 of the belt cord of the belt ply 4a constituting the angled belt layer 42 with respect to the tire equatorial plane E 10 ° ⁇ 1 ⁇ 25 ° and 15 ° ⁇ 2 ⁇ 1 ⁇ 25 ° It is said.
  • the tension of the belt layer 4 at the shoulder portion is compared with the tension of the belt layer 4 at the center portion when the tire rolls. Therefore, the tension of the belt layer 4 at the shoulder portion can be improved when the tire rolls.
  • the tension of the belt layer 4 at the center portion becomes insufficient.
  • the angled belt layer 42 is formed on the shoulder portion of the belt layer 4 when rolling the tire.
  • the tension of the belt layer 4 at the center portion can be supplemented without reducing the tension. Therefore, in the belt width direction, the tension of the belt layer 4 as a whole increases from the center portion to the shoulder portion, or the tension of the belt layer 4 becomes uniform in the tire width direction. As a result, the contact pressure on the road surface of the center portion is increased. While ensuring, the contact pressure to the road surface of a shoulder part increases, and uneven wear resistance can be improved.
  • the tension of the belt layer 4 at the center portion is greatly reduced during tire rolling, and there is a possibility that uneven wear at the center portion may occur. If the angle ⁇ 1 of the crossing belt layer 41 is 25 ° or more, the tension of the belt layer 4 at the shoulder portion during rolling of the tire does not increase to the extent that it contributes to the improvement in uneven wear resistance. Further, when ⁇ 2 ⁇ 1 ⁇ 15 ° in relation to the angles ⁇ 1 and ⁇ 2 , the tension of the belt layer 4 at the center portion is greatly reduced during tire rolling, and 25 ° ⁇ ⁇ 2 ⁇ 1. In this case, although the tension of the belt layer 4 at the center portion is improved, the tension of the belt layer 4 at the shoulder portion that is increased when the angle ⁇ 1 of the crossing belt layer 41 is within the above range is lowered.
  • 14 ° ⁇ 1 ⁇ 20 ° and 15 ° ⁇ 2 ⁇ 1 ⁇ 20 ° are more preferable from the viewpoint of improving both the partial wear resistance and the tire durability described later.
  • the angle ⁇ 2 is 35 ° or less, as will be described later, even if the radius of curvature R 1 is larger than R 2 and the distance Di is close to the distance D, the outer end of the belt layer 4 in the tire width direction is There is a tendency that the diameter growth amount tends to be large, and there is a possibility that the possibility of occurrence of separation at the outer end of the belt layer 4 in the tire width direction is increased. Further, if the angle ⁇ 2 is 50 ° or more, the compression input to the angled belt layer 42 tends to increase, and the possibility that the belt cord is damaged may increase.
  • the shape of the carcass 3 in the tire width direction cross section extends from the outermost position in the tire radial direction of the carcass 3 to the outermost position in the tire width direction.
  • Up to two arcs having different radii of curvature and having a center of curvature on the tire lumen side are formed.
  • the radius of curvature of the inner arc located inside the tire width direction is R 1
  • the radius of curvature of the outer arc located outside the tire width direction is R 2.
  • the tire on the other side passes from the outermost position in the tire radial direction to the outermost position in the tire radial direction.
  • the shape of the carcass 3 up to the outermost position in the width direction is 3 of the inner arc of the radius of curvature R 1 including the outermost position in the tire radial direction of the carcass 3 and the outer arc of both the radii of curvature R 2 on the outer side in the tire width direction. It is formed by connecting two arcs.
  • the curvature radii R 1 and R 2 described later is satisfied, the curvature radii of the respective outer arcs on the outer side in the tire width direction can be different from each other.
  • the radii of curvature R 1 and R 2 of the inner arc and the outer arc are set to R 1 > R 2 , and the tire extends from the tire equatorial plane E to the intersection I of the arcs.
  • the distance Di measured along the width direction is set to 80% or more of the distance D measured along the tire width direction from the tire equatorial plane E in a range where the belt plies 4a of the crossing belt layers 41 overlap.
  • the distance Di is set to 80% or more with respect to the distance D, the diameter growth amount at the outer end in the tire width direction of the belt layer 4 can be reduced, and the distortion in the tread rubber 21 can be sufficiently suppressed. In addition, it is possible to prevent the separation of the belt layer 4 at the outer end in the tire width direction, and hence the durability.
  • the heavy-duty pneumatic tire 1 of the present invention the radius of curvature R 1, R 2, it is preferable that R 1 / R 2 ⁇ 9.5. According to this, at the time of tire internal pressure filling, the amount of radial growth at the outer end in the tire width direction of the belt layer 4 toward the outer side in the tire radial direction is further reduced, so that the distortion of the tread rubber 21 can be more sufficiently suppressed. In addition, it is possible to more effectively prevent the separation of the belt layer 4 at the outer end in the tire width direction, and thus the durability.
  • the upper limit of the distance Di is not limited because it is possible to prevent a decrease in durability by setting it to 80% or more of the distance D, but from the viewpoint of manufacturing, the upper limit of the distance D 105% (that is, 80% ⁇ Di / D ⁇ 100 ⁇ 105%) is preferable.
  • the crossing belt layer 41 is formed so that the width of the belt ply 4a on the inner side in the tire radial direction is larger than the width of the belt ply 4a on the outer side in the tire radial direction, as shown in FIGS. It is also possible to reverse the magnitude relation of the widths or make them the same. However, it is preferable that the outer end in the tire width direction of each belt ply 4a is not the same position in the tire width direction. When the outer end in the tire width direction of each belt ply 4a is the same position in the position in the tire width direction, separation is likely to occur near the outer end.
  • the space rubber 5 can be disposed between the ends in the tire width direction of the pair of belt plies 4a constituting the crossing belt layer 41.
  • the inner end in the tire width direction of the space rubber 5 is between the pair of belt plies 4a of the crossing belt layer 41, and the tire of the narrow belt ply 4a of the pair of belt plies 4a. It is located on the inner side in the tire width direction than the outer end in the width direction.
  • the outer end in the tire width direction of the space rubber 5 is located on the outer side in the tire width direction of the pair of belt plies 4a, for example, than the outer end in the tire width direction of the wide belt ply 4a.
  • the space rubber 5 can have a trapezoidal cross section as shown in the figure, but can also be a sheet.
  • the cushion rubber 6 can be disposed on the outer side in the tire radial direction of the carcass 3 and on the inner side in the tire radial direction of the end portion in the tire width direction of the belt layer 4.
  • the inner end in the tire width direction of the cushion rubber 6 is located on the inner side in the tire width direction than the outer end in the tire width direction of the widest belt ply 4a in the belt layer 4, and in the illustrated example, an angle is provided.
  • the belt layer 42 is located on the inner side in the tire width direction from the outer end in the tire width direction.
  • the outer end in the tire width direction of the cushion rubber 6 is located on the outer side in the tire width direction from the outer end in the tire width direction of the belt layer 4 as illustrated.
  • the illustrated cushion rubber 6 is disposed so as to be sandwiched between the carcass 3 and the belt layer 4.
  • the elastic modulus E1 of the space rubber 5 and the elastic modulus E2 of the cushion rubber 6 are preferably 0.3 ⁇ E1 / E2 ⁇ 0.5. According to this configuration, the rolling resistance of the tire 1 can be reduced.
  • the angle ⁇ 1 and the angled belt layer ⁇ 2 of the crossing belt layer 41 are set within a predetermined range, the radii of curvature R 1 and R 2 are set to R 1 > R 2 , and the distance Di is set to the distance D If it is 80% or more, the tension of the belt layer 4, particularly the tension of the belt layer 4 when the tire 1 is reduced in flatness, increases, so that the belt layer 4 functions as a rigid ring.
  • the elastic modulus E1 of the space rubber 5, the elastic modulus E2 of the cushion rubber 6, and the elastic modulus E3 of the tread rubber 21 are 1.5 to 8.0 MPa, 1.5 to 8.0 MPa, 1.0 to It is preferably 5.0 MPa.
  • an auxiliary belt layer 43 having a width smaller than that of the belt layer 4 can be disposed on the tread portion 2 on the outer side in the tire radial direction of the belt layer 4. Even if the tire 1 gets over a stone or the like existing on the road surface, the tread portion 2 can be prevented from being damaged, and the durability of the tire 1 can be improved.
  • the auxiliary belt layer 43 is composed of a single belt ply 4 a, the width of which is substantially half of the angled belt layer 42, and the auxiliary belt cord has an angle ⁇ of the crossing belt layer 41.
  • the number of belt plies 4 a of the auxiliary belt layer 43, the width, the angle of the auxiliary belt cord, and the like are substantially zero with respect to the tire equatorial plane E. It can be changed arbitrarily unless it is °.
  • the heavy duty pneumatic tire 1 of the present invention preferably has a flatness ratio of 60 to 100%.
  • the tension applied to the belt layer during rolling of the tire tends to be larger than that of a tire with a flatness ratio of 60% to 100%, which places a burden on the angled belt layer. Therefore, it is more preferable to apply the configuration of the present invention to a tire with a flatness ratio of 60 to 100%.
  • the shape of the carcass in the cross section in the tire width direction is the tension in the carcass in a no-load state in which the tire 1 assembled to the applicable rim is filled with a prescribed air pressure. -Refers to the neutral axis of compression.
  • the tire of Example 1 has a size of 295 / 75R22.5, and the radii of curvature R 1 and R 2 of the two arcs forming the carcass shape as shown in FIGS. 1 and 2 are R 1 > R 2. Further, each dimension of the tire is constituted by specifications shown in Table 1.
  • the tire of Example 1 has a tread surface width of 117 mm, an overlapping belt layer overlapping range width of 95 mm, an angled belt layer composed of a single belt ply, and an angled belt layer. The width is 95 mm and the flatness is 75%.
  • Example 1 is provided with an auxiliary belt layer having a width of 34 mm and an angle of 72 ° with respect to the tire equatorial plane, which is composed of one belt ply.
  • the tires of Examples 2 to 8 and Comparative Example 1 have the same configuration as that of Example Tire 1 except that the configurations are changed according to the specifications shown in Table 1.
  • Each of the above test tires was subjected to the following initial to medium-term uneven wear resistance test, medium to end-stage uneven wear resistance test, durability test, and rolling resistance test, and the results are shown in Table 1.
  • each of the above test tires was mounted on a rim having a size of 8.25 ⁇ 22.5, and an air pressure of 690 kPa was applied inside.
  • the test tire was attached to an indoor drum tester, loaded with a load of 30 kN, and traveled a distance of 10,000 km at a speed of 60 km / h.
  • working was measured.
  • the lengths of the respective test tires are reciprocal, and are represented by an index with the separation length of the tire of Comparative Example 1 being 100, which is shown in Table 1.
  • a larger index means a shorter separation length and better durability.
  • Rolling resistance performance For rolling resistance performance, each of the above test tires was mounted on a rim having a size of 8.25 ⁇ 22.5, and an air pressure of 690 kPa was applied inside. The test tire was attached to an indoor drum testing machine having a steel plate surface having a diameter of 1.7 m, and a rolling resistance force (rolling resistance value) when running at a speed of 80 km / h under a load of 30 kN was measured. .
  • the rolling resistance value of the tire of Comparative Example 1 is represented by an index with 100 as shown in Table 1. The smaller the index, the smaller the rolling resistance and the better the rolling resistance performance.
  • An improvement of 2% or more is regarded as a significant difference from the viewpoint of market superiority while excluding errors. In particular, when an effect of 5% or more is seen, it can be said that it is a great effect.
  • the tires of Examples 1 to 8 satisfy 10 ° ⁇ 1 ⁇ 25 ° and 15 ° ⁇ 2 ⁇ 1 ⁇ 25 °, and the intersection distance Di / overlap compared to the tire of Comparative Example 1. It can be seen that the uneven wear resistance and durability are improved since the distance D in the range to be applied is 80% or more. Further, it can be seen that the rolling resistance of the tires of Examples 1 to 5 is reduced as compared with the tires of Examples 6 and 8.

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  • Mechanical Engineering (AREA)
  • Tires In General (AREA)

Abstract

The purpose of the present invention is to provide a pneumatic tire for heavy loads such that irregular wear resistance can be increased without decreasing durability. This pneumatic tire for heavy loads is characterized in that: there is no circumferential belt layer; a belt layer comprises an intersecting belt layer configured such that a pair of belt plies are stacked on each other and an angled belt layer including one or more belt plies; the angles (θ1) of belt cords in the intersecting belt layer and the angles (θ2) of belt cords in the angled belt layer are set to 10° < θ1 < 25° and 15° < θ2 - θ1 < 25°; the shape of the carcass is formed by linking two arcs with different radii of curvature; the radii of curvature (R1, R2) have a relationship wherein R1 > R2, where R1 is the radius of curvature of the inside arc on the inner side in a tire width direction and R2 is the radius of curvature of the outside arc on the outer side in the tire width direction; and the distance measured along the tire width direction from the tire equatorial plane to the point of intersection between the inside arc and the outside arc is larger than or equal to 80% of the distance measured in the same manner for the region where the belt plies of the intersecting belt layer overlap one another.

Description

重荷重用空気入りタイヤHeavy duty pneumatic tire
　本発明は、重荷重用空気入りタイヤに関し、特には、耐久性を低下させることなく、耐偏摩耗性を向上させた重荷重用空気入りタイヤに関する。 The present invention relates to a heavy-duty pneumatic tire, and more particularly to a heavy-duty pneumatic tire with improved uneven wear resistance without reducing durability.
　バスやトラック等の重車両に使用されるなど負荷荷重の大きい重荷重用空気入りタイヤでは、偏摩耗が、タイヤのトレッド部のショルダー部分に生じる傾向が有る。そして、そのショルダー部分に生じる偏摩耗を改善させて耐偏摩耗性を向上させるための技術が種々提案されている（例えば、特許文献１）。 In heavy-duty pneumatic tires with heavy loads such as those used in heavy vehicles such as buses and trucks, uneven wear tends to occur in the shoulder portion of the tire tread. Various techniques for improving uneven wear resistance by improving uneven wear generated in the shoulder portion have been proposed (for example, Patent Document 1).
特開２００９－１８６２９号公報JP 2009-18629 A
　ところで、上述のような従来の技術に基づく重荷重用空気入りタイヤでは、トレッド部のショルダー部分に生じる偏摩耗をまだ十分に低減することができないことがあったり、あるいは、耐偏摩耗性を向上させることができても、他の性能、例えばベルト端部のセパレーションに起因して耐久性などが低下するなど、耐偏摩耗性および他の性能との両立が困難なことがあったりした。 By the way, in the heavy-duty pneumatic tire based on the conventional technology as described above, the uneven wear generated in the shoulder portion of the tread portion may not be sufficiently reduced or the uneven wear resistance is improved. Even if it is possible, there are cases where it is difficult to achieve a balance between uneven wear resistance and other performances, such as a decrease in durability due to separation of the belt end portion, for example.
　そこで、本発明は、耐久性を低下させることなく、耐偏摩耗性を向上させることが可能な重荷重用空気入りタイヤを提供することを目的とする。 Therefore, an object of the present invention is to provide a heavy duty pneumatic tire capable of improving uneven wear resistance without reducing durability.
　本発明の重荷重用空気入りタイヤは、カーカスと、トレッド部で、該カーカスのタイヤ径方向外側に配設されるベルト層と、を備え、タイヤ周方向に沿って延びるベルトコードからなるベルトプライで構成される周方向ベルト層を有しない重荷重用空気入りタイヤであって、前記ベルト層は、１対のベルトプライをそれぞれ積層して構成されるとともに、それぞれの該ベルトプライのベルトコードをタイヤ赤道面を挟んで相互に交差させた交錯ベルト層と、１枚以上のベルトプライで構成される角度付きベルト層とを有し、前記交錯ベルト層を構成するそれぞれの前記ベルトプライの前記ベルトコードの、タイヤ赤道面に対する角度θ1、および、前記角度付きベルト層を構成する前記ベルトプライのベルトコードの、タイヤ赤道面に対する角度θ2を、
１０°＜θ1＜２５°かつ１５°＜θ2－θ1＜２５°
とし、タイヤ幅方向断面における前記カーカスの形状を、該カーカスのタイヤ径方向最外側位置からタイヤ幅方向最外側位置に至るまで、タイヤ内腔側に曲率中心を有する、曲率半径の互いに異なる２つの円弧をつないで形成し、前記２つの円弧のうち、タイヤ幅方向内側に位置する内側円弧、および、タイヤ幅方向外側に位置する外側円弧の曲率半径のそれぞれを、Ｒ1、Ｒ2としたとき、前記曲率半径Ｒ1、Ｒ2を、
Ｒ1＞Ｒ2
とし、タイヤ赤道面から前記内側円弧および前記外側円弧の交点までをタイヤ幅方向に沿って測った距離は、交錯ベルト層の各ベルトプライが重複する範囲をタイヤ赤道面からタイヤ幅方向に沿って測った距離の８０％以上であることを特徴とする。
　この発明の重荷重用空気入りタイヤによれば、耐偏摩耗性を向上させつつ、ベルト層のタイヤ幅方向外端でのセパレーションの防止ひいては耐久性の低下の防止が可能となる。
　なお、本発明において、「交錯ベルト層の各ベルトプライが重複する範囲（以下、「重複範囲」ともいう）」とは、交錯ベルト層の各ベルトプライがタイヤ径方向視において重なり合う範囲を指す。 A heavy-duty pneumatic tire according to the present invention is a belt ply including a carcass and a belt layer disposed at a tread portion on the outer side in the tire radial direction of the carcass and including a belt cord extending along a tire circumferential direction. A heavy-duty pneumatic tire having no circumferential belt layer, wherein the belt layer is formed by laminating a pair of belt plies, and the belt cords of the belt plies are connected to the tire equator. The belt cords of the belt plies of the belt plies constituting the crossing belt layer, each having a crossing belt layer crossing each other across the surface and an angled belt layer composed of one or more belt plies. , the angle theta 1 with respect to the tire equatorial plane, and, the belt cords of the belt plies constituting the angled belt layer, with respect to the tire equatorial plane The degree θ 2,
10 ° <θ 1 <25 ° and 15 ° <θ 2 −θ 1 <25 °
And the shape of the carcass in the cross section in the tire width direction has two different curvature radii having a center of curvature on the tire lumen side from the outermost position in the tire radial direction to the outermost position in the tire width direction of the carcass. When arcs are connected and the curvature radii of the inner arc located on the inner side in the tire width direction and the outer arc located on the outer side in the tire width direction are R 1 and R 2 , respectively. , Radius of curvature R 1 , R 2 ,
R 1 > R 2
The distance measured along the tire width direction from the tire equator plane to the intersection of the inner arc and the outer arc is a range where each belt ply of the crossing belt layer overlaps along the tire width direction from the tire equator plane. It is characterized by being 80% or more of the measured distance.
According to the heavy-duty pneumatic tire of the present invention, it is possible to prevent separation at the outer end in the tire width direction of the belt layer and thus to reduce durability while improving uneven wear resistance.
In the present invention, the “range where the belt plies of the crossing belt layers overlap (hereinafter also referred to as“ overlap range ”)” refers to a range where the belt plies of the crossing belt layers overlap in the tire radial direction.
　ここで、本発明の重荷重用空気入りタイヤでは、前記曲率半径Ｒ1、Ｒ2を、
Ｒ1／Ｒ2≧９．５
とすることが好ましい。これによれば、カーカスのショルダー部分付近でのタイヤ径方向への径成長量をさらに低減することができるので、タイヤの耐久性の低下をより確実に抑制することができる。 Here, in the heavy duty pneumatic tire of the present invention, the curvature radii R 1 and R 2 are
R 1 / R 2 ≧ 9.5
It is preferable that According to this, since the amount of radial growth in the tire radial direction in the vicinity of the shoulder portion of the carcass can be further reduced, it is possible to more reliably suppress a decrease in tire durability.
　なお、本発明において、角度および諸寸法、例えば、ベルト層のベルトコードのタイヤ赤道面に対する角度、重複範囲のタイヤ赤道面からの距離等は、特に断りのない限り、適用リムに組み付けたタイヤに規定の空気圧を充填した無負荷状態での角度および諸寸法を指す。ちなみに、「適用リム」とは、タイヤが生産され、使用される地域に有効な産業規格であって、日本ではＪＡＴＭＡ（日本自動車タイヤ協会）ＹＥＡＲ　ＢＯＯＫ、欧州ではＥＴＲＴＯ（Ｅｕｒｏｐｅａｎ　Ｔｙｒｅ　ａｎｄ　Ｒｉｍ　Ｔｅｃｈｎｉｃａｌ　Ｏｒｇａｎｉｓａｔｉｏｎ）　ＳＴＡＮＤＡＲＤＳ　ＭＡＮＵＡＬ、米国ではＴＲＡ（Ｔｈｅ　Ｔｉｒｅ　ａｎｄ　Ｒｉｍ　Ａｓｓｏｃｉａｔｉｏｎ，Ｉｎｃ．）ＹＥＡＲ　ＢＯＯＫ等に記載されている、適用サイズにおける標準リム（または、“Ａｐｐｒｏｖｅｄ　Ｒｉｍ”、“Ｒｅｃｏｍｍｅｎｄｅｄ　Ｒｉｍ”）を指す。また、「適用リムに組み付けたタイヤに規定の空気圧を充填し」た状態とは、タイヤを上記の適用リムに装着し、ＪＡＴＭＡ等に記載されている、適用サイズ・プライレーティングにおける単輪の最大負荷能力に対応する空気圧（最高空気圧）とした状態を指す。なお、ここでいう空気は、窒素ガス等の不活性ガスその他に置換することも可能である。 In the present invention, the angle and dimensions, for example, the angle of the belt cord of the belt layer with respect to the tire equatorial plane, the distance from the tire equatorial plane in the overlapping range, etc., unless otherwise specified, are applied to the tire assembled on the applicable rim. It refers to the angle and dimensions in a no-load state filled with a specified air pressure. By the way, “applicable rim” is an industrial standard that is effective in the area where tires are produced and used. In Japan, JATMA (Japan Automobile Tire Association) YEAR BOOK is used, and in Europe, ETRTO (European Tire and Rim Technical Organization) is used. STANDARDDS MANUAL, in the United States, refers to standard rims (or “Applied Rim” or “Recommended Rim”) in applicable sizes, as described in TRA (The Tire and Rim Association, Inc.) YEAR BOOK, etc. In addition, the state that “the tire mounted on the applicable rim is filled with the prescribed air pressure” means that the tire is mounted on the applicable rim and the maximum size of the single wheel in the applicable size / ply rating described in JATMA, etc. The air pressure (maximum air pressure) corresponding to the load capacity. The air here can be replaced with an inert gas such as nitrogen gas or the like.
　また、本発明の重荷重用空気入りタイヤでは、前記交錯ベルト層を構成する前記１対のベルトプライのタイヤ幅方向端部の間に配設されたスペースゴムと、前記カーカスのタイヤ径方向外側かつ前記ベルト層のタイヤ幅方向端部のタイヤ径方向内側に配設されたクッションゴムと、前記トレッド部で前記ベルト層のタイヤ径方向外側に配設され、トレッド踏面を形成するトレッドゴムと、を備え、前記スペースゴムの弾性率Ｅ１および前記クッションゴムの弾性率Ｅ２を、
０．３＜Ｅ１／Ｅ２＜０．５
とすることが好ましい。これによれば、タイヤの転がり抵抗を低減させることができる。 In the heavy-duty pneumatic tire according to the present invention, a space rubber disposed between tire width direction ends of the pair of belt plies constituting the crossing belt layer, a carcass tire outer side in the tire radial direction, A cushion rubber disposed on the inner side in the tire radial direction of the end portion in the tire width direction of the belt layer, and a tread rubber disposed on the outer side in the tire radial direction of the belt layer at the tread portion and forming a tread surface. An elastic modulus E1 of the space rubber and an elastic modulus E2 of the cushion rubber,
0.3 <E1 / E2 <0.5
It is preferable that According to this, the rolling resistance of the tire can be reduced.
　ここで、本発明において、「弾性率」は、「１００％モジュラス」を指し、「１００％モジュラス」とは、ＪＩＳダンベル状３号形サンプルを用意し、ＪＩＳ　Ｋ６２５１に準拠して、温度３０℃、速度５００±２５ｍｍ／ｍｉｎの条件下で引張試験を行って測定した、１００％伸長時の引張応力である。 Here, in the present invention, “elastic modulus” refers to “100% modulus”, and “100% modulus” refers to a JIS dumbbell-shaped No. 3 sample prepared, at a temperature of 30 ° C. in accordance with JIS K6251. The tensile stress at 100% elongation measured by performing a tensile test under the condition of speed 500 ± 25 mm / min.
　この本発明によれば、耐久性を低下させることなく、耐偏摩耗性を向上させることが可能な重荷重用空気入りタイヤを提供することができる。 According to the present invention, it is possible to provide a heavy-duty pneumatic tire capable of improving uneven wear resistance without reducing durability.
本発明の一実施形態に係る重荷重用空気入りタイヤのトレッド部周辺を示す、タイヤ幅方向の拡大断面図である。It is an expanded sectional view of the tread part circumference of the pneumatic tire for heavy loads concerning one embodiment of the present invention in the tire width direction. 図１の重荷重用空気入りタイヤのトレッド部のベルト層をカーカスとともに示す展開図である。FIG. 2 is a development view showing a belt layer of a tread portion of the heavy duty pneumatic tire of FIG. 1 together with a carcass.
　以下に、図面を参照しつつ、この発明の実施形態について例示説明する。
　図１は、本発明に従う重荷重用空気入りタイヤ（以下、タイヤともいう）のトレッド部（半部）周辺を、適用リムに装着したタイヤに規定の空気圧を充填した無負荷状態で示すタイヤ幅方向の一部拡大断面図である。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a tire width direction showing a tread portion (half portion) periphery of a heavy-duty pneumatic tire (hereinafter also referred to as a tire) according to the present invention in a no-load state in which a tire mounted on an applicable rim is filled with a prescribed air pressure. FIG.
　ここで、図１に示す重荷重用空気入りタイヤ１は、バスやトラックに装着するタイヤであって、一部図示を省略するが、トレッド部２と、トレッド部２の両側に連なる１対のサイドウォール部と、各サイドウォール部に連なる図示しないビード部とを備えている。さらに、重荷重用空気入りタイヤ１は、各ビード部内に埋設されたビードコアの間をトレッド部２、サイドウォール部およびビード部にわたってトロイド状に延在するカーカス３を有している。なお、図１に示すカーカス３は１枚のプライからなっているが、本発明のタイヤ１では、必要に応じて２枚以上のプライ数に変えることができる。 Here, the heavy-duty pneumatic tire 1 shown in FIG. 1 is a tire to be mounted on a bus or a truck, and a part of the pneumatic tire 1 is omitted, but a tread portion 2 and a pair of sides connected to both sides of the tread portion 2. A wall portion and a bead portion (not shown) connected to each sidewall portion are provided. Furthermore, the heavy-duty pneumatic tire 1 has a carcass 3 extending in a toroidal shape between a bead core embedded in each bead portion over the tread portion 2, the sidewall portion, and the bead portion. Although the carcass 3 shown in FIG. 1 is composed of one ply, in the tire 1 of the present invention, the number of plies can be changed to two or more if necessary.
　また、トレッド部２のカーカス３のタイヤ径方向外側に、より具体的には後述のベルト層４のタイヤ径方向外側には、トレッド踏面を形成するトレッドゴム２１が配設されている。トレッド踏面には、タイヤ周方向に延びる周方向溝２２が形成されている。なお、図示では、周方向溝２２が示されているが、タイヤ幅方向に延びる幅方向溝等を形成させることもでき、また、任意のトレッドパターン、例えばリブ状パターン、ブロック状パターン等とすることができる。 Further, a tread rubber 21 that forms a tread surface is disposed on the outer side in the tire radial direction of the carcass 3 of the tread portion 2 and more specifically on the outer side in the tire radial direction of the belt layer 4 described later. A circumferential groove 22 extending in the tire circumferential direction is formed on the tread surface. In the drawing, the circumferential groove 22 is shown, but a width direction groove or the like extending in the tire width direction can also be formed, and any tread pattern, for example, a rib-like pattern or a block-like pattern can be used. be able to.
　さらに、図１に示すように、トレッド部２のカーカス３のタイヤ径方向外側には、ベルトコード、例えばスチールコードをゴムで被覆して形成されるベルトプライ４ａを、複数枚積層して構成されるベルト層４が配設されている。また、本実施形態のタイヤ１は、タイヤ周方向に沿って延びるベルトコードからなるベルトプライで構成される周方向ベルト層を有しない。なお、「タイヤ周方向に沿って延びる」とは、実質的にタイヤ赤道面Ｅに対して角度θが０°であり、タイヤ赤道面Ｅに対してわずかに傾くこと（例えば、５°以内）は許容されることを意味する。
　そして、ベルト層４は、１対のベルトプライ４ａをそれぞれ積層して構成されるとともに、それぞれのベルトプライ４ａのベルトコードを、タイヤ赤道面Ｅを挟んで相互に交差させた交錯ベルト層４１と、１枚以上、図示では１枚のベルトプライ４ａで構成される角度付きベルト層４２とを有している。なお、交錯ベルト層４１を構成するそれぞれのベルトプライ４ａのベルトコードは、タイヤ赤道面Ｅに対して角度θ1を有するとともに、実質的に対称に配列されている。なお、タイヤ赤道面Ｅを挟んで相互に交差していれば、対称でなくとも（θ1が異なっても）よい。また、角度付きベルト層４２を構成するベルトプライ４ａのベルトコードは、タイヤ赤道面Ｅに対して角度θ2を有している。 Further, as shown in FIG. 1, a plurality of belt plies 4a formed by coating a belt cord, for example, a steel cord with rubber, are laminated on the outer side in the tire radial direction of the carcass 3 of the tread portion 2. A belt layer 4 is provided. Moreover, the tire 1 of this embodiment does not have the circumferential belt layer comprised by the belt ply which consists of a belt cord extended along a tire circumferential direction. Note that “extending along the tire circumferential direction” means that the angle θ is substantially 0 ° with respect to the tire equator plane E and is slightly inclined with respect to the tire equator plane E (for example, within 5 °). Means allowed.
The belt layer 4 is configured by laminating a pair of belt plies 4a, and a cross belt layer 41 in which the belt cords of the belt plies 4a intersect each other across the tire equatorial plane E. There is an angled belt layer 42 composed of one or more, in the drawing, one belt ply 4a. The belt cords of the respective belt plies 4a constituting the crossing belt layer 41 have an angle θ 1 with respect to the tire equatorial plane E and are arranged substantially symmetrically. In addition, as long as it cross | intersects on both sides of the tire equatorial plane E, it does not need to be symmetrical ((theta) 1 may differ). Further, the belt cord of the belt ply 4a constituting the angled belt layer 42 has an angle θ 2 with respect to the tire equatorial plane E.
　なお、図１および２に示すところでは、タイヤ径方向内側からタイヤ径方向外側に向かって１枚のベルトプライ４ａからなる角度付きベルト層４２および１対のベルトプライ４ａからなる交錯ベルト層４１の順でそれぞれ積層されているが、その積層の順は任意に変更することができる。 1 and 2, the angled belt layer 42 made up of one belt ply 4a and the cross belt layer 41 made up of a pair of belt plies 4a from the inside in the tire radial direction to the outside in the tire radial direction. Although the layers are stacked in order, the stacking order can be arbitrarily changed.
　ところで、従来の重荷重用空気入りタイヤでは、一般に、トレッド部に配設したベルト層の張力が、タイヤ転動時にトレッド部のセンター部分で最も大きくなり、トレッド部のタイヤ幅方向外側のショルダー部分にかけて減少するため、ショルダー部分の路面への接地圧が低くなり、タイヤが転動して路面を蹴り出す際、ショルダー部分が路面に対して滑ることがあり、その結果、ショルダー部分に偏摩耗が生じていた。
　そこで、本発明の重荷重用空気入りタイヤ１では、交錯ベルト層４１と角度付きベルト層４２とを有するベルト層４を備え、周方向ベルト層を有しなく、交錯ベルト層４１を構成するそれぞれのベルトプライ４ａのベルトコードのタイヤ赤道面Ｅに対する角度θ1、および角度付きベルト層４２を構成するベルトプライ４ａのベルトコードのタイヤ赤道面Ｅに対する角度θ2を、
１０°＜θ1＜２５°かつ１５°＜θ2－θ1＜２５°
としている。
　この構成によれば、交錯ベルト層４１の角度θ1を上記範囲にすることで、タイヤ転動時に、ショルダー部分でのベルト層４の張力が、センター部分でのベルト層４の張力と比して相対的に大きくなり、それゆえに、タイヤ転動時に、ショルダー部分でのベルト層４の張力を向上することができる。ところで、交錯ベルト層４１の角度θ1を上記範囲にすると、センター部分でのベルト層４の張力が不足することとなる。これに対しては、角度付きベルト層４２の角度θ2を交錯ベルト層４１よりも大きい上記範囲にすることにより、タイヤ転動時に、角度付きベルト層４２が、ショルダー部分でのベルト層４の張力を低下させることなく、センター部分でのベルト層４の張力を補うことができる。したがって、ベルト幅方向で、ベルト層４の張力が全体としてセンター部分からショルダー部分にかけて大きくなり、またはベルト層４の張力がタイヤ幅方向で均一になり、その結果、センター部分の路面への接地圧を確保しつつ、ショルダー部分の路面への接地圧が増し、耐偏摩耗性を向上させることができる。 By the way, in the conventional heavy-duty pneumatic tire, generally, the tension of the belt layer arranged in the tread portion becomes the largest in the center portion of the tread portion when the tire rolls, and the tire portion extends toward the shoulder portion on the outer side in the tire width direction of the tread portion. Since the contact pressure on the road surface of the shoulder portion decreases and the tire rolls and kicks the road surface, the shoulder portion may slide against the road surface, resulting in uneven wear on the shoulder portion. It was.
Therefore, the heavy duty pneumatic tire 1 of the present invention includes the belt layer 4 having the crossing belt layer 41 and the angled belt layer 42, and does not have the circumferential belt layer, and each of the crossing belt layers 41 constituting the crossing belt layer 41. The angle θ 1 of the belt cord of the belt ply 4a with respect to the tire equatorial plane E, and the angle θ 2 of the belt cord of the belt ply 4a constituting the angled belt layer 42 with respect to the tire equatorial plane E,
10 ° <θ 1 <25 ° and 15 ° <θ 2 −θ 1 <25 °
It is said.
According to this configuration, by setting the angle θ 1 of the crossing belt layer 41 within the above range, the tension of the belt layer 4 at the shoulder portion is compared with the tension of the belt layer 4 at the center portion when the tire rolls. Therefore, the tension of the belt layer 4 at the shoulder portion can be improved when the tire rolls. By the way, when the angle θ 1 of the crossing belt layer 41 is set in the above range, the tension of the belt layer 4 at the center portion becomes insufficient. For this, by setting the angle θ 2 of the angled belt layer 42 to the above range larger than that of the crossing belt layer 41, the angled belt layer 42 is formed on the shoulder portion of the belt layer 4 when rolling the tire. The tension of the belt layer 4 at the center portion can be supplemented without reducing the tension. Therefore, in the belt width direction, the tension of the belt layer 4 as a whole increases from the center portion to the shoulder portion, or the tension of the belt layer 4 becomes uniform in the tire width direction. As a result, the contact pressure on the road surface of the center portion is increased. While ensuring, the contact pressure to the road surface of a shoulder part increases, and uneven wear resistance can be improved.
　なお、交錯ベルト層４１の角度θ1を１０°以下にすると、タイヤ転動時にセンター部分でのベルト層４の張力が大きく低下することとなり、センター部分での偏摩耗が生じるおそれがある。また、交錯ベルト層４１の角度θ1を２５°以上にすると、タイヤ転動時にショルダー部分でのベルト層４の張力が、耐偏摩耗性の向上に寄与する程に増加しない。
　また、角度θ1およびθ2の関係で、θ2－θ1≦１５°にすると、タイヤ転動時にセンター部分でのベルト層４の張力が大幅に低下し、２５°≦θ2－θ1にすると、センター部分でのベルト層４の張力は向上するものの、交錯ベルト層４１の角度θ1を上記範囲にして上昇したショルダー部分でのベルト層４の張力が低下する。 If the angle θ 1 of the crossing belt layer 41 is 10 ° or less, the tension of the belt layer 4 at the center portion is greatly reduced during tire rolling, and there is a possibility that uneven wear at the center portion may occur. If the angle θ 1 of the crossing belt layer 41 is 25 ° or more, the tension of the belt layer 4 at the shoulder portion during rolling of the tire does not increase to the extent that it contributes to the improvement in uneven wear resistance.
Further, when θ 2 −θ 1 ≦ 15 ° in relation to the angles θ 1 and θ 2 , the tension of the belt layer 4 at the center portion is greatly reduced during tire rolling, and 25 ° ≦ θ 2 −θ 1. In this case, although the tension of the belt layer 4 at the center portion is improved, the tension of the belt layer 4 at the shoulder portion that is increased when the angle θ 1 of the crossing belt layer 41 is within the above range is lowered.
　さらになお、耐偏摩耗性の向上と、後述のタイヤ耐久性の両立の観点からは、１４°＜θ1＜２０°かつ１５°＜θ2－θ1＜２０°がより好ましい。 Furthermore, 14 ° <θ 1 <20 ° and 15 ° <θ 2 −θ 1 <20 ° are more preferable from the viewpoint of improving both the partial wear resistance and the tire durability described later.
　また、タイヤ耐久性の観点からは、３５°＜θ2＜５０°であることが好ましい。なお、角度θ2を３５°以下とすると、後述のように、曲率半径Ｒ1をＲ2よりも大きくし、距離Ｄｉを、距離Ｄに近づけても、ベルト層４のタイヤ幅方向外端の径成長量が大きくなりやすい傾向があり、ベルト層４のタイヤ幅方向外端でのセパレーションの発生の可能性が高くなる虞がある。また、角度θ2を５０°以上とすると、角度付きベルト層４２への圧縮入力が大きくなる傾向があり、ベルトコードが損傷する可能性が高くなる虞がある。 Further, from the viewpoint of tire durability, it is preferable that 35 ° <θ 2 <50 °. If the angle θ 2 is 35 ° or less, as will be described later, even if the radius of curvature R 1 is larger than R 2 and the distance Di is close to the distance D, the outer end of the belt layer 4 in the tire width direction is There is a tendency that the diameter growth amount tends to be large, and there is a possibility that the possibility of occurrence of separation at the outer end of the belt layer 4 in the tire width direction is increased. Further, if the angle θ 2 is 50 ° or more, the compression input to the angled belt layer 42 tends to increase, and the possibility that the belt cord is damaged may increase.
　ここで、図１に示すように、本発明の重荷重用空気入りタイヤ１では、タイヤ幅方向断面におけるカーカス３の形状を、カーカス３のタイヤ径方向最外側位置からタイヤ幅方向最外側位置に至るまで、タイヤ内腔側に曲率中心を有する、曲率半径の互いに異なる２つの円弧をつないで形成している。なお、２つの円弧のうち、タイヤ幅方向内側に位置する内側円弧の曲率半径をＲ1とし、また、タイヤ幅方向外側に位置する外側円弧の曲率半径をＲ2とする。
　なお、図１ではタイヤ半部しか示していないが、本実施形態のタイヤでは、タイヤ幅方向断面において、一方側のタイヤ幅方向最外側位置からタイヤ径方向最外側位置を経由し他方側のタイヤ幅方向最外側位置までのカーカス３の形状は、カーカス３のタイヤ径方向最外側位置を含む曲率半径Ｒ1の内側円弧と、タイヤ幅方向外側の両方の曲率半径Ｒ2の外側円弧との３つの円弧をつないで形成されている。ここで、後述する曲率半径Ｒ1、Ｒ2の関係を満たせば、タイヤ幅方向外側のそれぞれの外側円弧の曲率半径は、相互に異なるものとすることも可能である。 Here, as shown in FIG. 1, in the heavy-duty pneumatic tire 1 of the present invention, the shape of the carcass 3 in the tire width direction cross section extends from the outermost position in the tire radial direction of the carcass 3 to the outermost position in the tire width direction. Up to two arcs having different radii of curvature and having a center of curvature on the tire lumen side are formed. Of the two arcs, the radius of curvature of the inner arc located inside the tire width direction is R 1, also the radius of curvature of the outer arc located outside the tire width direction is R 2.
Although only the tire half is shown in FIG. 1, in the tire according to the present embodiment, in the tire width direction cross section, the tire on the other side passes from the outermost position in the tire radial direction to the outermost position in the tire radial direction. The shape of the carcass 3 up to the outermost position in the width direction is 3 of the inner arc of the radius of curvature R 1 including the outermost position in the tire radial direction of the carcass 3 and the outer arc of both the radii of curvature R 2 on the outer side in the tire width direction. It is formed by connecting two arcs. Here, if the relationship between the curvature radii R 1 and R 2 described later is satisfied, the curvature radii of the respective outer arcs on the outer side in the tire width direction can be different from each other.
　そして、上述のように交錯ベルト層４１の角度θ1および角度付きベルト層４２の角度θ2を規定の範囲にすることで耐偏摩耗性を向上させることが可能であるが、一方で、タイヤ１に内圧を充填すると、ベルト層４のタイヤ幅方向外端付近で、具体的には交錯ベルト層４１のタイヤ幅方向外端付近で、ショルダー部分でのベルト層４の張力が向上したことに起因してトレッドゴム２１に歪が生じることによるセパレーションが発生しやすくなり、それゆえにタイヤ１の耐久性が悪化する傾向がある。 Further, as described above, it is possible to improve the uneven wear resistance by setting the angle θ 1 of the crossing belt layer 41 and the angle θ 2 of the angled belt layer 42 within a specified range. 1 is filled with the internal pressure, the tension of the belt layer 4 at the shoulder portion is improved near the outer end of the belt layer 4 in the tire width direction, specifically, near the outer end of the cross belt layer 41 in the tire width direction. As a result, separation due to distortion in the tread rubber 21 is likely to occur, and therefore the durability of the tire 1 tends to deteriorate.
　そこで、本発明の重荷重用空気入りタイヤ１では、内側円弧および外側円弧のそれぞれの曲率半径Ｒ1、Ｒ2を、Ｒ1＞Ｒ2とし、タイヤ赤道面Ｅからそれら円弧の交点Ｉまでをタイヤ幅方向に沿って測った距離Ｄｉを、交錯ベルト層４１の各ベルトプライ４ａが重複する範囲をタイヤ赤道面Ｅからタイヤ幅方向に沿って測った距離Ｄの８０％以上とする。
　曲率半径Ｒ1をＲ2よりも大きくし、距離Ｄｉを、距離Ｄに近づけることにより、タイヤ内圧充填時において、ベルト層４のタイヤ幅方向外端がタイヤ径方向外側へ径成長するのを低減させることができる。そして、距離Ｄｉを、距離Ｄに対して８０％以上にすれば、ベルト層４のタイヤ幅方向外端の径成長量を低減させて、トレッドゴム２１内の歪みを十分に抑制することができ、ベルト層４のタイヤ幅方向外端でのセパレーションの防止ひいては耐久性の低下の防止が可能となる。 Therefore, in the heavy duty pneumatic tire 1 of the present invention, the radii of curvature R 1 and R 2 of the inner arc and the outer arc are set to R 1 > R 2 , and the tire extends from the tire equatorial plane E to the intersection I of the arcs. The distance Di measured along the width direction is set to 80% or more of the distance D measured along the tire width direction from the tire equatorial plane E in a range where the belt plies 4a of the crossing belt layers 41 overlap.
By making the radius of curvature R 1 larger than R 2 and making the distance Di close to the distance D, the outer end in the tire width direction of the belt layer 4 is prevented from growing radially outward in the tire radial pressure filling. Can be made. If the distance Di is set to 80% or more with respect to the distance D, the diameter growth amount at the outer end in the tire width direction of the belt layer 4 can be reduced, and the distortion in the tread rubber 21 can be sufficiently suppressed. In addition, it is possible to prevent the separation of the belt layer 4 at the outer end in the tire width direction, and hence the durability.
　また、本発明の重荷重用空気入りタイヤ１では、曲率半径Ｒ1、Ｒ2が、Ｒ1／Ｒ2≧９．５であることが好ましい。これによれば、タイヤ内圧充填時において、ベルト層４のタイヤ幅方向外端の、タイヤ径方向外側への径成長量がさらに低減するので、トレッドゴム２１の歪みをより十分に抑制することができ、ベルト層４のタイヤ幅方向外端でのセパレーションの防止ひいては耐久性の低下の防止がより効果的に可能となる。 Moreover, the heavy-duty pneumatic tire 1 of the present invention, the radius of curvature R 1, R 2, it is preferable that R 1 / R 2 ≧ 9.5. According to this, at the time of tire internal pressure filling, the amount of radial growth at the outer end in the tire width direction of the belt layer 4 toward the outer side in the tire radial direction is further reduced, so that the distortion of the tread rubber 21 can be more sufficiently suppressed. In addition, it is possible to more effectively prevent the separation of the belt layer 4 at the outer end in the tire width direction, and thus the durability.
　なお、距離Ｄｉの上限値は、距離Ｄの８０％以上とすることによって耐久性の低下を防止することが可能であることから限定されるものではないが、製造上の観点から、距離Ｄの１０５％（すなわち８０％≦Ｄｉ／Ｄ×１００≦１０５％）が好ましい。 The upper limit of the distance Di is not limited because it is possible to prevent a decrease in durability by setting it to 80% or more of the distance D, but from the viewpoint of manufacturing, the upper limit of the distance D 105% (that is, 80% ≦ Di / D × 100 ≦ 105%) is preferable.
　ここで、交錯ベルト層４１は、図１および２に示すところでは、タイヤ径方向内側のベルトプライ４ａの幅が、タイヤ径方向外側のベルトプライ４ａの幅よりも大きくして形成されているが、それらの幅の大小関係を逆にし、または同じにすることも可能である。ただし、それぞれのベルトプライ４ａのタイヤ幅方向外端が、タイヤ幅方向位置で同一の位置にならないことが好ましい。それぞれのベルトプライ４ａのタイヤ幅方向外端が、タイヤ幅方向位置で同一の位置になると、当該外端付近にセパレーションを発生しやすくなる。 Here, the crossing belt layer 41 is formed so that the width of the belt ply 4a on the inner side in the tire radial direction is larger than the width of the belt ply 4a on the outer side in the tire radial direction, as shown in FIGS. It is also possible to reverse the magnitude relation of the widths or make them the same. However, it is preferable that the outer end in the tire width direction of each belt ply 4a is not the same position in the tire width direction. When the outer end in the tire width direction of each belt ply 4a is the same position in the position in the tire width direction, separation is likely to occur near the outer end.
　ところで、本実施形態では、図示のように、交錯ベルト層４１を構成する１対のベルトプライ４ａのタイヤ幅方向端部の間に、スペースゴム５を配設することができる。具体的には、スペースゴム５のタイヤ幅方向内端は、交錯ベルト層４１の１対のベルトプライ４ａの間であって、当該１対のベルトプライ４ａのうち狭幅のベルトプライ４ａのタイヤ幅方向外端よりもタイヤ幅方向内側に位置している。また、図示の例では、スペースゴム５のタイヤ幅方向外端は、例えば当該１対のベルトプライ４ａのうち広幅のベルトプライ４ａのタイヤ幅方向外端よりもタイヤ幅方向外側に位置している。なお、スペースゴム５は、図示のように、断面台形状とすることができるが、シート状とすることもできる。 By the way, in this embodiment, as shown in the figure, the space rubber 5 can be disposed between the ends in the tire width direction of the pair of belt plies 4a constituting the crossing belt layer 41. Specifically, the inner end in the tire width direction of the space rubber 5 is between the pair of belt plies 4a of the crossing belt layer 41, and the tire of the narrow belt ply 4a of the pair of belt plies 4a. It is located on the inner side in the tire width direction than the outer end in the width direction. In the illustrated example, the outer end in the tire width direction of the space rubber 5 is located on the outer side in the tire width direction of the pair of belt plies 4a, for example, than the outer end in the tire width direction of the wide belt ply 4a. . The space rubber 5 can have a trapezoidal cross section as shown in the figure, but can also be a sheet.
　また、本実施形態では、図示のように、カーカス３のタイヤ径方向外側かつベルト層４のタイヤ幅方向端部のタイヤ径方向内側に、クッションゴム６を配設することができる。具体的には、クッションゴム６のタイヤ幅方向内端は、ベルト層４の中でも最も広幅のベルトプライ４ａのタイヤ幅方向外端よりもタイヤ幅方向内側に位置し、図示の例では、角度付きベルト層４２のタイヤ幅方向外端よりタイヤ幅方向内側に位置している。また、クッションゴム６のタイヤ幅方向外端は、図示のように、ベルト層４のタイヤ幅方向外端よりタイヤ幅方向外側に位置している。図示のクッションゴム６は、カーカス３とベルト層４の間に挟まれるように配置されている。 Further, in the present embodiment, as shown in the drawing, the cushion rubber 6 can be disposed on the outer side in the tire radial direction of the carcass 3 and on the inner side in the tire radial direction of the end portion in the tire width direction of the belt layer 4. Specifically, the inner end in the tire width direction of the cushion rubber 6 is located on the inner side in the tire width direction than the outer end in the tire width direction of the widest belt ply 4a in the belt layer 4, and in the illustrated example, an angle is provided. The belt layer 42 is located on the inner side in the tire width direction from the outer end in the tire width direction. Further, the outer end in the tire width direction of the cushion rubber 6 is located on the outer side in the tire width direction from the outer end in the tire width direction of the belt layer 4 as illustrated. The illustrated cushion rubber 6 is disposed so as to be sandwiched between the carcass 3 and the belt layer 4.
　そして、スペースゴム５の弾性率Ｅ１およびクッションゴム６の弾性率Ｅ２を、０．３＜Ｅ１／Ｅ２＜０．５とすることが好ましい。
　この構成によれば、タイヤ１の転がり抵抗を低減させることができる。具体的には、交錯ベルト層４１と角度付きベルト層４２とを有するベルト層４を備え、周方向ベルト層を有しないタイヤ１において、スペースゴム５およびクッションゴム６を配設しない場合、上述のように交錯ベルト層４１の角度θ1および角度付きベルト層θ2を所定の範囲にし、また、曲率半径Ｒ1、Ｒ2を、Ｒ1＞Ｒ2とし、さらに、距離Ｄｉを、距離Ｄの８０％以上とすると、ベルト層４の張力、特にタイヤ１を低偏平率化したときのベルト層４の張力が増加するためベルト層４が剛性をもったリングとして機能する。それゆえに、タイヤ転動時に、トレッド部２のタイヤ径方向の圧縮変形が増加し（トレッド部２が変形しやすくなり）、その結果として、トレッドゴム２１の歪エネルギーロスが発生し、転がり抵抗が悪化する虞があった。そこで、クッションゴム６やスペースゴム５を配設することによって、トレッド部２の変形をベルト層４の周辺のクッションゴム６やスペースゴム５で吸収させることで、転がり抵抗の増加を抑制することができる。また、クッションゴム６やスペースゴム５を上記のような関係の弾性率とすることにより、タイヤ転動時のベルト層４の変形をトレッド部２でなく、スペースゴム５が吸収し、転がり抵抗を低減させることができる。 The elastic modulus E1 of the space rubber 5 and the elastic modulus E2 of the cushion rubber 6 are preferably 0.3 <E1 / E2 <0.5.
According to this configuration, the rolling resistance of the tire 1 can be reduced. Specifically, in the tire 1 including the belt layer 4 having the crossing belt layer 41 and the angled belt layer 42 and having no circumferential belt layer, when the space rubber 5 and the cushion rubber 6 are not provided, Thus, the angle θ 1 and the angled belt layer θ 2 of the crossing belt layer 41 are set within a predetermined range, the radii of curvature R 1 and R 2 are set to R 1 > R 2 , and the distance Di is set to the distance D If it is 80% or more, the tension of the belt layer 4, particularly the tension of the belt layer 4 when the tire 1 is reduced in flatness, increases, so that the belt layer 4 functions as a rigid ring. Therefore, when the tire rolls, compression deformation in the tire radial direction of the tread portion 2 increases (the tread portion 2 is easily deformed). As a result, strain energy loss of the tread rubber 21 occurs, and rolling resistance is reduced. There was a risk of deterioration. Therefore, by disposing the cushion rubber 6 and the space rubber 5, the deformation of the tread portion 2 is absorbed by the cushion rubber 6 and the space rubber 5 around the belt layer 4, thereby suppressing an increase in rolling resistance. it can. Further, by setting the cushion rubber 6 and the space rubber 5 to have the above elastic modulus, the deformation of the belt layer 4 at the time of tire rolling is absorbed not by the tread portion 2 but by the space rubber 5 and rolling resistance is reduced. Can be reduced.
　また、０．３＜Ｅ１／Ｅ２とすることにより、スペースゴム５に大きな歪が生じないので、スペースゴム５ひいてはタイヤ１の耐久性が低下するのを防止することができる。Ｅ１／Ｅ２＜０．５とすることにより、クッションゴム６やスペースゴム５などのベルト層４の周辺ゴムによってタイヤ転動時のベルト層４の変形を吸収しきれなくなるのを防止し、その結果としての転がり抵抗の悪化を防止することができる。
　なお、クッションゴム６の弾性率Ｅ２をスペースゴム５の弾性率Ｅ１よりも低くすることで、タイヤ転動時のベルト層４の変形を吸収し、転がり抵抗の悪化を抑制することもできるが、弾性率Ｅ２を相対的に低くすると、スペースゴム５よりもクッションゴム６に変形が集中しやすくなり、クッションゴム６ひいてはタイヤ１の耐久性が低下する虞がある。 Moreover, since 0.3 <E1 / E2 is set, no great distortion is generated in the space rubber 5, so that the durability of the space rubber 5 and thus the tire 1 can be prevented from being lowered. By setting E1 / E2 <0.5, it is possible to prevent the peripheral rubber of the belt layer 4 such as the cushion rubber 6 and the space rubber 5 from completely absorbing the deformation of the belt layer 4 at the time of rolling the tire. As a result, deterioration of rolling resistance can be prevented.
In addition, by making the elastic modulus E2 of the cushion rubber 6 lower than the elastic modulus E1 of the space rubber 5, the deformation of the belt layer 4 at the time of tire rolling can be absorbed, and deterioration of rolling resistance can be suppressed. If the elastic modulus E2 is relatively low, deformation tends to concentrate on the cushion rubber 6 rather than the space rubber 5, and the durability of the cushion rubber 6 and thus the tire 1 may be reduced.
　また、スペースゴム５の弾性率Ｅ１、クッションゴム６の弾性率Ｅ２、およびトレッドゴム２１の弾性率Ｅ３は、それぞれ、１．５～８．０ＭＰａ、１．５～８．０ＭＰａ、１．０～５．０ＭＰａであることが好ましい。 The elastic modulus E1 of the space rubber 5, the elastic modulus E2 of the cushion rubber 6, and the elastic modulus E3 of the tread rubber 21 are 1.5 to 8.0 MPa, 1.5 to 8.0 MPa, 1.0 to It is preferably 5.0 MPa.
　ここで、図１に示すように、トレッド部２には、ベルト層４のタイヤ径方向外側に、ベルト層４に比して幅が狭い補助ベルト層４３を配設することができ、それにより、タイヤ１が路面上に存在する石等を乗り越えたとしてもトレッド部２の損傷を防止し、タイヤ１の耐久性を向上させることができる。なお、図示では、補助ベルト層４３は、１枚のベルトプライ４ａから構成され、その幅が、角度付きベルト層４２の略半分であり、また、その補助ベルトコードが交錯ベルト層４１の角度θ1と同等の角度を有しているが、補助ベルト層４３のベルトプライ４ａの枚数、幅、および補助ベルトコードの角度等は、当該補助ベルトコードのタイヤ赤道面Ｅに対する角度が実質的に０°でない限り任意に変更することができる。 Here, as shown in FIG. 1, an auxiliary belt layer 43 having a width smaller than that of the belt layer 4 can be disposed on the tread portion 2 on the outer side in the tire radial direction of the belt layer 4. Even if the tire 1 gets over a stone or the like existing on the road surface, the tread portion 2 can be prevented from being damaged, and the durability of the tire 1 can be improved. In the figure, the auxiliary belt layer 43 is composed of a single belt ply 4 a, the width of which is substantially half of the angled belt layer 42, and the auxiliary belt cord has an angle θ of the crossing belt layer 41. 1 , but the number of belt plies 4 a of the auxiliary belt layer 43, the width, the angle of the auxiliary belt cord, and the like are substantially zero with respect to the tire equatorial plane E. It can be changed arbitrarily unless it is °.
　ところで、本発明の重荷重用空気入りタイヤ１は、偏平率を６０～１００％とすることが好ましい。偏平率を６０％未満にしたタイヤでは、タイヤ転動時にベルト層に加わる張力が、偏平率を６０％～１００％としたタイヤと比して大きくなる傾向があり角度付きベルト層に負担がかかる虞があり、本願発明の構成を、偏平率を６０～１００％としたタイヤに適用することがより好適である。 Incidentally, the heavy duty pneumatic tire 1 of the present invention preferably has a flatness ratio of 60 to 100%. In tires with a flatness ratio of less than 60%, the tension applied to the belt layer during rolling of the tire tends to be larger than that of a tire with a flatness ratio of 60% to 100%, which places a burden on the angled belt layer. Therefore, it is more preferable to apply the configuration of the present invention to a tire with a flatness ratio of 60 to 100%.
　また、カーカスが２枚以上のプライからなる場合には、タイヤ幅方向断面におけるカーカスの形状とは、適用リムに組み付けたタイヤ１に規定の空気圧を充填した無負荷状態での、カーカス内の引張－圧縮の中立軸線を指す。 When the carcass is composed of two or more plies, the shape of the carcass in the cross section in the tire width direction is the tension in the carcass in a no-load state in which the tire 1 assembled to the applicable rim is filled with a prescribed air pressure. -Refers to the neutral axis of compression.
　以上、図面を参照して本発明の一実施形態を説明したが、本発明の重荷重用空気入りタイヤは、上記一例に限定されることはなく、上記した本発明の実施形態には、適宜変更を加えることができる。 As mentioned above, although one Embodiment of this invention was described with reference to drawings, the heavy-duty pneumatic tire of this invention is not limited to the said example, It changes suitably in above-described embodiment of this invention. Can be added.
　以下、実施例により本発明を更に詳細に説明するが、本発明は下記の実施例になんら限定されるものではない。 Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.
　実施例１のタイヤは、サイズが２９５／７５Ｒ２２．５であって、図１および２に示すような、カーカスの形状を形成する２つの円弧の曲率半径Ｒ1、Ｒ2がＲ1＞Ｒ2となる構造を有し、またタイヤの各寸法は表１に示す諸元で構成されている。また、実施例１のタイヤは、トレッド踏面の幅が１１７ｍｍであり、交錯ベルト層の重複範囲の幅が９５ｍｍであり、角度付きベルト層が１枚のベルトプライで構成され、角度付きベルト層の幅が９５ｍｍであり、偏平率が７５％である。また、実施例１のタイヤは、１枚のベルトプライからなる、幅が３４ｍｍでタイヤ赤道面に対する角度が７２°の補助ベルト層が配設されている。
　実施例２～８および比較例１のタイヤは、表１に示す諸元で各構成を変化させた以外、実施例タイヤ１と同様の構成を有している。
　上記のそれぞれの供試タイヤについて、後述の、初期～中期耐偏摩耗性試験、中期～末期耐偏摩耗性試験、耐久性試験、および転がり抵抗試験を実施し、その結果を表１に示す。 The tire of Example 1 has a size of 295 / 75R22.5, and the radii of curvature R 1 and R 2 of the two arcs forming the carcass shape as shown in FIGS. 1 and 2 are R 1 > R 2. Further, each dimension of the tire is constituted by specifications shown in Table 1. The tire of Example 1 has a tread surface width of 117 mm, an overlapping belt layer overlapping range width of 95 mm, an angled belt layer composed of a single belt ply, and an angled belt layer. The width is 95 mm and the flatness is 75%. Further, the tire of Example 1 is provided with an auxiliary belt layer having a width of 34 mm and an angle of 72 ° with respect to the tire equatorial plane, which is composed of one belt ply.
The tires of Examples 2 to 8 and Comparative Example 1 have the same configuration as that of Example Tire 1 except that the configurations are changed according to the specifications shown in Table 1.
Each of the above test tires was subjected to the following initial to medium-term uneven wear resistance test, medium to end-stage uneven wear resistance test, durability test, and rolling resistance test, and the results are shown in Table 1.
［初期～中期耐偏摩耗性試験］
　初期～中期耐偏摩耗性試験は、上記のそれぞれの供試タイヤをサイズ８．２５×２２．５のリムに装着し、内部に６９０ｋＰａの空気圧を適用した。その供試タイヤを、室内ドラム試験機に取り付けて、荷重２７ｋＮを負荷し、速度８０ｋｍ／ｈで距離１００００ｋｍを走行させた。そして、走行後の供試タイヤのトレッド部のショルダー部分での、偏摩耗量を測定した。偏摩耗量は、トレッド踏面端からの偏摩耗深さ（ｍｍ）と偏摩耗のタイヤ幅方向の長さとを乗じて２で除して得られた値を逆数にし、比較例１のタイヤについての値を１００とする指数で表し、それを表１に示す。この指数が大きいほど耐偏摩耗性がよいことを意味する。
［中期～末期耐偏摩耗性試験］
　中期～末期耐偏摩耗性試験は、新品の上記のそれぞれの供試タイヤについて、溝深さが約７ｍｍとなるようにトレッドゴムを削り、溝を浅くしたタイヤを作成し、走行中期～末期の状態を再現した。そして、そのタイヤを前記「初期～中期耐偏摩耗性試験」と同様の方法で、偏摩耗量を測定した。偏摩耗量は、トレッド踏面端からの偏摩耗深さ（ｍｍ）と偏摩耗のタイヤ幅方向の長さとを乗じて２で除して得られた値を逆数にし、比較例１のタイヤについての値を１００とする指数で表し、それを表１に示す。この指数が大きいほど耐偏摩耗性がよいことを意味する。
［耐久性試験］
　耐久性試験は、上記のそれぞれの供試タイヤをサイズ８．２５×２２．５のリムに装着し、内部に６９０ｋＰａの空気圧を適用した。その供試タイヤを、室内ドラム試験機に取り付けて、荷重３０ｋＮを負荷し、速度６０ｋｍ／ｈで距離１００００ｋｍを走行させた。そして、走行後の供試タイヤの交錯ベルト層のタイヤ幅方向外端でのセパレーション長さを測定した。それぞれの供試タイヤの当該長さを逆数にし、比較例１のタイヤのセパレーション長さを１００とする指数で表し、それを表１に示す。この指数が大きいほどセパレーション長さが短く、耐久性がよいことを意味する。
［転がり抵抗性能］
　転がり抵抗性能は、上記のそれぞれの供試タイヤをサイズ８．２５×２２．５のリムに装着し、内部に６９０ｋＰａの空気圧を適用した。その供試タイヤを、直径１．７ｍの鉄板表面を有する室内ドラム試験機に取り付けて、荷重３０ｋＮを負荷し、速度８０ｋｍ／ｈで走行させたときの転がり抵抗力（転がり抵抗値）を測定した。比較例１のタイヤの転がり抵抗値を１００とする指数で表し、それを表１に示す。この指数が小さいほど転がり抵抗が小さく、転がり抵抗性能がよいことを意味する。誤差を除きなおかつ市場優位性の観点から２％以上の改良を有意差とみなす。特に５％以上の効果が見られる場合は大きな効果であるといえる。 [Initial to medium-term uneven wear resistance test]
In the initial to medium-term uneven wear resistance test, each of the test tires described above was mounted on a rim having a size of 8.25 × 22.5, and an air pressure of 690 kPa was applied inside. The test tire was attached to an indoor drum testing machine, loaded with a load of 27 kN, and traveled a distance of 10,000 km at a speed of 80 km / h. Then, the amount of uneven wear at the shoulder portion of the tread portion of the test tire after running was measured. The amount of uneven wear is obtained by multiplying the uneven wear depth (mm) from the tread tread edge by the length of the uneven wear in the tire width direction and dividing the result by 2 to obtain the reciprocal of the tire of Comparative Example 1. It is represented by an index with a value of 100 and is shown in Table 1. A larger index means better uneven wear resistance.
[Medium-term to late-end uneven wear resistance test]
In the middle to end wear resistance test, for each of the above-mentioned new test tires, a tread rubber was shaved so that the groove depth was about 7 mm, and a tire with a shallow groove was created. The state was reproduced. Then, the amount of uneven wear of the tire was measured by the same method as in the “initial to medium term uneven wear resistance test”. The amount of uneven wear is obtained by multiplying the uneven wear depth (mm) from the tread tread edge by the length of the uneven wear in the tire width direction and dividing the result by 2 to obtain the reciprocal of the tire of Comparative Example 1. It is represented by an index with a value of 100 and is shown in Table 1. A larger index means better uneven wear resistance.
[Durability test]
In the durability test, each of the above test tires was mounted on a rim having a size of 8.25 × 22.5, and an air pressure of 690 kPa was applied inside. The test tire was attached to an indoor drum tester, loaded with a load of 30 kN, and traveled a distance of 10,000 km at a speed of 60 km / h. And the separation length in the tire width direction outer end of the crossing belt layer of the test tire after driving | running | working was measured. The lengths of the respective test tires are reciprocal, and are represented by an index with the separation length of the tire of Comparative Example 1 being 100, which is shown in Table 1. A larger index means a shorter separation length and better durability.
[Rolling resistance performance]
For rolling resistance performance, each of the above test tires was mounted on a rim having a size of 8.25 × 22.5, and an air pressure of 690 kPa was applied inside. The test tire was attached to an indoor drum testing machine having a steel plate surface having a diameter of 1.7 m, and a rolling resistance force (rolling resistance value) when running at a speed of 80 km / h under a load of 30 kN was measured. . The rolling resistance value of the tire of Comparative Example 1 is represented by an index with 100 as shown in Table 1. The smaller the index, the smaller the rolling resistance and the better the rolling resistance performance. An improvement of 2% or more is regarded as a significant difference from the viewpoint of market superiority while excluding errors. In particular, when an effect of 5% or more is seen, it can be said that it is a great effect.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１より、実施例１～８のタイヤでは、比較例１のタイヤと比較すると、１０°＜θ1＜２５°かつ１５°＜θ2－θ1＜２５°を満たし、交点距離Ｄｉ／重複する範囲の距離Ｄが８０％以上であるので、耐偏摩耗性および耐久性が向上していることがわかる。また、実施例１～５のタイヤでは、実施６、８のタイヤと比較すると、転がり抵抗が減少していることがわかる。 From Table 1, the tires of Examples 1 to 8 satisfy 10 ° <θ 1 <25 ° and 15 ° <θ 2 −θ 1 <25 °, and the intersection distance Di / overlap compared to the tire of Comparative Example 1. It can be seen that the uneven wear resistance and durability are improved since the distance D in the range to be applied is 80% or more. Further, it can be seen that the rolling resistance of the tires of Examples 1 to 5 is reduced as compared with the tires of Examples 6 and 8.
　本発明によれば、耐久性を低下させることなく、耐偏摩耗性を向上させることが可能な重荷重用空気入りタイヤを提供することができる。 According to the present invention, it is possible to provide a heavy duty pneumatic tire capable of improving uneven wear resistance without reducing durability.
１　重荷重用空気入りタイヤ；　２　トレッド部；　２１　トレッドゴム；　２２　周方向溝；　３　カーカス；　４　ベルト層；　４ａ　ベルトプライ；　４１　交錯ベルト層；　４２　角度付きベルト層；　４３　補助ベルト層；　５　スペースゴム；　６　クッションゴム；　Ｄ　（交錯ベルト層の各ベルトプライが重複する範囲をタイヤ赤道面からタイヤ幅方向に沿って測った）距離；　Ｄｉ　（交点を、タイヤ赤道面からタイヤ幅方向に沿って測った）距離；　Ｅ　タイヤ赤道面；　Ｉ　（内側円弧および外側円弧の）交点；　Ｒ1　（内側円弧の）曲率半径；　Ｒ2　（外側円弧の）曲率半径；　θ1　（交錯ベルト層のベルトコードのタイヤ赤道面に対する）角度；　θ2　（角度付きベルト層のベルトコードのタイヤ赤道面に対する）角度 1 Pneumatic tire for heavy load; 2 tread part; 21 tread rubber; 22 circumferential groove; 3 carcass; 4 belt layer; 4a belt ply; 41 crossing belt layer; 42 angled belt layer; 43 auxiliary belt layer; 6 (cushion rubber) D (measured from the tire equator plane along the tire width direction) distance (measured from the tire equator plane along the tire width direction) D (measured along the tire width direction from the tire equator plane) E) Tire equator plane; I Intersection of inner arc and outer arc; R 1 (radius of inner arc) radius of curvature; R 2 (radius of outer arc) radius of curvature; θ 1 (belt cord of cross belt layer) Angle relative to the tire equator; θ 2 Angle relative to the tire equator of the belt cord of the angled belt layer

Claims (3)

  1. 　カーカスと、トレッド部で、該カーカスのタイヤ径方向外側に配設されるベルト層と、を備え、タイヤ周方向に沿って延びるベルトコードからなるベルトプライで構成される周方向ベルト層を有しない重荷重用空気入りタイヤであって、
    　前記ベルト層は、１対のベルトプライをそれぞれ積層して構成されるとともに、それぞれの該ベルトプライのベルトコードをタイヤ赤道面を挟んで相互に交差させた交錯ベルト層と、１枚以上のベルトプライで構成される角度付きベルト層とを有し、
    　前記交錯ベルト層を構成するそれぞれの前記ベルトプライの前記ベルトコードの、タイヤ赤道面に対する角度θ1、および、前記角度付きベルト層を構成する前記ベルトプライのベルトコードの、タイヤ赤道面に対する角度θ2を、
    １０°＜θ1＜２５°かつ１５°＜θ2－θ1＜２５°
    とし、
    　タイヤ幅方向断面における前記カーカスの形状を、該カーカスのタイヤ径方向最外側位置からタイヤ幅方向最外側位置に至るまで、タイヤ内腔側に曲率中心を有する、曲率半径の互いに異なる２つの円弧をつないで形成し、
    　前記２つの円弧のうち、タイヤ幅方向内側に位置する内側円弧、および、タイヤ幅方向外側に位置する外側円弧の曲率半径のそれぞれを、Ｒ1、Ｒ2としたとき、前記曲率半径Ｒ1、Ｒ2を、
    Ｒ1＞Ｒ2
    とし、タイヤ赤道面から前記内側円弧および前記外側円弧の交点までをタイヤ幅方向に沿って測った距離は、交錯ベルト層の各ベルトプライが重複する範囲をタイヤ赤道面からタイヤ幅方向に沿って測った距離の８０％以上であることを特徴とする重荷重用空気入りタイヤ。     A carcass and a belt layer disposed on the outer side in the tire radial direction of the carcass at a tread portion, and does not have a circumferential belt layer composed of a belt ply including a belt cord extending along the tire circumferential direction A heavy duty pneumatic tire,
    The belt layer is formed by laminating a pair of belt plies, and an intersecting belt layer in which belt cords of the belt plies cross each other across the tire equatorial plane and one or more belts An angled belt layer composed of plies,
    The angle θ 1 of the belt cord of each belt ply constituting the crossing belt layer with respect to the tire equatorial plane, and the angle θ of the belt cord of the belt ply constituting the angled belt layer with respect to the tire equatorial plane 2 ,
    10 ° <θ 1 <25 ° and 15 ° <θ 2 −θ 1 <25 °
    age,
    The shape of the carcass in the tire width direction cross section has two arcs having different curvature radii and having a center of curvature on the tire lumen side from the outermost position in the tire radial direction to the outermost position in the tire width direction. Connected and formed
    Of the two arcs, when the radius of curvature of the inner arc located on the inner side in the tire width direction and the outer arc located on the outer side in the tire width direction are R 1 and R 2 , the radius of curvature R 1 , R 2
    R 1 > R 2
    The distance measured along the tire width direction from the tire equator plane to the intersection of the inner arc and the outer arc is a range where each belt ply of the crossing belt layer overlaps along the tire width direction from the tire equator plane. A heavy-duty pneumatic tire characterized by being 80% or more of the measured distance.
  2. 　前記曲率半径Ｒ1、Ｒ2を、
    Ｒ1／Ｒ2≧９．５
    とする、請求項１に記載の重荷重用空気入りタイヤ。     The curvature radii R 1 and R 2 are
    R 1 / R 2 ≧ 9.5
    The heavy-duty pneumatic tire according to claim 1.
  3. 　前記交錯ベルト層を構成する前記１対のベルトプライのタイヤ幅方向端部の間に配設されたスペースゴムと、前記カーカスのタイヤ径方向外側かつ前記ベルト層のタイヤ幅方向端部のタイヤ径方向内側に配設されたクッションゴムと、前記トレッド部で前記ベルト層のタイヤ径方向外側に配設され、トレッド踏面を形成するトレッドゴムと、を備え、
    　前記スペースゴムの弾性率Ｅ１および前記クッションゴムの弾性率Ｅ２を、
    ０．３＜Ｅ１／Ｅ２＜０．５
    とする、請求項１または２に記載の重荷重用空気入りタイヤ。     A space rubber disposed between tire width direction end portions of the pair of belt plies constituting the crossing belt layer, and a tire diameter at a tire radial direction outer side of the carcass and at a tire width direction end portion of the belt layer. A cushion rubber disposed on the inner side in the direction, and a tread rubber disposed on the outer side in the tire radial direction of the belt layer at the tread portion, and forming a tread surface.
    The elastic modulus E1 of the space rubber and the elastic modulus E2 of the cushion rubber are
    0.3 <E1 / E2 <0.5
    The heavy-duty pneumatic tire according to claim 1 or 2.
PCT/JP2015/004594 2014-10-03 2015-09-09 Pneumatic tire for heavy loads WO2016051685A1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114228404A (en) * 2021-12-03 2022-03-25 泰凯英(青岛)专用轮胎技术研究开发有限公司 Low-section tire belt ring for heavy load application and manufacturing method and application thereof

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JP2023094852A (en) * 2021-12-24 2023-07-06 株式会社ブリヂストン Heavy duty pneumatic tire

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009018629A (en) * 2007-07-10 2009-01-29 Yokohama Rubber Co Ltd:The Pneumatic tire
JP2010155533A (en) * 2008-12-26 2010-07-15 Bridgestone Corp Pneumatic tire
JP2013107426A (en) * 2011-11-17 2013-06-06 Bridgestone Corp Pneumatic radial tire for heavy load
WO2014156198A1 (en) * 2013-03-28 2014-10-02 株式会社ブリヂストン Heavy duty pneumatic tire

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009018629A (en) * 2007-07-10 2009-01-29 Yokohama Rubber Co Ltd:The Pneumatic tire
JP2010155533A (en) * 2008-12-26 2010-07-15 Bridgestone Corp Pneumatic tire
JP2013107426A (en) * 2011-11-17 2013-06-06 Bridgestone Corp Pneumatic radial tire for heavy load
WO2014156198A1 (en) * 2013-03-28 2014-10-02 株式会社ブリヂストン Heavy duty pneumatic tire

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114228404A (en) * 2021-12-03 2022-03-25 泰凯英(青岛)专用轮胎技术研究开发有限公司 Low-section tire belt ring for heavy load application and manufacturing method and application thereof

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