JP2017065637A - Tire for construction vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire for a construction vehicle which can reduce compression strain occurring in a carcass return-part to improve durability of a bead part, even if the tire is in a situation close to an actual usage environment where large lateral force is inputted to the tire.SOLUTION: In a tire 1 for a construction vehicle, when the tire is mounted on a wheel rim 100, a relational expression: 1.2HF≤HA≤2.5HF and 3.1HF≤HB≤4.5HF can be satisfied, where a height of a carcass cord 31 of a carcass main body part 40 which becomes the minimum value a from a baseline BL of the wheel rim 100, a height of the carcass cord 31 of the carcass main body part 40 which becomes the maximum value b from the baseline BL and a flange height of the wheel rim 100 from the baseline BL are set as HA, HB and HF respectively.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a construction vehicle tire, and more particularly, to a construction vehicle tire having improved durability of a bead portion.

  Construction vehicle tires that are mounted on construction vehicles with heavy loads while traveling on highly uneven road surfaces, such as construction sites, are subject to heavy loads. This is important from the viewpoint of prolonging

  In a construction vehicle tire used in the above-described environment, a large compression strain is repeatedly generated in a carcass folded portion that is folded from the carcass main body portion to the outer side in the tire radial direction by a bead core. A method has been proposed. For example, the distance between the carcass body part and the carcass folding part, specifically, the distance between carcass cords in the cross section along the tire width direction (intercord distance) is optimized according to the height position from the bead part. There is a known method (see Patent Document 1).

  More specifically, it has been proposed that the distance between cords once becomes the smallest in the vicinity of the bead core, then becomes wider as it goes outward in the tire radial direction, and becomes the largest at a predetermined height position from the bead portion. ing.

Japanese Unexamined Patent Publication No. 2009-113715 (page 5-7, FIG. 4)

  According to the conventional construction vehicle tire described above, the compressive strain generated in the carcass folded portion due to the vertical force (Fz) can be reduced. However, in the actual use environment, the carcass folded portion is also subjected to the compressive strain due to the lateral force (Fy). Arise. In other words, in a situation where the lateral force is high, it has been found that the inflection point of the carcass folding portion due to the compressive strain may deviate from the inflection point in the situation where the lateral force is low, and the compression strain may not be effectively reduced. It was.

  Specifically, in the situation where the lateral force is high, the position of the inflection point moves to the end side on the outer side in the tire radial direction of the carcass turn-up portion, and thus the carcass main body portion and carcass of the conventional construction vehicle tire described above. In the positional relationship between the folded portions, the compression distortion may not always be effectively reduced.

  Therefore, the present invention has been made in view of such a situation, and even in a situation close to the actual use environment where a large lateral force is input, the compression strain generated in the carcass folded portion is reduced, and the durability of the bead portion is reduced. It aims at providing the tire for construction vehicles which can improve property.

  A first feature of the present invention is that a carcass main body (carcass main body 40) covered with a carcass cord (carcass cord 31) and a carcass main body are connected to the carcass main body and tires from the inner side in the tire width direction of the bead core (bead core 61). A construction vehicle tire (construction vehicle tire 1) including a carcass folding portion (carcass folding portion 50) that is folded outward in the width direction and is covered with a carcass cord, the carcass cord of the carcass main body portion, The distance between the cords, which is the distance from the carcass cord of the carcass folding portion, decreases from the bead core to the outer side in the tire radial direction and becomes a minimum value a, and goes to the outer side in the tire radial direction where the minimum value a is reached. When the tire for a construction vehicle is mounted on an applicable rim (wheel rim 100), The carcass cord height HA of the carcass main body portion having the local minimum value a from the base line of the rim, the carcass cord height HB of the carcass main body portion having the local maximum value b from the base line of the applied rim, and The gist is that the flange height HF of the application rim from the base line of the application rim satisfies the relationship of 1.2HF ≦ HA ≦ 2.5HF and 3.1HF ≦ HB ≦ 4.5HF.

  In the first feature of the present invention, the distance L1 from the position of the minimum value a along the carcass cord of the carcass folded portion to the position of the maximum value b is the maximum along the carcass cord of the carcass folded portion. It may be longer than the distance L2 from the position of the value b to the end portion (end portion 51) on the outer side in the tire radial direction of the carcass folded portion.

  In the first feature of the present invention, there may be only one portion where the maximum value b is between the bead core and the end portion on the outer side in the tire radial direction of the carcass folded portion.

  In the first feature of the present invention, a ratio b / a between the minimum value a and the maximum value b may be 1.10 or more and less than 2.00.

  The second feature of the present invention is that a carcass body portion (carcass body portion 40) covered with a carcass cord (carcass cord 31) and a carcass body portion are connected to the carcass body portion and tires from the inside in the tire width direction of the bead core (bead core 61). A construction vehicle tire (construction vehicle tire 1A) including a carcass folded portion (carcas folded portion 50) that is folded outward in the width direction and is covered with a carcass cord, the carcass cord of the carcass main body portion, The distance between the cords, which is the distance from the carcass cord of the carcass folded portion, decreases from the bead core to the outer side in the tire radial direction and becomes a minimum value a, and after reaching the minimum value a, the outer side in the tire radial direction When the tire for construction vehicles is mounted on the applicable rim (wheel rim 100) The height HA of the carcass cord of the carcass main body portion that becomes the minimum value a from the base line of the applied rim, the height HB of the carcass cord of the carcass main body portion that becomes the maximum value b from the baseline of the applied rim, The flange height HF of the applied rim from the baseline of the applied rim satisfies the following relationships: 1.2HF ≦ HA ≦ 2.5HF, 2.6HF ≦ HB ≦ 3.5HF, 1.10 ≦ b / a <1.40 To do.

  In the second feature of the present invention, a straight line SL1 passing through the position of the carcass cord of the carcass main body portion at which the minimum value a is obtained and the position of the carcass cord of the carcass main body portion at which the maximum value b is obtained, The intersecting angle θ between the position of the carcass cord of the carcass folded portion at which the local minimum value a is reached and the straight line SL2 passing through the position of the carcass cord of the carcass folded portion at which the local maximum value b is obtained is 2.00 ° ≦ θ ≦ 5.00 You may be satisfied.

  In the second feature of the present invention, there may be only one location where the maximum value b is between the bead core and the outer end in the tire radial direction of the carcass folded portion.

  According to the features of the present invention, there is provided a tire for a construction vehicle that can reduce the compressive strain generated in the carcass folding portion and improve the durability of the bead portion even in a situation close to an actual use environment where a large lateral force is input. can do.

1 is a partial cross-sectional view of a construction vehicle tire 1 along a tire width direction and a tire radial direction. 2 is an enlarged cross-sectional view of a bead portion 60 of a construction vehicle tire 1. FIG. 3 is a diagram showing a specific positional relationship between a carcass main body 40 and a carcass turn-back portion 50 of a construction vehicle tire 1. FIG. FIG. 3 is a view showing a specific shape of a carcass folding portion 50 of a construction vehicle tire 1. FIG. 2 is an enlarged cross-sectional view of a bead portion 60 of a construction vehicle tire 1A. FIG. 3 is a diagram showing a specific positional relationship between a carcass main body 40 and a carcass folding portion 50 of a construction vehicle tire 1A. FIG. 2 is a schematic diagram for explaining compression deformation and tensile deformation that occur in the tire 1 for a construction vehicle. It is a figure which shows the test result of the tire for construction vehicles which concerns on a prior art example, a comparative example, and an Example.

[First Embodiment]
First, a construction vehicle tire according to a first embodiment of the present invention will be described with reference to the drawings.

(1) Schematic Configuration of Construction Vehicle Tire FIG. 1 is a partial cross-sectional view along the tire width direction and the tire radial direction of a construction vehicle tire 1 according to this embodiment. The construction vehicle tire 1 has a symmetrical shape with respect to the tire equator line CL.

  The construction vehicle tire 1 is suitably used for construction vehicle tires such as dump trucks, articulated dump trucks, wheel loaders and the like that travel on crushed stones, mines, and dam sites. As shown in FIG. 1, the construction vehicle tire 1 is connected to the tread portion 10 and the tread portion 10 that are in contact with the road surface, and is connected to the sidewall portion 15 and the sidewall portion 15 that are located on the inner side in the tire radial direction than the tread portion 10. The bead portion 60 is located on the inner side in the tire radial direction than the sidewall portion 15.

  A belt layer 20 composed of a plurality of (for example, 4 to 6) corded belts is provided inside the tread portion 10 in the tire radial direction. The tread portion 10 is formed with a pattern (not shown) according to the use environment of the construction vehicle tire 1 and the type of construction vehicle to be mounted.

  Further, a carcass layer 30 is provided on the inner side in the tire radial direction of the belt layer 20 so as to straddle the pair of left and right bead cores 61 and form a skeleton of the construction vehicle tire 1.

  In the present embodiment, the carcass layer 30 has a radial structure having carcass cords 31 (not shown in FIG. 1, refer to FIG. 2) arranged radially along the tire radial direction. However, the present invention is not limited to the radial structure, and a bias structure in which the carcass cords are arranged so as to cross in the tire radial direction may be used.

  As shown in FIG. 1, the construction vehicle tire 1 is a pneumatic tire, but the gas filled in the construction vehicle tire 1 assembled to the wheel rim 100 is not limited to air, but may be nitrogen gas or the like. The inert gas may be filled. Furthermore, a cooling liquid (coolant) may be filled.

(2) Configuration of Bead Part FIG. 2 is an enlarged cross-sectional view of the bead part 60 of the construction vehicle tire 1. As shown in FIG. 2, the carcass layer 30 includes a carcass body 40 and a carcass folding portion 50. The carcass main body 40 and the carcass folding portion 50 have a structure in which the carcass cord 31 is covered with rubber.

  The carcass main body portion 40 is located from the tread portion 10 (see FIG. 1) to the bead core 61 and constitutes a main portion of the carcass layer 30. The carcass folded portion 50 is a portion that is continuous with the carcass main body portion 40 and is folded from the inner side in the tire width direction of the bead core 61 to the outer side in the tire width direction. The carcass folded portion 50 extends from the bead core 61 toward the outer side in the tire radial direction. An end portion 51 of the carcass folded portion 50 terminates at the sidewall portion 15.

  FIG. 3 shows a specific positional relationship between the carcass main body portion 40 and the carcass folding portion 50 of the construction vehicle tire 1. As shown in FIG. 3, the inter-cord distance, which is the distance between the carcass cord 31 of the carcass main body portion 40 and the carcass cord 31 of the carcass folded-back portion 50, decreases with increasing distance from the bead core 61 in the tire radial direction. Minimum value a. After the cord distance reaches the minimum value a, the distance between the cords increases toward the outer side in the tire radial direction and reaches a maximum value b.

  The distance between the cords in the cross section along the tire width direction and the tire radial direction as shown in FIG. 2 is the carcass cord 31 of the carcass main body 40 with respect to the perpendicular to the carcass cord 31 of the carcass main body 40, and This is the distance (interval) between the carcass folded portion 50 and the carcass cord 31. More specifically, the inter-cord distance is a distance between the center in the thickness direction of the carcass cord 31 of the carcass main body portion 40 and the center in the thickness direction of the carcass cord 31 of the carcass folded portion 50.

  When the construction vehicle tire 1 is mounted on the wheel rim 100, which is an applicable rim, the height HA of the carcass cord 31 of the carcass main body portion 40, which is a minimum value a from the base line BL of the wheel rim 100, is maximum from the base line BL. The height HB of the carcass cord 31 of the carcass main body 40 having the value b and the height HF from the base line BL to the rim flange 110 of the wheel rim 100 satisfy the following relationship.

1.2HF ≦ HA ≦ 2.5HF
3.1HF ≦ HB ≦ 4.5HF
The base line BL is a straight line that is parallel to the rotation axis of the wheel rim 100 and passes through the end (bead heel) of the bead portion 60 on the outer side in the tire width direction.

  The applicable rim is, for example, the standard size wheel rim specified in the Japan Automobile Tire Association (JATMA) Year Book. The heights HA, HB and HF described above are the measurement conditions (applicable to JATMA). Measured with the rim mounted, specified internal pressure setting, set temperature, etc.). Note that other standards (TRA, ETRTO, etc.) may be used instead of JATMA.

  FIG. 4 shows a specific shape of the carcass folded portion 50 of the construction vehicle tire 1. As shown in FIG. 4, the distance from the position of the local minimum value a to the position of the local maximum value b along the carcass cord 31 of the carcass folding portion 50 is defined as a distance L1. Further, a distance from the position of the local maximum value b along the carcass cord 31 of the carcass folded portion 50 to the end 51 on the outer side in the tire radial direction of the carcass folded portion 50 is defined as a distance L2.

  In the construction vehicle tire 1, the distance L1 is longer than the distance L2. That is, in the positional relationship between the minimum value a, the maximum value b, and the end portion 51 of the carcass folded portion 50 in the tire radial direction, the location of the maximum value b is located on the outer side in the tire radial direction than the conventional example (described later).

  The end portion 51 of the carcass folded portion 50 terminates near the position of the maximum width SWmax at which the width of the sidewall portion 15 in the tire width direction is maximum. Note that the end 51 is preferably terminated on the inner side in the tire radial direction from the portion of the maximum width SWmax. Therefore, the position of the maximum value b in the tire radial direction is also located on the inner side in the tire radial direction than the portion of the maximum width SWmax. Alternatively, the position of the maximum value b in the tire radial direction is preferably positioned on the outer side in the tire radial direction from the position of half the height from the baseline BL (see FIG. 3) to the maximum width SWmax.

  Further, the relationship between the thickness of the rubber gauge at the position of the maximum value b is as follows: the thickness from the tire surface to the outer surface in the tire width direction of the carcass folded portion 50 is the inner surface in the tire width direction of the carcass folded portion 50 to the carcass main body portion 40. It is thinner than the thickness up to the outer surface in the tire direction. On the other hand, the relationship of the thickness of the rubber gauge at the position of the minimum value a is opposite to the position of the maximum value b, and the thickness from the tire surface to the outer surface in the tire width direction of the carcass folded portion 50 is the same as that of the carcass folded portion 50. It is thicker than the thickness from the inner surface in the tire width direction to the outer surface in the tire direction of the carcass main body 40.

  In the present embodiment, there is only one place where the maximum value b is between the bead core 61 and the end portion 51 of the carcass folded portion 50. However, the number of places where the local maximum value b is not necessarily limited to one. In this embodiment, the ratio b / a between the minimum value a and the maximum value b is 1.10 or more and less than 2.00.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. Hereinafter, differences from the construction vehicle tire 1 according to the first embodiment described above will be mainly described, and description of portions similar to the construction vehicle tire 1 will be omitted as appropriate.

  FIG. 5 is an enlarged cross-sectional view of the bead portion 60 of the construction vehicle tire 1A according to the present embodiment. The structure of the tread portion 10 and the belt layer 20 of the construction vehicle tire 1A is the same as that of the construction vehicle tire 1. As shown in FIG. 5, the construction vehicle tire 1 is different from the construction vehicle tire 1 in the shape (positional relationship) of the carcass folding portion 50.

  FIG. 6 shows a specific positional relationship between the carcass main body portion 40 and the carcass folding portion 50 of the construction vehicle tire 1A. As shown in FIG. 6, when the construction vehicle tire 1A is mounted on the wheel rim 100, the height HA of the carcass cord 31 of the carcass main body 40 that has a minimum value a from the baseline BL of the wheel rim 100, the baseline The height HB of the carcass cord 31 of the carcass main body 40 having the maximum value b from BL, and the height HF from the base line BL to the rim flange 110 of the wheel rim 100 satisfy the following relationship.

1.2HF ≦ HA ≦ 2.5HF
2.6HF ≦ HB ≦ 3.5HF
1.10 ≦ b / a <1.40
Further, a straight line SL1 that passes through the position of the carcass cord 31 of the carcass main body portion 40 at which the minimum value a is reached and the position of the carcass cord 31 of the carcass main body portion 40 at which the maximum value b is reached, and the carcass folding portion that has the minimum value a The crossing angle θ between the position of the carcass cord 31 and the straight line SL2 passing through the position of the carcass cord 31 of the carcass folding portion at which the maximum value b is satisfied satisfies the following relationship.

2.00 ° ≦ θ ≦ 5.00 °
Thus, the intersection angle θ is small, and in the construction vehicle tire 1A, the maximum value b of the inter-cord distance is small as compared with the conventional example and the construction vehicle tire 1.

  As in the construction vehicle tire 1 according to the first embodiment, there is only one location where the maximum value b is between the bead core 61 and the end portion 51 of the carcass folded portion 50. However, the number of places where the local maximum value b is not necessarily limited to one.

[Action / Effect]
FIG. 7 is a schematic diagram for explaining compression deformation and tensile deformation that occur in the tire 1 for a construction vehicle. As shown in FIG. 7, in the vicinity where the distance between the cords is the minimum value a, when the load is applied to the construction vehicle tire 1, the carcass folded portion 50 is compressed and deformed. On the other hand, tensile deformation occurs in the carcass folded portion 50 in the vicinity where the distance between cords reaches the maximum value b.

  The carcass cord 31 of the carcass folding portion 50 gradually spreads outward in the tire width direction from the position of the minimum value a to the position of the maximum value b, that is, away from the carcass cord 31 of the carcass main body 40. Therefore, even if the carcass folded portion 50 is compressed and deformed, the carcass folded portion 50 buckles, more specifically, the carcass cord 31 of the carcass folded portion 50 is bent due to the compressive deformation and meanders. The state can be suppressed.

  On the other hand, since a sufficient inter-cord distance is maintained near the position of the maximum value b, the position of the carcass cord 31 of the carcass folded portion 50 is sufficiently separated from the bending neutral axis AX near the position of the maximum value b. . For this reason, the carcass folded-back portion 50 is more adaptable to the tensile deformation, and the tensile deformation near the position of the maximum value b is emphasized. As a result, there is an effect that compression deformation near the position of the minimum value a can also be suppressed.

  Further, in the construction vehicle tire 1, the maximum value b is located on the outer side in the tire radial direction compared to the conventional example. Therefore, when the tensile deformation or the compression deformation occurs in the construction vehicle tire 1, the lateral force (Fy ) Is high, the state where the inflection point P between the tensile deformation and the compression deformation is located on the outer side in the tire radial direction from the maximum value b (reverse phenomenon) can be avoided more reliably.

  Such an effect is the same in the construction vehicle tire 1A in which the maximum value b of the distance between cords is reduced. In the case of the construction vehicle tire 1A, the fitness for tensile deformation is limited compared to the construction vehicle tire 1, but by reducing the maximum value b, the distribution of structural rigidity is reduced and the movement of the inflection point P Therefore, the above reversal phenomenon can be suppressed.

  FIG. 8 shows test results of construction vehicle tires according to a conventional example, a comparative example, and an example. The conventional example shown in FIG. 8 is a construction vehicle tire described in a prior art document (Japanese Patent Laid-Open No. 2009-113715). The comparative example is a tire for a construction vehicle in which the carcass folded portion 50 does not have a convex portion such as the maximum value b. Example 1 is a construction vehicle tire 1 and Example 2 is a construction vehicle tire 1A.

  Specifically, Example 1 has the following set values.

HA = 2.06HF
HB = 3.55HF
b / a = 1.34
Example 2 has the following set values.

HA = 2.06HF
HB = 3.00HF
b / a = 1.34
θ = 4 °
The size of the construction vehicle tire used in the test is 59 / 80R63.

  As shown in FIG. 8, both the conventional example and the construction vehicle tires according to Examples 1 and 2 do not input lateral force (Fy) but only input vertical force (Fz). The meandering amount (buckling) of the ply is kept low. On the other hand, in the comparative example, the amount of meandering is relatively large even when only the vertical force (Fz) is input. The vertical force (Fz) was set to 120 t.

  As the lateral force increases, the meandering amount increases in the conventional example. That is, the carcass layer cannot sufficiently cope with compression deformation. On the other hand, in the comparative example and Examples 1 and 2 (particularly, Example 2), even if the lateral force increases, the amount of meandering does not increase extremely, and it can sufficiently cope with the actual use environment.

  Thus, according to the construction vehicle tire 1 (Example 1) according to the first embodiment and the construction vehicle tire 1A (Example 2) according to the second embodiment, the minimum value a of the distance between cords and The maximum value b and HA, HB, HF, and b / a satisfy the relationship as described above. Thereby, even in a situation close to the actual use environment where a large lateral force is input, the compressive strain generated in the carcass folded portion 50 can be reduced, and the durability of the bead portion 60 can be improved.

  If HA, HB, HF, and b / a do not satisfy the above relationship, the characteristics as in Example 1 or Example 2 shown in FIG. Improvement is also limited.

  Further, as shown in FIG. 8, according to the construction vehicle tire 1 and the construction vehicle tire 1A, the meandering amount (buckling) of the carcass layer (ply) even when only the vertical force (Fz) is input. Is kept low, and does not adversely affect the durability of the bead portion 60.

[Other Embodiments]
As described above, the contents of the present invention have been disclosed through the embodiments of the present invention. For example, the embodiments of the present invention can be modified as follows.

  For example, in the above-described embodiment, the tire for a construction vehicle used for a dump truck or an articulated dump truck traveling on a crushed stone, a mine, or a dam site is assumed. However, the scope of the present invention is not necessarily limited to such a construction vehicle. It is not limited to tires. For example, the present invention may be applied to tires for construction vehicles other than dump trucks that travel on construction sites, rough terrain, and muddy grounds.

  Further, the number of the belt layers 20 is an example, and the configuration of the belt layers 20 may be appropriately changed according to the use of the tire for construction vehicles.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is determined only by the invention specifying matters according to the scope of claims reasonable from the above description.

1, 1A Construction vehicle tires
10 Tread
15 Side wall
20 belt layers
30 carcass layers
31 Carcass cord
40 Carcass body
50 Carcass folding part
51 edge
60 Bead section
61 Beadcore
100 wheel rim
110 Rim flange

Claims (4)

A carcass body covered with a carcass cord;
A tire for a construction vehicle, which is connected to the carcass main body, and is folded from the inner side in the tire width direction of the bead core to the outer side in the tire width direction, and includes a carcass folded portion covered with a carcass cord,
The distance between the cords, which is the distance between the carcass cord of the carcass main body portion and the carcass cord of the carcass turn-up portion, decreases from the bead core toward the outer side in the tire radial direction and becomes a minimum value a, and the minimum value a After that, as it goes to the outside in the tire radial direction, it becomes larger and becomes a maximum value b,
When the tire for a construction vehicle is mounted on an applicable rim, the carcass cord height HA of the carcass main body that becomes the minimum value a from the baseline of the applied rim, and the maximum value b from the baseline of the applied rim. The height HB of the carcass cord of the carcass main body portion, and the flange height HF of the application rim from the base line of the application rim,
1.2HF ≦ HA ≦ 2.5HF
3.1HF ≦ HB ≦ 4.5HF
Tires for construction vehicles that satisfy this relationship.   The distance L1 from the position of the minimum value a along the carcass cord of the carcass folded portion to the position of the maximum value b is the distance L1 from the position of the maximum value b along the carcass cord of the carcass folded portion. The tire for a construction vehicle according to claim 1, wherein the tire is longer than a distance L2 to an end portion on the outer side in the tire radial direction.   2. The construction vehicle tire according to claim 1, wherein there is only one portion having the maximum value b from the bead core to an end portion on the outer side in the tire radial direction of the carcass folded portion. The tire for construction vehicles according to claim 1, wherein a ratio b / a between the minimum value a and the maximum value b is 1.10 or more and less than 2.00.

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