Small-specification low-flatness-ratio truck radial tire

Abstract

The utility model discloses a truck radial tire with small specification and low flatness ratio, which is characterized in that a carcass ply and chafer are arranged at the end points of the axial outer side surface of a sidewall part and are respectively a carcass turn-up end point A and a chafer outer side end point B, and one end, close to lower apex, of filling rubber wraps the A and the B; a vertical line AC is led from a carcass turn-up endpoint A to the axial inner side face of the sidewall portion to intersect at C, the distance between the carcass turn-up endpoint A and the axial outer side face of the sidewall portion in the direction of the vertical line AC is w, the intersecting length of the vertical line AC and the filling rubber is t2, and t2 is larger than or equal to 0.3 w and smaller than or equal to 0.5 w. By adjusting the sizes of the upper apex, the lower apex and the filling rubber, selecting proper rubber loss angle tangent values of the upper apex, the lower apex and the filling rubber and optimizing rigid distribution, the distribution of the chafer and the tire body turn-up endpoints is adjusted, so that the rigid distribution condition of the tire bead part is optimized; the shear strain and the heat production condition of the turn-up endpoint of the tire body are reduced, so that the bearing capacity of the tire is improved while the service life of the tire is ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of radial tires, and particularly relates to a load-carrying radial tire with a small size and a low aspect ratio. Background Art

[0002] As is well known, a tire mainly includes: a crown structure that comes into contact with the ground to play a supporting role; a bead structure that is close to the wheel hub to play a sealing and fixing role; a sidewall structure that plays a role in shock absorption and protecting the tire between the bead and the crown; and a carcass structure that plays a role in maintaining the shape of the tire inside the tire. In the field of large-piece transportation, trailers generally transport oversized or overweight large equipment, mainly including wind power equipment transport vehicles, bridge transport vehicles, etc. The requirement for tires is to reduce the height of the trailer as much as possible, thereby increasing the height of the transported goods.

[0003] Existing trailer factories generally use radial tires with a small size and a low aspect ratio. A small size generally refers to a tire diameter of 17.5 inches, and the section width ≤ 245 mm. A low aspect ratio refers to a tire with an aspect ratio ≤ 75%. The section width refers to the cross-sectional width of the tire, and the aspect ratio refers to the ratio of the height of the tire to its width. The height of this kind of tire is relatively low, which can reduce the height of the trailer.

[0004] However, the sidewalls of existing radial tires with a small size and a low aspect ratio are relatively thin. During the high-load rolling process of the tires used on trailers, large bending deformations will occur in the sidewalls and beads. The shear strain at the carcass end point of the bead part is large, and the heat generation is high, which easily causes the rubber compound at the carcass end point to tear, ultimately leading to failures, and the use cost of trailers for large-piece transportation increases. Summary of the Utility Model

[0005] In order to solve the problem of weak load-bearing capacity of existing radial tires with a small size and a low aspect ratio, the utility model provides a load-carrying radial tire with a small size and a low aspect ratio. The specific technical solutions are as follows:

[0006] The load-carrying radial tire in the utility model includes a bead part, a sidewall part and a crown part. The bead part includes a bead wrapper, a carcass ply, a bead wire, a lower triangular rubber and an upper triangular rubber. The bead part includes: a filling rubber arranged between the axial outer side of the upper triangular rubber and the sidewall part. The endpoints of the carcass ply and the bead wrapper arranged on the axial outer side of the sidewall part are respectively a carcass turn-up endpoint A and a bead wrapper outer endpoint B. One end of the filling rubber close to the lower triangular rubber can wrap the carcass turn-up endpoint A and the bead wrapper outer endpoint B. A perpendicular line AC is drawn from the carcass turn-up endpoint A to the axial inner side of the sidewall part and intersects at C. The distance between the carcass turn-up endpoint A along the perpendicular line AC and the axial outer side of the sidewall part is w, and the intersecting length of the perpendicular line AC and the filling rubber is t2, where 0.3w ≤ t2 ≤ 0.5w.

[0007] Furthermore, the intersection length of the perpendicular line AC and the upper triangular rubber is t1, where 9 mm ≤ t1 ≤ 12 mm.

[0008] Preferably, the radial direction of the crown part is the vertical direction, a sidewall is provided on the outer axial surface of the sidewall part, the vertical distance from the carcass turn-up end point A to the mating diameter marking line is H1, and the vertical distance between the two ends of the sidewall is LSH, where 0.35 ≤ H1 / LSH ≤ 0.45.

[0009] Preferably, the vertical distance from the outer end point B of the bead filler to the mating diameter marking line is H2, where 10 mm ≤ H1 - H2 ≤ 20 mm.

[0010] Preferably, the vertical distance from the end of the upper triangular rubber near the crown part to the mating diameter marking line is H3, where 35 mm ≤ H3 - H1 ≤ 50 mm.

[0011] Preferably, the vertical distance from the end of the lower triangular rubber near the crown part to the mating diameter marking line is H4, where 0.35 ≤ H4 / H3 ≤ 0.65.

[0012] Preferably, the end point of the bead filler provided on the inner axial surface of the sidewall part is the inner end point P of the bead filler. A perpendicular line BD is drawn from the outer end point B of the bead filler to the inner axial surface of the sidewall part and intersects at D. The distance between the inner end point P of the bead filler and the perpendicular line BD is P1. The direction close to the crown part of the inner end point P of the bead filler is the positive direction, P1 ≥ 0 mm. The distance from the inner end point P of the bead filler to the perpendicular line AC is P2. The direction away from the crown part of the inner end point P of the bead filler is the negative direction, where -11 mm ≤ P2 ≤ 5 mm.

[0013] Preferably, the tangent of the loss angle of the upper triangular rubber tanδ1 ≤ 0.09, the tensile modulus is 3.5 - 4.5 MPA, the tangent of the loss angle of the filler rubber tanδ2 ≤ 0.09, the tensile modulus is 3.5 - 4.5 MPA, and the tensile modulus of the lower triangular rubber is 10 - 14 MPA.

[0014] Preferably, the number of bead wires is n, where 33 ≤ n ≤ 39.

[0015] Preferably, the radial cross-sections of the upper triangular rubber and the lower triangular rubber are both triangular, and the radial cross-section of the lower triangular rubber gradually narrows from the bead wire to the upper triangular rubber.

[0016] From the above technical solutions, it can be seen that the present utility model has the following beneficial effects:

[0017] By adjusting the dimensions and tangent of the loss angle of the upper triangular rubber, the lower triangular rubber, and the filler rubber, and adjusting the distribution of the inner and outer end points of the bead wrapper and the carcass turn-up end points, the rigidity distribution of the bead part is optimized, the shear strain and heat generation of the carcass turn-up end points are reduced, and the load-carrying capacity is improved while ensuring the service life of the tire. Brief Description of the Drawings

[0018] Figure 1 It is a schematic structural diagram of an embodiment of the present utility model;

[0019] Figure 2 is Figure 1 a partial enlarged view.

[0020] In the figure: 1, the crown part; 2, the sidewall part; 3, the bead part; 21, the sidewall rubber; 22, the carcass ply; 31, the upper triangular rubber; 32, the lower triangular rubber; 33, the filler rubber; 34, the bead wire; 35, the bead wrapper. Detailed Embodiment

[0021] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0022] In the description of the embodiments of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "inner", "outer", "upper", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present utility model is usually placed during use. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model.

[0023] As Figure 1 shown, a small-sized low-profile radial truck tire has a bead part 3, a sidewall part 2, and a crown part 1 distributed in sequence along the radial direction of the tire from the axis of the radial truck tire. From the end of the bead part 3, a bead wrapper 35, a carcass ply 22, a bead wire 34, a lower triangular rubber 32, and an upper triangular rubber 31 are distributed in sequence along the radial direction.

[0024] Specifically, the tread crown portion 1 contacts the bottom surface, the sidewall portions 2 are disposed on the two axial side surfaces of the tread crown portion 1. When the tread crown portion 1 is subjected to pressure, the sidewall portions 2 are bent and deformed. The bead portions 3 are disposed at one end of the sidewall portions 2 away from the tread crown portion 1 for contacting the wheel hub. Secondly, both ends of the carcass ply 22 are respectively turned up around the bead wire 34, and the lower triangular rubber 32 and the upper triangular rubber 31 are sequentially filled from the bead wire 34 to the carcass ply 22, so that the rigidity of the tire is sequentially increased from the axial side surface of the tread crown portion 1 to the bead portion 3.

[0025] Further, the bead portion 3 includes: a filler rubber 33 disposed between the upper triangular rubber 31 and the axial outer side surface of the sidewall portion 2. The tangent value of the loss angle tanδ1 of the upper triangular rubber 31 is ≤ 0.09, and the tensile modulus is 3.5 - 4.5 MPA. The tangent value of the loss angle tanδ2 of the filler rubber 33 is ≤ 0.09, and the tensile modulus is 3.5 - 4.5 MPA. The tensile modulus of the lower triangular rubber 32 is 10 - 14 MPA.

[0026] Specifically, the smaller the tangent value of the loss angle, the less energy is dissipated by the upper triangular rubber 31 during deformation, resulting in less heat generation, and the anti-turnup end point A of the carcass is not easily damaged, improving the durability. When tanδ1 ≤ 0.09, the heat generation of the upper triangular rubber 31 meets the requirements of the embodiments of the present invention. The smaller the tensile modulus, the lower the ability of the upper triangular rubber 31 and the lower triangular rubber 32 to resist deformation, reducing the ability of the sidewall portion 2 to resist deformation, improving the shock absorption ability of the tire, and reducing the rigidity of the tire. The larger the tensile modulus, the higher the ability of the upper triangular rubber 31 and the lower triangular rubber 32 to resist deformation, increasing the bending strength of the sidewall portion 2, increasing the rigidity of the tire, and increasing the load-bearing capacity of the tire, but reducing the shock absorption ability of the tire. Therefore, when the tensile modulus of the upper triangular rubber 31 is 3.5 - 4.5 MPA and the tensile modulus of the lower triangular rubber 32 is 10 - 14 MPA, the rigidity change of the sidewall portion 2 from the tread crown portion 1 to the bead portion 3 is uniform, and the bending strength of the sidewall portion 2 meets the requirements of the present invention.

[0027] As Figure 2 shown, the end points of the carcass ply 22 and the bead wrapper 35 disposed on the axial outer side surface of the sidewall portion 2 are the carcass anti-turnup end point A and the outer end point B of the bead wrapper respectively. One end of the filler rubber 33 close to the lower triangular rubber 32 can wrap the carcass anti-turnup end point A and the outer end point B of the bead wrapper. A perpendicular line AC is drawn from the carcass anti-turnup end point A to the axial inner side surface of the sidewall portion 2 and intersects at C. The distance between the carcass anti-turnup end point A along the perpendicular line AC and the axial outer side surface of the sidewall portion 2 is w, and the intersecting length of the perpendicular line AC and the filler rubber 33 is t2, where 0.3w ≤ t2 ≤ 0.5w.

[0028] Specifically, after the tire is loaded, the sidewall portion 2 bends, causing the bead portion 3 to bend, and the carcass cord 22 and the bead chafer 35 can improve the bending strength of the two by applying a force to resist deformation to the sidewall portion 2, thereby improving the load-bearing capacity of the tire; secondly, the filling rubber 33 wraps the carcass turn-up end point A and the outer end point B of the bead chafer so that the two do not undergo relative displacement when the sidewall portion 2 is bent, and then during the repeated bending of the sidewall portion 2, the carcass cord 22 and the bead chafer 35 on the axially outer side of the sidewall portion 2 are always connected, thereby improving the ability of the carcass cord 22 and the bead chafer 35 to resist deformation of the sidewall portion 2; secondly, the filling rubber 33 adopts a rubber material with a small loss tangent value, which generates little heat during the deformation process, the carcass turn-up end point A is not easily damaged, and the durability is improved.

[0029] Secondly, a sidewall portion 21 is arranged between the filling rubber 33 and the axial outer side of the sidewall portion 2. The sidewall portion 21 is used to protect the internal structure of the sidewall portion 2. Its anti-fatigue and anti-oxidation capabilities are stronger than those of the filling rubber 33, so that the fatigue limit of the sidewall portion 21 is higher than that of the filling rubber 33.

[0030] Among them, the vertical carcass turn-up endpoint AC is the line of action of the pressure at the carcass turn-up endpoint A when the sidewall portion 2 is bent. Therefore, w represents the total thickness of the filling rubber 33 and the sidewall portion 21 at the carcass turn-up endpoint A under pressure, and t2 represents the thickness of the filling rubber 33 at the carcass turn-up endpoint A under pressure. The greater the thickness of the filling rubber 33 at the carcass turn-up endpoint A, the smaller the thickness of the sidewall rubber 21 at the carcass turn-up endpoint A, so that the heat generation at the carcass turn-up endpoint is smaller, but the fatigue resistance and oxidation resistance are lower, thereby reducing the life of the tire; when the thickness of the filling rubber 33 at the carcass turn-up endpoint A is smaller, the thickness of the sidewall rubber 21 at the carcass turn-up endpoint A is larger, and it is more difficult for the filling rubber 33 to restrain the relative displacement of the carcass turn-up endpoint A and the outer end point B of the tire chafer and the ability of the filling rubber 33 to resist deformation, so that the heat generation at the carcass turn-up endpoint A increases, thereby reducing the bending strength and service life of the sidewall portion 2. When 0.3w≤t2≤0.5w, the thickness of the filling rubber 33 and the sidewall rubber 21 are balanced, so that a balance is formed between the low heat generation capacity of the filling rubber 33 and the anti-fatigue ability of the sidewall rubber 21, thereby achieving the best effect, thereby improving the load-bearing capacity of the tire without affecting its service life.

[0031] Furthermore, the intersecting length of the perpendicular line AC and the upper triangular rubber 31 is t1, where 9 mm ≤ t1 ≤ 12 mm. Specifically, t1 represents the thickness of the upper triangular rubber 31 when it bears pressure at the carcass turning-up end point A. Among them, to ensure the performance of the upper triangular rubber 31, the dimensions of the upper triangular rubber 31 are enlarged or reduced according to a fixed ratio. Therefore, when t1 decreases, the axial thickness of the upper triangular rubber 31 in the sidewall part 2 decreases. When the sidewall part 2 bends and deforms, the upper triangular rubber 31 has less bending deformation, while the lower triangular rubber 32 has greater bending deformation, resulting in more heat generated by the lower triangular rubber 32. Moreover, the rigid transition distribution from the lower triangular rubber 32 to the upper triangular rubber 31 is uneven, leading to a large shear strain at the carcass turning-up end point A, further intensifying heat generation and making the carcass turning-up end point A prone to damage. Secondly, the radial length of the upper triangular rubber 31 in the sidewall part 2 decreases, causing the end of the upper triangular rubber 31 near the crown part 1 to move away from the crown part 1. Consequently, when the sidewall part 2 bends and deforms, the bending strength of the section near the crown part 1 decreases, thereby reducing the overall bending strength of the sidewall part 2 and the load-bearing capacity of the tire.

[0032] Secondly, when t1 increases, the axial thickness of the upper triangular rubber 31 in the sidewall part 2 increases, making it difficult for the heat accumulated by the upper triangular rubber 31 during bending deformation to dissipate. As a result, the temperature of the upper triangular rubber 31 becomes too high, reducing its performance such as tear resistance. In addition, the increased thickness will increase the bending strength of the upper triangular rubber 31, increasing the bending strength of the sidewall part 2 in the area of the upper triangular rubber 31. The increased thickness will also increase the radial length of the upper triangular rubber 31 in the sidewall part 2, making the upper triangular rubber 31 closer to the deformation area with the largest deformation in the sidewall part 2, increasing the bending strength of some deformation areas, and thus destroying the bending strength distribution in the deformation area, making the deformation area more prone to fatigue damage and reducing the fatigue limit of the sidewall part 2. Secondly, when t1 increases, the total axial thickness of the upper triangular rubber 31 and the lower triangular rubber 32 in the sidewall part 2 increases, making the size of the sidewall part 2 not meet the requirements of aesthetics and cost. Therefore, when 9 mm ≤ t1 ≤ 12 mm, the thickness of the upper triangular rubber 31 and the sidewall 21 rubber reaches a balance, enabling the load-bearing capacity and durability of the tire to reach a balance and improving the comprehensive performance of the tire.

[0033] Furthermore, the radial direction of the crown part 1 is the vertical direction. A sidewall is provided on the outer axial surface of the sidewall part 2. The vertical distance from the carcass turning-up end point A to the mounting diameter marking line is H1, and the vertical distance between the two ends of the sidewall is LSH, where 0.35 ≤ H1 / LSH ≤ 0.45.

[0034] The mounting diameter refers to the diameter of the bead point, which is an important dimension for the tire to match with the rim in the tire technology field. Whether its geometric dimensions are reasonable directly affects the service life of the tire. It is Figure 2The radial diameter at the subscript position of LSH is shown in the middle. The bead diameter marking line is the marking line of the bead diameter on the tire, which is also the position of the bead heel point on the tire.

[0035] Specifically, LSH is approximately 0.5SH, and SH is determined according to the outer diameter of the tire and the diameter of the wheel hub. Therefore, when the outer diameter of the tire and the diameter of the wheel hub are determined, and combined with the usage requirements of the tire, LSH can also be determined accordingly. Therefore, the change trend of the value of H1 / LSH is approximately the same as the change trend of H1.

[0036] Among them, the smaller H1 is, the farther the end of the carcass ply 22, the carcass turn-up end point A, is from the crown part 1 and the deformation zone, and the closer it is to the bead wire 34 and the lower apex 32. This makes the length of the carcass ply 22 arranged on the axial outer surface of the sidewall part 2 in the radial direction of the sidewall part 2 shorter. As a result, when the sidewall part 2 bends and deforms, the part of the carcass ply 22 that can resist deformation is less, and further reduces the bending strength of the sidewall part 2 and the load-bearing capacity of the tire; the larger H1 is, the closer the end of the carcass ply 22, the carcass turn-up end point A, is to the crown part 1 and the deformation zone, and the farther it is from the bead wire 34 and the lower apex 32. This makes the length of the carcass ply 22 arranged on the axial outer surface of the sidewall part 2 in the radial direction of the sidewall part 2 longer. As a result, the carcass turn-up end point A is too close to the deformation zone, increasing the degree of deformation at the carcass turn-up end point A, and further accelerating the separation and cracking at the carcass turn-up end point A, resulting in a failure of the sidewall part 2. In addition, the too-long length of the bending deformation of the carcass ply 22 is likely to generate a large amount of heat during the deformation process, affecting the performance of the upper apex 31, the lower apex 32, and the filler rubber 33. Therefore, when 0.35 ≤ H1 / LSH ≤ 0.45, the position of the carcass turn-up end point A relative to the deformation zone and the bead wire 34 reaches a balance, making the bending strength and durability of the sidewall part 2 reach the optimal solution and improving the comprehensive performance of the tire.

[0037] Furthermore, the vertical distance from the bead wrapper turn-up end point B to the bead diameter marking line is H2, and 10mm ≤ H1 - H2 ≤ 20mm.

[0038] Specifically, when H1 is determined, the value of H1 - H2 represents the position of the outer end point B of the chafer relative to the turned-up end point A of the carcass and their positions relative to the sidewall part 2. Among them, when H1 - H2 is smaller, the two end points of the carcass ply 22 and the chafer 35 are closer. When the sidewall part 2 bends, stress concentration is likely to occur at the two end points, making it easy for the two end points to break away from the filler rubber 33 and cause cracking failures. When H1 - H2 is larger, the chafer turned-up end point B is closer to the bead 34, and the length of the chafer 35 on the radial direction of the sidewall part 2 is shorter, resulting in a smaller contact area between the chafer 35 and the outer axial surface of the sidewall part 2. Furthermore, when the sidewall part 2 bends, the part of the chafer 35 that resists bending deformation becomes smaller, and thus the bending strength of the sidewall part 2 decreases. Therefore, when 10mm ≤ H1 - H2 ≤ 20mm, the position of the chafer turned-up end point B relative to the carcass turned-up end point A can achieve a balance between improving the bending strength of the sidewall part 2 and reducing cracking, thereby improving the comprehensive performance of the tire.

[0039] Furthermore, the radial cross-sections of the upper apex rubber 31 and the lower apex rubber 32 are both triangular, and the radial cross-section of the lower apex rubber 32 gradually narrows from the bead 34 to the upper apex rubber 31.

[0040] Specifically, the bending strength of the upper apex rubber 31 is lower than that of the lower apex rubber 32. The upper apex rubber 31 is closer to the outer axial surface of the sidewall part 2 than the lower apex rubber 32, making the bending strength of the sidewall part 2 smaller closer to the crown part 1 and larger and less deformed farther away from the crown part 1.

[0041] Furthermore, the vertical distance from the end of the upper apex rubber 31 close to the crown part 1 to the mounting diameter marking line is H3, and 35mm ≤ H3 - H1 ≤ 50mm.

[0042] Specifically, when H1 is determined, H3 - H1 represents the position of one end of the upper triangular rubber 31 close to the deformation zone relative to the sidewall part 2. Among them, the smaller H3 - H1 is, the smaller the size of the upper triangular rubber 31, the smaller the axial thickness of the upper triangular rubber 31 in the sidewall part 2, resulting in fewer contact parts between the upper triangular rubber 31 and the lower triangular rubber 32, causing the points with the same bending strength in the sidewall part 2 to gradually move downward, making the deformation zone gradually move downward, and further increasing the bending deformation degree of the sidewall part 2 close to the bead part 3. When the sidewall part 2 bends and deforms, the pressure on the bead part 3 gradually increases, which is likely to cause failures in the bead part 3; the larger H3 - H1 is, the larger the size of the upper triangular rubber 31, the larger the axial thickness of the upper triangular rubber 31 in the sidewall part 2, causing the points with the same bending strength in the sidewall part 2 to gradually move upward, making the deformation zone gradually move upward, and further increasing the bending deformation degree of the sidewall part 2 close to the crown part 1. When the sidewall part 2 bends and deforms, the pressure on the intersection position of the axial side of the crown part 1 and the sidewall part 2 gradually increases, which is likely to cause failures and fatigue limits at the intersection position. Therefore, when 35mm ≤ H3 - H1 ≤ 50mm, the size of the upper triangular rubber 31 can make the deformation zone of the sidewall part 2 in a suitable position, improve the bending strength of the sidewall part 2, and not reduce the overall performance of the tire.

[0043] Further, the vertical distance from one end of the lower triangular rubber 32 close to the crown part 1 to the mounting diameter marking line is H4, and 0.35 ≤ H4 / H3 ≤ 0.65.

[0044] Specifically, when H3 is determined, H4 / H3 represents the position of the lower triangular rubber 32 relative to the sidewall portion 2, and more represents its overlapping area with the upper triangular rubber 31. Among them, the lower the H4 / H3, the smaller the radial length of the lower triangular rubber 32 in the sidewall portion 2, that is, the smaller the overlapping area between the lower triangular rubber 32 and the upper triangular rubber 31. Also, because the tensile modulus of the lower triangular rubber 32 is greater than that of the upper triangular rubber 31, in the rigid change trend of the bead portion 3 from one end far from the crown portion 1 to the deformation zone, the rigid change speed of the lower triangular rubber 32 and the triangular rubber accelerates, making the rigid change trend of the sidewall portion 2 uneven, making the bending strength change trend of the sidewall portion 2 uneven. Furthermore, when the sidewall portion 2 undergoes bending deformation, the deformation zone moves downward and approaches the bead portion 3, and the overlapping area between the lower triangular rubber 32 and the upper triangular rubber 31 is prone to fatigue limit, resulting in failures; when H3 is determined and the H4 / H3 is higher, the radial length of the lower triangular rubber 32 in the sidewall portion 2 is larger, and a part of it close to the deformation zone will occupy the position of the upper triangular rubber 31, making the size of the upper triangular rubber 31 decrease. Furthermore, the rigidity of the overlapping area between the lower triangular rubber 32 and the upper triangular rubber 31 is increased and the change speed is accelerated, making the deformation zone move upward and approach the crown portion 1, making the deformation amount of the portion of the sidewall portion 2 with weaker rigidity larger, making the sidewall portion 2 prone to fatigue limit and reducing its service life. When 0.35 ≤ H4 / H3 ≤ 0.65, the rigid change trend of the sidewall portion 2 from the bead portion 3 to the crown portion 1 is relatively gentle, and it can achieve a balance between improving the rigidity of the sidewall portion 2 and reducing its fatigue limit.

[0045] Furthermore, the end point of the bead filler 35 provided on the axial inner side of the sidewall portion 2 is P. A perpendicular line BD is drawn from the outer end point B of the bead filler to the axial inner side of the sidewall portion 2 and intersects at D. The distance between P and the perpendicular line BD is P1, and the direction of P close to the crown portion 1 is the positive direction, P1 ≥ 0 mm. The distance between P and the perpendicular line AC is P2, and the direction of P away from the crown portion 1 is the negative direction, -11 mm ≤ P2 ≤ 5 mm.

[0046] Specifically, when the positions of the carcass turn-up end point A and the outer end point B of the bead filler are determined relative to the sidewall portion 2, the position of the inner end point P of the bead filler relative to the sidewall portion 2 can be determined by P1 and P2. When P1 is less than 0 mm, the intersection point D is closer to the deformation zone than the inner end point P of the bead filler, that is, the outer end point B of the bead filler is closer to the deformation zone than the inner end point P of the bead filler, making the bending deformation area of the bead filler 35 larger when the sidewall portion 2 undergoes bending deformation. Therefore, more heat is generated and it is more likely to separate from the filler rubber 33 and cause cracks. Secondly, the pressure borne by the bead filler 35 on the axial inner side of the sidewall portion 2 is reduced, making the shear strain of the carcass turn-up end point A here increase, and point A is easily damaged; secondly, when P2 is larger, the inner end point P of the bead filler is closer to the deformation zone, and point P is prone to damage. When P2 is smaller, the effect is the same as when P1 is smaller.

[0047] Further, the number of bead wires 34 is n, where 33 ≤ n ≤ 39.

[0048] Specifically, the number of bead wires 34 determines the supporting ability of the bead part 3. When the tire is loaded, the bead part 3 resists deformation through the bead wires 34, thereby improving the load-bearing capacity of the tire. Among them, the smaller n is, the lower the rigidity of the bead part 3; the larger n is, the greater the rigidity of the bead part 3, but the cost also increases. Therefore, when 33 ≤ n ≤ 39, the bead part 3 reaches an optimum between rigidity and cost, improving the comprehensive performance of the tire. At this time, the tensile limit of the bead wire 34 is not less than 3825 N.

[0049] Examples 1 to 9 and Comparative Examples 1 to 3

[0050] Manufacture a small-sized low-profile load-carrying radial tire (245 / 70R17.5) as Figure 1 shown, and test its bead durability through the following method.

[0051] Table 1

[0052]

[0053]

[0054] Table 1 shows the shear strain and strain energy at the bead turn-up end point of the tire carcass under the load condition through finite element analysis, and arranges a machine durability test with an actual tire. The smaller the shear strain value, the smaller the deformation and the better the bead durability performance. The higher the temperature at the bead turn-up end point of the carcass, the worse the bead durability performance. The bead durability result index is the index of the actual machine test result. The larger the value, the longer the tire running time and the better the bead performance. It can be seen from the comparative examples and examples in Table 1 that Examples 1 and 2 effectively reduce the shear strain and temperature at the bead turn-up end point of the carcass, greatly improving the bead durability performance of the tire.

[0055] Manufacture a small-sized low-profile load-carrying radial tire (235 / 75R17.5) as Figure 1 shown, and test its bead durability through the following method.

[0056] Table 2

[0057]

[0058] Note: The temperature field analysis adopts the working condition of high load and low speed to examine the temperature at the carcass end point.

[0059] The inner end point of the chafer is end point C.

[0060] From Table 2, as the height of the inner end point of the wrap increases, the shear strain and temperature of the tire body wrap end point A gradually decrease, but when P2 = 10, the shear strain and temperature have gradually leveled off, and the inner end point is too high at this time, which is prone to internal cracks and failures. Therefore, P1 ≥ 0 and P2 ≤ 5 mm should be satisfied.

[0061] Table 3

[0062]

[0063] From Comparative Example 2, Example 6, and Example 7, it can be seen that as the thickness of the apex rubber at the end point A of the carcass turn-up increases, the shear strain at the end point A of the carcass turn-up decreases, but the temperature at the end point A of the carcass turn-up increases. Therefore, the design of the apex rubber thickness needs to take into account both the shear strain and the temperature, and should satisfy 9≤t1≤12, preferably t1=10.

[0064] Table 4

[0065]

[0066] From Table 4, as the number of wire rings increases, the shear strain and strain energy density of the tire body turn-up end point A decrease, the actual machine tool running time increases, and the tire bead durability improves. However, after reaching a certain level, the durability performance gradually slows down, and the cost-effectiveness of continuing to increase the number of wire rings is not high. 33≤n≤39 should be satisfied.

[0067] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

[0068] The technology, shape and structure parts not described in detail in the present invention are all known technologies.

Claims

1. A radial truck tire with a small size and a low aspect ratio, the radial truck tire comprising a bead portion (3), a sidewall portion (2) and a crown portion (1), the bead portion (3) comprising a bead filler (35), a carcass ply (22), a bead wire (34), a lower apex (32) and an upper apex (31), characterized in that, The bead portion (3) includes: A filler rubber (33) disposed between the upper apex rubber (31) and the axially outer side surface of the sidewall portion (2). The ends of the carcass ply (22) and the bead wrapper (35) disposed on the axially outer side surface of the sidewall portion (2) are the carcass turn-up end point A and the outer end point B of the bead wrapper respectively. One end of the filler rubber (33) near the lower apex rubber (32) can wrap the carcass turn-up end point A and the outer end point B of the bead wrapper; A perpendicular line AC is drawn from the carcass turn-up end point A to the axially inner side surface of the sidewall portion (2) and intersects at C. The distance between the carcass turn-up end point A along the perpendicular line AC and the axially outer side surface of the sidewall portion (2) is w, and the intersecting length of the perpendicular line AC and the filler rubber (33) is t2, where 0.3w ≤ t2 ≤ 0.5w.

2. The radial ply tyre for trucks according to claim 1, wherein: The intersecting length of the perpendicular line AC and the upper apex rubber (31) is t1, 9 mm ≤ t1 ≤ 12 mm.

3. The radial truck tire according to claim 1, wherein: The radial direction of the crown portion (1) is the vertical direction. A sidewall is provided on the axially outer side surface of the sidewall portion (2). The vertical distance from the carcass turn-up end point A to the marked line of the tire seating diameter is H1, and the vertical distance between the two ends of the sidewall is LSH, 0.35 ≤ H1 / LSH ≤ 0.

45.

4. The radial truck tire according to claim 3, characterized in that: The vertical distance from the outer end point B of the bead wrapper to the marked line of the seating diameter is H2, 10 mm ≤ H1 - H2 ≤ 20 mm.

5. The radial ply tyre for trucks according to claim 4, characterized in that: The vertical distance from the end of the upper apex rubber (31) near the crown portion (1) to the marked line of the seating diameter is H3, 35 mm ≤ H3 - H1 ≤ 50 mm.

6. The radial ply tyre for trucks according to claim 5, characterized in that: The vertical distance from the end of the lower apex rubber (32) near the crown portion (1) to the marked line of the seating diameter is H4, 0.35 ≤ H4 / H3 ≤ 0.

65.

7. The radial ply tyre for trucks according to claim 1, wherein: The end of the bead wrapper (35) disposed on the axially inner side surface of the sidewall portion (2) is the inner end point P of the bead wrapper. A perpendicular line BD is drawn from the outer end point B of the bead wrapper to the axially inner side surface of the sidewall portion (2) and intersects at D. The distance between the inner end point P of the bead wrapper and the perpendicular line BD is P1. The direction of the inner end point P of the bead wrapper near the crown portion (1) is the positive direction, P1 ≥ 0 mm. The distance between the inner end point P of the bead wrapper and the perpendicular line AC is P2. The direction of the inner end point P of the bead wrapper away from the crown portion (1) is the negative direction, -11 mm ≤ P2 ≤ 5 mm.

8. The radial truck tire according to claim 1, wherein: The tangent of the loss angle tanδ1 of the upper apex rubber (31) ≤ 0.09, and the tensile modulus is 3.5 - 4.5 MPA. The tangent of the loss angle tanδ2 of the filler rubber (33) ≤ 0.09, and the tensile modulus is 3.5 - 4.5 MPA. The tensile modulus of the lower apex rubber (32) is 10 - 14 MPA.

9. The radial truck tire according to claim 1, wherein: The number of the bead cores (34) is n, 33 ≤ n ≤ 39.

10. The radial truck tire according to claim 1, wherein: The radial cross-sections of the upper apex rubber (31) and the lower apex rubber (32) are both triangular, and the radial cross-section of the lower apex rubber (32) gradually narrows from the bead core (34) to the upper apex rubber (31).

Images