Pneumatic tire with apex structure with gradually-changed hardness

Abstract

The invention discloses a pneumatic tire with a gradually-changed hardness apex structure. The pneumatic tire comprises first apex arranged on the radial outer side of a steel wire ring. The second apex is arranged on the radial outer side of the first apex, the elastic modulus of the first apex is larger than that of the second apex, the interface of the second apex and the first apex is a curve ab, the curve ab protrudes towards the first apex, the point, with the largest curvature, of the curve ab is a vertex c, and the position of the vertex c meets the condition that H5-H4 = 5-15 mm; h2 / h1 is equal to 0.3 to 0.5. The axial thickness change trend of the first apex and the second apex is optimized by constraining the axial position and the radial position of the vertex c in the curve ab, so that the hardness of the tire bead from the left end point a to the vertex c to the right end point b is uniformly increased, the bearing performance of the tire bead and the tire side is further improved, the bending deformation degree of the tire bead and the tire side is increased, and the service life of the tire is prolonged. The stress concentration at the curve ab is reduced, and the durability of the tire is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of pneumatic tires, and particularly to a pneumatic tire having a triangular apex structure with a gradually changing hardness. Background Art

[0002] As the only component of a vehicle that contacts the ground, the durability of a tire is directly related to driving safety, fuel economy, and service life. Under complex road conditions and long-term loads, fatigue failure in the bead area (including the triangular apex) is one of the main manifestations of insufficient tire durability, and is likely to cause problems such as bead delamination and bulging. The triangular apex is located in the bead area of the tire and undertakes the following core functions: one is mechanical support, which disperses the stress in the bead area through high-hardness rubber compounds to prevent the ply and bead wire from separating due to excessive deformation; the other is a buffering effect, which can absorb the impact load in the contact area between the bead and the rim during driving and reduce local strain. However, there are the following problems in the design of the triangular apex of existing tires: a single-hardness rubber compound is likely to cause stress concentration. For example, a high-hardness rubber compound enhances the support performance but exacerbates bead buckling fatigue, while a low-hardness rubber compound may lead to out-of-control deformation of the tire body. In traditional designs, high-hardness and low-hardness rubber compounds are used in combination, but the quantitative relationship between the shape and durability at the boundary position between the two is not clear, and relying on empirical design results in low optimization efficiency.

[0003] As can be seen from the publicly disclosed Chinese patent CN107471923A, the solid line BBL represents the bead baseline, and the bead baseline is a line that defines the rim diameter of the rim for tire fitting; as can be seen from the publicly disclosed Chinese patent CN119408349A, the tire section width SW is common knowledge in the art; the sidewall deformation area is located in the sidewall area with less rubber, and its axial width is at most the tire section width SW.

[0004] The pneumatic tire disclosed in the publicly disclosed Chinese patent CN107471923A has a ratio (L4 / WC) of the height L4 from the outer end of the cross-sectional arrangement of the wire to the inner end of the second triangular apex to the width WC of the bead core of 0.4 or more and 0.9 or less, and a straight line connecting the two ends of the part where the first triangular apex and the second triangular apex contact is set as LA, and a ratio (DA / WC) of the depth DA of the depression based on the straight line LA to the width WC of 0.2 or more and 0.5 or less. The above technical features roughly limit the shape of the interface between triangular apices of different hardnesses, but do not specifically describe the shape of the combined part of triangular apices of different hardnesses, and thus the quantitative relationship between the combined part of triangular apices of different hardnesses and rigid transition cannot be clarified, and thus the durability of the tire cannot be improved by improving the shape of the combined part of triangular apices of different hardnesses. Summary of the Invention

[0005] The present invention provides a pneumatic tire with a triangular apex structure having a gradually changing hardness in order to improve the rigid transition of the combined part of triangular apexes with different hardnesses. The specific technical solution is as follows:

[0006] A pneumatic tire with a triangular apex structure having a gradually changing hardness, comprising: a carcass and a bead. The carcass includes a main part axially inside the bead and a turned-up part axially outside the bead. The bead includes a bead core provided at the end. The bead further includes: a first triangular apex provided radially outside the bead core; a second triangular apex provided radially outside the first triangular apex. The elastic modulus of the first triangular apex is greater than that of the second triangular apex. The interface between the second triangular apex and the first triangular apex is a curve ab, and the curve ab bulges towards the first triangular apex. The point with the maximum curvature of the curve ab is the vertex c. The radial distance between the vertex c and the bead base line BL is H5. The radial distance between the right endpoint b of the second triangular apex and the bead base line BL is H4. The axial distance between the vertex c and the main part is h2. The axial thicknesses of the first triangular apex and the second triangular apex at the vertex c are h1. The position of the vertex c satisfies: H5 - H4 = 5 to 15 mm; h2 / h1 = 0.3 to 0.5.

[0007] Furthermore, the cross-section of the bead core is an equiangular hexagon. The bead core forms a side surface A with an inclination angle of 15°. The extension line of the side surface A intersects the turned-up part at an intersection point q. The radial distance between the intersection point q and the bead base line BL is H8, and H8 is a determined value. The intersection point of the curve ab and the turned-up part is the right endpoint b. The radial distance between the right endpoint b and the bead base line BL is H4. -5 mm ≤ H8 - H4 ≤ 5 mm; H5 - H4 = h. The radial distance between the vertex c and the right endpoint b is h.

[0008] Furthermore, the bead core is arranged in the surrounded area of the main part and the turned-up part. The minimum distance between the outer side surface of the bead core and the right endpoint b is h4. The minimum distance between the outer side surface of the bead core and the curve ab is h3, and h3 ≥ h4.

[0009] Preferably, the radially outer side of the second triangular apex is in the direction close to the tread. The distance between the upper axial outer endpoint of the second triangular apex and the bead base line BL is H1. The radial distance between the sectional width SW of the mold tire and the bead base line BL is LSH, satisfying: H1 / LSH = 0.7 to 0.9.

[0010] Preferably, the radial distance between the axial outer endpoint f of the turned-up part and the bead base line BL is H2, satisfying: H2 / LSH = 0.3 to 0.5.

[0011] Preferably, the curve ab intersects the main part at the left endpoint a. The left endpoint a is the upper axial inner endpoint a of the first triangular apex. The radial distance between the upper axial inner endpoint a and the bead base line BL is H3, and H3 / H2 = 1 to 1.4.

[0012] Preferably, it further includes a steel cord fabric disposed on the outer side of the carcass. The distance between the axially outer end point e of the steel cord fabric and the axially outer end point f of the turned-up portion is H6, and H6 = 10 - 16 mm.

[0013] Preferably, the axially outer end point f of the turned-up portion is projected onto the projection point p along the perpendicular line perpendicular to the main portion. The distance between the projection point p and the axially inner end point g of the steel cord fabric is H7, and H7 = -10 - 10 mm.

[0014] Preferably, the elastic modulus of the first apex is E1, and E1 = 12 - 15 Mpa; the elastic modulus of the second apex is E2, and E2 = 3 - 6 Mpa.

[0015] From the above technical solutions, the present invention has the following beneficial effects:

[0016] By restricting the axial position and radial position of the vertex c in the constraint curve ab, and optimizing the axial thickness change trend of the first apex and the second apex, the hardness of the bead uniformly increases from the left end point a to the vertex c to the right end point b, thereby improving the load-bearing performance of the bead and the sidewall, increasing the bending deformation degree of both, reducing the stress concentration at the curve ab, and improving the durability of the tire. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a cross-sectional view of a part of the pneumatic tire according to the embodiment of the present invention;

[0018] Figure 2 is Figure 1 the enlarged view of the structure at A in

[0019] In the figure: 1, sidewall; 2, bead; 21, first apex; 22, second apex; 23, bead wire; 3, carcass; 31, main portion; 32, turned-up portion; 4, steel cord fabric. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0021] In the description of the embodiments of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "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 inventive product is usually placed during use. It is only for the convenience of describing the present invention 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 invention.

[0022] As Figure 1 shown, the up, down, left, and right in this embodiment respectively represent the radially outer side, the radially inner side, the axially inner side, and the axially outer side.

[0023] Furthermore, a pneumatic tire having a triangular rubber structure with a gradually changing hardness includes: a carcass 3 and a bead 2. The carcass 3 includes a main part 31 disposed on the axially inner side of the bead 2 and a turn-up part 32 disposed on the axially outer side of the bead 2. The bead 2 includes a bead wire 23 disposed at the end.

[0024] As is known to those skilled in the art, a pneumatic tire includes a tread, a sidewall 1, a carcass 3, and a bead 2. Among them, the part of the carcass 3 disposed on the inner side surface of the tread and the sidewall 1 is the main part 31, and the part where its axially two ends are turned up to the outer side surface of the sidewall 1 is the turn-up part 32. The bead 2 is disposed on the inner side surface of the part where the main part 31 transitions to the turn-up part 32. Secondly, in this embodiment, the bead 2 includes a bead wire 23 disposed at the end of the carcass 3. The cross-section of the bead wire 23 is an equiangular hexagon, and the positional relationship between its six sides and the carcass 3 is relatively fixed. Four sides are in contact with the inner side surface of the carcass 3 to provide support for it.

[0025] As Figure 2 shown, the side of the bead wire 23 facing the main part 31 is side A, and the side facing the turn-up part 32 is side B. The inclination angle of side A is 15°, and the inclination angle of side B is 135°. The reference line for measuring the angle is a straight line parallel to the axis. This inclination angle is the detection value during the production of the pneumatic tire in this embodiment. Furthermore, it can be known that the position of the bead wire 23 relative to the bead 2 is determined. When the diameter of the bead wire 23 is determined, the position of the intersection point q where the extension line of side A intersects the turn-up part 32 can be determined according to the position of the bead wire 23, and then H8 can be determined.

[0026] Furthermore, the bead 2 further includes: a first apex rubber 21 disposed radially outside the bead core 23; a second apex rubber 22 disposed radially outside the first apex rubber 21. The elastic modulus of the first apex rubber 21 is greater than that of the second apex rubber 22. The interface between the first apex rubber 21 and the second apex rubber 22 is a curve ab, which bulges towards the first apex rubber 21. The point with the maximum curvature of the curve ab is the vertex c. The radial distance between the vertex c and the bead base line BL is H5, and the radial distance between the right end point b of the second apex rubber 22 and the bead base line BL is H4. The axial distance between the vertex c and the main part 31 is h2, and the axial thickness of the first apex rubber 21 and the second apex rubber 22 at the vertex c is h1. The position of the vertex c satisfies: H5 - H4 = 5 - 15 mm; h2 / h1 = 0.3 - 0.5.

[0027] Specifically, the left side of the first apex rubber 21 coincides with the inner side of the main part 31, the bottom side of the first apex rubber 21 coincides with the top side of the bead core 23, the top side of the first apex rubber 21 coincides with the bottom side of the second apex rubber 22, and the right side of the first apex rubber 21 coincides with the inner side of the turned-up part 32. Among them, the length of the left side of the first apex rubber 21 is greater than the length of the right side of the first apex rubber 21, so that the first apex rubber 21 forms a trapezoid-like shape; the left side of the second apex rubber 22 coincides with the inner surface of the main part 31, and the right side of the second apex rubber 22 coincides with the inner surface of the turned-up part 32, so that the second apex rubber 22 forms a triangle-like shape, making the hardness of the sidewall 1 and the bead 2 increase gradually from the radially outer side to the radially inner side, thereby ensuring the buffering performance and load-bearing performance of the sidewall 1.

[0028] Secondly, the top side of the first apex rubber 21 is the curve ab, which bulges towards the first apex rubber 21. Its two ends intersect with the main part 31 and the turned-up part 32 respectively. And during the process of the curve ab from the left end point a to the vertex c, its curvature gradually increases, and during the process of the curve ab from the vertex c to the right end point b, its curvature gradually decreases. Thus, during the process from the left end point a to the right end point b, the elastic modulus of the bead 2 gradually increases, that is, the hardness of the bead 2 gradually increases, and the increase is non-linear. Thereby, the hardness distribution of the bead 2 is improved, and the stress concentration during the bending process of the sidewall 1 is reduced, and the service life of the tire is improved.

[0029] Secondly, H5 - H4 represents the radial distance between vertex c and the right endpoint b, which can reflect the hardness transition between the first apex 21 and the second apex 22. When H5 - H4 < 5 mm, the axial thickness of the first apex 21 increases too rapidly from vertex c to the right endpoint b, causing the hardness of the bead 2 to increase too rapidly from vertex c to the right endpoint b, thereby increasing the stress concentration at the curve cb and making it easy for the first apex 21 to separate from the second apex 22, reducing the service life of the bead 2; when H5 - H4 > 15 mm, the axial thickness of the first apex 21 increases too slowly from vertex c to the right endpoint b, causing the hardness of the bead 2 to increase too slowly from vertex c to the right endpoint b, thereby reducing the load-bearing capacity at the curve cb, reducing the load-bearing capacity of the bead 2, increasing its bending deformation degree, reducing its fatigue strength, and reducing the service life of the bead 2.

[0030] Secondly, h2 / h1 represents the distance from vertex c to the inner side edge of the main part 31. The axial distance between vertex c and the left endpoint a is proportional to it. When h2 / h1 increases, vertex c moves away from the left endpoint a; when h2 / h1 decreases, vertex c approaches the left endpoint a. When h2 / h1 < 0.3, the axial thickness of the second apex 22 increases too rapidly from the left endpoint a to vertex c, causing the hardness of the bead 2 to increase too slowly from the left endpoint a to vertex c, thereby reducing the load-bearing capacity at the curve ac, reducing the load-bearing capacity of the bead 2, increasing its bending deformation degree, reducing its fatigue strength, and reducing the service life of the bead 2; when h2 / h1 > 0.5, the axial thickness of the second apex 22 increases too slowly from the left endpoint a to vertex c, causing the hardness of the bead 2 to increase too rapidly from the left endpoint a to vertex c, thereby increasing the stress concentration at the curve ac and making it easy for the first apex 21 to separate from the second apex 22, reducing the service life of the bead 2.

[0031] Furthermore, the cross-section of the bead wire 23 is an equiangular hexagon. The bead wire 23 forms a side surface A with an inclination angle of 15°. The extension line of the side surface A intersects the turn-up part 32 at the intersection point q. The radial distance between the intersection point q and the bead base line BL is H8, and H8 is a determined value; the intersection point of the curve ab and the turn-up part 32 is the right endpoint b. The radial distance between the right endpoint b and the bead base line BL is H4, -5 mm ≤ H8 - H4 ≤ 5 mm; H5 - H4 = h, and the radial distance between vertex c and the right endpoint b is h.

[0032] Specifically, as described above, in this embodiment, side A is fixed relative to the bead 2 and has only a unique relative position. Therefore, H8 is a known dimension in this embodiment; H8 - H4 represents the distance between the intersection point q and the right endpoint b. When H8 - H4 is less than -5 mm or H8 - H4 is greater than 5 mm, the distance between the intersection point q and the right endpoint b is too large. When the first apex strip is bent and deformed, the side B of the bead wire cannot provide sufficient support for it, resulting in uneven hardness change during the transition of the second apex strip from the first apex strip to the side B of the bead wire, thereby increasing the fatigue limit of the first apex strip and the second apex strip, and reducing the durability of the bead.

[0033] From H4 + 5 ≤ H5 ≤ H4 + 15 mm, the specific range value of H5 can be known, and then the radial position of the vertex c relative to the bead base line BL can be determined.

[0034] As Figure 2 shown, the bead wire 23 is disposed in the enclosed area of the main part 31 and the turned-up part 32. The minimum distance between the outer side of the bead wire 23 and the right endpoint b is h4; the minimum distance between the outer side of the bead wire 23 and the curve ab is h3, and h3 ≥ h4.

[0035] Specifically, part of the side of the bead wire 23 coincides with the inner side of the main part 31 and the inner side of the turned-up part 32 to provide support for the carcass 3, and further provide support for the part where the tire contacts the rim, thereby improving the durability of the tire. Secondly, the distance between the side B of the bead wire 23 and the right endpoint b is h4, and the shortest distance between the side B of the bead wire 23 and the curve ab is h3. h3 represents the distance between the bottom of the second apex strip 22 and the bead wire 23. When h3 < h4, the curvature change of the curve cb is: gradually decreasing, then gradually increasing, and then gradually decreasing. The distance between the maximum curvature point of the curve cb and the side B is h3 which is less than h4. At this time, the distance between the bottom of the second apex strip 22 and the side B changes from the axially inner side to the axially outer side as: gradually decreasing, then gradually increasing, resulting in uneven hardness transition between the second apex strip 22 and the first apex strip 21, thereby intensifying the stress concentration in the right endpoint b area, and making it easy for the first apex strip 21 or the second apex strip 22 to separate from the carcass 3, reducing the durability of the tire.

[0036] Further, the radially outer side of the second apex strip 22 is the direction close to the crown. The distance between the axially outer upper endpoint m of the second apex strip 22 and the bead base line BL is H1; the radial distance between the tire section width SW and the bead base line BL is LSH, satisfying: H1 / LSH = 0.7 - 0.9.

[0037] Specifically, LSH is a determined value in this embodiment, H1-H4 are the lengths of the second apex strip 22 along the outer surface of the tire sidewall 1, and H4 is a determined value. Therefore, H1 represents the length of the second apex strip 22 along the outer surface of the tire sidewall 1. Thus, H1 / LSH represents the distance from the axially outer upper endpoint m of the second apex strip 22 to the deformation zone of the tire sidewall 1, where the axially outer upper endpoint m is the vertex m. When H1 / LSH < 0.7, the vertex m of the second apex strip 22 is too far from the deformation zone of the tire sidewall 1, resulting in a reduction in the bending strength of the tire sidewall 1, and further causing the tire sidewall 1 to be prone to fatigue damage, reducing its load-bearing capacity, and further reducing its durability. When H1 / LSH > 0.9, the vertex m of the second apex strip 22 is too close to the deformation zone of the tire sidewall 1, causing an increase in the bending strength of the deformation zone close to the second apex strip 22, making the bending strength change of the deformation zone uneven, and further intensifying the stress concentration at the vertex m. As a result, the second apex strip 22 at the vertex m is prone to separation from the tire sidewall 1, reducing the service life of the tire sidewall 1.

[0038] Furthermore, the radial distance between the axially outer endpoint f of the turn-up portion 32 and the bead base line BL is H2, satisfying: H2 / LSH = 0.3 - 0.5.

[0039] Specifically, H2 / LSH represents the distance along the outer side surface of the tire sidewall 1 between the axially outer endpoint f and the right endpoint b. When H2 / LSH < 0.3, the axially outer endpoint f and the right endpoint b are too close to each other, resulting in too little contact between the inner side surface of the turn-up portion 32 and the right side surface of the second apex strip 22. As a result, the turn-up portion 32 cannot provide sufficient support for the second apex strip 22. When the tire is loaded, the deformation degree of the second apex strip 22 is aggravated, making it prone to fatigue limit, and the axially outer endpoint f is too close to the top edge of the first apex strip 21, intensifying the stress concentration at the right endpoint b.

[0040] Furthermore, the curve ab intersects the main portion 31 at the left endpoint a, and the left endpoint a is the axially inner upper endpoint a of the first apex strip 21. The radial distance between the axially inner upper endpoint a and the bead base line BL is H3, and H3 / H2 = 1 - 1.4.

[0041] Specifically, H2 / LSH represents the distance along the outer side surface of the tire sidewall 1 between the axially outer endpoint f and the right endpoint b, and LSH is a determined value. H3 / H2 represents the height relationship along the radial direction between the left endpoint a and the axially outer endpoint f, which can represent the distance relationship along the radial direction between the left endpoint a and the right endpoint b.

[0042] Wherein, when H3 / H2 < 1, the left end point a is lower than the axially outer end point f, such that the contact area between the second apex rubber 22 and the main part 31 is larger than the contact area between the first apex rubber 21 and the main part 31. Further, during the bending process of the sidewall 1 under load, the bending amplitude of the second apex rubber 22 increases, making it more likely to reach the fatigue limit. The distance between the left end point a and the right end point b is too small, such that during the bending process of the sidewall 1 under load, the moment generated by the pressure on the first apex rubber 21 decreases, making it difficult to deform, and further intensifying the stress concentration at the left end point a, making it easy for the first apex rubber 21 and the second apex rubber 22 to separate, reducing the service life of the tire. When H3 / H2 > 1.4, the left end point a is higher than the axially outer end point f, but too close to the apex m of the second apex rubber 22, such that the contact area between the second apex rubber 22 and the main part 31 is too small, and the contact area between the first apex rubber 21 and the main part 31 is too large, further increasing the overall hardness of the sidewall 1, reducing its bending performance and the cushioning performance of the tire. At the same time, the left end point a is too close to the deformation zone of the sidewall 1, making the bending force it receives too large, and further intensifying the stress concentration at the left end point a.

[0043] Furthermore, it further includes a steel cord fabric 4 disposed on the outer side surface of the carcass 3. The distance between the axially outer end point e of the steel cord fabric 4 and the axially outer end point f of the turned-up part 32 is H6, and H6 = 10 - 16 mm.

[0044] Specifically, the steel cord fabric 4 is a key skeleton material of the tire. It is made by covering high-strength steel cord with rubber through a calendering process. It can be used for the carcass 3 to withstand the huge pressure, impact load, and vibration during tire driving, ensuring the strength, durability, and stability of the tire. Here, H6 represents the distance relationship between the axially outer end point e of the steel cord fabric 4 and the axially outer end point f of the turned-up part 32 along the surface direction of the sidewall 1. When H6 is less than 10 mm, the axially outer end point e of the steel cord fabric 4 and the axially outer end point f of the turned-up part 32 are too close. During the bending process of the sidewall 1 under load, the heat generation and stress concentration in the ef region are aggravated, making it easy for the rubber material performance in this region of the sidewall 1 to decrease under the influence of heat, and it is easy for the steel cord fabric 4 and the turned-up part 32 to separate from the rubber material, reducing the service life of the sidewall 1.

[0045] Furthermore, the perpendicular projection of the axially outer end point f of the turned-up part 32 on the perpendicular line perpendicular to the main part 31 is at the projection point p. The distance between the projection point p and the axially inner end point g of the steel cord fabric 4 is H7, and H7 = -10 - 10 mm.

[0046] Specifically, the distance between the axially outer end point f and the bead base line BL is determined, and H7 represents the distance relationship between the axially inner end point g and the bead base line BL and the deformed area of the sidewall 1. When H7 < -10 mm, the projection point p is lower than the axially inner end point g, and the axially inner end point g is too close to the deformed area of the sidewall 1. When the sidewall 1 bears bending deformation, the deformation amplitude of the axially inner end point g is too large, which further intensifies the stress concentration here, easily causing the steel cord 4 to separate from the inner side surface of the main part 31 of the carcass 3 and reducing the service life of the tire; when H7 > 10 mm, the projection point p is higher than the axially inner end point g, and the axially inner end point g is too close to the bead wire 23, resulting in too small a contact area between the steel cord 4 and the main part 31, thereby reducing the support effect on the main part 31, further reducing the load-bearing capacity of the sidewall 1 / bead 2, and further reducing the load-bearing capacity of the tire.

[0047] Furthermore, the elastic modulus of the first apex 21 is E1, and E1 = 12 - 15 Mpa; the elastic modulus of the second apex 22 is E2, and E2 = 3 - 6 Mpa.

[0048] Specifically, the elastic modulus of the first apex 21 is greater than that of the second apex 22. When the elastic modulus E1 < 12 Mpa, the support performance of the first apex 21 for the bead wire 23 is reduced, and the tire is easily detached from the rim. When the elastic modulus E1 > 15 Mpa, the hardness of the first apex 21 is too high, making it difficult to bend and deform, intensifying the stress concentration at the curve ab, and easily causing the separation of the first apex 21 and the second apex 22; when the elastic modulus E2 < 2 Mpa, the second apex 22 is easily bent and deformed, reducing its load-bearing capacity, and further reducing the load-bearing capacity of the sidewall 1. When the elastic modulus E2 > 6 Mpa, the hardness of the second apex 22 is too high, making it difficult for the second apex 22 to bend and deform during the bending process of the sidewall 1, thereby intensifying the stress concentration at the interface between the second apex 22 and the sidewall 1 rubber covering, and further making the second apex 22 easily separate from the sidewall 1 rubber covering. Among them, the hardness of the second apex 22 is higher than that of the sidewall rubber covering.

[0049] In the present invention, the dimensions and angles of the various components of the tire are measured under the condition that the tire is assembled on a regular rim and filled with air to reach the regular internal pressure, unless otherwise specified. During the measurement, no load is applied to the tire.

[0050]

Embodiment

[0051] The effects of the present invention will be clarified below according to the embodiments, but the present invention should not be construed restrictively based on the loading of these embodiments.

[0052] Comparative Example 1 was verified by the bead 2 durability test of a 12R22.5 18PR 152 / 149M truck tire. The test method was as follows: speed was 30 km / h; load: the maximum load of a single tire * 250% * 0.85 kg; the ambient temperature was 25 ± 3°C. Taking 24 h as a stage, after each stage ended, the machine was stopped for 15 min, and a single tire was tested to determine the time until damage occurred in part 1 of the tire side. The results were shown in Tables 1 to 7 below using an index with Comparative Example 1 set as 100, and the larger the value, the better.

[0053]

Table 1

[0054] Table 1 Evaluation Results

[0055]

[0056] Among them, H4 means H8 - H4 = 0, that is, the intersection point q coincides with the right endpoint b.

[0057]

Table 2

[0058] Table 2 Evaluation Results

[0059]

[0060]

Table 3

[0061] Table 3 Evaluation Results

[0062]

[0063]

Table 4

[0064] Table 4 Evaluation Results

[0065]

[0066]

Table 5

[0067] Table 5 Evaluation Results

[0068]

[0069]

Table 6

[0070] Table 6 Evaluation Results

[0071]

[0072]

Table 7

[0073] Table 7 Evaluation Results

[0074]

[0075] As can be seen from Tables 1 to 7, the preferred embodiments of the present invention are:

[0076] An inflatable tire with a triangular apex strip structure having a gradually changing hardness, comprising: a carcass 3 and a bead 2. The carcass 3 includes a main part 31 axially inside the bead 2 and a turn-up part 32 axially outside the bead 2. The bead 2 includes a bead core 23 provided at the end. The bead 2 further includes: a first triangular apex strip 21 provided radially outside the bead core 23; a second triangular apex strip 22 provided radially outside the first triangular apex strip 21. The elastic modulus of the first triangular apex strip 21 is greater than that of the second triangular apex strip 22. The interface between the second triangular apex strip 22 and the first triangular apex strip 21 is a curve ab, which bulges towards the first triangular apex strip 21. The point with the maximum curvature of the curve ab is the vertex c. The radial distance between the vertex c and the bead base line BL is H5. The radial distance between the right endpoint b of the second triangular apex strip 22 and the bead base line BL is H4. The axial distance between the vertex c and the main part 31 is h2. The axial thickness of the first triangular apex strip 21 and the second triangular apex strip 22 at the vertex c is h1, H5 = H4 + h, the radial distance between the vertex c and the right endpoint b is h, and h = 10 mm; h2 / h1 = 0.4.

[0077] Furthermore, the cross-section of the bead core 23 is an equiangular hexagon. The bead core 23 forms a side surface A with an inclination angle of 15°. The extension line of the side surface A intersects the turn-up part 32 at the right endpoint b. The radial distance between the right endpoint b and the bead base line BL is H4, and H4 is a determined value.

[0078] Furthermore, the bead core 23 is arranged in the enclosed area of the main part 31 and the turn-up part 32. The minimum distance between the outer side surface of the bead core 23 and the right endpoint b is h4; the minimum distance between the outer side surface of the bead core 23 and the curve ab is h3, and h3 = h4.

[0079] Preferably, the radial outside of the second triangular apex strip 22 is in the direction close to the crown. The distance between the upper endpoint on the axial outside of the second triangular apex strip 22 and the bead base line BL is H1; the radial distance between the section width SW of the mold tire and the bead base line BL is LSH, satisfying: H1 / LSH = 0.8.

[0080] Preferably, the radial distance between the axial outside endpoint f of the turn-up part 32 and the bead base line BL is H2, satisfying: H2 / LSH = 0.4.

[0081] Preferably, the curve ab intersects the main part 31 at the left endpoint a. The left endpoint a is the upper endpoint a on the axial inside of the first triangular apex strip 21. The radial distance between the upper endpoint a on the axial inside and the bead base line BL is H3, and H3 / H2 = 1.2.

[0082] Preferably, it further includes a steel cord 4 provided on the outer side surface of the carcass 3. The distance between the axial outside endpoint e of the steel cord 4 and the axial outside endpoint f of the turn-up part 32 is H6, and H6 = 13 mm.

[0083] Preferably, the axial outer end point f of the wrap-around part 32 projects onto the projection point p along the perpendicular line perpendicular to the main part 31, and the distance between the projection point p and the axial inner end point g of the steel cord fabric 4 is H7, and H7 = 0 mm.

[0084] Preferably, the elastic modulus of the first apex rubber 21 is E1, and E1 = 13.5 Mpa; the elastic modulus of the second apex rubber 22 is E2, and E2 = 4.5 Mpa.

[0085] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

[0086] The technologies, shapes, and structures not described in detail in the present invention are all well-known technologies.

Claims

1. An inflated tire having a triangular bead filler structure with a gradually changing hardness, comprising: A carcass (3) and a bead (2), wherein the carcass (3) includes a main part (31) disposed axially inside the bead (2) and a turn-up part (32) disposed axially outside the bead (2), and the bead (2) includes a bead core (23) disposed at the end, characterized in that the bead (2) further includes: A first chafer (21) disposed radially outside the bead core (23); A second chafer (22) disposed radially outside the first chafer (21), the elastic modulus of the first chafer (21) being greater than that of the second chafer (22), the interface between the second chafer (22) and the first chafer (21) being a curve ab, the curve ab protruding towards the first chafer (21), the point with the maximum curvature of the curve ab being the vertex c, the radial distance between the vertex c and the bead base line BL being H5, the radial distance between the right end point b of the second chafer (22) and the bead base line BL being H4, the axial distance between the vertex c and the main part (31) being h2, the axial thickness of the first chafer (21) and the second chafer (22) at the vertex c being h1, and the position of the vertex c satisfying: H5 - H4 = 5 to 15 mm; h2 / h1 = 0.3 to 0.

5.

2. The pneumatic tire according to claim 1, characterized in that: The cross-section of the bead core (23) is an equiangular hexagon, the bead core (23) forms a side surface A with an inclination angle of 15°, the extension line of the side surface A intersects the turn-up part (32) at an intersection point q, and the radial distance between the intersection point q and the bead base line BL is H8, and H8 is a determined value; The intersection point of the curve ab and the turn-up part (32) is the right end point b, the radial distance between the right end point b and the bead base line BL is H4, -5 mm ≤ H8 - H4 ≤ 5 mm; H5 - H4 = h, and the radial distance between the vertex c and the right end point b is h.

3. The pneumatic tire according to claim 2, wherein: The bead core (23) is disposed in the surrounding area of the main part (31) and the turn-up part (32), and the minimum distance between the outer side surface of the bead core (23) and the right end point b is h4; The minimum distance between the outer side surface of the bead core (23) and the curve ab is h3, and h3 ≥ h4.

4. The pneumatic tire according to claim 1, wherein: The radially outer side of the second chafer (22) is in the direction close to the crown, and the distance between the upper end point on the axially outer side of the second chafer (22) and the bead base line BL is H1; The radial distance between the sectional width SW of the mold tire and the bead base line BL is LSH, satisfying: H1 / LSH = 0.7 to 0.

9.

5. The pneumatic tire according to claim 4, characterized in that: The radial distance between the axially outer end point f of the turn-up part (32) and the bead base line BL is H2, satisfying: H2 / LSH = 0.3 to 0.

5.

6. The pneumatic tire according to claim 5, wherein: The curve ab intersects the main part (31) at the left end point a, the left end point a is the upper end point a on the axially inner side of the first chafer (21), and the radial distance between the axially inner upper end point a and the bead base line BL is H3, and H3 / H2 = 1 to 1.

4.

7. The pneumatic tire according to claim 1, characterized in that: It further includes a steel cord fabric (4) disposed on the outer side surface of the carcass (3), and the distance between the axially outer end point e of the steel cord fabric (4) and the axially outer end point f of the turned-up portion (32) is H6, and H6 = 10 - 16 mm.

8. The pneumatic tire according to claim 7, characterized in that: The axially outer end point f of the turned-up portion (32) projects onto the projection point p along the perpendicular line perpendicular to the main portion (31), and the distance between the projection point p and the axially inner end point g of the steel cord fabric (4) is H7, and H7 = -10 - 10 mm.

9. The pneumatic tire according to claim 1, wherein: The elastic modulus of the first apex rubber (21) is E1, and E1 = 12 - 15 Mpa; The elastic modulus of the second apex rubber (22) is E2, and E2 = 3 - 6 Mpa.

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