A high-crown structure all-steel radial pneumatic tire for urban rail vehicles

Abstract

This invention relates to the field of tire structure technology and discloses a high-reverse-wrap structure all-steel radial pneumatic tire for urban rail vehicles, comprising a tire carcass and a bead. The tire carcass is sequentially provided with an inner layer of cord and an outer layer of cord to form a high-reverse-wrap structure. The outer layer of cord forms a curved section AB near the bead, with the center of curvature of the curved section AB away from the inner layer of cord. The curved section AB forms an upper endpoint A, a lower endpoint B, and a apex C of an arc. The height of the upper endpoint A is H. A / H=0.24, height H of the lower endpoint B of the arc B / H=0.076, the depth Tc of the bending vertex C and the cross-sectional height H satisfy: 0.019≤Tc / H≤0.031. This invention improves the tire's load-bearing capacity by setting a high-reverse-wrap structure. It sets the outer ply of the tire bead to bend inwards and limits the depth of the bending vertex C, thus limiting the position of the bending segment AB relative to the tire bead. This ensures the tire carcass is always under tension, preventing the steel cords that make up the tire carcass from detaching from the rubber or even wearing and breaking due to periodic compression and tension cycles, thereby improving tire durability.

Description

Technical Field

[0001] This invention relates to the field of tire structure technology, specifically to a high-reverse-wrap structure all-steel radial pneumatic tire for urban rail vehicles. Background Technology

[0002] Urban rail vehicles using rubber-tired systems rely on horizontally placed tires to provide lateral force during turning. Due to the heavy weight of rail vehicles and extremely limited installation space, these horizontal tires must possess extremely high load-bearing capacity, small outer dimensions, and extremely high safety and reliability. To meet these high load-bearing requirements, techniques such as increasing tire inflation pressure are commonly used. However, if semi-steel radial tires are used, their carcass ply strength is insufficient to withstand such high loads and pressures; while conventional all-steel radial pneumatic tires, although meeting the carcass strength requirements, are prone to stress concentration at the bead area under harsh conditions of heavy loads and high pressures, leading to premature damage such as bead cracks.

[0003] To overcome the defect of bead cracking in all-steel tires, high-reverse-wrap tire carcass structures are commonly used in existing technologies. For example, utility model patent CN207772797U discloses a low-profile, high-reverse-wrap all-steel radial pneumatic tire. By placing the end of the reverse-wrap portion of the tire carcass near the end of the belt layer, stress concentration in the bead is reduced, thereby improving the tire's radial stiffness and resistance to side bursts.

[0004] However, through in-depth research, the inventors discovered a fundamental technical flaw in the aforementioned high-rebound structure when dealing with the heavy-load, high-pressure conditions unique to urban rail vehicles: when the tire rolls under heavy load, the bead in the contact patch undergoes significant deformation. During this process, the high-rebound tire carcass experiences intense radial pressure upon entering the contact patch and then transitions to a tensile state upon leaving it. This cyclical "compression-tension" stress acts on the tire carcass cords, which are made of multiple twisted steel wires, causing the steel wire cords to repeatedly alternate between "loose" and "tight" states. This microscopic instability severely weakens the adhesive interface between the steel wire cords and the surrounding rubber, ultimately leading to cord detachment, frictional wear, and even cord breakage. The macroscopic manifestation remains bulging, delamination, and even cracking in the bead area. In other words, the existing high-rebound structure only optimizes the macroscopic stress distribution but fails to address the interfacial fatigue failure of the cords caused by cyclic compression and tension at the microscopic level. Summary of the Invention

[0005] To address the problems of cord detachment from rubber and wear breakage due to cyclic compression and tension, this invention provides a high-reverse-coil all-steel radial pneumatic tire for urban rail vehicles. The specific technical solution is as follows: A high-reverse-wrap structure all-steel radial pneumatic tire for urban rail vehicles, comprising a tire carcass, a tread, a sidewall, and a bead, characterized in that the tire carcass is provided with an inner layer of ply fabric and an outer layer of ply fabric sequentially from the inside to the outside. The inner layer of ply fabric wraps around the bead and connects to the outer layer of ply fabric, while the outer layer of ply fabric extends to the tread to form a high-reverse-wrap structure. A curved section AB is formed near the bead of the outer layer of ply fabric, with the center of curvature of the curved section AB being far from the inner layer of ply fabric. The curved section AB forms an upper arc endpoint A, a lower arc endpoint B, and a apex C. The height H of the upper arc endpoint A is... A / H=0.24, the height H of the lower endpoint B of the arc B / H=0.076, the depth Tc of the curved vertex C and the cross-sectional height H satisfy: 0.019≤Tc / H≤0.031.

[0006] Furthermore, the sidewall forms an end point D, and the height of end point D is H. D / Cross section height H=0.19, thickness T at endpoint D D The section height H and the section height H both satisfy the following condition: 0.123 ≤ T D / H≤0.176.

[0007] Preferably, the hardness of the triangular rubber is between 75HA and 105HA.

[0008] Preferably, the tire sidewall is provided with, from the inside to the outside along the axial direction, a filler rubber that adheres to the outer surface of the curved section of the outer ply, and a wear-resistant rubber that adheres to the outer surface of the filler rubber. The hardness of the filler rubber is lower than that of the hard triangular rubber and the wear-resistant rubber. The thickness T of the filler rubber passes through the vertex E of the hard triangular rubber and is perpendicular to the thickness direction of the outer ply. F and the thickness T of the abrasion-resistant rubber G Satisfy: 0.8≤T F / T G ≤1.5.

[0009] Furthermore, the inner layer of fabric forms a transition arc that bulges outward from the outer layer of fabric. The two ends of the transition arc are the upper end point J and the lower end point K, respectively. The height HK / section height H of the lower end point K is 0.24. The upper end point J of the transition arc is at the same height as the widest point of the tire's radial section. The height h of the widest point of the tire's radial section and the section height H satisfy: 0.52≤h / H≤0.58.

[0010] Preferably, the tire carcass also includes a plywood interlayer disposed between the inner plywood and the outer plywood, wherein the hardness of the plywood interlayer is between 67HA and 73HA. The outer cord forms a parallel endpoint L and a reverse end M that connects to the tread. The parallel endpoint L and the upper endpoint A of the arc are the same endpoints. The outer cord from the parallel endpoint L to the reverse end M is parallel to the inner cord at the corresponding position, and the parallel gap Δ satisfies: 0.5mm≤Δ≤2mm.

[0011] Preferably, it further includes a first belt layer formed between the tread and the carcass, the first belt layer being connected to the outer ply, and the distance between the reverse end point M of the outer ply and the axial center plane of the tread being L. M Distance L M The width L of the tire tread satisfies: 0.233 ≤ L M / L≤0.436.

[0012] As can be seen from the above technical solution, the present invention has the following beneficial effects: This invention improves the load-bearing capacity of the tire by setting a high-reverse wrap structure. Secondly, it sets the outer cord of the tire bead to bend inward and limits the depth of the bending apex C, thereby limiting the position of the bending segment AB relative to the tire bead. This ensures that the tire body is always under tension, thereby preventing the steel cords that make up the tire body from detaching from the rubber or even wearing and breaking due to periodic compression and tension cycles, thus improving the durability of the tire. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the radial cross-sectional structure according to an embodiment of the present invention; Figure 2 for Figure 1 A magnified view of point P in the image; Figure 3 for Figure 1 A magnified view of point P in the image; Figure 4 for Figure 1 A magnified view of point P in the image; Figure 5 for Figure 1 A magnified view of point S in the image.

[0014] In the diagram: 1. Tire carcass; 11. Inner ply; 12. Outer ply; 13. Ply laminate; 2. Tread; 3. Sidewall; 4. Bead; 41. Hard triangle rubber; 42. Bead wire; 5. First belt layer; 6. Filler rubber; 7. Abrasion-resistant rubber; 8. Shoulder pad rubber. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] In the description of the embodiments of the present invention, it should be noted that the terms "inner", "outer", "upper", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0017] like Figure 1 As shown, this embodiment is a high-reverse-wrap structure all-steel radial pneumatic tire for urban rail vehicles. The pneumatic tire includes a tire body 1, a tire tread 2, a tire sidewall 3, and a tire bead 4. The tire body 1 is characterized by having an inner layer cord 11 and an outer layer cord 12 arranged sequentially from the inside to the outside. The inner layer cord 11 wraps around the tire bead 4 and connects with the outer layer cord 12. The outer layer cord 12 extends to the tire tread 2 to form a high-reverse-wrap structure.

[0018] Specifically, after the pneumatic tire is inflated, the internal cavity pressure of the tire is greater than the external atmospheric pressure, which in turn applies outward pressure to the tire body 1, causing the inner cord 11 and the outer cord 12 to be subjected to outward forces, so that both are in a tensile state. Secondly, the inner cord 11 is closer to the internal cavity of the tire than the outer cord 12. The end of the inner cord 11 near the bead 4 wraps around the steel wire ring 42 and then folds back upward to connect with the outer cord 12. The end of the outer cord 12 away from the inner cord 11 is set between the belt layers in the tire crown, forming a high reverse wrap structure, thereby improving the lateral support capacity of the sidewall 3 and reducing the degree of deformation of the sidewall 3 after the tire bearing tread 2 contacts the ground.

[0019] Table 1 below shows the test data for this embodiment. The tires used in the test and the tires used as comparative examples are both 150 / 75R8, with an outer diameter of 428mm and a cross-sectional width of 152mm. The internal air pressure and external load are also the same. Furthermore, a larger shear strain value indicates a smaller shear strain, and a larger strain energy value indicates a smaller strain energy. The minimum force value represents the minimum absolute force within the range; a larger absolute force value indicates a larger force. A negative value indicates that the outer ply 12 or inner ply 11 of the tire bead 4 is under pressure. The positive value indicates that the outer cord 12 or inner cord 11 located at the bead 4 is under tension. Secondly, the comparative example is the most effective embodiment. The shear strain, strain energy, force at the reverse end point M, minimum force on the outer cord 12 located at the bead 4, and minimum force on the inner cord 11 located at the sidewall 3 in the comparative example are all set to 100. The shear strain, strain energy, force at the reverse end point M, minimum force on the outer cord 12 located at the bead 4, and minimum force on the inner cord 11 located at the sidewall 3 in the embodiment are converted according to the ratio to obtain the table values.

[0020] Table 1

[0021] like Figure 2 As shown in Table 1, the outer cord fabric 12 forms a curved section AB near the bead 4. The center of curvature of the curved section AB is far from the inner cord fabric 11. The curved section AB forms an upper arc endpoint A, a lower arc endpoint B, and a bend vertex C. The height H of the upper arc endpoint A is... A / H=0.24, the height H of the lower endpoint B of the arc B / H=0.076, the depth Tc of the curved vertex C and the cross-sectional height H satisfy: 0.019≤Tc / H≤0.031.

[0022] Specifically, the reference height refers to the vertical distance from the toe point Q, and the section height H refers to the vertical distance of the tread 2 from the toe point Q at its farthest point. A The vertical distance H between the upper endpoint A of the arc and the toe point Q is the height of the arc. B The vertical distance between the lower end point B of the arc and the toe point Q is: First, the curvature center of the curved segment AB is far from the outer cord 12. The positions of the upper end point A and the lower end point B of the arc relative to the toe point Q determine the position of the curved segment AB relative to the toe point Q, that is, the position of the bead 4 in contact with the hard triangular rubber 41. The depth Tc of the curved vertex C refers to the maximum distance between the curved segment AB and the line segment AB with the line segment AB as the reference.

[0023] Secondly, Tc / H refers to the bending radius of the bending segment AB. When the tire is under load and the bead 4 is turned outward, the bead 4 is in a state of compression deformation. The bending segment AB becomes more curved due to the compression deformation of the bead 4. In this process, assuming that the bending segment AB is not under stress before deformation, the tire body 1 will be under pressure after deformation. The bending stiffness of the tire body 1 is inversely proportional to the degree of bending, that is, the greater the degree of bending of the bending segment AB, the smaller the bending stiffness, and the smaller the absolute value of the pressure after deformation. Conversely, the smaller the degree of bending of the bending segment AB, the smaller the absolute value of the pressure after deformation. The greater the bending stiffness, the greater the absolute value of the pressure after deformation. Since the tire is in an inflated state, the bending segment AB of the tire carcass 1 is under tension before deformation. When the tire is under load and the bead 4 is compressed and deformed, as Tc / H increases, the degree of bending of the bending segment AB increases, and the reduction in tension of the outer ply 12 will decrease, keeping the outer ply 12 under tension. Conversely, as Tc / H decreases, the degree of bending of the bending segment AB decreases, and the reduction in tension of the outer ply 12 will increase, causing the outer ply 12 to change from a tension to a compression state.

[0024] Secondly, as shown in the comparative examples, Examples 9, 10, 11, 12, and 13 in Table 1, when Tc / H decreases, under tire load and bead 4 compression deformation, the minimum force on the outer cord 12 located at bead 4 gradually decreases, while the minimum force on the inner cord 11 located at sidewall 3 gradually increases; until Tc / H < 0.019, the minimum force on the outer cord 12 located at bead 4 becomes negative, changing from tension to compression. Consequently, the repeated changes between tension and compression cause the steel cords of the outer cord 12 to wear and break or detach from the adhesive rubber; when Tc / H > 0.0... At 31, when the tire is under load and the bead 4 is compressed and deformed, the minimum force on the inner cord 11 located at position 3 on the sidewall is negative, as it changes from tension to compression. Consequently, the repeated changes between tension and compression cause the steel cords of the inner cord 11 to wear and break or detach from the adhesive rubber. When 0.019≤Tc / H≤0.031, the minimum force on the outer cord 12 located at position 4 and the minimum force on the inner cord 11 located at position 3 on the sidewall are both positive. During tire load-bearing, both are under tension, preventing the steel cords from detaching from the adhesive rubber and wearing and breaking due to periodic compression and tension cycles, thus improving tire lifespan.

[0025] Furthermore, the sidewall 3 forms end point D, and the height of end point D is H. D / Cross section height H=0.19, thickness T at endpoint D D The section height H and the section height H both satisfy the following condition: 0.123 ≤ T D / H≤0.176.

[0026] Specifically, endpoint D is located on the outer side of sidewall 3, and its position relative to the curved section AB is fixed. Its thickness direction refers to the normal direction of sidewall 3 at endpoint D, and its thickness T is... D The thickness of the tire sidewall 3 at end point D.

[0027] Secondly, as can be seen from Examples 14, 15, 16, Comparative Examples, 17, 18, 19, and 20 in Table 1, when T D When / H decreases, the minimum force on the outer ply 12 located at the bead 4 gradually increases, while the maximum force on the inner ply 11 located at the sidewall 3 gradually decreases; secondly, when T D When / H < 0.123, the stiffness of the bead 4 decreases, causing a reduction in the overall stiffness of the tire. Under the same load, the tire deformation increases. Due to the increased deformation, the inner cord 11 located on the sidewall 3 experiences a negative minimum force, changing from tension to compression. Consequently, the repeated changes between tension and compression in the inner cord 11 lead to wear and breakage of the steel cords or detachment from the adhesive rubber. Secondly, when T D As / H increases from 0.135, the tensile force on the reverse end point M gradually decreases, and when T...D When / H > 0.176, the thickness of the sidewall 3 at end point D increases, the stiffness of the bead 4 increases, the deformation of the bead 4 decreases, and the tensile force on the reverse end point M is less than 0.5. When the load on the tire fluctuates, the force on the reverse end point M may decrease to a negative value, and it changes from being under tension to being under compression. As a result, the reverse end point M causes the steel cord to separate from the rubber located on the tire crown due to repeated changes of "tension-compression", and then separates from the first belt layer 5.

[0028] Furthermore, the hardness of the hard triangular rubber 41 is between 75HA and 105HA.

[0029] Specifically, the hardness of the hard triangular rubber 41 is related to the stiffness of the bead 4. As the hardness gradually decreases, the stiffness of the bead 4 gradually decreases, and the overall stiffness of the tire also gradually decreases. Under the same tire load, the deformation of the sidewall 3 also increases accordingly. As the overall deformation of the tire increases, the reduction in the tensile force on the inner cord 11 increases, posing a risk of pressure. As the hardness gradually increases, the stiffness of the bead 4 gradually increases, and the deformation of the bead 4 gradually decreases. The deformation of the tire under load will gradually transfer to the sidewall 3. The reduction in the tensile force on the inner cord 11 of the sidewall 3 increases, posing a risk of pressure.

[0030] As shown in Examples 25, 24, Comparative Examples, 21, 22, and 23 of Table 1, when the hardness of the hard triangular rubber 41 gradually decreases from 95HA, the minimum stress on the inner ply 11 located on the tire sidewall 3 gradually decreases. The decrease in the minimum stress on the inner ply 11 located on the tire sidewall 3 is greatest when the hardness of the hard triangular rubber 41 decreases from 95HA to 75HA. When the hardness is <75HA, the minimum stress on the inner ply 11 located on the tire sidewall 3 is negative, and it changes from tension to compression. Consequently, the repeated changes between tension and compression cause the steel cords of the inner ply 11 to wear and break or break with the adhesive rubber. When the hardness of the hard triangular rubber 41 gradually increases from 95HA, the deformation of the bead 4 will become very small, and the deformation of the tire will mainly occur on the sidewall 3. The deformation of the sidewall 3 gradually increases, and the curvature of the inner cord 11 located at the widest part of the tire gradually increases. The reduction in the tensile force on the inner cord 11 at this position gradually increases. When the hardness is >105HA, the minimum force on the inner cord 11 located at the sidewall 3 is negative, and it changes from being under tension to being under compression. As a result, the inner cord 11 is worn and broken or separated from the adhesive rubber due to repeated changes of "tension-compression". Preferably, the hardness is 95HA.

[0031] Furthermore, along the axial direction from the inside to the outside, the tire sidewall 3 is provided with a filler rubber 6 that adheres to the outer surface of the curved section of the outer ply 12, and a wear-resistant rubber 7 that adheres to the outer surface of the filler rubber 6. The hardness of the filler rubber 6 is lower than that of the hard triangular rubber 41 and the wear-resistant rubber 7. The thickness T of the filler rubber 6 passes through the vertex E of the hard triangular rubber 41 and is perpendicular to the thickness direction of the outer ply 12. F And the thickness T of the wear-resistant rubber 7 G Satisfy: 0.8≤T F / T G ≤1.5.

[0032] Specifically, filler 6 is located between the hard triangular rubber 41 and the wear-resistant rubber 7, which is located on the outer surface of the tire sidewall 3. The hardness of filler 6 is lower than that of the hard triangular rubber 41 and the wear-resistant rubber 7, causing the tire sidewall 3 and bead 4 to bend and deform, and the hard triangular rubber 41 and the wear-resistant rubber 7 to move relative to each other. Filler 6, being between the two, can act as a buffer, preventing them from separating when they are in direct contact and moving relative to each other, thus reducing tire life. Secondly, the thickness T of filler 6... F The thickness TG of the wear-resistant rubber 7 refers to the length of the normal line of the sidewall 3 passing through vertex E to the length of the wear-resistant rubber 7. When the thickness of the sidewall 3 passing through vertex E is fixed, T... F and T G When the sum is fixed, T F / T G The increase indicates that the thickness of filler 6 is increased, while the thickness of wear-resistant adhesive 7 is decreased. Wear-resistant adhesive 7 comes into contact with the rim, reducing its wear resistance. (T) F / T G The reduction indicates that the thickness of the filler 6 is reduced and the thickness of the abrasion-resistant adhesive 7 is increased, which reduces the buffering effect of the filler 6 on the hard triangular adhesive 41 and the abrasion-resistant adhesive 7; in the preferred embodiment, the hardness of the filler 6 is 70HA and the hardness of the abrasion-resistant adhesive 7 is 76HA.

[0033] Secondly, T F / T G When T = 1.2, the thickness of filler 6 is appropriate, allowing it to absorb the relative displacement of the hard triangular adhesive 41 and the wear-resistant adhesive 7 to the greatest extent, reducing stress concentration; when T F / T G When the thickness is less than 0.8, the thickness of filler 6 is too small, resulting in insufficient cushioning for the hard triangular rubber 41 and abrasion-resistant rubber 7. This prevents them from absorbing the relative displacement between the two, causing them to separate from filler 6 during relative movement and reducing tire lifespan. F / T G When the thickness is greater than 1.5, the thickness of the wear-resistant rubber 7 is too small, its wear resistance decreases, and when it is in contact with the rim and there is relative displacement, it is easy to crack due to excessive wear, which reduces the service life of the tire.

[0034] like Figure 4 As shown, the inner cord fabric 11 forms a transition arc that protrudes towards the outer cord fabric 12. The two ends of the transition arc are the upper end point J and the lower end point K of the transition arc, respectively. The height HK / section height H of the lower end point K of the transition arc is 0.24. The upper end point J of the transition arc is at the same height as the widest point of the tire's radial section. The height h of the widest point of the tire's radial section and the section height H satisfy: 0.52≤h / H≤0.58.

[0035] Specifically, the inner ply 11 is divided into upper and lower sections. The two ends of the upper section are located at the tire crown and the widest point of the tire's radial cross-section, respectively. The lower section includes a transition arc, with its two ends located at the widest point of the tire's radial cross-section and at the tire bead 4, respectively. Furthermore, the transition arc is an arc centered inside the tire, with its arc length being the arc length between the upper endpoint J and the lower endpoint K of the transition arc. The lower endpoint K of the transition arc is higher than the vertex E of the hard triangular rubber 41. The height HK of the lower endpoint K of the transition arc refers to the vertical distance between this point and the toe point Q. When HK / H = 0.24, the position of the lower endpoint K of the transition arc relative to the toe point Q is fixed, thus making the starting point of the transition arc relative to the tire sidewall 3. First, the upper endpoint J of the transition arc is at the same height as the widest point of the tire's radial section. The widest point of the tire's radial section is the outermost edge of the sidewall 3, i.e., the section width position. The bending deformation of the sidewall 3 is greatest at this position. When h / H increases, the arc length of the transition arc increases, the widest point of the tire's radial section moves upward, and the outermost edge of the sidewall 3 moves upward, which increases the deformation of the tire shoulder relative to the tread 2 when the tire crown contacts the ground. When h / H decreases, the arc length of the transition arc decreases, the widest point of the tire's radial section moves downward, and the outermost edge of the sidewall 3 moves downward, which reduces the transition path of stiffness from the upper endpoint J of the transition arc to the lower endpoint K of the transition arc, thus increasing the transition amplitude.

[0036] Secondly, when h / H=0.55, the height of the outermost edge of sidewall 3 is appropriate, and the stiffness gradually decreases from the first belt layer 5 to the outermost edge of sidewall 3, and then gradually increases from the outermost edge of sidewall 3 to the bead 4. The change in stiffness is uniform without abrupt changes, reducing stress concentration during the bending deformation of the inner cord 11 and outer cord 12. When h / H<0.52, the outermost edge of sidewall 3 is excessively lowered, making the transition path of stiffness from the upper end point J of the transition arc to the lower end point K of the transition arc too small, resulting in an excessive increase in the stiffness of sidewall 3. This causes excessive stress concentration between the outermost edge of sidewall 3 and the vertex E of the hard triangular rubber 41, making the inner cord 1 at this position... Excessive bending of the outer cord 12 and the inner cord 1 causes one or both to be under pressure. The repeated changes of tension and pressure cause the steel cord to wear and break or detach from the adhesive rubber. When h / H > 0.58, the outermost edge of the sidewall 3 moves excessively upward, causing the shoulder to deform too much relative to the tread 2 when the tread contacts the ground. This results in excessive deformation of the outer cord 12 located on the shoulder and tread, which in turn causes excessive displacement of the reverse end point M. This may reduce the force to a negative value, changing it from tension to pressure. Consequently, the reverse end point M, due to the repeated changes of tension and pressure, causes the steel cord to detach from the rubber located on the tread and then separate from the first belt layer 5.

[0037] Furthermore, the tire carcass 1 also includes a ply laminate 13 disposed between the inner ply 11 and the outer ply 12, the hardness of the ply laminate 13 being between 67HA and 73HA; the outer ply 12 forms a parallel endpoint L and a reverse end M connected to the tread 2, the parallel endpoint L and the upper endpoint A of the arc are the same endpoint, the outer ply 12 from the parallel endpoint L to the reverse end M is parallel to the inner ply 11 at the corresponding position, and the parallel gap Δ satisfies: 0.5mm≤Δ≤2mm.

[0038] Specifically, under tire load, the inner cord 11 and outer cord 12 move relative to each other. The cord interlayer 13 is placed between them to buffer the relative movement and prevent them from directly contacting each other and separating. Secondly, when the hardness of the cord interlayer 13 increases, its buffering effect decreases. When the hardness of the cord interlayer 13 is greater than 73HA, its hardness is too high, so when the inner cord 11 and outer cord 12 move relative to each other, the cord interlayer 13 cannot buffer the relative displacement, thus causing the two to separate from the cord at an angle. Thirdly, when the hardness of the cord interlayer 13 decreases, its supporting effect decreases. When the hardness of the cord interlayer 13 is less than 67HA, its hardness is too low. When the tire sidewall 3 bends and deforms, the distance between the inner cord 11 and outer cord 12 becomes too close due to compression, so the cord interlayer 13 cannot buffer the relative displacement, thus causing the two to separate from the cord interlayer 13.

[0039] Secondly, the arc LM of the outer cord 12 is parallel to that of the inner cord 11, making the distance between them equal. When the parallel gap Δ increases, the distance between them increases, which increases the thickness of the tire shoulder and sidewall 3, and increases the heat at the tire shoulder and sidewall 3. When the parallel gap Δ > 2 mm, the distance between them is too large, which makes the thickness of the tire shoulder and sidewall 3 too large, and the heat at the tire shoulder and sidewall 3 increases sharply, reducing the performance of the rubber. When the parallel gap Δ decreases, the distance between them decreases, which reduces the thickness of the cord interlayer 13 between them, and reduces its buffering effect on them. When the parallel gap Δ < 0.5 mm, the distance between the outer cord 12 and the inner cord 11 is too small, and the thickness of the cord interlayer 13 between them is too small, which makes the cord interlayer 13 unable to buffer the relative displacement between them, thus causing them to separate from the cord interlayer 13. Preferably, in the comparative example, Δ = 1.2 mm.

[0040] like Figure 5 As shown, this embodiment also includes a first belt layer 5 formed between the tread 2 and the carcass 1. The first belt layer 5 is connected to the outer ply 12, and the distance between the reverse end point M of the outer ply 12 and the axial center plane of the tread 2 is L. M Distance L M The width L of tread 2 satisfies: 0.233 ≤ L M / L≤0.436.

[0041] Specifically, the first belt layer 5 is furthest from the tread 2, and its bottom is connected to the outer ply 12, while the bottom of the outer ply 12 is connected to the inner ply 11; secondly, the axial center plane of the tread 2 is perpendicular to the axis, and the axial distance between it and the reverse end point M is distance L. M L M As / L increases, the distance between the reverse end point M and the axial center plane of the tread 2 increases, and L M When / L decreases, the reverse end point M moves towards the axial center plane of the tread 2; as can be seen from Examples 1, 2, 3, 4, Comparative Examples, 5, 6, 7, and 8 in Table 1, when L M As L decreases, the strain energy and minimum stress at the reverse end M gradually increase, the minimum stress on the outer ply 12 of the bead 4 gradually increases, and the minimum stress on the inner ply 11 of the sidewall 3 gradually decreases until L... M When L < 0.233, the minimum force on the inner cord 11 located on the tire sidewall 3 is negative, changing from tension to compression. Consequently, the repeated changes between tension and compression cause the steel cords of the inner cord 11 to wear and break or detach from the adhesive rubber. When L M As / L increases, the strain energy and minimum force at the reverse end point M gradually decrease until L... MWhen L > 0.436, the minimum force at the reverse end point M is negative, changing from tension to compression. This repeated tension-compression cycle causes the steel cord at the reverse end point M to detach from the rubber in the tire crown, and subsequently separate from the first belt layer 5. Therefore, 0.233 ≤ L M When / L≤0.436, the strain energy and minimum force of the reverse end point M, the minimum force of the outer cord 12 located at the bead 4, and the minimum force of the inner cord 11 located at the sidewall 3 are all positive values. The tire body 1 is always under tension, which prevents the steel cord from separating from the rubber or even wearing and breaking due to periodic compression and tension cycles.

[0042] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0043] The technologies, shapes, and structures not described in detail in this invention are all known technologies.

Claims

1. A high-reverse-shrinkage all-steel radial pneumatic tire for urban rail vehicles, the pneumatic tire comprising a carcass (1), a tread (2), a sidewall (3), and a bead (4), characterized in that, The tire carcass (1) is provided with an inner layer cord fabric (11) and an outer layer cord fabric (12) from the inside to the outside. The inner layer cord fabric (11) wraps around the tire bead (4) and connects with the outer layer cord fabric (12). The outer layer cord fabric (12) extends to the tire tread (2) to form a high reverse wrap structure. The outer cord fabric (12) forms a curved section AB near the tire bead (4). The center of curvature of the curved section AB is far from the inner cord fabric (11). The curved section AB forms an upper arc endpoint A, a lower arc endpoint B, and a bend vertex C. The height H of the upper arc endpoint A is... A / H=0.24, the height H of the lower endpoint B of the arc B / H=0.076, the depth Tc of the curved vertex C and the cross-sectional height H satisfy: 0.019≤Tc / H≤0.031; The outer cord fabric (12) is disposed at one end away from the inner cord fabric (11) between the belt layers in the tire crown, forming a high reverse wrap structure; It also includes a first belt layer (5) formed between the tread (2) and the carcass (1), the first belt layer (5) being connected to the outer ply (12), the distance between the reverse end point M of the outer ply (12) and the axial center plane of the tread (2) being LM, and the distance LM and the width L of the tread (2) satisfying: 0.233≤LM / L≤0.

436.

2. The pneumatic tire according to claim 1, characterized in that: The sidewall (3) forms an end point D, and the height of end point D is H. D / Cross section height H=0.19, thickness T at endpoint D D The section height H and the section height H both satisfy the following condition: 0.123 ≤ T D / H≤0.

176.

3. The pneumatic tire according to claim 2, characterized in that: The hardness of the hard triangular rubber (41) is between 75HA and 105HA.

4. The pneumatic tire according to claim 3, characterized in that: The tire sidewall (3) is provided with a filler (6) that is attached to the outer side of the curved section of the outer ply (12) and a wear-resistant adhesive (7) that is attached to the outer side of the filler (6) in sequence from the inside to the outside along the axial direction. The hardness of the filler (6) is lower than that of the hard triangular adhesive (41) and the wear-resistant adhesive (7). The thickness T of the filler adhesive (6) is perpendicular to the thickness direction of the outer fabric (12) and passes through the vertex E of the hard triangular adhesive (41). F and the thickness T of the wear-resistant adhesive (7) G Satisfy: 0.8≤T F / T G ≤1.

5.

5. The pneumatic tire according to claim 1, characterized in that: The inner cord fabric (11) forms a transition arc that protrudes towards the outer cord fabric (12). The two ends of the transition arc are the upper end point J and the lower end point K, respectively. The height HK / section height H of the lower end point K is 0.

24. The upper end point J of the transition arc is at the same height as the widest part of the tire's radial section. The height h of the widest part of the tire's radial section and the section height H satisfy: 0.52≤h / H≤0.

58.

6. The pneumatic tire according to claim 5, characterized in that: The tire carcass (1) also includes a plywood interlayer (13) disposed between the inner plywood (11) and the outer plywood (12), wherein the hardness of the plywood interlayer (13) is between 67HA and 73HA. The outer cord fabric (12) forms a parallel endpoint L and a reverse end M connected to the tread (2). The parallel endpoint L and the upper end A of the arc are the same endpoints. The outer cord fabric (12) from the parallel endpoint L to the reverse end M is parallel to the inner cord fabric (11) at the corresponding position, and the parallel gap Δ satisfies: 0.5mm≤Δ≤2mm.

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