Pneumatic tire

Abstract

The present application provides a kind of pneumatic tire, including the shoulder of the tread pattern, the length w2 and width w3 of the fine groove of the shoulder of the tread pattern are opened along the tire circumferential direction, and meet the following relationship: 0.4≤w2 / L≤0.6, 1mm≤w3≤3mm, wherein L is unit pitch.The present application opens fine groove in the shoulder of the block and forms flared cavity at the end thereof, and the continuous ventilation cavity can be formed by the communication of multiple flared cavities in the fine groove, which improves the heat dissipation effect in the rolling of tire;The shape trend of belt layer is also constrained, which is more smooth, thereby reducing the shear strain of belt layer endpoint and improving the durability of tire.

Description

Technical Field

[0001] This invention relates to the field of tire technology, and specifically to a durable, stone-resistant, pneumatic all-steel radial tire for heavy-duty freight vehicles. Background Technology

[0002] In recent years, with changes in the market environment and the development of the transportation industry, people's consumption patterns have changed, and their demands for products have become increasingly diversified. Furthermore, due to the rise of online shopping and other forms of consumption, distance has become a smaller constraint on consumption. This has promoted the rapid transformation from regional economies to broader economies, and the long-distance freight market, as a bridge connecting these broader economies, has experienced significant prosperity and development against this backdrop.

[0003] Given the operating environment of the long-haul freight market (high total mileage, high timeliness requirements, and long continuous driving time), the tires used in vehicles must possess superior wear resistance and durability. Excellent durability prevents excessive heat buildup in the tire shoulder after prolonged continuous driving, thus preventing premature durability damage, increased tire operating costs, and impact on the timeliness of cargo transportation. Furthermore, the terminal transport environment in long-haul freight often includes roads with varying lengths of gravel paving. This necessitates tires with superior anti-stone-trapping properties to prevent stones from puncturing the bottom of the circumferential main grooves and causing tire blowouts, or from crushing and damaging the tread blocks within the circumferential main grooves, ultimately leading to premature tire failure.

[0004] The tires currently used in the long-haul freight market are often those with good wear resistance that are prone to trapping stones and damaging the tread, or those with poor durability. It is difficult to achieve a unified design direction for tire durability, stone-trapping performance, and wear resistance.

[0005] To achieve tire wear resistance, existing technologies commonly employ two methods: First, using high-abrasion tread compounds. However, high-abrasion compounds often have weak puncture resistance, leading to reduced puncture resistance of the tire tread. Especially when stones get stuck in the circumferential main grooves of the tire tread, as the tire rolls, the stones puncture the bottom of the main grooves, reaching the belt layer, causing corrosion of the belt layer steel wires and tire blowout. Alternatively, the stones may continuously crush the tread blocks inside the main grooves, causing damage and peeling of the tread blocks, ultimately leading to premature tire failure. Second, increasing the wear volume of the tread pattern. The disadvantage of increasing the wear volume is reduced tire heat dissipation, resulting in excessive heat accumulation in the tire shoulder after continuous long-term driving, leading to premature durability damage. Summary of the Invention

[0006] This invention provides an all-steel radial tire with excellent durability and anti-stone trapping performance through a special design of the tread pattern and belt layer orientation. This makes it suitable for all road conditions, taking into account both the durability of long-distance highway driving and the anti-stone trapping performance of terminal gravel roads.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] A pneumatic tire includes a tread pattern, wherein the shoulder of the tread pattern has fine grooves along the circumference of the tire, and the length w2 and width w3 of the fine grooves satisfy the following relationship:

[0009] 0.4≤w2 / L≤0.6, 1mm≤w3≤3mm, where L is the unit pitch.

[0010] Furthermore, at least one first flared cavity is formed in the radial direction of the tire within the fine groove. The first flared cavity is connected to the outside. The cross-sectional radius R of the first flared cavity and the width W3 of the fine groove satisfy: 1≤R / w3≤1.5.

[0011] Furthermore, at least one second expansion cavity is provided along the length direction of the fine groove, and the second expansion cavity communicates with the first expansion cavity within a single fine groove to form a continuous ventilation cavity.

[0012] Furthermore, it also includes a belt layer that is bonded to the tire circumferentially. The belt layer includes a first belt layer, a second belt layer, a third belt layer, and a fourth belt layer arranged sequentially from the inside of the tire cavity outward. The vertical distance H from the center line of the second belt layer in the lateral cross-sectional width direction to the tread surface, the vertical distance H2 from the endpoint of the second belt layer to the tread surface, the vertical distance H1 from the midpoint of the distance from the endpoint of the second belt layer to the center line of the lateral cross-sectional width direction to the tread surface, and the vertical distance H3 from the endpoint of the third belt layer to the tread surface have the following relationships: 0.9≤H2 / H≤1.1, 0.45≤H1 / (H+H2)≤0.55, and 0.85≤H3 / H2≤0.90.

[0013] The present invention also takes into account the combination of the fine groove and the trend of the belt layer. The vertical distance h1 between the second expansion cavity and the third belt layer satisfies: 4mm≤h1≤10mm. The width distance w1 from the center line of the tire's transverse cross-section to the second expansion cavity satisfies: -5mm≤w1-w3B≤5mm.

[0014] Furthermore, a turning groove is provided at the bottom of the circumferential main groove along the tire circumference, and at least one reinforcing rib is provided in the turning groove within a unit pitch L.

[0015] Preferably, the reinforcing rib is a split structure consisting of a first reinforcing block and a second reinforcing block in the transverse cross-sectional width direction of the tire, and the interval Q2 between the first reinforcing block and the second reinforcing block satisfies: 1mm≤Q2≤2mm.

[0016] As can be seen from the above technical solutions, the present invention opens fine grooves on the shoulder of the tread block and forms an enlarged cavity at its end. Multiple enlarged cavities connected in the fine groove can form a continuous ventilation cavity, which improves the heat dissipation effect during tire rolling. It also constrains the shape and trend of the belt layer to make the transition smoother, thereby reducing the shear strain at the end of the belt layer and improving tire durability. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the cross-sectional structure of the pneumatic tire of the present invention;

[0018] Figure 2 This is a perspective view of the shoulder of the tread pattern of the present invention;

[0019] Figure 3 This is a schematic diagram of the tread pattern of the present invention. Detailed Implementation

[0020] A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

[0021] Due to the shear force at the ends of the belt layer, a large amount of heat accumulates there. Prolonged tire driving exposes the rubber compound at these ends to high temperatures, leading to performance degradation and durability failure. Therefore, one way to improve tire durability is to reduce the driving temperature at the ends of the belt layer.

[0022] Traditional methods involve reducing the thickness of the tread shoulder, but this leads to a decrease in wear resistance. This invention addresses this issue by creating fine grooves 1 along the tire circumference on the tread shoulder of the pneumatic tire for heat dissipation and cooling. To maximize the heat dissipation efficiency of the fine grooves 1, the shape and distribution of the fine grooves 1 are designed with constraints. Increasing the number of conventional fine grooves reduces the tread stiffness of the tread shoulder, decreasing the tire's resistance to lateral forces and making it more prone to abnormal wear on the tread shoulder. Therefore, the design of the shape and dimensions of the fine grooves needs to strike a balance between maximizing heat dissipation efficiency and minimizing the weakening of tread stiffness.

[0023] like Figure 1 and 3 As shown, the length w2 and width w3 of the fine groove 1 of the present invention need to satisfy the following relationship: 0.4≤w2 / L≤0.6, 1mm≤w3≤3mm, where L is the unit pitch. If w2 / L is greater than 0.6, the reduction in stiffness of the tread pattern shoulder block will increase. The tire tread pattern is composed of pitches L1, L2, ... Ln, all with the same pattern characteristics and a width of L.

[0024] To further improve the ventilation and cooling effect, at least one first expansion cavity 11 is provided in the radial direction of the tire in the fine groove 1. The first expansion cavity 11 can communicate with the outside and quickly dissipate the heat in the tire shoulder area. In this embodiment, the two ends of the fine groove 1 in the length direction have the first expansion cavity 11. The first expansion cavity 11 can also be evenly distributed in the length direction of the fine groove. However, considering the influence of the fine groove on the tire rigidity, the distance between adjacent fine grooves also needs to be set.

[0025] In another embodiment of the present invention, at least one second expansion cavity 12 is provided along the length direction of the fine groove 1. The second expansion cavity 12 and the first expansion cavity 11 can communicate in a single fine groove to form a continuous ventilation cavity. In this embodiment, the second expansion cavity 12 is located at the bottom of the fine groove. The cross-sectional radius R of the first expansion cavity 11 and the second expansion cavity 12 and the width W3 of the fine groove 1 satisfy: 1≤R / w3≤1.5.

[0026] When there are flared openings at the edges and bottom of the fine grooves, the temperature drop at the belt layer endpoints is significant, and the stiffness reduction at the tread shoulder is relatively small. This is because the connected flared openings form continuous ventilation chambers, resulting in better heat dissipation during tire rolling. Simultaneously, the non-flared sections of the fine grooves are designed with a relatively thin thickness (1mm≤w3≤3mm), allowing the tires to abut against each other when subjected to lateral forces, minimizing stiffness reduction. Furthermore, due to the abutment support of the non-flared sections, the ventilation chambers connecting the flared openings at the edges and bottom of the fine grooves will not close even in the contact patch area, further enhancing heat dissipation. However, when the size of the flared opening, R / w3, is ≥1.5, the fine groove steel sheet in the mold may damage the tire tread pattern or break during vulcanization and demolding due to the flared opening. Therefore, a relationship of 1≤R / w3≤1.5 is adopted.

[0027] The influence of the shape of the fine groove 1 on the end temperature of the belt layer and the stiffness of the shoulder pattern is analyzed below through different embodiments and comparative examples 1-3.

[0028] Table 1: Influence of the fine groove shape on the end temperature and shoulder pattern stiffness of the belt layer in the examples

[0029]

[0030] In Table 1, compared with Comparative Examples 2 and 3 and Examples 1 and 2, as the w2 / L of the fine groove 1 increases, the temperature at the end of the belt layer decreases slightly. However, the stiffness of the tread pattern shoulder block also decreases slightly. In particular, when w2 / L = 0.7 (Comparative Example 3), the decrease in tread pattern shoulder block stiffness increases slightly. Comparing Examples 2, 3, and 4, when mm1 ≤ w3 ≤ 3 mm, although the tread pattern shoulder stiffness decreases, the decrease in the temperature at the end of the belt layer is greater, resulting in greater tire performance gains. Comparing Examples 3, 5, and 6, when the flared cavity of the fine groove 1 is at 1 ≤ R / w3 ≤ 1.5, the temperature decrease at the end of the belt layer is significant, and the decrease in tread pattern shoulder stiffness is relatively small.

[0031] Tire damage due to insufficient durability is often caused by excessive shear force on the ends of the belt layer, especially the end of the third belt layer 3B. This shearing deformation during tire operation leads to the failure of the bond between the steel wire ends of the belt layer and the surrounding rubber, resulting in damage. Therefore, reducing the shear strain at the ends of the belt layer is another way to improve tire durability.

[0032] Because of the significant height difference between the shoulder and center sections of the tread pattern, the shoulder of the tread pattern undergoes the greatest deformation during tire rolling, specifically at contact with and off the ground. This results in substantial deformation at the belt layer endpoints, increasing the shear force at these endpoints. Therefore, reducing the vertical distance between the belt layer endpoints and the tread pattern profile weakens the impact of tread pattern shoulder deformation on the belt layer endpoints, thereby reducing the shear strain at the belt layer endpoints.

[0033] like Figure 2 As shown, in this embodiment, the belt layer includes a first belt layer 1B, a second belt layer 2B, a third belt layer 3B, and a fourth belt layer 4B arranged sequentially from the inside of the tire cavity outwards.

[0034] Specifically, the vertical distance from the centerline of the second belt layer 2B in the lateral width direction of the tire to the tread pattern surface is H; the vertical distance from the endpoint of the second belt layer 2B to the tread pattern surface is H2; the vertical distance from the midpoint of the distance from the endpoint of the second belt layer to the centerline of the lateral width direction of the tire to the tread pattern surface is H1; and the vertical distance from the endpoint of the third belt layer 3B to the tread pattern surface is H3. The specific values ​​are set as follows: 0.9≤H2 / H≤1.1, 0.45≤H1 / (H+H2)≤0.55, and 0.85≤H3 / H2≤0.90.

[0035] The following analysis examines the influence of the belt layer shape trend parameters on reducing the shear strain at the belt layer endpoints through different embodiments and Comparative Example 4.

[0036] Table 2: Influence of the shape trend parameters of the belt layer on the reduction of shear strain at the endpoints of the belt layer in the examples

[0037]

[0038] Note: A higher shear strain index indicates a greater shear force at the ends of the belt layer, making the tire more prone to damage due to insufficient durability.

[0039] In Table 2, in Examples 7, 8, and 9, H2 is reduced compared to Comparative Example 4, resulting in a decrease in the strain reduction index at the belt layer endpoints, and the rate of decrease is also decreasing. In Examples 9, 10, and 11, H3 is reduced compared to the Comparative Example, resulting in a decrease in the strain reduction index at the belt layer endpoints, and the rate of decrease is also decreasing. However, if H2 / H and H3 / H2 are too small, on the one hand, the reduction in the strain reduction index at the belt layer endpoints will be relatively small, and on the other hand, the vertical height of the belt layer endpoints on the tire's transverse cross-section will exceed the bottom of the circumferential main groove, affecting tire retreading performance. Therefore, values ​​of 0.9 ≤ H2 / H ≤ 1.1 and 0.85 ≤ H3 / H2 ≤ 0.90 are selected, and 0.45 ≤ H1 / (H+H2) ≤ 0.55 is also selected to further constrain the shape of the belt layer, making the transition smoother.

[0040] like Figure 1 As shown, the pneumatic tire contains four belt layers. The endpoint of the third belt layer 3B is prone to initial damage. To further maximize the heat dissipation effect of the fine grooves on the endpoint of the third belt layer, the second flared cavity 12, where the fine groove 1 is embedded to its deepest point, is positioned as close as possible to the endpoint of the third belt layer 3B. Considering the actual manufacturing variations in the width direction of the tire belt layers, the width distance w1 from the centerline of the tire's transverse cross-section to the second flared cavity 12 satisfies: -5mm ≤ w1 - w3B ≤ 5mm. In the depth direction, to avoid compromising the rubber's protection of the belt layer endpoints (preserving the integrity of the rubber above 4mm from the endpoint of the third belt layer), the vertical distance h1 between the second flared cavity 12 and the third belt layer 3B is set to: 4mm ≤ h1 ≤ 10mm.

[0041] like Figure 1 and 3 As shown, the present invention includes a circumferential main groove 4, and a turning groove 3 is provided at the bottom of the circumferential main groove along the tire circumference. The turning groove is provided with at least one reinforcing rib 2 within a unit pitch L. This embodiment shows that there is one reinforcing rib 2 within a unit pitch L, so the reinforcing ribs on adjacent pitches L are discontinuous.

[0042] The reinforcing rib 2 is a split structure consisting of a first reinforcing block 21 and a second reinforcing block 22 in the transverse cross-sectional width direction of the tire. The interval Q2 between the first reinforcing block 21 and the second reinforcing block 22 satisfies: 1mm≤Q2≤2mm.

[0043] The reinforcing rib 2 has a width of Q1 in the tire circumferential direction, a vertical height of Q3 from the bottom of the circumferential main groove, a maximum opening depth of GH in the circumferential main groove 4, a maximum opening width of GW and a maximum opening depth of GH in the circumferential main groove 4, and a turning angle of α in the turning groove 3. The anti-stone trapping performance of the tire of the present invention is related to the design of the opening size of the circumferential main groove, the design of the turning angle α of the turning groove at the bottom of the circumferential main groove, and the use of reinforcing ribs in the circumferential main groove.

[0044] In this invention, the following relationships are required: 0.35≤Q1 / w2≤0.50, 0.4≤Q3 / GH≤0.6, 0.7≤GW / GH≤0.9, and 150°≤α≤170°.

[0045] The reinforcing ribs 2 within the circumferential main groove 4 are split in the lateral direction of the tire. When the tire tread wears down to the position of the reinforcing ribs, the circumferential main groove at the tire's contact patch will not form a closed space with the contact patch, increasing tire noise. Furthermore, the circumferential distribution of the reinforcing ribs 2 is discontinuous. The width Q1 and height Q2 within the circumferential main groove are limited to minimize interference with the function of the circumferential main groove, especially at the position where the tread wears down to the reinforcing ribs 2. The functions of the circumferential main groove 4 include maintaining straight-line driving, drainage, and heat dissipation. Therefore, values ​​of 0.35 ≤ Q1 / w2 ≤ 0.50 and 0.4 ≤ Q3 / GH ≤ 0.6 are taken. Furthermore, the centers of the fine groove 1, the reinforcing rib 2, and the centers of two adjacent turning points of the turning groove 3 are located within the same tire cross-section, and Q2 satisfies 1mm≤Q2≤2mm. Therefore, when the tire is subjected to lateral force, the separate reinforcing ribs will abut against each other, increasing the stiffness of the tread pattern shoulder and compensating for the reduced stiffness of the tread pattern shoulder within the same cross-section due to the fine grooves. Furthermore, the tread pattern shoulder exhibits a more uniform stiffness distribution in the tire circumferential direction, which is beneficial for resisting irregular wear on the shoulder.

[0046] The influence of circumferential main channel parameters on the anti-stone-clamping performance is analyzed below through different embodiments and Comparative Example 5.

[0047] Table 3: Influence of circumferential main channel parameters on anti-stone-entrapment performance in the examples

[0048]

[0049] When GW / GH increases, the opening angle of the circumferential main groove 4 will increase, and the stones will not be easily trapped in the circumferential main groove by the two sides of the groove wall. As shown in Table 3, Comparative Example 5 and Examples 12, 13, 14 and 15, the number of stones trapped decreases as GW / GH increases. However, as GW / GH increases to a certain extent, the effect of preventing stones from being trapped weakens. In addition, when GW / GH is too large (≥1.0), the overall stiffness of the tread pattern will decrease or the wear volume will decrease, making it difficult to balance the reduction in wear performance. Therefore, we take 0.7≤GW / GH≤0.9. Furthermore, simply designing the GW / GH alone cannot achieve the ideal anti-stone-clamping effect. Further improvements are made by controlling α to enhance the anti-stone-clamping effect, as shown in Examples 14, 16, 17, 18, and 19. When α ≤ 170°, the anti-stone-clamping effect improves with increasing α angle. However, when α is too large (≤ 140°), the turning angle at the bottom of the circumferential main groove is too small, easily causing stress concentration at the turning point during tire operation, leading to stress cracks and affecting tire lifespan. Further improvements are made by adding reinforcing ribs within the circumferential main groove, as shown in the comparison of Examples 18 and 20.

[0050] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A pneumatic tire, comprising a tread pattern, characterized in that, The shoulder of the tread pattern has fine grooves along the tire circumference, and the length w2 and width w3 of the fine grooves satisfy the following relationship: 0.4≤w2 / L≤0.6, 1mm≤w3≤3mm, where L is the unit pitch between adjacent fine grooves; At least one first flared cavity is formed radially along the tire in the fine groove. The first flared cavity is connected to the outside. The cross-sectional radius R of the first flared cavity and the width W3 of the fine groove satisfy: 1≤R / w3≤1.

5. Both ends of the fine groove along its length have a first flared cavity; At least one second expansion cavity is provided along the length direction of the fine groove, and the second expansion cavity communicates with the first expansion cavity in a single fine groove to form a continuous ventilation cavity; The pneumatic tire also includes a belt layer that is bonded to the tire circumference. The belt layer includes a first belt layer, a second belt layer, a third belt layer, and a fourth belt layer arranged sequentially from the inside of the tire cavity outward. The vertical distance H from the center line of the second belt layer in the transverse cross-sectional width direction to the tread pattern surface, the vertical distance H2 from the endpoint of the second belt layer to the tread pattern surface, the vertical distance H1 from the midpoint of the distance from the endpoint of the second belt layer to the center line of the transverse cross-sectional width direction to the tread pattern surface, and the vertical distance H3 from the endpoint of the third belt layer to the tread pattern surface have the following relationships: 0.9≤H2 / H≤1.1, 0.45≤H1 / (H+H2)≤0.55, and 0.85≤H3 / H2≤0.

90. The vertical distance h1 between the second expansion cavity and the third belt layer satisfies: 4mm≤h1≤10mm. The width distance w1 from the center line of the tire's transverse cross-section to the second expansion cavity satisfies: -5mm≤w1-w3B≤5mm, where w3B is the distance from the center line of the tire's transverse cross-section to the end of the third belt layer.

2. The pneumatic tire according to claim 1, characterized in that, It also includes a circumferential main groove, the bottom of which has a turning groove along the tire circumference, and the turning groove has at least one reinforcing rib within a unit pitch L.

3. The pneumatic tire according to claim 2, characterized in that, The reinforcing rib is a split structure consisting of a first reinforcing block and a second reinforcing block in the transverse cross-sectional width direction of the tire. The interval Q2 between the first reinforcing block and the second reinforcing block satisfies: 1mm≤Q2≤2mm.

4. The pneumatic tire according to claim 2, characterized in that, The width Q1 of the reinforcing rib in the tire circumferential direction, the vertical height Q3 of the reinforcing rib from the bottom of the circumferential main groove, and the maximum opening depth GH of the circumferential main groove have the following relationships: 0.35≤Q1 / w2≤0.50 and 0.4≤Q3 / GH≤0.

6.

5. The pneumatic tire according to claim 2, characterized in that, The maximum opening width GW and maximum opening depth GH of the circumferential main groove, and the turning angle α of the turning groove, have the relationship 0.7≤GW / GH≤0.9 and 150°≤α≤170°.

6. The pneumatic tire according to claim 2, characterized in that, The center of the fine groove, the center of the reinforcing rib, and the center of two adjacent turning points of the turning groove are located within the same tire cross-section.

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