Anti-skewing low rolling resistance load tire

Abstract

The application relates to the technical field of tires and discloses a heavy-load tire with anti-deviation wear and low rolling resistance, wherein the radial distance from a tire center point A to the intersection point B of a pattern groove outer side groove wall and a tire surface forms a rolling radius difference h1; the radial distance from the tire center point A to a tire shoulder point C forms a rolling radius difference h2; the distance L from the intersection point B to the tire shoulder point C is the width of a pattern strip; and the proportion of the difference between the rolling radius difference h2 and the rolling radius difference h1 and the width L of the pattern strip is 0.08-0.13. By adjusting the radial difference of the tire running surface, the relationship between the protective groove setting and the radial difference of the running surface is regulated, the relative slip amount of the tire shoulder relative to the rubber in the middle part of the tire crown is sufficiently reduced, the anti-deviation wear performance of the tire is effectively improved, and the wear performance of the tire is ensured.

Description

Technical Field

[0001] This invention relates to the field of tire technology, and specifically to a heavy-duty tire with anti-uniform wear and low rolling resistance. Background Technology

[0002] During the operation of heavy-duty truck tires, due to the high inflation pressure and load, and the uneven rolling radius from the center to the shoulder, relative slippage occurs, leading to faster wear on the shoulder rubber compared to the center rubber. This is called uneven wear, which reduces tire lifespan. Similarly, during driving, tire deformation and the inherent hysteresis of the rubber cause energy dissipation, known as rolling resistance. Tire rolling resistance affects vehicle fuel economy and environmental performance. To address uneven wear, methods typically include reducing the difference in rolling radius or increasing shoulder grooves. However, reducing the radius difference increases the contact length between the shoulder and the ground, thus increasing rolling resistance. Furthermore, for guide and trailer tires, which are more affected by lateral forces, a reduced radius difference also degrades steering performance. Adding shoulder tread grooves separates the area prone to uneven shoulder wear from the main tread surface, eliminating relative slippage between the shoulder and the main body, which can reduce the likelihood of uneven wear to some extent. However, because the shoulder tread strips are divided by the grooves, some rigidity is reduced, which will also increase tire rolling resistance and reduce wear life. Furthermore, the tread strips divided by the grooves are more prone to tearing under pressure and from road debris.

[0003] Because various tire performance characteristics interact and influence each other, parameters affecting uneven wear performance also affect rolling resistance, tear resistance, and other properties. Current technologies often reduce uneven wear by adjusting the tread crown arc and adding protective grooves. However, adjusting the crown arc and adding protective grooves can potentially increase rolling resistance. Crown arc adjustment also affects tire steering, with a more pronounced effect on directional and trailer-mounted tires. The shoulder protective grooves themselves are prone to tearing due to compression and road debris, leading to premature tire failure and reduced wear life. Although existing technologies specify the shape of the groove bottom to minimize tear risk, this effect is limited. Furthermore, the relationship between the added protective grooves and the difference in tire rolling radius is not considered. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a heavy-duty tire with anti-uniform wear and low rolling resistance. By setting the relationship between the running surface diameter difference and the protective groove, and increasing the three-dimensional sipe design of the protective groove, the tire's anti-uniform wear and anti-cracking performance is significantly improved and the rolling resistance is reduced.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A heavy-duty tire with anti-uniform wear and low rolling resistance includes a tread, a pair of first main tread grooves and a pair of second main tread grooves arranged circumferentially on the tread, and a tread strip. The two first main tread grooves are symmetrically arranged about the tire's center plane, and the two second main tread grooves are also symmetrically arranged about the tire's center plane. The second main tread grooves are located axially outside the first main tread grooves, and the tread strip is located axially outside the second main tread grooves. The tire is characterized in that: the radial distance from the center point A of the tread to the intersection point B of the outer wall of the tread groove and the tread forms a rolling radius difference h1; the radial distance from the center point A of the tread to the shoulder point C forms a rolling radius difference h2; the distance L from the intersection point B to the shoulder point C is the width of the tread strip; the ratio of the difference between the rolling radius difference h2 and the rolling radius difference h1 to the tread strip width L is 0.08 to 0.13, i.e., 0.08 ≤ (h2 - h1) / L ≤ 0.13.

[0007] Furthermore, the tread strip is provided with a three-dimensional sipe pattern arranged along the circumference of the tire; on the cross-section of the tire, the three-dimensional sipe pattern is wavy, with a radial depth of d, which is less than the depth d21 of the first main tread groove and the depth d22 of the second main tread groove; the bottom of the three-dimensional sipe pattern is composed of a first arc r1 and a second arc r2, the first arc r1 being tangent to the main body line segment p1 of the first sipe, and the second arc r2 being tangent to the main body line segment p2 of the second sipe; the sipe thickness t is at least 1 mm greater than the s thickness of the sipe body, i.e., t ≥ s + 1 mm.

[0008] Furthermore, the groove at the junction of the three-dimensional sipe pattern and the tread surface is called the protective groove. The thickness of the sipe body is equal to the width of the protective groove, and both are s. The amplitude width w of the three-dimensional sipe pattern is 1.8 to 3.0 times the thickness s, that is, 1.8 ≤ w / s < 3.0.

[0009] Compared with the prior art, the beneficial technical effects of the present invention are:

[0010] This invention provides a heavy-duty radial tire with low rolling resistance that exhibits excellent resistance to uneven wear and tear. By adjusting the tire's tread diameter difference and specifying the relationship between the protective grooves and the tread diameter difference, the relative slippage between the tire shoulder and the center of the tread is significantly reduced, effectively improving the tire's resistance to uneven wear while ensuring its wear resistance. To address the increased rolling resistance and shoulder tear risk caused by the increased protective grooves, a three-dimensional sipe design is used in the protective grooves, with specified shape and dimensions. This reduces the relative creep of the tread strips on both sides of the protective grooves during tire operation, reduces stress concentration at the groove bottom, and increases shoulder rigidity, thereby reducing tire rolling resistance and improving shoulder tear resistance. Attached Figure Description

[0011] Figure 1 This is a cross-sectional schematic diagram of the tire in this invention;

[0012] Figure 2 (a) is a schematic diagram of the tire contact patch shape under the low diameter difference of the tire; Figure 2 (b) is a schematic diagram of the tire contact patch shape under the tire height-diameter difference;

[0013] Figure 3 This is a partial schematic diagram of the tire tread of the present invention;

[0014] Figure 4 This is a schematic diagram of the three-dimensional groove pattern in this invention;

[0015] Figure 5 (a) is a schematic diagram of the fit between a traditional protective trench and the ground; Figure 5 (b) is a schematic diagram of the fit between the three-dimensional grooved protective trench and the ground in this invention;

[0016] Figure 6 A comparison diagram showing the impact of the shoulder protection trench on rolling resistance. Detailed Implementation

[0017] A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

[0018] Existing technologies typically employ tread crown arc design or the addition of shoulder protective grooves to reduce uneven wear and improve wear life. However, they fail to consider the resulting changes in rolling resistance, the reduction in wear volume caused by the grooves themselves, and the inherent risk of tearing. During tire operation, a difference in rolling radius exists between the tread and the rim center. Within a certain range of this difference, adding protective grooves can reduce uneven wear; beyond this range, adding grooves fails to prevent uneven wear and leads to increased rolling resistance and a higher risk of failure. Shoulder protective grooves are prone to tearing under pressure and from road debris, resulting in premature tire failure and reduced wear life—a unique risk inherent to protective grooves. This invention addresses the aforementioned problems.

[0019] Furthermore, existing technologies typically design protective grooves by simply creating vertical or angled fine sipes along the tire's radial direction. It is known that adding any groove to the tread increases rolling resistance, and shoulder protective grooves, being located at the shoulder, are prone to tearing. To address this problem, the present invention employs a three-dimensional sipe design for the shoulder protective groove, reducing the mutual creep between tread strips, increasing rigidity, and lowering rolling resistance and tear risk.

[0020] This invention improves the tire's resistance to uneven wear and tear while ensuring rolling resistance through the design of the tire's tread shape and tread grooves.

[0021] like Figure 1As shown, the anti-uniform wear and low rolling resistance heavy-duty tire of the present invention includes a tread 1, a carcass 6, and an inner liner 7. Between the tread 1 and the carcass 6 is a belt layer 5, composed of steel cords and rubber coating, which is attached circumferentially to the tire. The tread 1 has two pairs of circumferential main tread grooves, namely a first main tread groove 21 and a second main tread groove 22, and a protective groove 4 near the shoulder and arranged circumferentially to the tire. The present invention does not limit the number of circumferential main tread grooves. The tread 1 is divided into several circumferential tread strips by the main tread grooves, including tread strips 3 outside the second main tread groove 22. The tread strips 3 are divided into shoulder tread strips 3a by the protective groove. Figure 1 It is half the cross-section of the tire crown.

[0022] like Figure 1 As shown, the tread 1 is arc-shaped, and different radii are present at different positions on the tread from the tire's rotation center. The radial distance from the tread center point A to the intersection point B of the outer wall of the second main tread groove 22 and the tread forms the rolling radius difference h1. The radial distance from the tread center point A to the shoulder point C forms the rolling radius difference h2. The distance L from the intersection point B to the shoulder point C is the width of the tread strip 3. The ratio of the difference between the radius differences h2 and h1 to the width L of the tread strip 3 is 0.08 to 0.13, i.e., 0.08 ≤ (h2-h1) / L ≤ 0.13. Within this range, adding protective grooves to the shoulder can effectively improve the tire's resistance to uneven wear while ensuring certain wear and rolling resistance performance. This is because when the radius difference (h2-h1) is smaller than the width L of the tread strip 3, the reduction in the shoulder radius difference reduces the relative slippage between the shoulder and the middle of the tread crown rubber, thus reducing uneven wear. However, at the same time, the reduction in the radius difference produces... Figure 2 (a) The increased contact area between the tire and the ground in the ground shape (a) increases the amount of rubber involved in deformation, thus worsening rolling resistance. In this case, increasing the shoulder guard groove has little effect on reducing uneven wear; on the contrary, it reduces the rigidity of the shoulder tread strip, further increasing rolling resistance and increasing the risk of premature wear due to tearing of the shoulder tread strip 3a. Conversely, when the diameter difference (h2-h1) is too large relative to the width L of the tread strip 3, the increased shoulder diameter difference produces... Figure 2 (b) The ground contact shape reduces the rolling resistance due to the reduced contact area between the tire tread and the ground, but increases the wear on one side. In this case, adding a shoulder guard groove does almost no reduction in wear on one side, because the large diameter difference causes the shoulder tread strips to not be grounded or to have less ground contact, thus losing the role of the tire shoulder in wear and reducing wear performance. Figure 2 (a) shows the tire contact patch shape under the low diameter difference of the tire. Figure 2 (b) is the tire contact shape under the tire height-diameter difference.

[0023] like Figure 3 As shown, the protective groove 4 on the tire shoulder adopts a three-dimensional sipe pattern design, with the three-dimensional sipe pattern extending along the entire circumference of the tire tread. Figure 3This is a partial three-dimensional view of the tire crown with the second main tread groove 22, protective groove 4, and shoulder tread strip 3a. Figure 4 This is an enlarged view of the 3D tool groove pattern. (Example) Figure 4 As shown, the three-dimensional sipe pattern is roughly wavy and curved, with a radial depth of d along the tire and lateral amplitudes of 41 distributed along the tire crown cross-section. The number of amplitudes is at least three. During tire operation, the protective grooves adhere to the ground upon contact. Figure 5 (a) shows the traditional form of contact between the protective ditch and the ground. Figure 5 (b) This describes the contact pattern between the three-dimensional sipe pattern protective groove and the ground. Compared to traditional protective grooves, the three-dimensional sipe pattern design allows for a tighter fit between the tread strips at both ends of the groove, reducing radial and circumferential creep of the rubber and improving tire shoulder rigidity, thereby reducing rolling resistance and the risk of shoulder tread strip tearing. The sipe depth d is less than the depth d21 of the first main tread groove 21 and the depth d22 of the second main tread groove 22. This is because the protective groove mainly serves to separate the tread body from the tire shoulder; excessive depth would reduce the uniformity of the overall tread pattern block rigidity distribution and weaken the rigidity of the shoulder tread strip 3a, making it more prone to tearing. The bottom of the sipe adopts a teardrop shape design, consisting of two arcs r1 and r2, which are tangent to the main sipe body segments p1 and p2, respectively. The sipe thickness t is at least 1 mm greater than the main sipe body thickness s, i.e., t ≥ s + 1 mm. This avoids excessive stress concentration at the bottom of the groove and reduces the risk of bottom tearing. Further specifications are provided for the dimensions of the three-dimensional groove pattern of the protective groove. The thickness s of the groove body is equal to the width s of the protective groove. The amplitude width w is 1.8 to 3.0 times the thickness s, i.e., 1.8 ≤ w / s < 3.0. This is because when the amplitude width is too small relative to the groove thickness, it has no significant effect on improving the shoulder stiffness; when the amplitude width is too large, it is difficult to demold after the tire vulcanization process, and the shoulder protective groove is easily damaged.

[0024] Example

[0025] The tire size in the subsequent comparative examples and embodiments is 295 / 75R22.5.

[0026] Table 1

[0027]

[0028] Table 1 shows the relationship between diameter difference and protective grooves. As can be seen from Table 1, without shoulder protective grooves, the tire's anti-uneven wear index decreases with the increase of the (h2-h1) / L ratio (a larger index value indicates better performance). This is because the increased relative diameter difference leads to increased relative slippage from the tire tread center to the shoulder, resulting in increased uneven wear. When protective grooves are added to the shoulder, the overall anti-uneven wear index improves compared to tires without protective grooves. This is because the added shoulder protective grooves separate the part prone to shoulder uneven wear from the main body of the tread, eliminating the relative slippage between the shoulder and the main body, thus reducing uneven wear to some extent. Meanwhile, when 0.08 ≤ (h2-h1) / L ≤ 0.13, the anti-uneven wear indexes of Examples 1, 2, 3, and 4 all improve. In Comparative Examples 1 and 2, (h2-h1) / L exceeds this range, and their anti-uneven wear indexes show almost no change compared to tires without protective grooves. This is because when the relative diameter difference (h2-h1) / L is too small, the relative slippage between the tire shoulder and the center of the tread rubber is already very small. At this point, increasing the shoulder guard groove has little effect on reducing uneven wear; on the contrary, it will further increase rolling resistance. When the relative diameter difference (h2-h1) / L is too large, the contact between the tire shoulder and the shoulder guard groove and the ground is very small or even non-existent, thus failing to reduce uneven wear and also losing the role of the tire shoulder in wear, resulting in a decrease in wear performance.

[0029] Figure 6 This demonstrates the impact of shoulder grooves on rolling resistance. When a tire has traditional shoulder grooves, the rolling resistance index decreases (a higher index indicates better rolling resistance). This is because the shoulder is cut by the grooves, reducing tread rigidity and increasing rubber deformation, leading to decreased rolling resistance. The tire of this invention uses a three-dimensional sipe design for its shoulder grooves, resulting in a higher rolling resistance index compared to tires with traditional grooves, and its rolling resistance performance is close to that of tires without grooves. This is because the three-dimensional sipe design allows the tread strips at both ends of the grooves to fit more tightly, reducing radial and circumferential creep of the rubber, increasing shoulder rigidity, thereby reducing rolling resistance and minimizing the risk of shoulder tread strip tearing.

[0030] Table 2

[0031] Comparative Example 3 Comparative Example 4 Example 5 Example 6 Example 7 s(mm) 1.5 1.5 1.5 1.5 1.5 t(mm) 1.5 2.0 2.5 3.0 3.0 w / s 1.6 1.8 2.2 2.6 3.0 Tear resistance index 100 100.5 104 106 107 Rolling resistance index 100 101 103 105 106

[0032] Table 2 shows the effects of the thickness and amplitude width of the three-dimensional sipe pattern on the tear resistance of the shoulder protective groove and the rolling resistance performance of the tire. When t ≥ s + 1, the tear resistance index of the protective grooves in Examples 5, 6, and 7 is significantly higher than that in Comparative Examples 3 and 4 (the larger the index, the better the performance). This is because the bottom of the groove is a stress concentration point, and a bottom thickness greater than the main body thickness by more than 1 mm can effectively disperse the stress at the bottom of the groove and make the stress change from the bottom of the groove to the tread smooth, thereby reducing the risk of tearing at the bottom of the groove. On the other hand, when the ratio of the amplitude width of the three-dimensional sipe pattern to the thickness of the sipe body w / s ≥ 1.8, the rolling resistance performance of Examples 5, 6, and 7 is improved compared with the comparative examples. This is because the wider the amplitude, the tighter the tread strips at both ends of the protective groove fit and the less creep, which improves the shoulder rigidity and thus improves the rolling resistance performance. Theoretically, the larger w / s is, the better, but in actual tires, excessively wide amplitudes make demolding difficult during the vulcanization process, causing damage to the protective groove and the mold. Therefore, w / s < 3.0 is further specified.

[0033] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

[0034] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A heavy-duty tire with anti-uniform wear and low rolling resistance, comprising a tread, a pair of first main tread grooves and a pair of second main tread grooves arranged circumferentially on the tread, and tread strips, wherein the two first main tread grooves are symmetrically arranged about the tire's central plane, the two second main tread grooves are symmetrically arranged about the tire's central plane, the second main tread grooves are located axially outside the first main tread grooves, and the tread strips are located axially outside the second main tread grooves; characterized in that: The radial distance from the center point A of the tread to the intersection point B of the outer wall of the second main tread groove and the tread forms the rolling radius difference h1; the radial distance from the center point A of the tread to the shoulder point C forms the rolling radius difference h2; the distance L from the intersection point B to the shoulder point C is the width of the tread strip; the ratio of the difference between the rolling radius difference h2 and the rolling radius difference h1 to the tread strip width L is 0.08~0.13, that is, 0.08≤(h2-h1) / L≤0.13; The tread pattern has three-dimensional sipes arranged along the circumference of the tire; on the cross-section of the tire, the three-dimensional sipes are wavy; the grooves where the three-dimensional sipes connect with the tread surface are called protective grooves, the thickness of the sipe body is equal to the width of the protective groove, and both are s; the amplitude width w of the three-dimensional sipes is 1.8 to 3.0 times the thickness s, that is, 1.8 ≤ w / s < 3.

0.

2. The anti-uniform wear and low rolling resistance heavy-duty tire according to claim 1, characterized in that: The radial depth is d, which is less than the depth d21 of the first main groove and the depth d22 of the second main groove. The bottom of the three-dimensional groove pattern is composed of the first arc r1 and the second arc r2. The first arc r1 is tangent to the main body line segment p1 of the first groove, and the second arc r2 is tangent to the main body line segment p2 of the second groove. The thickness t of the groove bottom pattern is at least 1 mm greater than the thickness s of the groove body, i.e., t ≥ s + 1 mm.

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