Pneumatic tire
By designing a tread block structure with alternating circumferential and width-direction grooves on the tread surface of the pneumatic tire, and setting fine grooves and sipes within the tread blocks, the problem of excessive lateral force in the central land area during wear is solved, thereby improving the tire's wear resistance and traction performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TOYO TIRE CORP
- Filing Date
- 2026-01-15
- Publication Date
- 2026-07-21
Smart Images
Figure CN122425994A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a pneumatic tire, and more particularly to a pneumatic tire for use in high-load areas. Background Technology
[0002] When heavy-duty vehicles such as buses and trucks turn, a large lateral force is applied to the pneumatic tires, so the central land area, which has a high ground pressure, is prone to wear. Patent Document 1 discloses a tread that aims to ensure traction performance, resistance to eccentric wear, and resistance to sideslip. It uses an axle slit with a bend and a circumferential slit at both ends that connect to the axle slit at the bend to cut the central land area into tread blocks, and sipes that close in the tread blocks are formed on the extension line of the circumferential slit.
[0003] Existing technical documents
[0004] Patent documents
[0005] Patent Document 1: Japanese Patent Application Publication No. 2022-143838 Summary of the Invention
[0006] The problem that the invention aims to solve
[0007] Typically, the tread pattern of a pneumatic tire changes with use from the early to the later stages of wear. The technology disclosed in Patent Document 1 has room for improvement in suppressing the lateral forces exerted on the central land area during cornering from the early to the later stages of wear.
[0008] The purpose of this invention is to provide a pneumatic tire that can reduce the lateral force applied to the central land area during cornering from the early to the middle and late stages of wear.
[0009] Methods for solving problems
[0010] The pneumatic tire of the present invention includes a tread, characterized in that the tread has a central landmass and a shoulder landmass, and a first circumferential groove extending along the tire circumference is formed between the central landmass and the shoulder landmass. The central landmass is cut into a first central tread block and a second central tread block by a first width direction groove and a second width direction groove arranged alternately in the tire circumferential direction. A first fine groove is formed in the first central tread block, which is connected to the first width direction groove, extends along the tire circumferential direction and is closed in the first central tread block. A second fine groove is formed in the second central tread block, which is connected to the first width direction groove, extends along the tire circumferential direction and is closed in the second central tread block. A first sipe formed on the bottom surface of the first fine groove is substantially parallel to the first fine groove, and a second sipe formed on the bottom surface of the second fine groove is substantially parallel to the second fine groove.
[0011] Based on the aforementioned pneumatic tire, the depth of the first and second sipes may be 80% to 90% of the depth of the first circumferential groove. Alternatively, the first width-direction groove may extend in a serrated pattern with two bends, and the first and second fine grooves may connect to the first width-direction groove between the two bends. Furthermore, the first and second fine grooves, which are opposite each other across the first width-direction groove, overlap in the tire width direction by an overlap of 2 mm or less.
[0012] Invention Effects
[0013] The pneumatic tire of the present invention can reduce the lateral force applied to the central land area during cornering from the early stage of wear to the middle and late stage of wear, thus exhibiting excellent wear resistance. Attached Figure Description
[0014] Figure 1 This is a perspective view showing a portion of an inflatable tire as an example of an embodiment.
[0015] Figure 2 This is an enlarged view of a portion of the central land area in an inflatable tire, which is one example of an implementation.
[0016] Figure 3 It is shown Figure 2 The diagram shows the cross-section of line AA in the diagram.
[0017] Figure 4 This is an enlarged view of the vicinity of the end of the second cutting groove formed on the bottom surface of the second width direction groove in an inflatable tire, which is an example of an embodiment.
[0018] Figure 5 It is shown Figure 4 A diagram of the BB line section.
[0019] Figure 6 This is an enlarged view of the vicinity of the first and second grooves formed in the central land portion of an inflatable tire, which is an example of an embodiment.
[0020] Figure 7 It is shown Figure 6 A diagram of the CC line cross section.
[0021] Explanation of reference numerals in the attached figures:
[0022] 1. Pneumatic tire; 10. Tread; 11. Sidewall; 12. Bead; 12a. Bead core; 12b. Bead filler; 13. Carcass; 14. Belt layer; 16. Airtight layer rubber; 20. Central landmass; 22. Shoulder landmass; 25. First circumferential groove; 27. Second circumferential groove; 31. First width direction groove; 33. Second width direction groove; 36. First central tread block; 38. Second central tread block; 41. First fine groove; 43. Second fine groove; 51. First cut-off groove; 53. Second cut-off groove; 53E. End; 54. End; 61. First sipe; 63. Second sipe. Detailed Implementation
[0023] Hereinafter, an example of an embodiment of the pneumatic tire of the present invention will be described in detail with reference to the accompanying drawings. The embodiment described below is merely an example, and the present invention is not limited to the following embodiment. Furthermore, the present invention includes the selective combination of the constituent elements of the various embodiments and modifications described below.
[0024] Figure 1 This is a perspective view showing a portion of a pneumatic tire 1 as an example of an embodiment, and also illustrating the internal structure of the tire. Figure 1 As shown, the pneumatic tire 1 includes a tread 10 that is in contact with the road surface, a pair of sidewalls 11 extending radially inward from the tread 10, and a pair of bead 12 that contacts the rim of the wheel. The tread 10, sidewalls 11, and bead 12 are formed in a ring shape along the tire circumference. The sidewalls 11 and bead 12 form the left and right sides of the pneumatic tire 1.
[0025] The pneumatic tire 1 comprises a carcass 13, a belt layer 14, and an airtight rubber layer 16. The carcass 13 is a rubber-covered cord layer that forms the skeleton of the pneumatic tire 1, resistant to loads, impacts, air pressure, etc. The carcass 13 is mounted radially inside the tire on the tread 10 between a pair of bead layers 12, folding back from the axially inside to the outside at the bead layers 12. The belt layer 14 is a reinforcing belt located radially outside the carcass 13, strongly securing the carcass 13 to improve the rigidity of the pneumatic tire 1. The belt layer 14 is, for example, composed of rubber-covered steel cords. The airtight rubber layer 16 is a rubber layer located radially inside the carcass 13, maintaining the air pressure of the pneumatic tire 1.
[0026] The pneumatic tire 1 has a bead core and a bead filler. The bead core and the bead filler are respectively located on the left and right sides of the bead 12. The bead core is a ring-shaped component made of steel wire covered with rubber. The bead filler is made of hard rubber and has the function of improving the rigidity of the bead 12.
[0027] The pneumatic tire 1 may also have on the outer surface of the support (buttress) portion from the tread 10 to the sidewall 11 Figure 1 Side ribs (not shown). These side ribs protrude outwards from the tire's axial direction, forming a ring along the tire's circumference. The side ribs function to protect the tire sidewall from obstacles and other influences.
[0028] The tread 10 has a central land area 20 and a shoulder land area 22. A first circumferential groove 25 extending in the tire circumferential direction is formed between the central land area 20 and the shoulder land area 22. Figure 1 In the example shown, a second circumferential groove 27 is formed, extending approximately along the tire equator in the tire circumferential direction. The central land portion 20 is divided in the tire width direction by the second circumferential groove 27, and the left and right treads, divided by a plane passing through the tire equator and perpendicular to the tread 10, have the same shape. The first circumferential groove 25 can extend in a serrated pattern relative to the tire circumferential direction, and similarly, the second circumferential groove 27 can also extend in a serrated pattern relative to the tire circumferential direction. It should be noted that the pattern of the tread 10 is not limited to... Figure 1 In the example shown, a second circumferential groove 27 may not be formed. Figure 1 In the example shown, the second circumferential groove 27 and the two first circumferential grooves 25 have approximately the same depth. Here, the depth of the first circumferential groove 25 and the second circumferential groove 27 refers to the radial distance of the tire from the upper surface of the tread 10 to the bottom of the groove. The depths of the first circumferential groove 25 and the second circumferential groove 27 can also be approximately the same along the entire circumference of the tire.
[0029] The central land area 20 is divided into a first central tread block 36 and a second central tread block 38 by alternating first width-direction grooves 31 and 33 arranged along the tire circumference. A first groove 41 is formed in the first central tread block 36, connecting to the first width-direction groove 31, extending along the tire circumference and closing within the first central tread block 36. A second groove 43 is formed in the second central tread block 38, connecting to the first width-direction groove 31, extending along the tire circumference and closing within the second central tread block 38. Figure 1 In the example shown, the first groove 41 and the second groove 43 have approximately the same length. Here, a groove is a groove whose width is narrower than both the circumferential groove and the width-direction groove.
[0030] The first width-direction groove 31 extends in a serrated shape with two bends. The second width-direction groove 33 is inclined at a certain angle relative to the tire width direction. The angle of the second width-direction groove 33 relative to the tire equator is, for example, in the range of 55° to 85°. By making the angle of the second width-direction groove 33 relative to the tire equator 55° or more, the lateral force exerted on the central land area 20 when the vehicle is turning can be reduced. In addition, by making the angle of the second width-direction groove 33 relative to the tire equator 85° or less, the uneven wear of the central land area 20 can be reduced.
[0031] The shoulder portion 22 is cut into tread blocks, for example, by a third width direction groove 35 that communicates with the first circumferential groove 25 and is arranged alternately along the tire circumference. From a drainage point of view, the third width direction groove 35 is preferably formed at a position opposite to the second width direction groove 33, separated from the first circumferential groove 25. In addition, by having the second width direction groove 33 and the third width direction groove 35 inclined in approximately the same direction relative to the tire width direction, wear on the step-in side can be suppressed.
[0032] Third width direction groove 35 as shown Figure 1 The groove is bent as shown. Alternatively, a kerf can be formed at the bottom of the third width direction groove 35. This further improves the wear resistance and traction performance of the pneumatic tire 1. Furthermore, the kerf formed at the bottom of the third width direction groove 35 can be cut off in the same way as the severing kerf formed in the first width direction groove 31 (described later), so that no kerf is present in the bent portion of the third width direction groove 35. Here, a kerf refers to a fine, linear groove with a width thinner than a fine groove. In this specification, a groove with a width of 1.0 mm or less is defined as a kerf.
[0033] exist Figure 1 In the example shown, a protrusion projecting radially outward is formed at the bottom of the second circumferential groove 27. This helps to suppress stones from getting into the second circumferential groove 27. Furthermore, the protrusion can be truncated at predetermined intervals in the tire circumferential direction, forming a serrated shape corresponding to the bending of the second circumferential groove 27. This suppresses large deformation of the protrusion and improves its durability.
[0034] Next, refer to Figures 2-7 A more detailed explanation of the Central Land Department 20. Figure 2 This is an enlarged view of a portion of the central land area 20 in an inflatable tire 1, which is an example of an embodiment.
[0035] A first cutting groove 51, which is substantially parallel to and truncated by the first width direction groove 31, is formed on the bottom surface of the first width direction groove 31. A second cutting groove 53, which is substantially parallel to and truncated by the second width direction groove 33, is formed on the bottom surface of the second width direction groove 33. This ensures traction performance from the initial wear stage to the later wear stage while maintaining wear resistance. Here, the initial wear stage refers to the state where the tread 10 has worn down to a thickness equivalent to 0% to 10% of the depth of the first circumferential groove 25 before use. The later wear stage refers to the state where the tread 10 has worn down to a thickness equivalent to 60% to 90% of the depth of the first circumferential groove 25 before use. It should be noted that in the later wear stage, when the tread 10 has worn down to a thickness equivalent to more than 90% of the depth of the first circumferential groove 25 before use, tread wear indicators appear on the tire surface, marking the tire replacement period. In addition, during the later stages of wear, the first width direction groove 31 and the second width direction groove 33 disappear from the tread 10, and the first cut-off groove 51 and the second cut-off groove 53 appear on the surface of the tread 10.
[0036] Figure 3 It is shown Figure 2 The diagram showing the cross-section along line AA illustrates the cross-sections of the first width-direction groove 31 and the first cutting-off groove 51. The first width-direction groove 31 has a generally rectangular cross-section. The first cutting-off groove 51 is formed approximately at the center of the width direction of the bottom surface of the first width-direction groove 31, and similarly has a generally rectangular cross-section.
[0037] The depth d1 of the first sipe groove 51 is, for example, more than 80% and less than 90% of the depth of the first circumferential groove 25. This significantly improves wear resistance and ensures traction performance. Here, the depth d1 of the first sipe groove 51 refers to the radial distance of the tire from the surface of the second central tread block 38 to the bottom surface of the first sipe groove 51. Figure 2 In the example shown, the second width direction groove 33 and the second cutting-off groove 53 have cross-sectional shapes that are approximately the same as those of the first width direction groove 31 and the first cutting-off groove 51, respectively. The depth of the second cutting-off groove 53 is also more than 80% and less than 90% of the depth of the first circumferential groove 25, just like the first cutting-off groove 51.
[0038] exist Figure 2 In the example shown, the first cutting groove 51 is not formed near the two bending points of the first width-direction groove 31, but is cut into three, with a short groove, a long groove, and a short groove arranged sequentially from the inside to the outside in the tire axial direction. The two short grooves can also be approximately the same length. When the groove is bent, stress is applied to the bent part, which can easily cause cracks. Therefore, by cutting the groove near the two bending points of the first width-direction groove 31, cracks can be prevented.
[0039] The first cutting groove 51 is generally oriented upwards to the left, while the second cutting groove 53 is generally oriented upwards to the right. In this way, by alternately arranging the first cutting groove 51 and the second cutting groove 53, which are inclined in the opposite direction to the tire axial direction, the force required for the two tread blocks, the first central tread block 36 and the second central tread block 38, to mesh with each other is exerted, thereby increasing the rigidity of the central land portion 20.
[0040] exist Figure 2 In the example shown, the second cut-off groove 53 is longer than the first cut-off groove 51. This results in a more significant effect in maintaining wear resistance and ensuring traction performance. Here, the lengths of the first cut-off groove 51 and the second cut-off groove 53 refer to the sum of the lengths of the multiple grooves cut off in the tire width direction.
[0041] Figure 4 This is an enlarged view of the vicinity of the end of the second slit groove 53. The second slit groove 53 has a bend point and an end portion 53E located further outward in the tire width direction than the bend point. The end portion 53E intersects the first circumferential groove 25 at an angle of 85° or more and 92° or less. That is, the angle θ between the extension line of the side of the first central tread block 36 and the second central tread block 38 connected to the second width direction groove 33, located further outward in the tire width direction, and the end portion 53E is 85° or more and 92° or less. The end of the groove is more prone to cracking than other parts of the groove, but the presence of the bend portion can suppress the propagation of cracks from the bend portion towards the axial inward side of the tire.
[0042] Figure 5 It is shown Figure 4 The diagram of the BB line section shows the section near the location where the second cutting groove 53 intersects with the first circumferential groove 25. It should be noted that... Figure 5 In order to show the sipes and the depth of the grooves, an imaginary line 38i representing the surface of the second central tread block 38 is depicted. The bottom surface of the end 53E becomes shallower towards the end 54, thereby more significantly suppressing the propagation of cracks generated at the end 54 towards the axial inward side of the tire. Figure 5 In the example shown, end 53E is located at end 54, away from the second cut-off groove 53, as... Figure 3 The bottom surface shown has a depth d1, and near the end 54 of the second cutting groove 53, it has a shelf-like bottom surface with a depth d2 that is shallower than d1. The inclined length L1 of the bottom surface of the end 53E is, for example, 1 mm to 10 mm. Furthermore, as mentioned above, d1 is 80% to 90% of the depth D of the first circumferential groove 25, and d2 is, for example, 25% to 45% of the depth D of the first circumferential groove 25. It should be noted that the shape of the end 53E is not limited to any shape where the bottom surface of the end 53E becomes shallower towards the end 54. Figure 5The example shown.
[0043] Figure 6 This is an enlarged view of the vicinity of the first groove 41 and the second groove 43. A first sipe 61, substantially parallel to the first groove 41, is formed on the bottom surface of the first groove 41, and a second sipe 63, substantially parallel to the second groove 43, is formed on the bottom surface of the second groove 43. With the first sipe 61 and the second sipe 63, lateral forces generated on either the inner or outer side of the tire axial direction are not directly transmitted to the other, thus releasing the lateral forces applied to the first central tread block 36 and the second central tread block 38. It should be noted that without the sipes, the lateral forces would be applied to the entire surface of the wider tread block, causing wrinkles on the tread block surface. Furthermore, the grooves around the sipes improve traction performance in the early stages of wear.
[0044] The first width-direction groove 31 extends in a serrated shape with two bends, and the first groove 41 and the second groove 43 are connected to the first width-direction groove 31 between the two bends. This significantly reduces the lateral force applied to the central land area 20 when the vehicle is turning. By providing the first groove 41 and the second groove 43 near the center of the tread blocks constituting the central land area in the tire width direction, the sizes of the inner and outer portions of the first groove 41 and the second groove 43 in the tire axial direction are approximately the same, and the stress applied to the inner and outer portions is also approximately the same, thus achieving the aforementioned effect.
[0045] The first fine groove 41 and the second fine groove 43, which are opposite each other in the first width direction groove 31, overlap in the tire width direction, and the overlap amount L2 is less than 2 mm. As a result, the first fine groove 41 and the second fine groove 43 can be provided near the center of the tread blocks that constitute the central land area in the tire width direction, so the effect of reducing lateral force is more significant.
[0046] The first sipe 61 and the second sipe 63 preferably extend to the center of the first central tread block 36 and the second central tread block 38 in the tire circumference, respectively. The longer the sipe, the greater the effect of reducing lateral force; however, if the sipe extends far beyond the center of the tread block in the tire circumference, the possibility of cracks forming in the tread block increases. Figure 6 In the example shown, the first groove 41 and the second groove 43, as well as the first sipe 61 and the second sipe 63, extend approximately to the center of the tire circumference of the first central tread block 36 and the second central tread block 38, respectively. It should be noted that the present invention is not limited to... Figure 6 As shown in the example, for instance, the first groove 41 and the second groove 43 may be cut off and the grooves may extend to approximately the center of the tire circumference of the tread block.
[0047] Figure 7 It is shown Figure 6 The diagram showing the cross-section along the CC line illustrates the cross-sections of the second groove 43 and the second cutter groove 63. The second groove 43 has a generally rectangular cross-section. The second cutter groove 63 is formed approximately at the center of the width direction of the bottom surface of the second groove 43, and similarly has a generally rectangular cross-section.
[0048] The depth d3 of the second sipe 63 is, for example, more than 80% and less than 90% of the depth D of the first circumferential groove 25. By making d3 more than 80% of D, the effect of the sipe can be more significantly exerted until the middle and late stages of wear. Furthermore, when d3 is less than 80% of D, the effect of reducing lateral force sometimes becomes smaller. When d3 exceeds 90% of D, the rigidity of the tread block sometimes decreases. Here, the depth d3 of the second sipe 63 refers to the radial distance of the tire from the surface of the second central tread block 38 to the bottom surface of the second sipe 63. Figure 6 In the example shown, the first groove 41 and the first cutting groove 61 have approximately the same cross-sectional shape as the second groove 43 and the second cutting groove 63, and the depth of the first cutting groove 61 is also more than 80% and less than 90% of the depth of the first circumferential groove 25, just like the second cutting groove 63.
[0049] As described above, the pneumatic tire of the present invention can reduce the lateral force applied to the central land area during cornering from the early to the middle and late stages of wear. Specifically, the central land area, which is cut into tread blocks, has a groove, one end of which communicates with a groove extending along the tire axial direction and the other end is closed in the tread block. Moreover, the above-mentioned effect can be obtained by having a sipe on the bottom surface of the groove.
Claims
1. A pneumatic tire comprising a tread, wherein, The tread has a central land area and a shoulder land area. A first circumferential groove extending along the tire circumference is formed between the central land portion and the shoulder land portion. The central landmass is divided into a first central tread block and a second central tread block by a first width-direction groove and a second width-direction groove arranged alternately in the tire circumferential direction. A first groove is formed in the first central tread block, which is connected to the first width-direction groove, extends along the tire circumference, and closes in the first central tread block. A second groove is formed in the second central tread block, which is connected to the first width-direction groove, extends along the tire circumference, and closes in the second central tread block. A first cutting groove, which is substantially parallel to the first fine groove, is formed on the bottom surface of the first fine groove, and a second cutting groove, which is substantially parallel to the second fine groove, is formed on the bottom surface of the second fine groove.
2. The pneumatic tire according to claim 1, wherein, The depth of the first cutting groove and the second cutting groove is more than 80% and less than 90% of the depth of the first circumferential groove.
3. The pneumatic tire according to claim 1, wherein, The first width-direction groove extends in a serrated manner with two bends, and the first and second fine grooves are connected to the first width-direction groove between the two bends.
4. The pneumatic tire according to claim 1, wherein, The first and second fine grooves, which are opposite each other across the first width direction groove, overlap in the tire width direction, with an overlap of less than 2 mm.
5. The pneumatic tire according to claim 1, wherein, The shoulder land portion is cut into tread blocks by a third width direction groove that communicates with the first circumferential groove and is arranged alternately in the tire circumferential direction. The third width direction groove is formed at a position opposite to the second width direction groove, separated by the first circumferential groove.
6. The pneumatic tire according to claim 1, wherein, A first cutting groove, which is approximately parallel to and truncated by the first width direction groove, is formed on the bottom surface of the first width direction groove. A second cutting groove is formed on the bottom surface of the second width direction groove, which is substantially parallel to and cut off from the second width direction groove.
7. The pneumatic tire according to claim 6, wherein, The depths of the first cutting groove and the second cutting groove are more than 80% and less than 90% of the depth of the first circumferential groove.
8. The pneumatic tire according to claim 6, wherein, The first cutting groove and the second cutting groove are inclined in the opposite direction relative to the tire axis.
9. The pneumatic tire according to claim 6, wherein, The second cutting groove is longer than the first cutting groove.
10. The pneumatic tire according to claim 1, wherein, The first sipe and the second sipe extend to the center of the tire circumference of the first central tread block and the second central tread block, respectively.