Pneumatic tires

Abstract

The present invention provides a pneumatic tire, which comprises: a plurality of main grooves formed on a tread portion and extending along the circumferential direction of the tire, the plurality of main grooves comprising: a shoulder main groove located at the outermost position in the width direction of the tire, the shoulder main groove comprising: a raised portion formed by raising the first side in the width direction of the tire in the groove bottom of the shoulder main groove compared to the second side, the raised portion being lower than the outer surface of the tread portion and extending continuously over the entire circumference of the tire.

Description

Technical Field

[0001] The present invention relates to a pneumatic tire. Background Art

[0002] The pneumatic tire disclosed in the following patent document 1 comprises: a main groove (hereinafter referred to as a shoulder main groove), which is located at the outermost position in the tire width direction of the contact surface and extends along the tire circumferential direction; a transverse groove, which extends from the shoulder main groove to the outer side of the tire contact end; and a bottom raised portion, which includes a boundary portion from the transverse groove to the shoulder main groove, is arranged across the shoulder main groove and the transverse groove, and is formed by protruding from the groove bottom. By providing the bottom raised portion, the rigidity of the corner of the pattern block in the shoulder portion that is prone to deformation can be improved. However, since the bottom raised portion is intermittently arranged in the tire circumferential direction together with the transverse groove, it hardly contributes to the improvement of traction performance. In addition, since the bottom raised portion is intermittently arranged, the rigidity of the corner of the pattern block is not sufficient, and there is room for improvement in the uneven wear resistance, especially the toe wear resistance (top heel wear resistance) performance.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2016-147598 Summary of the invention

[0006] Therefore, an object of the present invention is to provide a pneumatic tire capable of improving traction performance and uneven wear resistance (toe and heel wear resistance).

[0007] The pneumatic tire of the present invention comprises: a plurality of main grooves formed in the tread portion and extending in the tire circumferential direction;

[0008] The plurality of main grooves include: a shoulder main groove located at the outermost position in the tire width direction;

[0009] The shoulder main groove includes a protrusion formed by raising a first side of a groove bottom of the shoulder main groove in the tire width direction more than a second side.

[0010] The raised portion is lower than the outer surface of the tread portion and extends continuously over the entire circumference of the tire. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a cross-sectional view of a main part of the pneumatic tire according to the present embodiment, taken along the tire meridian plane.

[0012] Figure 2 It is a front view of the pneumatic tire according to the present embodiment.

[0013] Figure 3yes Figure 2 A magnified view of region III.

[0014] Figure 4 yes Figure 3 This is an enlarged cross-sectional view of the main part of the IV-IV line.

[0015] Figure 5 yes Figure 3 An enlarged cross-sectional view of the main part of the V-V line.

[0016] Description of Reference Numerals

[0017] 1…pneumatic tire; 2…tread portion; 2a…tread surface; 2d…ground contact end; 2e…ground contact end; 3a…main groove (shoulder main groove); 3b…main groove (shoulder main groove); 4a…land portion (shoulder land portion); 4b…land portion (shoulder land portion); 4c…land portion (center land portion); 5…lateral groove; 6…raised portion; 7…sipe; 30…groove bottom; 31…groove wall; 32…groove wall; 40…shoulder block; 61…top surface of the raised portion; 62…outer surface of the raised portion; 63…extended portion; 311…curved portion; 312…flat portion; D1…tire width direction; D11…first side in the tire width direction; D12…second side in the tire width direction; D2…tire radial direction; D3…tire circumferential direction; S1…tire equatorial plane. DETAILED DESCRIPTION

[0018] Below, refer to Figure 1 to Figure 5 , an embodiment of a pneumatic tire is described. In addition, in each figure, the dimension ratio of the drawings and the actual dimension ratio are not necessarily consistent, and the dimension ratios between the drawings are not necessarily consistent.

[0019] In each figure, the first direction D1 is: the tire width direction D1 parallel to the rotation center of the pneumatic tire (hereinafter also referred to as "tire") 1, that is, the tire rotation axis, the second direction D2 is: the diameter direction of the tire 1, that is, the tire radial direction D2, and the third direction D3 is: the tire circumferential direction D3 around the tire rotation axis.

[0020] In the tire width direction D1, the inner side is the side close to the tire equatorial plane S1, and the outer side is the side away from the tire equatorial plane S1. In addition, in the tire width direction D1, the first side D11 is also referred to as the first width direction side D11, and the second side D12 is also referred to as the second width direction side D12. In addition, in the tire radial direction D2, the inner side is the side close to the tire rotation axis, and the outer side is the side away from the tire rotation axis.

[0021] The tire equatorial plane S1 is a plane that is orthogonal to the tire rotation axis and is located at the center position in the tire width direction D1 of the tire 1. The tire meridian plane is a plane that includes the tire rotation axis and is orthogonal to the tire equatorial plane S1. In addition, the tire equatorial line is a line where the outer surface (tread surface 2a described later) of the tire 1 in the tire radial direction D2 intersects the tire equatorial plane S1.

[0022] like Figure 1 As shown, the tire 1 involved in this embodiment includes: a pair of bead portions 1a, which have bead cores; sidewall portions 1b, which extend from each bead portion 1a toward the outside of the tire radial direction D2; and a tread portion 2, which is connected to the outer end portions of the pair of sidewall portions 1b in the tire radial direction D2, and the outer surface in the tire radial direction D2 contacts the road surface. In this embodiment, the tire 1 is an inflatable tire 1 filled with air inside, and is mounted on a rim 20.

[0023] The tire 1 includes a carcass portion 1c which is mounted between a pair of bead cores, and an inner liner 1d which is arranged inside the carcass portion 1c and has an excellent function of preventing gas from passing through so as to maintain air pressure. The carcass portion 1c and the inner liner 1d are arranged along the inner circumference of the tire and spread over the bead portion 1a, the sidewall portion 1b, and the tread portion 2.

[0024] The tread portion 2 includes: a tread rubber 2b having a tread surface 2a in contact with the road surface; and a belt layer 2c disposed between the tread rubber 2b and the carcass portion 1c. The tread surface 2a has a ground contact surface that actually contacts the road surface, and the outer ends of the ground contact surface in the tire width direction D1 are referred to as ground contact ends 2d and 2e. In addition, the ground contact surface refers to the tread surface 2a in contact with the road surface when the tire 1 is mounted on a regular rim 20 and filled with a regular internal pressure, and the tire 1 is placed vertically on a flat road surface and a regular load is applied.

[0025] The regular rim 20 is a rim 20 that is determined for each tire 1 in accordance with the specification in a specification system including the specification on which the tire 1 is based, for example, a "standard rim" in the case of JATMA, a "design rim" in the case of TRA, and a "measurement rim" in the case of ETRTO.

[0026] The normal internal pressure is: the air pressure determined for each tire 1 according to each specification in the specification system including the specification on which the tire 1 is based. If it is JATMA, it is the maximum air pressure. If it is TRA, it is the maximum value recorded in the table "Tire load limit at various cold inflation pressures". If it is ETRTO, it is the "inflation pressure". When the tire 1 is used for a passenger car, the normal internal pressure is 180 kPa.

[0027] The normal load is a load determined for each tire 1 according to each specification in a specification system including the specification to which the tire 1 is based. If it is JATMA, it is the maximum load capacity. If it is TRA, it is the maximum value recorded in the above table. If it is ETRTO, it is the "load capacity". When the tire 1 is used for a passenger car, the normal load is 85% of the corresponding load of the internal pressure of 180 kPa.

[0028] like Figure 1 as well as Figure 2 As shown, the tread rubber 2b has: a plurality of main grooves 3a, 3b extending in the tire circumferential direction D3. The main grooves 3a, 3b extend continuously in the tire circumferential direction D3. The main grooves 3a, 3b are repeatedly bent and extend in a zigzag shape. In addition, the number of main grooves 3a, 3b is not particularly limited, but is 2 in this embodiment.

[0029] The main grooves 3a and 3b may have a portion forming a shallow groove, i.e., a so-called tread wear indicator (not shown), so that the wear degree can be known by being exposed as the wear progresses. In addition, for example, the main grooves 3a and 3b may have a groove width of 3% or more of the distance between the ground contact ends 2d and 2e (the dimension in the tire width direction D1). In addition, for example, the main grooves 3a and 3b may have a groove width of 5 mm or more.

[0030] Among the plurality of main grooves 3a, 3b, a pair of main grooves 3a, 3b arranged on the outermost sides in the tire width direction D1 are called shoulder main grooves 3a, 3b. In addition, when more than three main grooves are provided, the main groove arranged between the pair of shoulder main grooves 3a, 3b is called center main groove. The center main groove can be configured to extend in a straight line or in a zigzag shape.

[0031] The tread rubber 2b includes a plurality of land portions 4a to 4c which are divided by a plurality of main grooves 3a and 3b and a pair of ground contact edges 2d and 2e. The number of the land portions 4a to 4c is not particularly limited, but is three in the present embodiment.

[0032] The land portions 4a, 4b defined by the shoulder main grooves 3a, 3b and the ground contact edges 2d, 2e are referred to as shoulder land portions 4a, 4b, and the land portion 4c defined by the shoulder main grooves 3a, 3b is referred to as a center land portion 4c.

[0033] The shoulder land portion 4a includes a plurality of lateral grooves 5 extending from the shoulder main groove 3a toward the first width direction side D11. The lateral grooves 5 open into the shoulder main groove 3a. The shoulder land portion 4a includes a plurality of shoulder blocks 40 divided by the plurality of lateral grooves 5 in the tire circumferential direction D3.

[0034] The lateral groove 5 has a first portion 5a extending in a direction inclined with respect to the tire width direction D1 and a second portion 5b extending parallel to the tire width direction D1. The groove width of the lateral groove 5 is, for example, 3.8 to 6.6 mm. The groove depth of the lateral groove 5 is, for example, 8.9 to 9.7 mm.

[0035] The shoulder land portion 4a has a sipe pattern 51. The sipe pattern 51 extends parallel to the first portion 5a of the lateral groove 5. One end of the sipe pattern 51 is open in the shoulder main groove 3a, and the other end thereof forms a terminal in the shoulder pattern block 40. In addition, the shoulder land portion 4a has a width groove 52. The width groove 52 extends along the tire width direction D1. In addition, in this specification, "sipe pattern" refers to: a groove on the tread surface 2a having a width dimension less than 1.6 mm. In addition, in this specification, "parallel" means: not only a completely parallel situation, but also a substantially parallel situation with a crossing angle of less than 5 degrees (the same applies below).

[0036] The shoulder main groove 3a includes a groove bottom 30, a groove wall 31 on the first width direction side D11, and a groove wall 32 on the second width direction side D12.

[0037] The groove wall 32 on the second width direction side D12 extends in a zigzag shape along the tire circumferential direction D3. On the other hand, the groove wall 31 on the first width direction side D11 includes a curved portion 311 extending in a curved manner parallel to the opposing groove wall 32, and a flat portion 312 extending in parallel to the tire circumferential direction D3. The curved portion 311 and the flat portion 312 are arranged adjacent to each other. Since the groove wall 31 includes the flat portion 312, the uneven wear resistance (toe and heel wear resistance) is improved compared to the case where the groove wall 31 and the groove wall 32 are formed in the same zigzag shape as a whole.

[0038] The length L2 of the flat portion 312 is preferably equal to or greater than 50% of the total length L1+L2 of the length L1 of the curved portion 311 and the length L2 of the flat portion 312 (see Figure 2 ). By making the length L2 equal to or greater than 50% of the length L1+L2, the uneven wear resistance can be further improved. Here, the length L1 and the length L2 are the lengths in the tire circumferential direction D3.

[0039] The shoulder main groove 3a includes a protrusion 6 formed by raising the first width direction side D11 of the groove bottom 30 more than the second width direction side D12. The protrusion 6 extends continuously over the entire circumference of the tire circumferential direction D3. The protrusion 6 has a top surface 61 parallel to the tread surface 2a and an outer side surface 62 parallel to the groove wall 31. In addition, the groove wall 31 is a wall surface exposed to the outside of the tire radial direction D2 than the protrusion 6.

[0040] like Figure 4As shown, the top surface 61 of the raised portion 6 is lower than the tread surface 2a. The depth d6 from the tread surface 2a to the top surface 61 is, for example, 6.0 to 7.0 mm. The depth d6 is constant over the entire raised portion 6, but is not limited thereto. By providing the raised portion 6 in the shoulder main groove 3a, the traction performance can be improved by utilizing the step difference of the raised portion 6. In addition, by providing the raised portion 6 continuously over the entire circumference, the traction performance can be further improved. In addition, by providing the raised portion 6, not only the rigidity of the shoulder block 40 adjacent to the raised portion 6 can be improved, but also the deformation of the main groove surface shape can be suppressed. Accordingly, the toe and heel wear of the shoulder block 40 can be suppressed.

[0041] The height h6 of the protrusion 6 from the groove bottom 30 is preferably 10 to 50% of the groove depth d3 of the shoulder main groove 3a. By setting the height h6 of the protrusion 6 within this range, the deterioration of the drainage performance of the shoulder main groove 3a can be prevented, and the traction performance and uneven wear resistance can be improved.

[0042] The outer side surface 62 of the second width direction side D12 of the protrusion 6 extends in a zigzag shape along the tire circumferential direction D3. In addition, the outer side surface 62 is curved and extends in parallel with the groove wall 32 of the opposite shoulder main groove 3a. By making the outer side surface 62 zigzag, the traction performance can be improved by utilizing the curved edge of the outer side surface 62.

[0043] The first bending point 62a of the outer side surface 62 protrudes toward the first width direction side D11 and is adjacent to the opening of the lateral groove 5 in the tire width direction D1. In addition, the second bending point 62b of the outer side surface 62 protrudes toward the second width direction side D12 and is opposite to the flat portion 312 of the shoulder main groove 3a in the tire width direction D1.

[0044] The protrusion 6 includes an extension portion 63 extending into the lateral groove 5. The depth from the tread surface 2a to the top surface of the extension portion 63 is the same as the depth d6 from the tread surface 2a to the top surface 61 of the protrusion 6. The width of the extension portion 63 is the same as the groove width of the lateral groove 5. The extension portion 63 extends to the middle of the first portion 5a of the lateral groove 5. The end portions 63a of the plurality of extension portions 63 are arranged at the same position in the tire width direction D1 and are arranged in a straight line in the tire circumferential direction D3.

[0045] The extended portion 63 includes a sipe 7 extending in the direction in which the lateral groove 5 extends. One end of the sipe 7 opens in the shoulder main groove 3a, and the other end thereof terminates in the extended portion 63. Thus, the protrusion 6 is not interrupted by the sipe 7 but is continuous in the tire circumferential direction D3. The sipe 7 is arranged at the width center of the extended portion 63. By providing the sipe 7 in the extended portion 63, it is possible to prevent the rigidity of the corner of the shoulder block 40 from becoming too high due to the extended portion 63, thereby suppressing the deterioration of the ground contact performance.

[0046] The groove depth d7 of the sipe 7 is shallower than the groove depth d3 of the shoulder main groove 3a. If the sipe 7 is too deep, it will become a major cause of cracks. The sipe 7 of this embodiment is formed with a groove width of 0.8 mm and a groove depth of 8.0 to 8.5 mm.

[0047] like Figure 2 As shown, the center land portion 4c includes a plurality of circumferential grooves 81 extending along the tire circumferential direction D3, a plurality of width grooves 82 extending along the tire width direction D1, and a plurality of sipes 83. The circumferential grooves 81 and the width grooves 82 intersect with each other.

[0048] As described above, the pneumatic tire 1 according to the present embodiment includes: a plurality of main grooves 3a, 3b formed in the tread portion 2 and extending along the tire circumferential direction D3;

[0049] The plurality of main grooves 3a, 3b include a shoulder main groove 3a located at the outermost position in the tire width direction D1,

[0050] The shoulder main groove 3a includes a protrusion 6 formed by raising a first side D11 of a groove bottom 30 of the shoulder main groove 3a in the tire width direction D1 more than a second side D12.

[0051] The raised portion 6 is lower than the outer surface 2 a of the tread portion 2 , and extends continuously over the entire circumference in the tire circumferential direction D3 .

[0052] According to this configuration, by providing the protrusion 6 in the shoulder main groove 3a, the traction performance can be improved by utilizing the step difference of the protrusion 6. In addition, by providing the protrusion 6 continuously over the entire circumference, the traction performance can be further improved. In addition, by providing the protrusion 6 continuously over the entire circumference, not only can the rigidity of the shoulder block 40 adjacent to the protrusion 6 be sufficiently improved, but also the uneven wear resistance (toe and heel wear resistance) can be improved.

[0053] In the pneumatic tire 1 according to the present embodiment, the outer side surface 62 of the protrusion 6 on the second side D12 in the tire width direction extends in a zigzag shape along the tire circumferential direction D3.

[0054] According to this configuration, by forming the outer side surface 62 into a serrated shape, the traction performance can be improved by utilizing the curved edge of the outer side surface 62 .

[0055] In addition, in the pneumatic tire 1 involved in this embodiment, the structure is as follows: the groove wall 32 of the second side D12 in the tire width direction of the shoulder main groove 3a extends in a zigzag shape along the tire circumferential direction D3, and the groove wall 31 of the first side D11 in the tire width direction of the shoulder main groove 3a includes a flat portion 312 extending parallel to the tire circumferential direction D3.

[0056] According to this configuration, compared with the case where both groove walls 31 and 32 are serrated, it is possible to exhibit better uneven wear resistance.

[0057] Furthermore, in the pneumatic tire 1 according to the present embodiment, the first side D11 in the tire width direction is configured to be the outer side in the tire width direction D1.

[0058] According to this configuration, it is possible to suppress toe and heel wear of the shoulder blocks 40 located further outward in the tire width direction D1 than the shoulder main groove 3a.

[0059] In addition, in the pneumatic tire 1 involved in the present embodiment, the shoulder land portion 4a divided by the shoulder main groove 3a and the ground contact end 2d has: a plurality of lateral grooves 5 extending from the shoulder main groove 3a toward the first side D11 in the tire width direction, and the protrusion 6 has: an extended portion 63 extending into the lateral groove 5, and the extended portion 63 has: a sipe pattern 7 extending along the direction in which the lateral groove 5 extends.

[0060] According to this configuration, it is possible to suppress deterioration in ground contact performance due to the extended portion 63 and to ensure traction at the groove bottom and drainage performance after wear.

[0061] In addition, the pneumatic tire 1 is not limited to the configuration of the above-mentioned embodiment, and is not limited to the above-mentioned effects. In addition, the pneumatic tire 1 can be modified in various ways without departing from the gist of the present invention. For example, the configurations or methods of the above-mentioned multiple embodiments can be arbitrarily adopted and combined. In addition, one or more of the configurations and methods involved in the various modified examples below can be arbitrarily selected and used in the configurations and methods involved in the above-mentioned embodiments.

[0062] (1) In the pneumatic tire 1 according to the above embodiment, the outer side surface 62 of the protrusion 6 on the second side D12 in the tire width direction extends in a zigzag shape along the tire circumferential direction D3. However, the pneumatic tire 1 is not limited to this structure. For example, when the outer side surface 62 of the protrusion 6 extends in a straight line along the tire circumferential direction D3, the traction performance and the uneven wear resistance performance can also be improved.

[0063] (2) In the pneumatic tire 1 involved in the above-mentioned embodiment, the groove wall 32 of the shoulder main groove 3a on the second side D12 in the tire width direction extends in a zigzag shape along the tire circumferential direction D3, and the groove wall 31 of the shoulder main groove 3a on the first side D11 in the tire width direction includes a flat portion 312 extending parallel to the tire circumferential direction D3. However, the pneumatic tire 1 is not limited to this structure. For example, the groove wall 31 of the shoulder main groove 3a on the first side D11 in the tire width direction may not include the flat portion 312, but may extend in a zigzag shape along the tire circumferential direction D3 in the same manner as the groove wall 32 on the second side D12 in the tire width direction. In addition, the groove wall 31 of the shoulder main groove 3a on the first side D11 in the tire width direction may not include the curved portion 311, but may extend as a whole in parallel to the tire circumferential direction D3.

[0064] (3) In the pneumatic tire 1 according to the above embodiment, the first side D11 in the tire width direction is the outer side in the tire width direction D1. However, the pneumatic tire 1 is not limited to this configuration. For example, the first side D11 in the tire width direction may be the inner side in the tire width direction D1. That is, the protrusion 6 may be provided adjacent to the center land portion 4c.

[0065] (4) In the pneumatic tire 1 according to the above-mentioned embodiment, the shoulder land portion 4a divided by the shoulder main groove 3a and the ground contact edge 2d includes a plurality of lateral grooves 5 extending from the shoulder main groove 3a toward the first side D11 in the tire width direction, and the protrusion 6 includes an extended portion 63 extending into the lateral groove 5, and the extended portion 63 includes a sipe 7 extending in the direction in which the lateral groove 5 extends. However, the pneumatic tire 1 is not limited to this configuration. For example, the sipe 7 may not be provided in the extended portion 63, and the extended portion 63 itself may not be provided.

[0066] (5) In addition, although the shoulder main groove 3a is described in the above embodiment, the tire 1 of the present embodiment is a tire whose installation direction on the vehicle is not specified, and the shoulder main groove 3b has the same shape as the shoulder main groove 3a. Therefore, the protrusion 6 is preferably provided in the same shape on both the shoulder main grooves 3a and 3b. However, the present embodiment is also applicable to a tire having a so-called asymmetric pattern whose installation direction on the vehicle is specified. In this case, the protrusion 6 can be provided on any one of the shoulder main grooves 3a and 3b, or the shape of the protrusion 6 can be different in the shoulder main grooves 3a and 3b, or the depth d6 from the tread surface 2a to the top surface 61 can be different in the shoulder main grooves 3a and 3b.

Claims

1. A pneumatic tire comprising: a plurality of main grooves formed in a tread portion and extending in a circumferential direction of the tire, characterized in that: The plurality of main grooves include: a shoulder main groove located at the outermost position in the tire width direction; The shoulder main groove includes a protrusion formed by raising a first side of a groove bottom of the shoulder main groove in the tire width direction more than a second side. The protrusion is lower than the outer surface of the tread portion and extends continuously over the entire circumference of the tire. The shoulder land portion defined by the shoulder main groove and the contact edge includes: a plurality of lateral grooves extending from the shoulder main groove toward a first side in the tire width direction; The protrusion includes: an extension portion extending into the lateral groove; The extended portion includes: a sipe extending along the direction in which the lateral groove extends; One end of the sipe is open in the shoulder main groove, and the other end of the sipe terminates in the extended portion.

2. The pneumatic tire according to claim 1, characterized in that The outer side surface of the protrusion on the second side in the tire width direction extends in a zigzag shape along the tire circumferential direction.

3. The pneumatic tire according to claim 1, wherein: The groove wall of the shoulder main groove on the second side in the tire width direction extends in a zigzag shape along the tire circumferential direction. The groove wall of the shoulder main groove on the first side in the tire width direction includes a flat portion extending parallel to the tire circumferential direction.

4. The pneumatic tire according to claim 1, wherein: The first side in the tire width direction is the outer side in the tire width direction.

5. The pneumatic tire according to claim 2, wherein: The outer side surface of the protrusion on the second side in the tire width direction is curved and extends in parallel with the groove wall of the shoulder main groove on the second side in the tire width direction.

6. The pneumatic tire according to claim 1, wherein: The height of the protrusion measured from the groove bottom of the shoulder main groove is 10 to 50% of the groove depth of the shoulder main groove.

7. The pneumatic tire according to claim 3, characterized in that: The groove wall on the first side of the shoulder main groove in the tire width direction includes a curved portion extending in a curved manner parallel to the groove wall on the second side of the shoulder main groove in the tire width direction. The length of the flat portion is greater than or equal to 50% of the total length of the length of the curved portion and the length of the flat portion.

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