Tire

Abstract

To provide a tire capable of improving traveling performance on a deep snow road surface.SOLUTION: A tire includes a first shoulder block 3. The first shoulder block 3 includes a first tread 5 elongated to a tire-axial inner side from a first tread edge T1, a first lateral surface 6 elongated to a tire radial inner side from the first tread end T1, and a second tread 7 elongated to the tire axially outer side from the first lateral surface 6. The second tread 7 is elongated at an angle θ of 10° or less with respect to a tangential line 5n of the first tread 5 passing through the first tread edge T1. At least one line groove 8 is provided on the second tread 7.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] A pneumatic tire capable of running on off-road surfaces is described in Patent Document 1. The pneumatic tire is provided with a side protector that protrudes axially outward on at least one of the sidewall portions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-03948 Summary of the Invention [Problem to be solved by the invention]

[0004] The pneumatic tire of Patent Document 1 tends to lack traction when traveling on deep snowy roads.

[0005] The present invention has been devised in view of the above problems, and has as its main object to provide a tire capable of improving driving performance on deep snowy roads. [Means for solving the problem]

[0006] The present invention is a tire having a tread portion, the tread portion including a first tread edge and at least one first shoulder block including the first tread edge, the first shoulder block including a first tread surface extending axially inward from the first tread edge, a first side surface extending radially inward from the first tread edge, and a second tread surface extending axially outward from the first side surface, in a tire meridian cross section of the first shoulder block, the second tread surface extends at an angle of 10 degrees or less with respect to a tangent to the first tread surface that passes through the first tread edge, and the second tread surface is provided with at least one groove. Effect of the Invention

[0007] By adopting the above-mentioned configuration, the tire of the present invention can improve the driving performance on deep snowy road surfaces. [Brief description of the drawings]

[0008] [Figure 1] 1 is a development view of the left half of a tread portion of a tire according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a tire meridian cross-sectional view of a first shoulder block. [Diagram 3] FIG. 2 is a schematic perspective view of a first shoulder block and a second shoulder block. [Figure 4] FIG. 2 is a tire meridian cross-sectional view of a first shoulder block. [Diagram 5] FIG. [Figure 6] FIG. 2A is a development view of a first shoulder block of another embodiment, and FIG. 2B is a tire meridian cross-sectional view of the first shoulder block of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The drawings include exaggerated expressions and expressions different from the dimensional ratio of the actual structure in order to facilitate understanding of the present invention. In addition, when there are multiple embodiments, the same or common elements are given the same reference numerals throughout the specification, and duplicated explanations are omitted.

[0010] Fig. 1 is a development view of the left half of a tread portion 2 of a tire 1 showing one embodiment of the present invention. The tread portion 2 is formed, for example, as a point-symmetric pattern with an arbitrary point on the tire equator C as the center of symmetry. Fig. 1 also shows, as a preferred embodiment, a tire 1 for passenger cars that is suitable for mounting on 4WD vehicles capable of running on deep snowy roads. However, the present invention may also be adopted, for example, in a tire 1 for heavy loads. The tread portion 2 is not limited to the embodiment shown in the figure.

[0011] The tread portion 2 includes a first tread edge T1 and at least one first shoulder block 3 including the first tread edge T1.

[0012] Fig. 2 is a tire meridian cross-sectional view of the first shoulder block 3. As shown in Figs. 1 and 2, the first shoulder block 3 includes a first tread surface 5 extending axially inward from the first tread edge T1, a first side surface 6 extending radially inward from the first tread edge T1, and a second tread surface 7 extending axially outward from the first side surface 6. The first side surface 6 extends continuously from the first tread edge T1 to the axially outward side. In this embodiment, the second tread surface 7 has a smaller angle with respect to the axial direction of the tire than the first side surface 6, and is inclined radially inward toward the axially outward side of the tire.

[0013] In the tire meridian cross section of the first shoulder block 3, the second tread surface 7 extends at an angle θ of 10 degrees or less with respect to a tangent 5n of the first tread surface 5 passing through the first tread edge T1. Therefore, when traveling on a deep snowy road surface, the second tread surface 7 can compact the deep snow firmly. In this specification, the angle θ is the absolute value of the difference in angle between the second tread surface 7 and a virtual tangent 5v obtained by moving the tangent 5n in parallel and intersecting it with the second tread surface 7. For example, the angle θ is preferably 0 degrees.

[0014] At least one groove 8 is provided on the second tread surface 7. Such groove 8 forms tightly packed snow pillars within the groove 8, which are then sheared, thereby improving traction. Therefore, the tire 1 of the present invention can improve driving performance on deep snowy roads. In addition, since the present invention does not increase the edge components of the first tread surface 5, it is possible to suppress a decrease in the rigidity of the first tread surface 5 and suppress the occurrence of chipping, such as wear and chipping. Therefore, the tire 1 of this embodiment can maintain high wear resistance and chipping resistance.

[0015] 1, the tread portion 2 of the present embodiment includes, for example, a second tread edge T2 located axially outboard of the first tread edge T1, and a second shoulder block 4 including the second tread edge T2. The tread portion 2 also includes a first shoulder lateral groove 9 adjacent to the first shoulder block 3 and extending axially.

[0016] In the case of a pneumatic tire, the first tread edge T1 and the second tread edge T2 are the axially outermost ground contact positions of the tire 1 in each block 3, 4 under normal load. The normal load condition is a state in which the tire 1 in a normal state is loaded with a normal load and is in contact with a flat surface with a camber angle of 0°. The first tread surface 5 is a surface that contacts the flat surface under the normal load condition, and the second tread surface 7 is a surface that does not contact the flat surface under the normal load condition.

[0017] The "normal state" refers to a state in which the tire 1 is mounted on a normal rim, inflated to a normal internal pressure, and no load is applied. In this specification, unless otherwise specified, the dimensions of each part of the tire 1 are values ​​measured in the normal state.

[0018] A "genuine rim" is a rim that is determined for each tire by a standard system that includes the standards on which tire 1 is based, for example, a "standard rim" in the case of JATMA, a "Design Rim" in the case of TRA, and a "Measuring Rim" in the case of ETRTO.

[0019] "Normal internal pressure" is the air pressure set for each tire by a standard system that includes the standard on which tire 1 is based, in the case of JATMA, it is the "maximum air pressure", in the case of TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", and in the case of ETRTO, it is the "INFLATION PRESSURE".

[0020] The "normal load" is a load determined for each tire by each standard in a standard system including the standard on which tire 1 is based, and is the "maximum load capacity" in the case of JATMA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the case of TRA, and the "LOAD CAPACITY" in the case of ETRTO.

[0021] The first shoulder lateral groove 9 extends, for example, beyond the first tread edge T1 and the second tread edge T2 toward the outside in the tire axial direction. As a result, the first shoulder lateral groove 9 of the present embodiment is adjacent to the first side surface 6 and the second tread surface 7 in the tire circumferential direction.

[0022] In this embodiment, the first shoulder lateral groove 9 includes a first lateral groove portion 9A connected to the circumferential groove 10, a second lateral groove portion 9B connected to the second tread edge T2, and a third lateral groove portion 9C connecting the first lateral groove portion 9A and the second lateral groove portion 9B. The first lateral groove portion 9A and the second lateral groove portion 9B extend, for example, parallel to the tire axial direction. In this embodiment, the third lateral groove portion 9C is inclined with respect to the tire axial direction.

[0023] Furthermore, the tread portion 2 of this embodiment includes a circumferential groove 10 extending continuously in a zigzag shape in the tire circumferential direction, a plurality of crown blocks 11 located on the tire equator C, and middle blocks 12 located between the crown blocks 11 and the circumferential grooves 10. The circumferential grooves 10 of this embodiment are connected to the first shoulder lateral grooves 9.

[0024] In the tread portion 2 of this embodiment, the first shoulder blocks 3 and the second shoulder blocks 4 are arranged alternately in the tire circumferential direction. In other words, the first tread edge T1 and the second tread edge T2 are arranged alternately in the tire circumferential direction. In this embodiment, a first shoulder lateral groove 9 is arranged between the first shoulder blocks 3 and the second shoulder blocks 4.

[0025] The first shoulder block 3 of this embodiment includes a second side surface 13 extending inward in the tire radial direction from the second tread surface 7. The second side surface 13, for example, has a larger angle with respect to the tire axial direction than the second tread surface 7, and extends from the second tread surface 7 toward the outside in the tire axial direction. The first shoulder block 3 further includes, for example, a first edge 6e where the first side surface 6 and the second tread surface 7 intersect, and a second edge 7e where the second tread surface 7 and the second side surface 13 intersect. For example, when the first side surface 6 and the second tread surface 7 intersect via an arc or a straight line, the first edge 6e is defined as the midpoint of the arc or the straight line in the tire meridian cross section of the first shoulder block 3. The second edge 7e is also defined in a similar manner.

[0026] The second shoulder block 4 includes a third tread surface 15 extending axially inward from the second tread edge T2, and a third side surface 16 extending radially inward from the second tread edge T2. The third tread surface 15 is a surface that contacts the plane under the normal load condition. The third side surface 16 has, for example, a larger angle with respect to the tire axial direction than the second tread surface 7, and extends axially outward from the second tread edge T2. The third side surface 16 has, for example, an overlapping portion 17 that overlaps with the second side surface 13 in the tire meridian cross section of the first shoulder block 3.

[0027] Fig. 3 is a schematic perspective view of the first shoulder block 3 and the second shoulder block 4. As shown in Fig. 3, in the tread portion 2 of this embodiment, a large snow pillar S can be formed between the first tread edge T1 and the second edge 7e between the second shoulder blocks 4, 4 adjacent in the tire circumferential direction. This allows the snow pillar S to be sheared by the groove wall 9a of the first shoulder lateral groove 9, further improving the driving performance on deep snowy roads.

[0028] FIG. 4 is a tire meridian cross-sectional view of the first shoulder block 3. As shown in FIG. 4, the second tread surface 7 of this embodiment is located radially outward of the groove bottom 9s of the first shoulder lateral groove 9. Such a second tread surface 7 can pack snow more firmly when traveling on a deep snowy road surface. Although not particularly limited, the distance La in the tire radial direction between the groove bottom 9i and the inner end 7i of the first shoulder lateral groove 9 at the position of the inner end 7i (first edge 6e) in the tire axial direction of the second tread surface 7 is preferably 0.5 mm or more, more preferably 1 mm or more, more preferably 5 mm or less, and more preferably 4 mm or less. In addition, the groove depth Da of the first shoulder lateral groove 9 is, for example, preferably 8 mm or more, more preferably 10 mm or more, more preferably 18 mm or less, and more preferably 16 mm or less. In this specification, the groove depth is the length in the normal direction of the tread surface 5.

[0029] 5 is a development view of the left half of the tread portion 2. As shown in FIG. 5, the axial length L2 of the second tread surface 7 is preferably 18% or more of the axial length L1 of the first tread surface 5 of the first shoulder block 3, more preferably 20% or more, more preferably 23% or less, and even more preferably 21% or less. Since the length L2 of the second tread surface 7 is 18% or more of the length L1 of the first tread surface 5, the effect of increasing the snow column shear force on the second tread surface 7 is exhibited. Since the length L2 of the second tread surface 7 is 23% or less of the length L1 of the first tread surface 5, the length L1 of the first tread surface 5 is maintained, and damage such as wear and chipping occurring on the first shoulder block and the second shoulder block 4 is suppressed.

[0030] The grooves 8 extend in the tire axial direction. In this way, the grooves 8 having an axial component can increase the snow column shear force. It is desirable that the grooves 8 extend in the tire axial direction at least on the second tread surface 7.

[0031] A plurality of grooves 8 are provided on the second tread surface 7. In this embodiment, two grooves 8 are provided on the second tread surface 7. The grooves 8 include a first groove 8A that extends parallel to the tire axial direction on the second tread surface 7, and a second groove 8B that extends at an angle to the tire axial direction on the second tread surface 7. Such grooves 8 appropriately reduce the rigidity of the second tread surface 7 and increase the deflection when the snow touches down on deep snow, which helps to pack the snow more firmly.

[0032] As shown in FIG. 4 and FIG. 5, the groove 8 has a closed end 18 on the first side surface 6. In this embodiment, the groove 8 has an outer end (outer end) 18e in the tire radial direction on the first side surface 6. The outer end 18e is located, for example, on the inner side in the tire radial direction than the midpoint 6c in the tire radial direction of the first side surface 6. The groove 8 has a closed inner end (inner end) 18i in the tire radial direction on the second side surface 13. The inner end 18i is located, for example, at the inner end 13i in the tire radial direction of the second side surface 13. In this way, the groove 8 in this embodiment crosses the second tread surface 7. As a result, a relatively large snow column is formed by the groove 8, so that high traction can be generated.

[0033] Although not particularly limited, it is preferable that the groove width W1 of the groove 8 is smaller than the groove width W2 of the first shoulder lateral groove 9. If the groove width W1 of the groove 8 is too small, the snow pillar formed in the groove 8 will be small, and the snow pillar shear force may decrease. Conversely, if the groove width W1 of the groove 8 is large, the surface of the second tread surface 7 that compacts deep snow will be small. From this perspective, the groove width W1 of the groove 8 is preferably 1.5 mm or more, more preferably 2.0 mm or more, more preferably 3.5 mm or less, and even more preferably 3.0 mm or less. From the same perspective, the groove depth D1 of the groove 8 is preferably 15% or more of the groove depth Da of the first shoulder lateral groove 9, more preferably 20% or more, more preferably 35% or less, and even more preferably 30% or less.

[0034] The second shoulder block 4 is provided with a second groove 19 extending in the tire axial direction on the third side surface 16. In this embodiment, two second grooves 19 are provided on the third side surface 16. Such second grooves 19 appropriately reduce the rigidity of the second shoulder block 4 to cause bending, making it easier to remove deep snow buried in the first shoulder lateral grooves 9. The second groove 19 is connected, for example, to the inner end 16i of the third side surface 16 in the tire radial direction. The second groove 19 in this embodiment is desirably the same as the groove width W1 and groove depth D1 of the groove 8.

[0035] The first shoulder block 3 and the second shoulder block 4 are provided with sipes 25 extending in the tire axial direction. Each sipe 25 is provided on the first tread surface 5 or the third tread surface 15. Each sipe 25 includes a first sipe portion 25A located on the tire equator C side, a second sipe portion 25B located on the first tread edge T1 side, and a third sipe portion 25C connecting the first sipe portion 25A and the second sipe portion 25B. In this embodiment, the first sipe portion 25A extends parallel to the first lateral groove portion 9A. The second sipe portion 25B extends parallel to the second lateral groove portion 9B, for example. In this embodiment, the third sipe portion 25C extends parallel to the third lateral groove portion 9C. In this specification, the term "extending in parallel" refers to a state in which the absolute value of the difference between the angle of each of the lateral groove portions 9A-9C relative to the tire axial direction and the angle of each of the sipe portions 25A-25C relative to the tire axial direction is 5 degrees or less, and in this embodiment, the absolute value is 0 degrees. In addition, in this specification, the sipe refers to a notch having a width of less than 1.5 mm, and is clearly distinguished from a groove having a width of 1.5 mm or more.

[0036] As shown in FIG. 1, the middle blocks 12 include, for example, a first middle block 12A positioned axially inward of the first shoulder block 3 and a second middle block 12B positioned axially inward of the second shoulder block 4.

[0037] The crown block 11 and the middle block 12 of this embodiment are each provided with a plurality of sipes 26. This prevents the rigidity of the crown block 11 and the middle block 12 from becoming excessively high, increases the deflection when the block touches deep snow, and enhances the effect of the crown block 11 and the middle block 12 in compacting deep snow.

[0038] Generally, rubber with a low rubber hardness bends relatively more when the tire touches the ground during running, so that deep snow can be effectively compacted and the snow column shear force can be increased. On the other hand, if the rubber hardness is too low, the rubber is more likely to be damaged, such as chipped or worn. For this reason, as shown in FIG. 4, the first shoulder block 3 includes a first rubber portion 28 including the first tread 5 and a second rubber portion 29 including the second tread 7, and it is desirable that the rubber hardness of the second rubber portion 29 is equal to or less than the rubber hardness of the first rubber portion 28. In addition, in order to increase the snow column shear force on the second tread 7 and suppress damage to the first tread 5, it is more desirable that the rubber hardness of the second rubber portion 29 is smaller than that of the first rubber portion 28. Although not particularly limited, the rubber hardness of the first rubber portion 28 is, for example, 60 to 75°. The rubber hardness of the second rubber portion 29 is, for example, 40 to 55°. In this specification, the rubber hardness is a durometer A hardness measured in an environment of 23° C. using a durometer type A based on JIS-K6253.

[0039] Fig. 6(A) is a development view of the first shoulder block 3 of another embodiment. Fig. 6(B) is a tire meridian cross-section of the first shoulder block 3 of Fig. 6(A). The groove 8 has a closed end 18 on the second tread surface 7. The groove 8 has a closed outer end (outer end) 18e in the tire radial direction on the second tread surface 7. The snow pillar formed by such a groove 8 prevents the force from escaping during snow compaction, so that high traction can be maintained. The outer end 18e of the groove 8 is located at the first edge 6e.

[0040] Although a particularly preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the illustrated embodiment and can be modified and carried out in various forms. EXAMPLES

[0041] Tires having the basic pattern of FIG. 1 were prototyped based on the specifications in Table 1, and each test tire was tested for its running performance on deep snowy roads. The common specifications and test methods for each test tire are as follows. In Tables 1 and 2, "A" in "groove shape" means that the groove extends from the first side surface to the second tread surface (second edge). In addition, the "- (negative)" indication in "distance La (mm)" means that the second tread surface is located radially inward of the groove bottom of the first shoulder lateral groove. Furthermore, the groove depth of the first shoulder lateral groove is 14 mm in Comparative Examples 1 to 3 and Examples 1 to 7, 9, and 10, and 12 mm in Example 8. Tire size: LT275 / 70R18 Rim: 8.0J Internal pressure: 420kPa (front wheels), 520kPa (rear wheels)

[0042] <Driving performance on deep snowy roads> In accordance with the test method of standard ASTM F1805, the traction (frictional force) acting on the test tire on a deep snowy road surface was measured when the following vehicle was used and the tire was driven at the following speed. The results are expressed as an index, with the traction of Example 1 being set at 10. The higher the value, the better the driving performance on a deep snowy road surface. Vehicle: 6000cc four-wheel drive passenger car (pickup truck) Driving speed: 8km / h

[0043] [Table 1]

[0044] [Table 2]

[0045] As a result of the test, it can be confirmed that the tires of the examples have better driving performance on deep snowy roads than the tires of the comparative examples. In addition, the tests were conducted using tires of different tire sizes, but the results were similar. Furthermore, the tires of the examples maintain high steering stability, wear resistance, and chipping resistance.

[0046] [Note] The present invention includes the following aspects.

[0047] [Invention 1] A tire having a tread portion, The tread portion includes a first tread edge and at least one first shoulder block including the first tread edge, The first shoulder block is A first tread surface extending axially inward from the first tread end; A first side surface extending radially inward from the first tread edge; a second tread extending from the first side surface toward an outer side in the tire axial direction, In a tire meridian cross section of the first shoulder block, the second tread surface extends at an angle of 10 degrees or less with respect to a tangent to the first tread surface passing through the first tread edge, The second tread surface is provided with at least one groove. tire. [Invention 2] The tread portion includes a first shoulder lateral groove adjacent to the first shoulder block and extending in the tire axial direction, The tire according to claim 1, wherein the second tread surface is located radially outboard of a groove bottom of the first shoulder lateral groove. [Invention 3] 3. A tire according to claim 1 or 2, wherein the groove has a closed end on the second tread surface. [Invention 4] 3. A tire according to claim 1 or 2, wherein the groove has a closed end on the first side. [Invention 5] 5. The tire according to any one of claims 1 to 4, wherein the groove extends in the tire axial direction. [Invention 6] The tire according to any one of claims 1 to 5, wherein the second tread surface is provided with a plurality of the grooves. [Invention 7] The tire according to any one of Inventions 1 to 6, wherein the groove has a width of 1.5 to 3.5 mm. [Invention 8] The tire according to any one of claims 1 to 7, wherein the axial length of the second tread surface is 18% to 23% of the axial length of the first tread surface of the first shoulder block. [The present invention 9] The first shoulder block includes a first rubber portion including the first tread surface and a second rubber portion including the second tread surface, 9. The tire according to claim 8, wherein the second rubber portion has a rubber hardness equal to or lower than a rubber hardness of the first rubber portion. [The present invention 10] The tire according to claim 9, wherein the second rubber portion has a rubber hardness smaller than a rubber hardness of the first rubber portion. [The present invention 11] The tread portion includes a second tread edge located axially outboard of the first tread edge, and a second shoulder block including the second tread edge, The tire according to any one of claims 1 to 10, wherein the first shoulder blocks and the second shoulder blocks are provided alternately in the tire circumferential direction. [Explanation of symbols]

[0048] 1 Tire 3. First Shoulder Block 5 1st tread 5n tangent 6 First aspect 7 Second tread 8 grooves T1 First tread edge θ angle

Claims

1. A tire having a tread portion, The tread portion includes a first tread edge and at least one first shoulder block including the first tread edge, The first shoulder block is A first tread surface extending axially inward from the first tread end; a first side surface extending radially inward from the first tread edge; a second tread extending from the first side surface toward an outer side in the tire axial direction, In a tire meridian cross section of the first shoulder block, the second tread surface extends at an angle of 10 degrees or less with respect to a tangent to the first tread surface passing through the first tread edge, The second tread surface is provided with at least one groove. tire.

2. the tread portion includes a first shoulder lateral groove adjacent to the first shoulder block and extending in the tire axial direction, The tire according to claim 1 , wherein the second tread surface is located radially outboard of a groove bottom of the first shoulder lateral groove.

3. The tire of claim 1 , wherein said groove has a closed end on said second tread surface.

4. The tire of claim 1 , wherein said groove has a closed end on said first side.

5. The tire according to claim 1 , wherein the groove extends in an axial direction of the tire.

6. The tire according to claim 1 , wherein the second tread surface includes a plurality of grooves.

7. A tire according to any one of claims 1 to 4, wherein the groove width is between 1.5 and 3.5 mm.

8. 5. The tire according to claim 1, wherein the axial length of the second tread surface is 18% to 23% of the axial length of the first tread surface of the first shoulder block.

9. The first shoulder block includes a first rubber portion including the first tread surface and a second rubber portion including the second tread surface, The tire according to claim 8 , wherein a rubber hardness of the second rubber portion is equal to or lower than a rubber hardness of the first rubber portion.

10. The tire according to claim 9 , wherein a rubber hardness of the second rubber portion is smaller than a rubber hardness of the first rubber portion.

11. the tread portion includes a second tread edge located axially outboard of the first tread edge, and a second shoulder block including the second tread edge, The tire according to claim 1 , wherein the first shoulder blocks and the second shoulder blocks are provided alternately in the tire circumferential direction.

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