JP2013147141A - Tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire effectively improved in abrasion resistance, particularly the uneven abrasion resistance of a block while securing wet performance.SOLUTION: A tire includes: a plurality of peripheral grooves extending in the tire peripheral direction; a plurality of width grooves extending in the tire width direction; and a block which is formed with the plurality of peripheral grooves and the plurality of width grooves. A peripheral direction sidewall angle formed of one of the peripheral direction sidewall surfaces formed on the block by the peripheral direction grooves and a tread is changed to be obtuse at one end in the tire peripheral direction of the block while being acute at the other end in the tire peripheral direction of the block. A width direction sidewall angle formed of the width direction sidewall surface formed on the block by the other width direction grooves and the tread is changed from an acute angle to an obtuse angle as approaching the peripheral direction sidewall surface. A bottom raised portion raised to the outside in the tire diameter direction is formed on the bottom of width direction grooves.

Description

  The present invention includes a plurality of circumferential grooves extending in the tire circumferential direction, a plurality of widthwise grooves extending in the tire width direction, a block portion formed by the plurality of circumferential grooves and the plurality of widthwise grooves, It relates to a tire provided with.

  Conventionally, various improved techniques have been proposed for suppressing uneven wear generated in pneumatic tires (hereinafter referred to as tires) mounted on vehicles such as automobiles. For example, the tire described in Patent Document 1 has a block section defined by a plurality of main grooves extending along the tire circumferential direction and a plurality of width direction grooves extending along the tire width direction. The angle α between the tread-side groove wall located in front of the tire rotation direction and the tread surface contacting the road surface, and the angle β between the kick-out groove wall located rearward in the tire rotation direction and the tread surface contacting the road surface And α> β. Further, the rigidity of the block portion is set within a predetermined range from various conditions such as the length of the block portion in the tire circumferential direction, the height from the groove bottom, and the Young's modulus of rubber. According to this, the compressive deformation of the block portion that occurs when the block portion comes into contact with the road surface reaches the entire block portion without concentrating on the kicking end portion. As a result, it is possible to suppress the slip that occurs when the kicking end portion is separated from the road surface, thereby avoiding uneven wear (so-called heel and toe wear).

JP-A-5-270214

  Incidentally, it is known that it is effective to widen the groove width in order to ensure the wet performance of the tire. However, when the groove width is increased, the area of the tread surface of the block portion is reduced, so that the contact pressure applied to the tread surface increases. In such a tire, the shear strain applied to the block portion increases, and uneven wear tends to occur.

  As described above, in the prior art, there is a trade-off relationship between ensuring wet performance and improving wear resistance, so it is difficult to achieve both, and improvement has been demanded.

  Accordingly, an object of the present invention is to provide a tire that effectively improves the wear resistance performance of the block portion, particularly uneven wear resistance, while ensuring wet performance.

  The first feature of the present invention is that a plurality of circumferential grooves (circumferential groove 10) extending along the tire circumferential direction, a plurality of width grooves (width groove 21) extending in the tire width direction, A tire (pneumatic tire 1) including a block portion (central block portion 110) formed by a circumferential groove and the plurality of widthwise grooves, and is formed in the block portion by the circumferential groove. A circumferential side wall angle (for example, circumferential side wall angle θ11) formed by one circumferential side wall surface (for example, circumferential side wall surface 111) and a tread surface that contacts the road surface of the block portion is adjacent to the tire circumferential direction. One end (end portion 110B) formed in the block portion by one width direction groove has an obtuse angle, and the other end (end portion 110D) formed in the block portion by the other width direction groove adjacent in the tire circumferential direction. The width direction side wall angle (width direction) formed by the width direction side wall surface (width direction side wall surface 112) formed in the block portion by the other width direction groove and the tread surface. The side wall angle θ12) changes from an acute angle to an obtuse angle as it approaches the circumferential side wall surface, and a bottom raised portion (bottom raised portion 200) raised to the outside in the tire radial direction is formed at the groove bottom of the widthwise groove. The gist is that it is formed.

  The second feature of the present invention is that the circumferential side wall angle formed by the other circumferential side wall surface and the tread surface changes so as to be an acute angle at one end of the block portion in the tire circumferential direction and an obtuse angle at the other end. The gist is to do.

The gist of the third feature of the present invention is that the widthwise groove has a narrow groove formed between the raised bottom portion and the block portion.

  The gist of the fourth feature of the present invention is that the narrow groove wall surface formed in the bottom raised portion by the narrow groove portion changes along the side wall surface in the width direction.

  The fifth feature of the present invention is summarized as that the groove width of the narrow groove portion is 10% or more and 20% or less of the groove width of the width direction groove.

  The sixth feature of the present invention is summarized in that the depth in the tire radial direction from the tread surface to the bottom raised portion is 30% or more and 60% or less of the depth of the circumferential groove.

  A seventh feature of the present invention is that the groove width of the circumferential groove is 5% or more and 28% or less of the block width of the block portion in the tire width direction.

  The eighth feature of the present invention is that the groove width of the width direction groove is 12% or more and 22% or less of the block length of the block portion in the tire circumferential direction.

  ADVANTAGE OF THE INVENTION According to this invention, the tire which improved the wear resistance performance of the block part, especially the uneven wear resistance effectively, ensuring wet performance can be provided.

FIG. 1 is a partial plan view showing a tread pattern of a pneumatic tire 1 according to the first embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view along the tire equator line CL and the tire radial direction Td of the pneumatic tire 1 according to the first embodiment. FIG. 3 is an enlarged plan view of the central block 110 according to the first embodiment. FIG. 4A is a cross-sectional view taken along lines A1-A1 'and A2-A2' in FIG. FIG. 4B is a cross-sectional view taken along line B1-B1 'and line B2-B2' in FIG. FIG. 4C is a cross-sectional view taken along line C1-C1 'and line C2-C2' in FIG. FIG. 5A is a cross-sectional view taken along lines D1-D1 'and D2-D2' in FIG. FIG. 5B is a cross-sectional view taken along lines E1-E1 'and E2-E2' in FIG. FIG. 5C is a cross-sectional view taken along lines F1-F1 'and F2-F2' in FIG. FIG. 6 is a sectional view of the tire equator line CL and the tire radial direction when the pneumatic tire 1 according to the first embodiment is grounded in FIG. 6.

  Next, embodiments according to the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones. Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, the part from which the relationship and ratio of a mutual dimension differ also in between drawings may be contained.

  In addition, although the pneumatic tire which concerns on the following embodiment is a pneumatic tire provided with a beat part, a carcass layer, and a belt layer (not shown), this structure is abbreviate | omitted and demonstrated. Moreover, although the pneumatic tire 1 which concerns on this embodiment assumes the tire for heavy loads, it is not limited to this. Further, the pneumatic tire according to the present embodiment may be filled with an inert gas such as nitrogen gas.

[First Embodiment]
First, a first embodiment of the present invention will be described.

(1) Configuration of Tread Pattern FIG. 1 is a partial plan view showing a tread pattern constituting the pneumatic tire 1 according to the first embodiment of the present invention.

  As shown in FIG. 1, the pneumatic tire 1 includes a plurality of circumferential grooves 10 extending along the tire circumferential direction Tc and a plurality of widthwise grooves 20 extending in the tire width direction Tw on the tread surface of the tread portion. A block portion 100 formed by a plurality of circumferential grooves 10 and a plurality of width grooves 20 is provided. Note that lug grooves extending along the tire width direction Tw are formed in the shoulder land portion formed on the outermost side in the tire width direction Tw at predetermined intervals in the tire circumferential direction Tc.

  In addition, the range of the tire width direction Tw of a tread surface is in the range of the tire width direction Tw inside from the tread end TE located in the tire width direction Tw outer side of a tread part. Here, the tread end TE is defined by the applicable size / ply rating of the JATMAYEAR BOOK when the pneumatic tire 1 is mounted on a standard rim defined in JATMA YEAR BOOK (2007 edition, Japan Automobile Tire Association Standard). An air pressure corresponding to the maximum load capacity is filled as an internal pressure, and indicates the outermost ground contact portion in the tire width direction Tw when the maximum load capacity is loaded. Note that, when the TRA standard, the ETRTO standard, or the like is applied in the place of use or manufacturing, it conforms to each standard.

  In the present embodiment, the circumferential groove 10 extends in the tire circumferential direction Tc in a so-called zigzag shape that is bent in the tire width direction Tw. The circumferential groove 10 may be formed so as to extend linearly in the tire circumferential direction Tc. In the present embodiment, a total of four circumferential grooves 10 are formed. Specifically, two circumferential grooves 10 are formed on one side in the tire width direction Tw and two are formed on the other side of the tire equator line CL. The number of circumferential grooves 10 is not limited to this.

  Further, in the present embodiment, the central land portion row is formed at a position including the tire equator line CL by the four circumferential grooves 10, and one outer side in one side in the tire width direction Tw than the central land portion row. A land portion row is formed, and one outer land portion row is formed on the other outer side.

  In the present embodiment, each of the plurality of width direction grooves 20 extends in a direction inclined by a predetermined angle in the tire width direction Tw. In the pneumatic tire 1, as the width direction groove | channel 20, it has the width direction groove | channel 21 formed in a center land part row | line | column, and the width direction groove | channel 22 formed in an outer land part row | line | column. The direction in which the width direction groove 21 formed in the central land portion row extends is different from the direction in which the width direction groove 22 formed in the outer land portion row extends.

  In the pneumatic tire 1, a plurality of block portions 100 are formed by being divided into a plurality of circumferential grooves 10 and a plurality of width-direction grooves 20. Each of the plurality of block portions 100 has a tread surface that contacts the road surface. Specifically, a plurality of central block portions 110 are formed in the central land portion row by being partitioned into the width direction grooves 21, and the outer land portion row is partitioned into the width direction grooves 22. As a result, a plurality of outer block portions 120 are formed.

  In the present embodiment, the groove width W10 of the circumferential groove 10 is set in the range of 5% to 28% of the block width W110 of the central block portion 110 in the tire width direction Tw. The block width W110 indicates a distance between one endmost portion and the other endmost portion of the central block portion 110 in the tire width direction Tw.

  Here, the reason why the groove width W10 of the circumferential groove 10 is within the above-described range is as follows. This is because if the groove width W10 of the circumferential groove 10 is less than 5% of the block width W110, the drainage performance decreases. On the other hand, if the groove width W10 of the circumferential groove 10 is larger than 28% of the block width W110, the area of the tread surface 110X of the central block portion 110 is excessively reduced, and is given to the tread surface 110X of the central block portion 110. The contact pressure increases and the shear strain increases. As a result, the wear resistance of the pneumatic tire 1 is reduced.

  In the present embodiment, the groove width W21 of the width direction groove 21 is set within a range of 12% or more and 22% or less of the block length L110 of the central block portion 110 in the tire circumferential direction Tc. The block length L110 indicates a distance between one endmost portion and the other endmost portion of the central block portion 110 in the tire circumferential direction Tc.

  Here, the reason why the groove width W21 of the width direction groove 21 is within the above-described range is as follows. This is because if the groove width W21 of the width direction groove 21 is less than 12% of the block width W110, the drainage performance decreases. On the other hand, if the groove width W10 of the circumferential groove 10 is larger than 22% of the block width W110, the area of the tread surface 110X of the block portion 110 is excessively reduced, and the contact pressure applied to the tread surface 110X of the block portion 110 is reduced. This is because of an increase in wear resistance.

  Here, FIG. 2 shows an enlarged cross-sectional view of the pneumatic tire 1 along the tire equator line CL and the tire radial direction Td. In the present embodiment, a bottom raised portion 200 that is raised to the outside in the tire radial direction Td is formed at the groove bottom of the width direction groove 21 formed in the central land portion row.

  As shown in FIG. 2, a predetermined gap is formed by the narrow groove portion 25 between the central block portion 110 and the bottom raised portion 200. In the present embodiment, the width direction groove 21 is configured to include a narrow groove portion 25 formed between the bottom raised portion 200 and the block portion 110. Further, the innermost side in the tire radial direction Td of the narrow groove portion 25 is the groove bottom of the width direction groove 21.

  The groove width W25 of the narrow groove portion 25 is narrower than the groove width W21 of the width direction groove 21. The groove width W25 of the narrow groove portion 25 is such that the tread surface is grounded by filling the pneumatic tire 1 with the air pressure specified by the above-mentioned standard and applying a load having the maximum load capacity specified by the above-mentioned standard. It is preferred that the groove width be occasionally closed.

  Specifically, preferably, the groove width W25 of the narrow groove portion 25 is in the range of 10% or more and 20% or less of the groove width W21 of the width direction groove 21. Here, the reason why the groove width W25 of the narrow groove portion 25 is within the above range is as follows. This is because when the groove width W25 is less than 10%, the drainage performance decreases as the groove volume of the narrow groove portion 25 decreases. On the other hand, when the groove width W25 is larger than 20%, the contact area between the bottom raised portion 200 and the central block portion 110 is reduced when the tread surface 110X of the central block portion 110 is grounded, and the collapse of the central block portion 110 is suppressed. This is because the effect to do becomes low. That is, if the groove width W25 is greater than 20%, the bottom raised portion 200 becomes difficult to supplement the shear strain applied to the central block portion 110, and the improvement in wear resistance performance in the central block portion 110 is suppressed. It is.

  In the present embodiment, the depth D1 in the tire radial direction Td from the tread 110X to the bottom raised portion 200 is in the range of 30% to 60% of the depth D2 of the circumferential groove 10. The depth D1 is a depth from the tread surface 110X to the surface 200X formed outside the tire radial direction Td of the raised bottom portion 200.

  Here, the reason why the depth D1 of the bottom raised portion 200 is within the above-described range is as follows. This is because when the depth D1 is less than 30%, improvement in wet performance at the initial stage of wear is suppressed as the groove volume of the width direction groove 21 decreases. Further, when the depth D1 is less than 30%, there is a concern that heat generation due to contact with the central block portion 110 is increased. On the other hand, when the depth D1 is larger than 60%, the rigidity of the bottom raised portion 200 is lowered, and the rigidity for suppressing the collapse of the central block portion 110 is insufficient.

(2) Configuration of Block Unit Next, the configuration of the central block unit 110 will be described with reference to the drawings. FIG. 3 is an enlarged plan view of the central block 110 according to the present embodiment.

  As shown in FIG. 3, the central block portion 110 includes a tread surface 110X, a circumferential side wall surface 111 formed by one circumferential groove 10 adjacent to the tire width direction Tw, and the other adjacent to the tire width direction Tw. A circumferential side wall surface 113 formed by the circumferential groove 10, a width side wall surface 112 formed by one width direction groove 21 adjacent to the tire circumferential direction Tc, and the other width direction adjacent to the tire circumferential direction Tc. And a side wall surface 114 in the width direction formed by the groove 21.

  The bottom raised portion 200 is formed by the surface 200X in the tire radial direction Td, the narrow groove wall surface 211 formed by one narrow groove portion 25 adjacent to the tire circumferential direction Tc, and the other narrow groove portion 25 adjacent to the tire circumferential direction Tc. And a narrow groove side wall surface 212. The narrow groove wall surface 211 is formed in parallel with the width direction side wall surface 112, and the narrow groove side wall surface 212 is formed in parallel with the width direction side wall surface 114.

  Further, as shown in FIG. 3, in the central block portion 110, the tread surface 110X includes an end portion 110A formed on the circumferential side wall surface 111 side, an end portion 110D formed on the width side wall surface 112 side, It has the edge part 110C formed in the direction side wall surface 113 side, and the edge part 110B formed in the width direction side wall surface 114 side.

  In the present embodiment, the inclination angle of the side wall formed around the central block portion 110 differs depending on the location. Below, the side wall angle of the center block part 110 is demonstrated concretely.

  The central block portion 110 has a circumferential side wall angle θ11 formed by one circumferential side wall surface 111 formed on the central block portion 110 by the circumferential groove 10 and the tread surface 110X, and is one width adjacent to the tire circumferential direction Tc. An obtuse angle at one end 110B formed in the central block 110 by the directional groove 20 and an acute angle at the other end 110D formed in the central block 110 by the other widthwise groove 20 adjacent to the tire circumferential direction Tc. Change.

  Here, FIG. 4A shows a cross-sectional view taken along the line A1-A1 'of FIG. FIG. 4B shows a cross-sectional view taken along line B1-B1 'of FIG. FIG. 4C shows a cross-sectional view taken along line C1-C1 'of FIG. 4A is the same as the cross-sectional view taken along the line A2-A2 ′ in FIG. 3, and the cross-sectional view shown in FIG. 4B is the cross-sectional view taken along the line B2-B2 ′ in FIG. The sectional view shown in FIG. 4C is the same as the sectional view taken along the line C2-C2 ′ of FIG.

  As shown in FIG. 4A, the circumferential side wall angle θ11 is configured to be an obtuse angle, that is, larger than 90 degrees on the side wall surface 114 side in the width direction. Further, as shown in FIG. 4B, the circumferential side wall angle θ11 is an intermediate portion of the circumferential side wall surface 111 in the tire circumferential direction Tc (here, the center of the end portion 100A of the tread surface 110X in the tire circumferential direction Tc). Is configured to be 90 degrees. Further, as shown in FIG. 4C, the circumferential side wall angle θ11 is configured to be smaller than an acute angle, that is, 90 degrees on the side wall surface 112 in the width direction.

  On the other hand, in the central block portion 110, as shown in FIGS. 4A to 4C, the circumferential side wall angle θ13 formed by the other circumferential side wall surface 113 and the tread surface 110X is the central block portion in the tire circumferential direction Tc. 110 changes to an obtuse angle at one end 110D and an acute angle at the other end 110B. That is, in the central block 110, the circumferential side wall angle θ11 and the circumferential side wall angle θ13 change to the opposite side along a predetermined direction in the tire circumferential direction Tc.

  Next, the width direction side wall angle θ12 formed by the width direction side wall surface 112 formed in the central block portion 110 by the width direction groove 20 and the tread surface 110X will be described.

  In the central block portion 110, the width-direction side wall angle θ12 formed by the width-direction side wall surface 112 formed on the central block portion 110 by the width-direction groove 20 and the tread surface 110X increases with increasing proximity to the circumferential side wall surface 111. Changes from obtuse to obtuse.

  Here, FIG. 5A shows a cross-sectional view taken along line D1-D1 'of FIG. FIG. 5B shows a cross-sectional view taken along line E1-E1 'of FIG. FIG. 5C shows a cross-sectional view taken along line F1-F1 'of FIG. 5A is the same as the cross-sectional view taken along the line D2-D2 ′ of FIG. 3, and the cross-sectional view of FIG. 5B is the cross-sectional view taken along the line E2-E2 ′ of FIG. The sectional view of FIG. 5C is the same as the sectional view taken along line F2-F2 ′ of FIG.

  As shown in FIG. 5 (a), the width direction side wall angle θ12 is configured to be an acute angle, that is, smaller than 90 degrees on the circumferential side wall surface 113 side in the tire width direction Tw, as shown in FIG. 5 (b). Further, the intermediate portion of the width direction side wall surface 112 in the tire width direction Tw (here, the center in the tire width direction Tw of the end portion 110D of the tread surface 110X) is configured to be 90 degrees, as shown in FIG. As shown, the obtuse angle, that is, larger than 90 degrees is formed on the side wall surface 111 side in the circumferential direction.

  On the other hand, as shown in FIGS. 5A to 5C, the central block portion 110 has a width direction side wall formed by a width direction side wall surface 114 formed on the center block portion 110 by the width direction groove 20 and a tread surface 110X. The angle θ <b> 14 changes from an acute angle to an obtuse angle as it approaches the circumferential side wall surface 113. That is, in the central block portion 110, the width direction side wall angle θ12 and the width direction side wall angle θ14 change to the opposite side as they extend in the tire width direction Tw.

  In addition, it is preferable that the circumferential side wall angles θ11 and θ13 and the width direction side wall angles θ12 and 14 described above vary within a range of 70 degrees to 110 degrees. This is due to the following reason. That is, when the side wall angle is less than 70 degrees, the rigidity of the central block portion 110 is lowered and the body block is likely to fall down, and the steering stability is lowered. Furthermore, there is a concern that uneven wear is promoted by increasing the amount of collapse. On the other hand, when it is larger than 110 degrees, the groove volume is reduced and the drainage performance is reduced.

  Further, as shown in FIGS. 5A to 5C, the narrow groove wall surface 211 formed by the narrow groove portion 25 on one side in the tire circumferential direction Tc of the bottom raised portion 200 changes along the width direction side wall surface 112. . Specifically, the narrow groove wall surface 211 is formed in parallel with the width direction side wall surface 112. Therefore, the narrow groove sidewall angle θ211 formed by the narrow groove wall surface 211 formed on the bottom raised portion 200 by the narrow groove portion 25 and the surface 200X is an acute angle when the width direction sidewall angle θ12 is an obtuse angle, and the width direction sidewall angle θ12 is an acute angle. In the case of, it changes to become an obtuse angle. The narrow groove wall surface 212 formed on the other side in the tire circumferential direction Tc of the bottom raised portion 200 changes along the width direction side wall surface 114 of the central block portion 110 adjacent to the other.

  Thus, since the narrow groove wall surfaces 211 and 212 change along the side wall surfaces 112 and 114 in the width direction, when the center block portion 110 is grounded, the contact area between the center block portion 110 and the bottom raised portion 200 is increased. it can. Therefore, the fall of the central block part 110 can be suppressed.

(3) Actions / Effects Next, actions and effects of the pneumatic tire 1 according to the first embodiment will be described. Here, in a general pneumatic tire, when the vehicle travels, the block portion 100 bulges toward the kicking end side due to the contact pressure due to gravity, the weight of the vehicle, and the incompressibility of rubber. Also, in a pneumatic tire, when contact pressure is applied to the tread surface of the block portion, the wall surface formed by the groove bulges into the groove, and the greater the amount of bulge, the greater the shear strain when the tread surface moves away from the road surface. Becomes larger.

  Further, when kicking out, when the block portion 100 is separated from the road surface, a large shear strain is generated on the tread due to the bulged portion of the block portion 100. As a result, the tread surface slides on the road surface, and the block portion 100 is likely to be initially worn at the kicking end. Further, when the wear progresses according to the travel distance of the vehicle, the grounding pressure on the road shoulder side kicking end becomes weak, and as a result, the road surface becomes more slippery. For this reason, the wear of the block portion 100 further progresses forward in the tire rotation direction.

  That is, in order to suppress wear, it is effective to reduce the bulge amount when the ground pressure is applied to the block portion 100. As a result of intensive research on the amount of swelling of the block portion 100 in the ground contact state when the vehicle travels, the amount of swelling of the block portion 100 when contact pressure is applied is the angle formed by the tread surface and the groove wall of the block portion 100. It was found that the smaller the angle is than 90 degrees or the larger it is, the greater the suppression. This is due to the following reason. That is, as compared with the case where the angle formed by the tread surface and the groove wall of the block portion 100 is 90 degrees, the entire area of the groove wall surface is increased as the angle is smaller than 90 degrees or larger than 90 degrees. Can do. According to such a configuration, since the ground pressure is dispersed when the ground pressure is applied to the block portion 100, the amount of swelling of the groove wall of the block portion 100 can be suppressed.

  Further, the rubber constituting the block portion 100 generally flows from the kicking end side to the stepping end side around the center of the block portion 100 in the tire circumferential direction Tc due to the incompressibility of the rubber. That is, in the block portion 100, if the rubber flows from the kicking end side to the stepping end side so as to cancel the braking force while suppressing the bulging amount at the kicking end, the shear strain in the tire circumferential direction Tc is reduced. Therefore, it can suppress that the initial wear which generate | occur | produced in the block part 100 progresses to a tire rotation direction front.

  The pneumatic tire 1 according to the first embodiment described above includes a plurality of circumferential grooves 10 extending along the tire circumferential direction Tc and a plurality of width direction grooves 20 (width direction grooves 21 and 22) extending in the tire width direction Tw. And a block portion 100 (a central block portion 110 and an outer block portion 120) defined by the plurality of circumferential grooves 10 and the plurality of width direction grooves 20.

  In the pneumatic tire 1, the circumferential side wall angle θ <b> 11 of the circumferential side wall surface 111 formed in the central block portion 110 by the circumferential groove 10 is one end 110 </ b> B formed in the central block portion 110 by one width direction groove 21. At the other end 110 </ b> D formed in the block portion 100 by the other width direction groove 20. Moreover, the width direction side wall angle θ12 changes from an acute angle to an obtuse angle as it approaches one of the circumferential side wall surfaces 111.

  Further, according to the pneumatic tire 1, the circumferential side wall angle θ13 of the circumferential side wall surface 113 formed in the central block portion 110 is at one end 110 </ b> B formed in the central block portion 110 by one width direction groove 20. It becomes an obtuse angle, and it changes so that it may become an acute angle in the other end 110D formed in the center block part 110 by the other width direction groove | channel 20. FIG. Further, the width direction side wall angle θ <b> 14 changes from an acute angle to an obtuse angle as it approaches the circumferential direction side wall surface 113.

  That is, according to the pneumatic tire 1 according to the present embodiment, the circumferential side wall angles θ11 and θ13 and the width direction side wall angles θ12 and θ14 of the central block portion 110 are larger than 90 degrees and from 90 degrees. Therefore, the amount of swelling on the wall surface when the ground pressure is applied to the central block portion 110 can be suppressed. For this reason, since shear strain at the end portions 110B and 110D in the tire circumferential direction Tc of the central block portion 110 can be suppressed, it is possible to suppress uneven wear occurring at the end portions 110B and 110D.

  In the pneumatic tire 1 according to the present embodiment, a bottom raised portion 200 that is raised to the outside in the tire radial direction Td is formed at the groove bottom of the width direction groove 21 formed in the central land portion row. According to the pneumatic tire 1, for example, even when the ground pressure applied to the central block portion 110 is increased by widening the groove width W <b> 21 of the width direction groove 21, the bottom raised portion 200 is formed in the central block portion. 110 falls down. That is, since the bottom raised portion 200 can suppress the shear strain applied to the central block portion 110, uneven wear that occurs in the central block portion 110 can be suppressed.

  Thus, according to the pneumatic tire 1 according to the present embodiment, it is possible to effectively improve the wear resistance performance of the block portion, particularly the uneven wear resistance, while ensuring the wet performance.

  Moreover, in the center block part 110 which concerns on this embodiment, the circumferential direction side wall surfaces 111 and 121 become an obtuse angle in the edge part 110D in the tire circumferential direction Tc of the center block part 110, and become an acute angle in the edge part 110B. Change. On the other hand, in the central block portion 110, the circumferential side wall surface 113 changes so as to have an obtuse angle at the end portion 110B in the tire circumferential direction Tc of the central block portion 110 and an acute angle at the end portion 110D. According to this, even if the user mistakes the tire rotation direction Tr and attaches the pneumatic tire 1 to the vehicle, the circumferential side wall surfaces 111 and 113 and the width side wall surfaces 112 and 114 in the block portion 100 Can be placed at the kicking end. Therefore, it is possible for the user to mount the vehicle without being aware of the tire rotation direction.

  In the present embodiment, the width direction groove 21 formed in the central land portion row includes a narrow groove portion 25 formed between the bottom raised portion 200 and the block portion 110. That is, a predetermined gap is formed by the narrow groove portion 25 between the central block portion 110 and the bottom raised portion 200. According to the pneumatic tire 1, since the groove volume of the width direction groove 21 can be increased, drainage performance can be improved.

  The groove width W25 of the narrow groove portion 25 is set to a groove width that can be closed when the tread surface is grounded. FIG. 6 shows a tire equator line CL and a sectional view in the tire radial direction when the pneumatic tire 1 according to the present embodiment is grounded. As shown in FIG. 6, in the present embodiment, in the non-grounded region A of the pneumatic tire 1, a gap corresponding to the groove width W25 of the narrow groove portion 25 is provided between the central block portion 110 and the bottom raised portion 200. Yes, the central block portion 110 and the bottom raised portion 200 are not in contact with each other. On the other hand, in the region B where the pneumatic tire 1 is grounded, the narrow groove portion 25 is closed between the central block portion 110 and the bottom raised portion 200, and the central block portion 110 and the bottom raised portion 200 are in contact with each other. Further, in the region C away from the ground contact surface of the pneumatic tire 1, the central block portion 110 and the bottom raised portion 200 do not contact each other as in the region A.

  According to the pneumatic tire 1, the narrow groove wall surfaces 211 and 212 formed on the bottom raised portion 200 by the narrow groove portion 25 when the central block portion 110 is grounded are the side wall surfaces 112 and 114 in the width direction of the central block portion 110. Therefore, the center block part 110 can be prevented from falling down. Further, since the narrow groove wall surfaces 211 and 212 formed in the bottom raised portion 200 are in contact with the width direction side wall surfaces 112 and 114 of the central block portion 110, the expansion of the width direction side wall surfaces 112 and 114 of the central block portion 110 is suppressed. it can. That is, according to the pneumatic tire 1, since shear strain applied to the central block portion 110 can be suppressed, uneven wear can be suppressed.

  Further, in the pneumatic tire 1 according to the present embodiment, the narrow groove wall surface 211 formed on the bottom raised portion 200 by the narrow groove portion 25 is formed on the side wall surface 112 in the width direction of the central block portion 110 adjacent to one side in the tire circumferential direction Tc. Change along. The narrow groove wall surface 212 formed in the bottom raised portion 200 also changes along the width direction side wall surface 114 of the central block portion 110 adjacent to the other in the tire circumferential direction Tc. Thus, since the narrow groove wall surfaces 211 and 212 change along the side wall surfaces 112 and 114 in the width direction, when the center block portion 110 is grounded, the contact area between the center block portion 110 and the bottom raised portion 200 is increased. it can. Therefore, according to the pneumatic tire 1, the center block portion 110 can be prevented from falling down, and the width-direction side wall surfaces 112 and 114 of the center block portion 110 can be prevented from bulging.

[Comparison evaluation]
Next, in order to further clarify the effect of the present invention, a comparative evaluation performed using pneumatic tires according to the following conventional examples and examples will be described. Specifically, (1) an evaluation method and (2) an evaluation result will be described. In addition, this invention is not limited at all by these examples.

(1) Evaluation method A test was performed using plural types of pneumatic tires, and the amount of uneven wear was evaluated.

  For the evaluation of the uneven wear amount, in the pneumatic tire after running, the wear amount after running for a predetermined travel distance was measured by actual measurement, and the average value of the measurement results was calculated. In Table 1, the smaller the numerical value, the smaller the amount of uneven wear.

  Moreover, the data regarding the pneumatic tire used for the test were measured on the conditions shown below.

・ Size: 295 / 80R22.5
・ Internal pressure: 900 kPa
・ Load: 3000kg (per tire)
-Wet performance evaluation test: The wet road surface was suddenly started from a stopped state, and the time until 100 m travel completion was measured.

Wear resistance performance evaluation test: Wear life performance was evaluated with the remaining groove after running 10,000 km at a speed of 60 km / h.

-Uneven wear resistance evaluation test: The uneven wear resistance performance was evaluated from the uneven wear amount (heel and toe wear amount) generated in the block portion during the above-described wear resistance performance evaluation test.

  In Table 1, the tires according to Examples 1 to 4 use the pneumatic tire according to the first embodiment of the present invention. In addition, the side wall angle of the block portion and the depth of the bottom raised portion are as shown in Table 1. The tire according to Conventional Example 1 is a pneumatic tire that does not have a bottom raised portion, although the side wall angle of the block portion changes. As the tire according to Conventional Example 2, a pneumatic tire having a side wall angle of the block portion constant at 97 degrees and having a raised bottom portion was used. Other configurations are the same in the conventional examples 1 and 2 and the examples 1 to 6.

(2) Evaluation result The evaluation result of each pneumatic tire will be described with reference to Table 1. Moreover, in Table 1, the wet performance, the wear resistance performance, and the uneven wear resistance performance indicate index values when the tire according to Conventional Example 1 is used as a reference (100). In addition, it shows that it is excellent, so that an index value is high. Moreover, about the wet performance, since the tire according to Conventional Example 2 is the lower limit value of the wet performance, if it is 90 or more, it indicates that there is no problem in traveling.

  As shown in Table 1, the pneumatic tires according to Examples 1 to 4 are superior in wear resistance and uneven wear resistance while ensuring wet performance as compared with the pneumatic tires according to Conventional Examples 1 and 2. I understand that In particular, it can be seen that the pneumatic tire according to Example 1 has dramatically improved uneven wear resistance.

  Therefore, according to the pneumatic tire of the present invention, it has been proved that the effect of improving the wear resistance, particularly the knitting wear resistance, is large while ensuring the wet performance.

[Other embodiments]
Although the contents of the present invention have been disclosed through the embodiments of the present invention as described above, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples, and operational techniques will be apparent to those skilled in the art.

  For example, the present invention may be a pneumatic tire filled with air or nitrogen gas, or a solid tire not filled with air or nitrogen gas.

  Moreover, in embodiment mentioned above, it is comprised so that the side wall angle of the circumferential direction side wall surfaces 111 and 113 of the central block part 110 formed in a center land part row | line | column and the side wall angle of the width direction side wall surfaces 112 and 114 may change. However, it is configured so that the side wall angle of the circumferential side wall surface and the side wall angle of the width side wall surface of the outer block portion 120 formed in the outer land portion row are changed. Also good.

  In the above-described embodiment, the case where the bottom raised portion 200 is provided at the groove bottom of the width direction groove 21 formed in the central land portion row has been described as an example. However, the embodiment is formed in the outer land portion row. A bottom raised portion may be formed at the groove bottom of the width direction groove 22.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is determined only by the invention specifying matters according to the scope of claims reasonable from the above description.

DESCRIPTION OF SYMBOLS 1 ... Pneumatic tire, (theta) 11, (theta) 13 ... Circumferential side wall angle, (theta) 12, (theta) 14 ... Width direction side angle, (theta) 211 ... Fine groove side wall angle, CL ... Tire equator line, L110 ... Block length, W110 ... Block width, TE ... Tread End, Tc ... tire circumferential direction, Td ... tire radial direction, Tr ... tire rotation direction, Tw ... tire width direction, W10 ... groove width, W21 ... groove width, W25 ... groove width, 10 ... circumferential groove, 20 ... width Direction grooves, 21, 22 ... Width direction grooves, 25 ... Narrow groove portions, 100 ... Block portions, 110 ... Central block portions, 110A to D ... End portions, 110X ... Treading surfaces, 111,113 ... Circumferential side wall surfaces, 112,114 ... side wall surface in width direction, 120 ... outer block, 200X ... surface, 211, 212 ... narrow groove wall surface

Claims (8)

A plurality of circumferential grooves extending along the tire circumferential direction; a plurality of widthwise grooves extending in the tire width direction; and a block portion formed by the plurality of circumferential grooves and the plurality of widthwise grooves. Tire,
The circumferential side wall angle formed by one circumferential side wall surface formed on the block portion by the circumferential groove and the tread surface contacting the road surface of the block portion is determined by one width direction groove adjacent to the tire circumferential direction. It becomes an obtuse angle at one end formed in the block part, and changes to become an acute angle at the other end formed in the block part by the other width direction groove adjacent to the tire circumferential direction,
The width-direction side wall angle formed by the width-direction side wall surface formed in the block portion by the other width-direction groove and the tread surface changes from an acute angle to an obtuse angle as it approaches the circumferential side wall surface,
A tire characterized in that a bottom raised portion is formed at the groove bottom of the width direction groove and is raised to the outside in the tire radial direction. The circumferential side wall angle formed by the other circumferential side wall surface and the tread surface changes so as to be an acute angle at one end of the block portion in the tire circumferential direction and an obtuse angle at the other end. Tire described in. The tire according to claim 1 or 2, wherein the width direction groove has a narrow groove portion formed between the bottom raised portion and the block portion. The tire according to claim 3, wherein a narrow groove wall surface formed in the bottom raised portion by the narrow groove portion changes along the side wall surface in the width direction. The tire according to claim 3 or 4, wherein a groove width of the narrow groove portion is 10% or more and 20% or less of a groove width of the width direction groove. 6. The depth in the tire radial direction from the tread surface to the bottom raised portion is 30% or more and 60% or less of the depth of the circumferential groove. 6. tire. The tire according to any one of claims 1 to 6, wherein a groove width of the circumferential groove is not less than 5% and not more than 28% of a block width in the tire width direction of the block portion. The tire according to any one of claims 1 to 7, wherein a groove width of the width direction groove is 12% or more and 22% or less of a block length of the block portion in a tire circumferential direction.

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