JP2013169827A - Tire, and tire manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire that can further suppress rolling resistance, and a tire manufacturing method.SOLUTION: A tire (pneumatic tire 1) is configured such that recesses recessed from the tire surface in the tire inside direction are arranged regularly at least in a partial area on the tire surface. The maximum width L of the recesses is within the range of ≥0.1 μm to <50 μm in the direction along the tire surface. The depth D of the recesses from the tire surface to a point, located at the innermost position, of each of the recesses in the tire inside direction is within the range of ≥0.1 μm to <10 μm. The arrangement interval P between the recesses is within the range of >0.1 μm to <100 μm in the direction along the tire surface.

Description

  The present invention relates to a tire and a tire manufacturing method.

  In recent years, the use of microfabrication technology for forming irregularities of several micrometers on the tire surface of pneumatic tires (hereinafter referred to as tires) is becoming widespread (see, for example, Patent Document 1).

  Such a fine processing technique is expected as one of the effective techniques for suppressing the rolling resistance of the tire. Specifically, one of the causes of rolling resistance is the frictional resistance of air (outside air). A tire in which unevenness is formed on the tire surface by the above-described microfabrication technique can intentionally generate air turbulence on the tire surface when the tire rotates, thereby forming an air relaxation layer. A tire having an air relaxation layer formed on the tire surface can reduce the rolling resistance of the tire because it can reduce the frictional resistance due to the air positioned in the tire outer direction of the relaxation layer when the tire rotates. It is done.

JP 2003-246209 A

  However, in the tire according to the conventional technique, although the unevenness can be formed on the tire surface by the microfabrication technique, the optimal unevenness shape and arrangement interval are not considered. As a result, the tire according to the related art has a problem that when the tire rotates, the air relaxation layer is disturbed, and the rolling resistance cannot be sufficiently suppressed.

  Then, this invention is made | formed in view of such a condition, and it aims at providing the tire and tire manufacturing method which can suppress rolling resistance still more.

  The tire (pneumatic tire 1) according to the present invention is characterized in that in at least a partial region of the tire surface (tire surface 50), a recess (recess 80) that is recessed from the tire surface toward the tire inner side is regular. In the direction along the tire surface, the maximum width L of the recess is within a range of 0.1 μm or more and less than 50 μm, and the most of the recess from the tire surface toward the tire inner side. The depth D of the recesses up to the point located inside is in a range of 0.1 μm or more and less than 10 μm, and the arrangement interval P of the recesses is larger than 0.1 μm in the direction along the tire surface. The gist is that it is within a range of less than 100 μm.

  In such a tire, the recesses are regularly arranged in at least a part of the tire surface. The maximum width L of the recess is in the range of 0.1 μm or more and less than 50 μm, and the depth D of the recess is in the range of 0.1 μm or more and less than 10 μm. The arrangement interval P of the recesses is in the range of more than 0.1 μm and less than 100 μm.

  The tire is optimally arranged in a partial region of the tire surface by the air (outside air) around the tire when the tire rotates by regularly arranging the concave portions having such a shape according to the arrangement interval described above. An air relaxation layer can be formed. Therefore, since the tire can further reduce the frictional resistance between the tire surface and the air, the rolling resistance of the tire can be further suppressed.

  The tire according to the present invention is characterized in that in at least a partial region of the tire surface (tire surface 50), convex portions (convex portions 90) protruding from the tire surface toward the tire outer direction are regularly arranged. In the direction along the tire surface, the maximum width L of the convex portion is within a range of 0.1 μm or more and less than 50 μm, and the outermost portion of the convex portion from the tire surface toward the tire outer side direction. The height H of the projections up to the point located in the range is 0.1 μm or more and less than 10 μm, and in the direction along the tire surface, the arrangement interval P of the projections is more than 0.1 μm. The gist is that it is within the range of less than 100 μm.

  In such a tire, convex portions are regularly arranged in at least a partial region of the tire surface. The maximum width L of the convex portion is in the range of 0.1 μm or more and less than 50 μm, and the height H of the convex portion is in the range of 0.1 μm or more and less than 10 μm. The arrangement interval P of the convex portions is in the range of more than 0.1 μm and less than 100 μm.

  The tire is optimally arranged in a part of the tire surface due to the air (outside air) around the tire when the tire rotates by regularly arranging the convex portions having such a shape according to the arrangement interval described above. An air relaxation layer can be formed. Therefore, since the tire can further reduce the frictional resistance between the tire surface and the air, the rolling resistance of the tire can be further suppressed.

  Another feature of the present invention includes a tread portion (tread portion 40) and a pair of tire side portions (tire side portions 30) formed outside the tread portion in the tread width direction. The gist of the partial region is a region where a tire outer surface (tire side surface 31) of the tire side portion is formed.

  Another feature of the present invention includes the tread portion and a pair of tire side portions formed on the tread width direction outer side of the tread portion, and the tread portion includes a tire circumferential direction or a tire circumferential direction. A groove (groove 10) extending in a direction intersecting with the groove is formed. The groove has a pair of groove wall surfaces (groove wall surface 11a) and a groove bottom surface (groove bottom surface 11b). The gist of the region is a region in which at least one of the pair of groove wall surfaces or the groove bottom surface is formed.

  A feature of the tire manufacturing method according to the present invention is a tire manufacturing method for manufacturing a tire using a tire molding die (for example, an upper side mold 133) for molding a raw tire which is a tire before vulcanization. In the inner peripheral surface (for example, inner peripheral surface 133a) of the tire molding die, a convex forming portion (convex forming portion 133c) that molds the convex portion in at least a partial region of the tire surface, or A recess forming portion (for example, a recess forming portion 133c) that molds the recess is formed in at least a partial region of the tire surface, and the protrusion or the protrusion is formed on the raw tire using the tire molding die. The gist is to include a vulcanization step (step S20) in which the concave portion is molded and the tire according to claim 1 is molded.

  Another feature of the present invention is that, in the tire manufacturing method, the convex forming portion or the concave forming portion is formed on an inner peripheral surface of the tire molding die by laser processing. .

  According to the present invention, it is possible to provide a tire and a tire manufacturing method capable of further suppressing rolling resistance.

FIG. 1 is a tire width direction cross-sectional view illustrating a configuration of a pneumatic tire 1 according to an embodiment of the present invention. FIG. 2 is an enlarged perspective view of the tire outer surface 31 of the tire side portion 30 where the recess 80 according to the first embodiment of the present invention is formed. FIG. 3 is a cross-sectional view in the tire width direction (tread width direction) of the tire molding die 100 according to the first embodiment of the present invention. FIG. 4 is an enlarged cross-sectional view showing the concave forming portion 133c of the upper side mold 133 according to the first embodiment of the present invention. FIG. 5 is a flowchart showing the tire manufacturing method according to the first embodiment of the present invention. FIG. 6 is a partial perspective view showing an example of a recess 80 according to a modified example of the present invention. FIG. 7 is a partial perspective view showing an example of a recess 80 according to a modified example of the present invention. FIG. 8 is a partial perspective view showing an example of a recess 80 according to a modified example of the present invention. FIG. 9 is an enlarged perspective view of the tire outer surface 31 of the tire side portion 30 where the convex portion 90 according to the second embodiment of the present invention is formed. FIG. 10 is an enlarged cross-sectional view showing the convex forming portion 133X of the upper side mold 133 according to the second embodiment of the present invention. FIG. 11 is a partial perspective view showing an example of a convex portion 90 according to a modified example of the present invention. FIG. 12 is a partial perspective view showing an example of the convex portion 90 according to the modified example of the present invention. FIG. 13 is a partial perspective view showing an example of the convex portion 90 according to the modified example of the present invention.

  Next, an embodiment of a tire 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.

[First Embodiment]
(1) Overall Schematic Configuration of Tire Hereinafter, the overall configuration of a pneumatic tire will be described with reference to the drawings. FIG. 1 is a cross-sectional view in the tread width direction illustrating the configuration of the pneumatic tire 1. The pneumatic tire 1 has a line-symmetric pattern with respect to the tire equator line CL. FIG. 1 shows only one side of the pneumatic tire 1 with respect to the tire equator line CL.

  The pneumatic tire 1 is a pneumatic tire mainly mounted on a passenger car. The pneumatic tire 1 assembled to the rim wheel may be filled with an inert gas such as nitrogen gas instead of air.

  The pneumatic tire 1 according to the present embodiment includes a tread portion 40 and a pair of tire side portions 30 formed on the outer side of the tread portion 40 in the tread width direction. Specifically, the pneumatic tire 1 includes a pair of bead portions 20 having a bead core 15, a pair of tire side portions 30, and a tread portion 40 that is continuous with the pair of tire side portions 30. In FIG. 1, the bead part 20, the tire side part 30, and the tread part 40 are shown only on one side with respect to the tire equator line CL of the pneumatic tire 1.

  The pneumatic tire 1 includes a carcass 16 straddling a toroidal shape between a pair of bead cores 15. Between the tread portion 40 and the carcass 16, a belt layer 17 composed of a plurality of belts 17a to 17b is provided.

  The pneumatic tire 1 is attached to the regular rim 19. The regular rim 19 is a rim defined in the standard. The standard is determined by an industrial standard effective in an area where a tire is produced or used. For example, “the TIRE and Rim Association Inc. year book” in the United States, “The European TIRE and Rim Technical Organization Standards Manual” in Japan, and “the Japan automobile tire association” in Japan.

  The tread portion 40 is formed with a groove 10 extending in the tire circumferential direction or a direction crossing the tire circumferential direction. The tire circumferential direction is a direction orthogonal to the tread width direction Tw and the tire radial direction Td. A plurality of grooves 10 are formed at intervals in the tread width direction Tw. The groove 10 has a pair of groove wall surfaces 11a and a groove bottom surface 11b.

  Here, the pneumatic tire 1 according to the present embodiment has a tire surface 50 exposed to the outside air. Below, the tire surface 50 which concerns on this embodiment is demonstrated.

  The tire surface 50 includes a tire outer surface 41 (hereinafter, tread surface 41) of the tread portion 40 and a tire outer surface 31 (hereinafter, tire side surface 31) of the tire side portion 30. The tread surface 41 includes a grounding surface 42, a pair of groove wall surfaces 11a, and a groove bottom surface 11b.

  Further, the width of the tread surface 41 in the tread width direction Tw is a range in which the tire contacts the road surface when a normal load is applied to the pneumatic tire having a normal internal pressure. In the example of FIG. 1, the end of the tread surface 41 on the outer side in the tread width direction Tw is shown as an end Z21.

  The normal internal pressure is the air pressure defined by the tire measurement method of the Year Book 2008 version of JATMA (Japan Automobile Tire Association). The normal load is a load corresponding to the maximum load capacity when a single wheel prescribed in “JATMA Year Book” is applied.

  Further, the range of the tire side surface 31 of the tire side portion 30 is a range from the end portion Z21 of the tire outer surface 41 of the tread portion 40 to the end portion Z22 where the pneumatic tire 1 contacts the regular rim 19. The end Z22 is an end where the pneumatic tire 1 contacts the normal rim 19 when a normal load is applied to the pneumatic tire having a normal internal pressure.

  The bead portion 20 has a rim contact surface 21 that contacts the regular rim 19. In the present embodiment, the range of the rim contact surface 21 ranges from the end Z22 where the tire side surface 31 contacts the regular rim 19 to the end Z23 inside the tread width direction Tw where the pneumatic tire 1 contacts the regular rim 19. The range is between. It should be noted that the rim contact surface 21 is not included in the tire surface 50.

  In the present embodiment, in at least a partial region of the tire surface 50, the recesses 80 that are recessed from the tire surface 50 toward the tire inner side are regularly arranged. In the present embodiment, the tire inner direction is the direction toward the inner side of the tire in the normal direction of the tire surface 50. The tire outer direction is a direction toward the outer side of the tire in the normal direction of the tire surface 50.

  The recess 80 is formed by using a fine processing technique. Details of the shape and arrangement of the recesses 80 will be described later. In the present embodiment, the partial region of the tire surface 50 where the recess 80 is formed is a region where the tire side surface 31 of the tire side portion 30 is formed. Further, the wider the range in which the recess 80 is formed, the more effective. Since the tire side surface 31 requires a space for marking characters such as tire specifications according to regulations, it cannot be formed substantially in the entire range (100%). It is more preferable to form the recess 80. However, it should be noted that the range in which the recess 80 is formed is effective even if it is a part of the tire side surface 31.

(2) Shape and Arrangement of Recesses Next, the shape and arrangement of the recesses 80 will be described with reference to FIG. FIG. 2 is an enlarged perspective view of a recess 80 formed on the tire side surface 31 using a microfabrication technique.

  As shown in the figure, in the pneumatic tire 1 according to this embodiment, when the tire side surface 31 is viewed in the normal direction along the normal direction of the tire side surface 31, a circle is formed on the tire side surface 31. A concave portion 80 having a shape is formed.

  Moreover, when the direction along the tire side surface 31 (tire surface 50) is the width direction of the recess 80, the maximum width L of the recess 80 is in a range of 0.1 μm or more and less than 50 μm. In addition, the direction along the tire side surface 31 can be rephrased as a direction parallel to the tire side surface 31. In the present embodiment, since the recess 80 is circular, the maximum width L of the recess 80 is the diameter of the recess 80. In the present embodiment, the maximum width L of the recess 80 is 0.6 μm. Further, the maximum width L of the recess 80 may be an average value Lave of the maximum width L of the recess. Here, the average value “Lave” is an average value of the maximum width L of a plurality of (for example, 100) concave portions 80 extracted at random.

  The maximum width L of the recess 80 is more preferably in the range of 0.1 μm to 5 μm in the above-described range. When the maximum width L is smaller than 0.1 μm, it is difficult for rubber to enter the edge of the concave portion of the mold during vulcanization in the manufacturing process, and the shape is difficult to adjust. When the maximum width L is larger than 5 μm, dust or the like enters the recess 80 during use of the tire, which deteriorates the tire appearance.

  Further, the depth D of the recess 80 is from 0.1 μm to less than 10 μm from the tire surface 50 to the point DZ located at the innermost side of the recess 80 in the tire inner direction. In the present embodiment, the depth D of the recess 80 is 0.24 μm. Note that the depth D of the recess 80 may be an average value Dave of the depth D of the recess. Here, the average value Dave is an average value of the depth D of a plurality of (for example, 100) recessed portions 80 extracted at random.

  Further, the depth D of the recess 80 may be defined by a ratio with the maximum width L of the recess 80. Specifically, the depth D of the recess 80 and the maximum width L may satisfy the relationship of 0.1 ≦ D / L ≦ 10. In the present embodiment, the depth D (0.24 μm) of the recess 80 and the maximum width L (0.6 μm) of the recess 80 are D / L = 0.4.

  The depth D of the recess 80 is more preferably in the range of 0.1 to 5 μm within the range satisfying the above-described relationship. When the depth D of the concave portion 80 is smaller than 0.1 μm, it becomes susceptible to deformation with time of rubber, and the effect becomes small. When the depth D of the concave portion 80 is larger than 5 μm, it becomes difficult for rubber to enter the edge portion, and the shape becomes difficult to adjust.

  In the direction along the tire surface, the arrangement interval P of the recesses 80 is in the range of more than 0.1 μm and less than 100 μm. The arrangement interval P indicates the distance between the center of the concave portion 80 and the center of another concave portion 80 adjacent to the nearest portion. In the present embodiment, the arrangement interval P is 1.2 μm. Note that the arrangement interval P of the recesses 80 may be an average value Pave of the arrangement interval P of the recesses 80. Here, the average value Pave is an average value of a distance between a plurality of (for example, 100) concave portions 80 (between the centers) extracted at random.

  Further, the arrangement interval P of the recesses 80 may be defined by a ratio with the width L of the recesses 80. Specifically, the arrangement interval P of the recesses 80 and the width L preferably satisfy the relationship of 1.0 <P / L, and particularly satisfy the relationship of 1.05 ≦ P / L ≦ 5. Good. In the present embodiment, the arrangement interval P (1.2 μm) of the recesses 80 and the maximum width L (0.6 μm) of the recesses 80 are P / L = 2.

  In addition, it is more preferable that the arrangement interval P of the recesses 80 is in a range larger than 0.1 μm and not larger than 10 μm in a range satisfying the above-described relationship. When the arrangement interval P is 0.1 μm or less, the shape of the recesses cannot be adjusted. Further, the distortion generated in the concave portion 80 which can be the base point of the surface crack that ultimately impairs the appearance is alleviated when the arrangement interval P is short. However, when the arrangement interval P is larger than 10 μm, the relaxation effect is reduced and surface cracks are likely to occur.

(3) Configuration of Tire Molding Mold Next, a tire molding mold 100 for molding the pneumatic tire 1 according to the present embodiment will be described with reference to the drawings. FIG. 3 is a cross-sectional view in the tire width direction (tread width direction) of the tire molding die 100 in a state where the sector mold 130, the lower side mold 131, and the upper side mold 133 are combined with each other.

  The tire TR before vulcanization is accommodated in a space (referred to as a vulcanization space) formed between the bladder 121, the sector mold 130, the lower side mold 131, and the upper side mold 133. The tire TR is a general tire including a bead core, a carcass, and a belt layer (not shown). The tire TR has a tread portion TR1 (corresponding to the tread portion 40 in FIG. 1), and sidewall portions TR2 and TR3 (corresponding to the tire side portion 30 in FIG. 1). Concave portions 80 are formed in the sidewall portions TR2 and TR3.

  On the inner peripheral surface 133a of the upper side mold 133 and the inner peripheral surface 131a of the lower side mold 131, there are formed concave forming portions that mold the concave portions 80 on the tire side surfaces 31 of the sidewall portions TR2 and TR3. The detailed configuration of the concave forming portion will be described later.

  The inner peripheral surface of the sector mold 130 includes a tread pattern forming surface 130a on which irregularities for forming a tread pattern such as the groove 10 are formed, and an inclined surface 130b. In the cross section in the tire width direction, the sector mold 130 has a lower end portion longer than an upper end portion.

  The outer ring 134 has an inclined surface 134a that contacts the inclined surface 130b. In the cross section in the tire width direction of the outer ring 134, the length of the upper end is longer than the length of the lower end.

  Therefore, when the outer ring 134 is further lowered in the downward direction of the arrow V from the state in which the inclined surface 134a of the outer ring 134 is in contact with the inclined surface 130b of the sector mold 130, the inclined surface 134a of the outer ring 134 and the sector mold The 130 inclined surfaces 130b slide.

  At this time, force acts in a direction in which the sector mold 130, the lower side mold 131, and the upper side mold 133 are in close contact with each other (that is, a direction from the outer side of the tire toward the center along the tire radial direction). Thereby, the sector mold 130, the lower side mold 131, and the upper side mold 133 are firmly adhered to each other to form a vulcanization space.

  The sector mold 130, the lower side mold 131, and the upper side mold 133 are movable inward and outward in the tire radial direction by a moving mechanism (not shown). In addition, during vulcanization, the heated and pressurized fluid R is blown into the bladder 121, so that the bladder 121 expands inside the tire TR. The tire TR is molded into the sector mold 130, the lower side mold 131, and the upper side mold 133 when the expanded bladder 121 expands.

(4) Configuration of Side Mold Next, the configuration of the side mold will be described with reference to the drawings. FIG. 4 is an enlarged cross-sectional view showing a cross section in the tire width direction of the concave forming portion 133 c of the upper side mold 133.

  As shown in the figure, on the inner peripheral surface 133a of the upper side mold 133, a sidewall forming surface 133b for molding the tire side surface 31 of the sidewall portion TR3 of the tire TR and a recess 80 on the tire side surface 31 are molded. A concave forming portion 133c is formed. Specifically, the concave forming portion 133c protrudes from the sidewall forming surface 133b toward the tire inner side.

  Moreover, the concave formation part 133c is formed in the internal peripheral surface 133a of the upper side mold 133 by laser processing. The concave forming portion 133c may be formed on a part of the inner peripheral surface 133a of the upper side mold 133.

  Here, as a technique for processing the inner peripheral surface 133a of the upper side mold 133, a chemical polishing process technique or the like can be used, but in this embodiment, the concave forming portion 133c is used by using a laser processing process technique. Is formed. This is due to the following reason. That is, it is for forming the optimal shape and the optimal arrangement | positioning space | interval of the recessed part 80 in the tire side surface 31 more correctly. In order to form the recess 80 in the tire side surface 31, it is more preferable to apply a rubber member having a low rubber hardness to the rubber member constituting the tire side surface 31.

  Similarly, a concave forming portion is formed on the inner peripheral surface 131 a of the lower side mold 131. Since the upper side mold 133 and the lower side mold 131 have the same structure, detailed description of the lower side mold 131 is omitted. Using the upper side mold 133 and the lower side mold 131 configured as described above, the concave portions 80 are formed on the tire outer surfaces of the sidewall portions TR2 and TR3.

(5) Tire manufacturing method Next, with reference to drawings, the tire manufacturing method of the pneumatic tire 1 is demonstrated. Here, FIG. 5 shows a flowchart showing a tire manufacturing method of the pneumatic tire 1.

  First, the raw tire preparation step S10 is a step of preparing a raw tire. Specifically, members necessary for constituting a tire including a cap rubber, a base rubber, a belt layer, a carcass, a bead core, and the like are prepared. Using the molding machine, the prepared members are assembled into a single tire. Thereby, a green tire is prepared.

  The vulcanization step S20 is a step of vulcanizing the raw tire and molding the pneumatic tire 1. Specifically, in the vulcanization step S20, the pneumatic tire 1 is molded using the sector mold 130, the upper side mold 133, the lower side mold 131, and the like.

  In the vulcanization step S20, the raw tire generated in the raw tire preparation step S10 is placed in the tire molding die 100.

  The raw tire is vulcanized by setting the inside of the tire molding die 100 containing the raw tire to a high temperature and high pressure. During this vulcanization, the tire side surface 30 is formed with a recess 80 on the tire side surface 31 by the recess forming portion of the upper side mold 133 and the recess forming portion of the lower side mold 131. That is, using the upper side mold 133 and the lower side mold 131, the concave portion 80 is formed on the green tire, and the pneumatic tire 1 is molded.

  Further, the vulcanized raw tire is taken out from the tire molding die 100, and the pneumatic tire 1 in which the recess 80 is formed on the tire side surface 31 of the tire side portion 30 is manufactured.

(6) Action / Effect In the pneumatic tire 1 according to the present embodiment, the recesses 80 are regularly arranged in at least a partial region of the tire surface 50. Specifically, the recesses 80 are regularly arranged on the tire outer surface 31 (tire side surface 31) of the tire side portion 30.

  The maximum width L of the recess 80 is in the range of 0.1 μm or more and less than 50 μm, and the depth D of the recess 80 is in the range of 0.1 μm or more and less than 10 μm. The arrangement interval P of the recesses 80 is in the range of more than 0.1 μm and less than 100 μm.

  In the pneumatic tire 1, the recesses 80 having such a shape are regularly arranged at the above-described arrangement interval, so that when the pneumatic tire 1 rotates, the tire side surface 31 is caused by air around the tire (outside air). It is possible to form an air relaxation layer optimal for the above.

  Thus, according to the pneumatic tire 1 according to the present embodiment, the frictional resistance between the tire surface 50 and the air around the tire can be further reduced, so that the rolling resistance of the tire can be further suppressed. .

  In the pneumatic tire 1 according to the present embodiment, the recess 80 is formed in the tire side surface 31. In the pneumatic tire 1, for example, the concave portion 80 is less likely to be worn compared to the case where the concave portion 80 is formed on the ground contact surface 42 of the tread portion 40, and therefore, the rolling resistance of the tire can be suppressed for a long period of time. It becomes possible.

  In general, a smooth surface is often formed on the tire side surface 31. Such a smooth surface is less likely to form an air relaxation layer when the pneumatic tire 1 rotates, and air friction resistance tends to increase.

  In the pneumatic tire 1 according to the present embodiment, since the concave portion 80 is formed on the tire side surface 31 where the frictional resistance of air is likely to increase, the friction of air is larger than when the concave portion 80 is formed in other portions. Resistance can be reduced efficiently and reliably.

(7) Modification Example Next, a modification example according to the first embodiment will be described.

(7.1) Modification 1
In the above-described embodiment, the case where the partial region of the tire surface 50 where the recess 80 is formed is the tire side surface 31 has been described as an example, but the region is a pair of groove wall surfaces 11a or groove bottom surfaces. It may be a region where at least one of 11b is formed.

  According to the pneumatic tire 1 according to this modification, for example, the concave portion 80 is less likely to be worn compared to the case where the tread portion 40 is formed on the ground contact surface 42, so that the rolling resistance of the tire is suppressed over a long period of time. It becomes possible to do.

  The partial region of the tire surface 50 where the recess 80 is formed may be a region where any one of the tire side surface 31, the pair of groove wall surfaces 11a, and the groove bottom surface 11b is formed. It may be a region where all these surfaces are formed.

(7.2) Modification 2
Next, Modification Example 2 according to the first embodiment will be described. Here, the configuration of the recess 80 is not limited to the configuration of the recess 80 according to the first embodiment. Below, the structure of the other recessed part 80 is demonstrated.

  For example, in the above-described embodiment, when the tire side surface 31 is viewed in the tire inner direction along the normal direction of the tire side surface 31, the recess 80 is formed in a circular shape. 80 may be a polyhedral shape.

  FIG. 6 shows an example of the recess 80a according to this modification. As shown in the figure, the recess 80 a is formed in a hexagonal shape when the tire surface 50 is viewed in the tire inner direction along the normal direction of the tire side surface 31.

  In this case, the maximum width L of the recess 80a is preferably 10 μm. The depth D of the recess 80a is preferably 2 μm. The arrangement interval P of the recesses 80a is preferably 12 μm.

(7.3) Modification 3
FIG. 7 shows an example of another recess 80b according to the third modification. As shown in the figure, the bottom surface of the recess 80b is formed in a curved shape.

  In this case, the maximum width L of the recess 80b is preferably 50 μm. The depth D of the recess 80b is preferably 25 μm. The arrangement interval P of the recesses 80b is preferably 55 μm.

(7.4) Modification 4
Further, FIG. 8 shows an example of another recess 80c according to the modification example 4. As shown in the figure, in the recess 80 c, the depth D of the recess 80 c is formed to be larger than the width L.

  In this case, the maximum width L of the recess 80c is preferably 7 μm. The depth D of the recess 80c is preferably 70 μm. The arrangement interval P of the recesses 80c is preferably 9 μm.

  As described above, in the pneumatic tire 1 according to this modified example, by arranging the concave portions 80a to 80c regularly, an optimal air relaxation layer can be formed when the pneumatic tire 1 rotates. . That is, according to the pneumatic tire 1 according to this modification, the rolling resistance of the tire can be further suppressed.

(8) Comparative Evaluation Next, in order to further clarify the effect of the present invention, comparative evaluation performed using pneumatic tires according to the following comparative examples and examples will be described. In addition, this invention is not limited at all by these examples.

(8.1) Description of Comparative Examples and Examples In order to evaluate the performance of rolling resistance for a pneumatic tire having a recess, the following comparative evaluation was performed. Specifically, the following conventional examples, comparative examples A1 to A10, and examples A1 to A30 were prepared. This will be described with reference to Table 1.

  In addition, the pneumatic tire which concerns on a prior art example, a comparative example, and an Example used the tire size whose tire size is 155 / 65R13. Moreover, except the structure shown below, another structure is the same structure in a prior art example, a comparative example, and an Example.

  First, a pneumatic tire according to a conventional example will be described. As the pneumatic tire according to the conventional example, a tire having no recess formed on the tire surface was used.

  Next, a pneumatic tire according to a comparative example and a pneumatic tire according to an example will be described. As the pneumatic tire according to Comparative Examples A1 to A10 and the pneumatic tire according to Examples A1 to A30, tires having recesses formed in a pair of groove wall surfaces in the tire side portion or the tread portion were used. The detailed configuration is as shown in Table 1.

  Here, as shown in Table 1, in the pneumatic tires according to Comparative Examples A1 and A5, it was found that it was extremely difficult to form the recesses during manufacturing. This is due to the following reason. That is, since the width L of the concave portion is less than 0.1 μm, it is difficult for rubber to enter the edge of the concave portion of the mold during vulcanization in the manufacturing process, and the shape of the concave portion is not adjusted. Therefore, considering the feasibility, the width L of the concave portion needs to be 0.1 μm or more.

  As described above, when the width L of the recesses is 0.1 μm or more, the lower limit value of the arrangement interval P is inevitably larger than 0.1 μm. In consideration of this point, in the pneumatic tire according to Comparative Examples A1 to A10 and the pneumatic tire according to Examples A1 to A30, the width L, the depth D, and the arrangement interval P of the recesses are set. Yes.

(8.2) Evaluation method A test for evaluating rolling resistance was performed using the pneumatic tires of the conventional example, the comparative examples A1 to A12, and the examples A1 to A30. The evaluation test was measured under the following conditions.

<Evaluation test>
-Rim size: Standard rim specified by JATMA-Internal pressure condition: 210 kPa
Evaluation method: The rolling resistance force of the axle at 80 km / h was measured using a drum testing machine including a drum having a diameter of 1.7 m. The rolling resistance was measured by a force method based on a method based on ISO18164.

(8.3) Evaluation Results The evaluation results of each pneumatic tire will be described with reference to Table 1. In Table 1, the rolling resistance performance indicates the measurement results of the tires of the comparative example and the example by an index with the measurement result of the pneumatic tire according to the conventional example as a reference (100). In Table 1, the larger the index value shown as rolling resistance performance, the more the rolling resistance is suppressed.

  From the results shown in Table 1, it was proved that the tires according to Examples A1 to A30 can suppress the rolling resistance as compared with the tires according to the conventional examples and Comparative Examples A1 to A12.

  In other words, the maximum width L of the recesses is 0.1 μm or more and less than 50 μm, the depth D is 0.1 or more and less than 10 μm, and the arrangement interval P is greater than 0.1 and less than 100 μm. It has been proved that such a tire can suppress rolling resistance.

  Further, the tire according to the example in which the maximum width L of the recesses is 0.1 μm or more and less than 5 μm, the depth D is 0.1 μm or more and less than 1 μm, and the arrangement interval P is 0.1 μm or more and less than 10 μm. It was proved that rolling resistance can be further suppressed.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the first embodiment described above, the case where the concave portion 80 is formed in a partial region of the tire surface 50 has been described as an example. However, in the present embodiment, the convex portion 90 is formed in a partial region of the tire surface 50. Is formed. Below, the structure of the pneumatic tire 2 which concerns on this embodiment is demonstrated.

(1) Shape and arrangement of convex portions FIG. 9 is an enlarged perspective view of the convex portions 90 formed in the pneumatic tire 2 according to the present embodiment.

  As shown in the figure, in the pneumatic tire 2 according to the present embodiment, when the tire side surface 31 is viewed in the tire inner direction along the normal direction of the tire side surface 31 (tire surface 50). A circular convex portion 90 is formed on the tire side surface 31.

  Further, when the direction along the tire side surface 31 is the width direction of the convex portion 90, the maximum width L of the convex portion 90 in the direction along the tire side surface 31 is within a range of 0.1 μm or more and less than 50 μm. is there. In addition, the direction along the tire side surface 31 can be rephrased as a direction parallel to the tire side surface 31. In the present embodiment, since the convex portion 90 is circular (cylindrical), the maximum width L of the convex portion 90 is the diameter of the convex portion 90. In the present embodiment, the maximum width L of the convex portion 90 is 0.6 μm. Further, the maximum width L of the convex portion 90 may be an average value Lave of the maximum width L of the convex portion. Here, the average value “Lave” is an average value of the maximum width L of a plurality of (for example, 100) convex portions 90 extracted at random.

  The maximum width L of the convex portion 90 is more preferably 0.1 μm or more and 5 μm or less in the above-described range. When the maximum width L is smaller than 0.1 μm, after the vulcanization in the manufacturing process, when the tire comes off from the mold, the rubber becomes difficult to come off from the mold, and the convex part is cut, and the intended shape cannot be obtained. When the maximum width L is larger than 5 μm, the buffer layer does not have a sufficient thickness at the top of the convex portion, and the frictional resistance with air cannot be reduced.

  Further, the height H of the convex portion 90 from the tire side surface 31 to the point Dx located on the outermost side of the convex portion 90 in the tire outer direction is in the range of 0.1 μm or more and less than 10 μm. In the present embodiment, the height H of the convex portion 90 is 3 μm. The height H of the convex portion 90 may be an average value Have of the height H of the convex portion 90. Here, the average value Have is an average value of the heights H of a plurality of (for example, 100) convex portions extracted at random.

  Further, the height H of the convex portion 90 may be defined by a ratio with the maximum width L of the convex portion 90. Specifically, the height H of the convex portion 90 and the maximum width L may satisfy the relationship of 0.1 ≦ H / L ≦ 10. In the present embodiment, the height H (3 μm) of the convex portion 90 and the maximum width L (0.6 μm) of the convex portion 90 are H / L = 5.

  In addition, it is more preferable that the height H of the convex portion 90 is in a range of 0.1 μm or more and 1 μm or less in a range satisfying the above-described relationship. When the height H of the convex part 90 is smaller than 0.1 μm, since the creep deformation of rubber is large in an area exposed to high temperature, the shape is greatly deformed and the effect is lowered. When the height H of the convex portion 90 is larger than 1 μm, it becomes difficult for rubber to enter during vulcanization, and thus the shape of the convex portion 90 is difficult to be adjusted.

  Further, in the direction along the tire side surface 31, the arrangement interval P of the protrusions 90 is in the range of 0.1 μm or more and less than 100 μm. The arrangement interval P indicates the distance between the center of the convex part 90 and the center of another convex part 90 adjacent to the nearest. In the present embodiment, the arrangement interval P of the convex portions 90 is 0.66 μm. The arrangement interval P of the protrusions 90 may be an average value Pave of the arrangement interval P of the protrusions 90. Here, the average value Pave is an average value of a distance between a plurality of (for example, 100) convex portions 90 (between the centers) extracted at random.

  Further, the arrangement interval P of the protrusions 90 may be defined by a ratio with the width L of the protrusions 90. Specifically, the arrangement interval P of the protrusions 90 and the maximum width L of the protrusions 90 may satisfy a relationship of 1.05 ≦ P / L ≦ 5. In the present embodiment, the arrangement interval P (0.66 μm) of the protrusions 90 and the maximum width L (0.6 μm) of the protrusions 90 are P / L = 1.1.

  The arrangement interval P of the convex portions 90 is more preferably in the range of 0.1 μm or more and 5 μm or less within the range satisfying the above-described relationship. When the arrangement interval P is smaller than 0.1 μm, it is difficult for rubber to enter the edge portion, and the shape is difficult to arrange. When the arrangement interval P is larger than 5 μm, the tensile strain acting between the convex portions 90 becomes large, so that the convex portions 90 are easily cut without being removed from the mold during vulcanization.

(2) Configuration of Side Mold Next, the configuration of the side mold according to the present embodiment will be described with reference to the drawings. FIG. 10 is an enlarged cross-sectional view showing a cross section in the tire width direction of the convex forming portion 133c forming the convex portion 90 in the upper side mold 133 according to the present embodiment.

  As shown in the figure, the inner peripheral surface 133a of the upper side mold 133 has a sidewall forming surface 133b that molds the tire side surface 31 of the sidewall portion TR3 of the tire TR, and a convex portion 90 on the tire side surface 31. A convex forming portion 133X to be molded is formed. Specifically, the convex forming portion 133X is formed to be recessed from the sidewall forming surface 133b toward the tire outer side.

  Further, the convex forming portion 133X is formed on the inner peripheral surface 133a of the upper side mold 133 by laser processing.

  Here, as a technique for processing the inner peripheral surface 133a of the upper side mold 133, a chemical polishing process technique or the like can be used. However, in the present embodiment, the convex forming portion 133X is used by using a laser processing process technique. Is formed. This is due to the following reason. That is, it is for forming the optimal shape and the optimal arrangement | positioning space | interval of the convex part 90 on the tire side surface 31 more correctly. In order to form the convex portion 90 on the tire side surface 31, it is more preferable to apply a rubber member having a low rubber hardness to the rubber member constituting the tire side surface 31.

  Similarly, a convex forming portion is formed on the inner peripheral surface 131 a of the lower side mold 131. Since the upper side mold 133 and the lower side mold 131 have the same structure, detailed description of the lower side mold 131 is omitted. Using the upper side mold 133 and the lower side mold 131 configured as described above, the convex portions 90 are formed on the tire outer surfaces of the sidewall portions TR2 and TR3.

  Moreover, as a method of manufacturing the pneumatic tire 2 according to the present embodiment, the tire side surface 31 is used by using the upper side mold 133 and the lower side mold 131 described above in the vulcanization step S20 shown in FIG. A convex portion 90 is formed. That is, by using the upper side mold 133 and the lower side mold 131 to mold the convex portion 90 on the raw tire, the pneumatic tire 2 having the convex portion 90 on the tire side surface 31 is molded.

(3) Action / Effect Also in the pneumatic tire 2 according to the present embodiment, an optimal air relaxation layer is formed when the pneumatic tire 2 rotates by regularly arranging the convex portions 90 described above. it can. That is, according to the pneumatic tire 2 according to the present embodiment, the rolling resistance of the tire can be further suppressed.

(4) Modification Example Next, a modification example according to the second embodiment will be described.

(4.1) Modification 1
In the above-described embodiment, the case where the partial region of the tire surface 50 where the convex portions 90 are formed is the tire side surface 31 has been described as an example. However, such a region is a pair of groove wall surfaces 11a. Or the area | region in which at least one of the groove bottom face 11b is formed may be sufficient. In this case, as compared with the case where the protrusion 90 is formed on the ground contact surface 42 of the tread portion 40, the tire rolling resistance can be suppressed over a long period of time.

  Further, the partial region of the tire surface 50 where the protrusion 90 is formed may be a region where any one of the tire side surface 31, the pair of groove wall surfaces 11a, and the groove bottom surface 11b is formed. A region where all these surfaces are formed may be used.

(4.2) Modification 2
Next, Modification Example 2 according to the second embodiment will be described. Here, the structure of the convex part 90 is not limited to the structure of the convex part 90 which concerns on 2nd Embodiment. Below, the structure of the other convex part 90 is demonstrated.

  For example, in the above-described embodiment, when the tire side surface 31 is viewed in the tire inner direction, the convex portion 90 is formed in a circular shape, but the convex portion 90 may be rectangular. .

  FIG. 11 shows an example of the convex portion 90a according to this modified example. As shown in the figure, the convex portion 90a is formed in a rectangular shape when the tire side surface 31 is viewed in the tire inner direction.

  In this case, the maximum width L of the convex portion 90a is preferably 1 μm. The height H of the protrusions 90a is preferably 5 μm, and the arrangement interval P of the protrusions 90a is preferably 3 μm.

(4.3) Modification 3
FIG. 12 shows an example of another convex portion 90b according to the modification example 3. As shown in the figure, when the tire side surface 31 is viewed in the tire inner direction, the convex portion 90 is formed in a circular shape, but the convex portion 90b is a polyhedral shape (in the example of FIG. 12). , Regular hexagonal shape).

  In this case, the maximum width L of the protrusion 90b is preferably 0.5 μm. The height H of the convex portion 90b is preferably 0.1 μm. The arrangement interval P of the convex portions 90b is preferably 1.5 μm.

(4.4) Modification 4
In addition, FIG. 13 illustrates an example of another convex portion 90c according to the modification example 4. As shown in the figure, the convex portion 90c is formed so as to taper in the tire outer surface direction along the normal direction of the tire side surface 31. The convex portion 90 c is formed in a circular shape when the tire side surface 31 is viewed in the tire inner direction along the normal direction of the tire side surface 31.

  In this case, the maximum width L of the protrusion 90c is preferably 4 μm. The height H of the convex portion 90c is preferably 9 μm. The arrangement interval P of the protrusions 90c is preferably 20 μm.

  As described above, in the pneumatic tire 2 according to this modified example, an optimal air relaxation layer is formed when the pneumatic tire 2 rotates by regularly arranging the convex portions 90a to 90c. it can. That is, according to the pneumatic tire 2 according to this modification, the rolling resistance of the tire can be further suppressed.

(5) Comparative Evaluation Next, in order to further clarify the effect of the present invention, comparative evaluation performed using pneumatic tires according to the following comparative examples and examples will be described. In addition, this invention is not limited at all by these examples.

(5.1) Description of Comparative Examples and Examples In order to evaluate the performance of rolling resistance for pneumatic tires having convex portions, the following comparative evaluation was performed. Specifically, the following conventional examples, comparative examples B1 to B12, and examples B1 to B30 were prepared. This will be described with reference to Table 2.

  In addition, the pneumatic tire which concerns on a prior art example, a comparative example, and an Example used the tire size whose tire size is 155 / 65R13. Moreover, except the structure shown below, another structure is the same structure in a prior art example, a comparative example, and an Example.

  First, a pneumatic tire according to a conventional example will be described. As the pneumatic tire according to the conventional example, a tire having no convex portion formed on the tire surface was used.

  Next, a pneumatic tire according to a comparative example and a pneumatic tire according to an example will be described. As the pneumatic tire according to Comparative Examples B1 to B12 and the pneumatic tire according to Examples B1 to B2, a tire in which convex portions are formed on a pair of groove wall surfaces in a tire side portion or a tread portion was used. The detailed configuration is as shown in Table 2.

  Here, as shown in Table 2, in the pneumatic tires according to Comparative Examples B1 and B5, it has been found that it is extremely difficult to form a convex portion during manufacturing. This is due to the following reason. That is, since the width L of the convex portion is less than 0.1 μm, rubber is difficult to enter the edge of the concave portion of the mold during vulcanization in the manufacturing process, and the shape of the convex portion is not adjusted. Therefore, considering the feasibility, the width L of the convex portion needs to be 0.1 μm or more.

  In this way, when the width L of the convex portions is 0.1 μm or more, the lower limit value of the arrangement interval P is necessarily larger than 0.1 μm. Considering this point, in the pneumatic tire according to Comparative Examples B1 to B10 and the pneumatic tire according to Examples B1 to B30, the width L, the depth D, and the arrangement interval P are set. Yes.

(5.2) Evaluation Method A test for evaluating rolling resistance was performed using the conventional tires, the pneumatic tires of Comparative Examples B1 to B10 and Examples B1 to B30. The evaluation test was measured under the following conditions.

<Evaluation test>
-Rim size: Standard rim specified by JATMA-Internal pressure condition: 210 kPa
Evaluation method: The rolling resistance force of the axle at 80 km / h was measured using a drum testing machine including a drum having a diameter of 1.7 m. The rolling resistance was measured by a force method based on a method based on ISO18164.

(5.3) Evaluation Results The evaluation results of each pneumatic tire will be described with reference to Table 2. In Table 2, the rolling resistance performance indicates the measurement results of the tires of the comparative example and the example by an index with the measurement result of the pneumatic tire according to the conventional example as a reference (100). In Table 2, the larger the value of the index shown as the rolling resistance performance, the more the rolling resistance force is suppressed.

  From the results shown in Table 2, it was proved that the tires according to Examples B1 to B30 can suppress rolling resistance as compared with the tires according to the conventional examples and comparative examples B1 to B12.

  That is, the maximum width L of the convex portion is 0.1 μm or more and less than 50 μm, the height H is 0.1 μm or more and less than 10 μm, and the arrangement interval P is greater than 0.1 μm and less than 100 μm. It has been proved that the tire according to can suppress rolling resistance.

  Furthermore, the maximum width L of the convex portion is 0.1 μm or more and less than 5 μm, the height H is 0.1 μm or more and less than 1 μm, and the arrangement interval P is greater than 0.1 μm and less than 5 μm. It has been proved that the tire according to can further suppress the rolling resistance.

[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 embodiment of the present invention can be modified as follows. In the embodiment described above, the concave portion 80 or the convex portion 90 is formed in a partial region (the tire side portion 30 or the groove 10) of the tire surface 50. However, the concave portion 80 or the convex portion 90 is formed in all the regions of the tire surface 50. The convex part 90 may be formed.

  Moreover, you may form in the one part area | region (tire side part 30 or the groove | channel 10) of the tire surface 50 combining the recessed part 80 and the convex part 90. FIG.

  Further, the above-described embodiment and modification examples can be combined. Thus, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the invention specifying matters in the scope of claims reasonable from this disclosure.

  DESCRIPTION OF SYMBOLS 1 ... Pneumatic tire, 2 ... Pneumatic tire, 10 ... Groove, 11a ... Groove wall surface, 11b ... Groove bottom surface, 15 ... Bead core, 16 ... Carcass, 17 ... Belt layer, 19 ... Regular rim, 20 ... Bead part, 21 Rim contact surface, 30 tire side portion, 31 tire side surface, 40 tread portion, 41 tread surface, 42 contact surface, 50 tire surface, 80 concave portion, 90 convex portion, 100 tire Mold: 130 ... Sector mold, 131 ... Lower side mold, 131a ... Inner peripheral surface, 133 ... Upper side mold, 133a ... Inner peripheral surface, 133b ... Side wall forming surface, 133c ... Concave forming portion, 133X ... Convex Forming part

Claims (6)

In at least a partial region of the tire surface, recesses that are recessed from the tire surface toward the tire inner side are regularly arranged,
In the direction along the tire surface, the maximum width L of the recess is in a range of 0.1 μm or more and less than 50 μm,
The depth D of the recess from the tire surface to a point located on the innermost side of the recess in the tire inner direction is in a range of 0.1 μm or more and less than 10 μm,
In the direction along the tire surface, the arrangement interval P of the recesses is in the range of more than 0.1 μm and less than 100 μm. In at least a partial region of the tire surface, convex portions protruding from the tire surface toward the tire outer direction are regularly arranged,
In the direction along the tire surface, the maximum width L of the convex portion is within a range of 0.1 μm or more and less than 50 μm,
The height H of the convex part from the tire surface to the point located on the outermost side of the convex part in the tire outer direction is within a range of 0.1 μm or more and less than 10 μm,
In the direction along the tire surface, the arrangement interval P of the convex portions is in the range of more than 0.1 μm and less than 100 μm. A tread portion and a pair of tire side portions formed on the outer side in the tread width direction of the tread portion;
3. The tire according to claim 1, wherein a partial region of the tire surface is a region where a tire outer surface of the tire side portion is formed. The tread portion, and a pair of tire side portions formed on the tread width direction outer side of the tread portion,
In the tread portion, a groove extending in the tire circumferential direction or a direction intersecting the tire circumferential direction is formed,
The groove has a pair of groove wall surfaces and a groove bottom surface,
The tire according to any one of claims 1 to 3, wherein a partial region of the tire surface is a region where at least one of the pair of groove wall surfaces or the groove bottom surface is formed. A tire manufacturing method for manufacturing a tire using a mold for molding a tire that is a tire before vulcanization,
On the inner peripheral surface of the tire molding die, a convex forming portion that molds the convex portion into at least a partial region of the tire surface, or a concave portion that molds the concave portion into at least a partial region of the tire surface. Forming part is formed,
The tire manufacturing method characterized by including the vulcanization | cure process which shape | molds the said convex part or the said recessed part to the said raw tire using the said tire shaping | molding die, and shape | molds the tire of Claims 1 thru | or 4. The tire manufacturing method according to claim 5, wherein the convex forming portion or the concave forming portion is formed on an inner peripheral surface of the tire molding die by laser processing.