A tire including a decorative portion that is formed at a tire side portion (tire outer face) and that includes a base face, and a first patterned region and a second patterned region, in each of which a plurality of protrusions, that project from the base face of the decorative portion to a projection height of from 0.1 mm to 1.0 mm, are formed at a pitch of from 0.1 mm to 1.0 mm. Shapes of the protrusions in the first patterned region and the second patterned region are different from each other as viewed along a direction orthogonal to the base face.

TECHNICAL FIELD

The present disclosure relates to a tire in which minute protrusions are formed at an outer face of the tire.

BACKGROUND ART

Tires have hitherto been formed with minute protrusions on a side portion of the tire to form a contrasting patterned region. For example, International Publication (WO) No. 2012/131089 discloses technology in which a large contrast is created on a side portion of a tire using plural protrusions formed across an entire patterned region.

SUMMARY OF INVENTION

Technical Problem

A decorative portion on a side portion of a tire includes one region formed with protrusions. By using the protrusions to control light reflection, the brightness of this one region is set lower than the brightness of another region where light reflection is not controlled. However, if the brightness of the entirety of the one region where the protrusions are formed is simply lowered to a uniform brightness, the scope for expression using the decorative portion of the tire where the protrusions are formed is limited.

The present disclosure aims to increase the scope for expression using a decorative portion including a region where protrusions are formed at a tire.

Solution to Problem

A tire according to the present disclosure includes a decorative portion that is formed at a tire outer face and that includes a base face, and a first patterned region and a second patterned region, in each of which plural protrusions, that project from the base face of the decorative portion to a projection height of from 0.1 mm to 1.0 mm, are formed at a pitch of from 0.1 mm to 1.0 mm. Shapes of the protrusions in the first patterned region and the second patterned region are different from each other as viewed along a direction orthogonal to the base face.

Advantageous Effects of Invention

The present disclosure is capable of increasing the scope for expression using a decorative portion including a region where protrusions are formed at a tire.

DESCRIPTION OF EMBODIMENTS

First Exemplary Embodiment

Explanation follows regarding an example of a tire10according to a first exemplary embodiment in the present invention, with reference toFIG. 1toFIG. 6. Note that in the drawings, the arrow C indicates a tire circumferential direction, the arrow R indicates a tire radial direction, and the arrow W indicates a tire width direction.

As illustrated inFIG. 1andFIG. 2, a decorative portion14is formed at a tire side portion12, serving as an example of an outer face of the tire10. As viewed along an axial direction of the tire10, for example, the decorative portion14has a circular arc shape and is disposed at a desired position in the tire circumferential direction. The decorative portion14includes a base face40(FIG. 4). The base face40is set back with respect to another region18of the tire side portion12, this being a region outside the decorative portion14that is not formed with protrusions or the like. The base face40configures a bottom face of the decorative portion14, and has a curved face shape with a convex profile toward the width direction outer side of the tire10as viewed along the tire circumferential direction. In the present exemplary embodiment, the base face40is set back by 0.4 mm with respect to the other region18.

First patterned regions21and a second patterned region22that appear black due to exhibiting lower brightness than the other region18are formed in the decorative portion14. As an example, the first patterned regions21and the second patterned region22have the same brightness as each other.

The second patterned region22formed at the decorative portion14extends in the tire circumferential direction. The first patterned regions21are used to express letters of the alphabet, such as A to H, in the decorative portion14. Any other desired letters, graphics, symbols, patterns, or the like may also be expressed by the first patterned regions21. The first patterned regions21are arranged within the range of the second patterned region22. In other words, the first patterned regions21are adjacent to the second patterned region22and are surrounded by the second patterned region22.

Note that the first patterned regions21and the second patterned region22are formed by recesses and projections provided to a mold (die) for molding the tire10at portions corresponding to the first patterned regions21and the second patterned region22. From the perspective of visibility in a state in which the tire10is mounted to a vehicle, the first patterned regions21and the second patterned region22are preferably disposed further toward the tire radial direction outer side than a tire maximum width portion (a portion where the linear distance between tire side portions is at its maximum).

Rib-shaped protrusions52, serving an example of protrusions, are formed in both the first patterned regions21and the second patterned region22(FIG. 5).

First Patterned Regions21

First asterisk protrusions34and second asterisk protrusions36, serving as an example of plural protrusions projecting from the base face40, are formed in the first patterned regions21(FIG. 3andFIG. 4). The first asterisk protrusions34and the second asterisk protrusions36are arranged alternately to each other in both the tire circumferential direction and the tire radial direction.

First Asterisk Protrusions34

As illustrated inFIG. 4, as viewed along the direction orthogonal to the base face40(in a rotation axis direction of the tire10(FIG. 1andFIG. 2)), each of the first asterisk protrusions34is configured by first extension portions35A-1,35A-2, second extension portions35B-1,35B-2, and third extension portions35C-1,35C-2that extend in different directions to one another from a center O1, serving as an origin. These six extension portions are hereafter collectively referred to as extension portions34E. Together, one and another of these extension portions34E (excluding extension portions34E that extend in opposite directions to each other from the center O1) configure linear shapes bent at the center O1.

The first extension portion35A-1and the first extension portion35A-2extend in opposite directions to each other from the center O1, such that the first extension portion35A-1and the first extension portion35A-2configure a continuous straight line shape. The first extension portion35A-1extends toward the tire radial direction outer side from the center O1, and the first extension portion35A-2extends toward the tire radial direction inner side from the center O1. The first extension portion35A-1and the first extension portion35A-2have similar lengths to each other. The first extension portion35A-1and the first extension portion35A-2are hereafter collectively referred to as the first extension portions35A.

The second extension portion35B-1and the second extension portion35B-2extend in opposite directions to each other from the center O1, such that the second extension portion35B-1and the second extension portion35B-2configure a continuous straight line shape. The second extension portion35B-1and the second extension portion35B-2are inclined with respect to the tire circumferential direction such that end portions thereof on one tire circumferential direction side (the left side inFIG. 4) is positioned further toward the tire radial direction outer side than end portions thereof on the other tire circumferential direction side (the right side inFIG. 4).

The second extension portion35B-1extends toward the one tire circumferential direction side from the center O1, and the second extension portion35B-2extends toward the other tire circumferential direction side from the center O1. The second extension portion35B-1is longer than the second extension portion35B-2. The second extension portion35B-2curves toward the tire radial direction inner side at a leading end side portion. The second extension portion35B-1and the second extension portion35B-2are hereafter collectively referred to as the second extension portions35B.

The third extension portion35C-1and the third extension portion35C-2extend in opposite directions to each other from the center O1, such that the third extension portion35C-1and the third extension portion35C-2configure a continuous straight line shape. The third extension portion35C-1and the third extension portion35C-2are inclined with respect to the tire circumferential direction such that an end portion on the one tire circumferential direction side (the left side inFIG. 4) is positioned further toward the tire radial direction inner side than an end portion on the other tire circumferential direction side (the right side inFIG. 4).

The third extension portion35C-1extends toward the other tire circumferential direction side from the center O1, and the third extension portion35C-2extends toward the one tire circumferential direction side from the center O1. The third extension portion35C-1is shorter than the third extension portion35C-2. The third extension portion35C-1and the third extension portion35C-2are hereafter collectively referred to as the third extension portions35C.

A 60° angle is formed between adjacent extension portions34E of the six extension portions34E. In other words, the six extension portions34E extend from the center O1in a radial shape to form the first asterisk protrusion34.

As illustrated inFIG. 5, each of the extension portions34E of the first asterisk protrusion34has a substantially isosceles triangle shaped cross-section profile including a flat apex face34C as sectioned along a direction orthogonal to its extension direction. Namely, the first asterisk protrusion34includes the apex face34C and pairs of side faces34D. In the present exemplary embodiment, a width (W1inFIG. 5) of the apex face34C is 0.02 mm, and an apex angle (D inFIG. 5) of the first asterisk protrusion34is 26°. A height (H inFIG. 5) of the first asterisk protrusion34is a prescribed value from 0.1 mm to 1.0 mm. In cases in which the height of the protrusion (projection height) is less than 0.1 mm, it becomes difficult to mold the protrusion, and it might not be possible to attenuate incident light sufficiently to lower the brightness to a degree that appears black. By making the height of the protrusion 1.0 mm or less, the difference between the rigidity of the protruding portion and the rigidity of portions surrounding the protrusion is reduced, thereby suppressing localized concentration of stress.

Note that dimensions such as the height of the protrusions and pitch (interval) of the protrusions, described later, in the present exemplary embodiment may for example be measured using the One-Shot 3D Measuring Macroscope, VR-3000 Series, manufactured by Keyence Corporation.

Second Asterisk Protrusions36

As illustrated inFIG. 4, the second asterisk protrusions36are similar in shape to the first asterisk protrusions34. Specifically, as viewed along the direction orthogonal to the base face40, each of the second asterisk protrusions36has a shape obtained by rotating a first asterisk protrusion34clockwise through 90° about its center O1, and then top-to-bottom inverting the first asterisk protrusion34that has been rotated by 90° about its center O1.

Portions of the second asterisk protrusion36corresponding to the first extension portions35A-1,35A-2, the second extension portions35B-1,35B-2, the third extension portions35C-1,35C-2, and the center O1of the first asterisk protrusion34are respectively referred to as first extension portions37A-1,37A-2, second extension portions37B-1,37B-2, third extension portions37C-1,37C-2, and a center O2. These six extension portions are hereafter collectively referred to as extension portions36E.

A portion of the second asterisk protrusion36corresponding to the apex face34C of the first asterisk protrusion34is referred to as an apex face36C. Portions of the second asterisk protrusion36corresponding to the side faces34D of the first asterisk protrusion34are referred to as side faces36D (seeFIG. 5).

Other

As illustrated inFIG. 2C, the first asterisk protrusions34and the second asterisk protrusions36are arranged alternately to each other in both the tire circumferential direction and the tire radial direction so as to completely fill the first patterned regions21.

As illustrated inFIG. 4, for each of the first asterisk protrusions34, the leading ends of the first extension portions35A-1,35A-2are respectively inserted between the second extension portion37B-2and the third extension portion37C-1, and between the second extension portion37B-1and the third extension portion37C-2, of the adjacent second asterisk protrusions36in the tire radial direction. For each of the adjacent second asterisk protrusions36, the leading ends of the first extension portions37A-1,37A-2are respectively inserted between the second extension portion35B-1and the third extension portion35C-2, and between the second extension portion35B-2and the third extension portion35C-1, of the adjacent first asterisk protrusions34in the tire circumferential direction.

A leading end of the third extension portion35C-1of each of the first asterisk protrusions34is coupled to a leading end of the second extension portion37B-1of the second asterisk protrusion36that is disposed at the tire radial direction outer side of the first asterisk protrusion34. A coupled portion34A is thereby formed. A leading end of the second extension portion35B-1of each of the first asterisk protrusions34is coupled to a leading end of the third extension portion37C-1of the second asterisk protrusion36that is disposed on the one tire circumferential direction side of the first asterisk protrusion34. A coupled portion34B is thereby formed.

In this configuration, the first asterisk protrusions34and the second asterisk protrusions36are coupled together in a staircase pattern through the coupled portions34A,34B on progression from the tire radial direction inner side toward the tire radial direction outer side.

A pitch (hereafter referred to as a pitch P) between the center O1and the center O2of the first asterisk protrusions34and the second asterisk protrusions36that are adjacent to each other in the tire radial direction and the tire circumferential direction is a prescribed value from 0.1 mm to 1.0 mm. In cases in which the pitch P is less than 0.1 mm, it becomes difficult to mold the protrusions. In cases in which the pitch P is greater than 1.0 mm, it might not be possible to attenuate incident light sufficiently to lower the brightness to a degree that appears black.

Note that a brightness L* of the first patterned regions21and the second patterned region22that appear black in the present exemplary embodiment, as measured using a Handy Spectrophotometer (NF333) manufactured by Nippon Denshoku Industries Co. (Ltd), is for example a value within a region below 10. Namely, the possible range of the brightness L* is between 0 and 100, values closer to 0 having an appearance closer to black, and values closer to 100 having an appearance closer to white. As an example, the other region18of the tire side portion12that is outside the decorative portion14has a brightness L* value of greater than 20.

As illustrated inFIG. 5, the second patterned region22illustrated inFIG. 1andFIG. 2is configured by plural rib-shaped protrusions52, serving as an example of protrusions. As viewed along the direction orthogonal to the base face40of the decorative portion14, the rib-shaped protrusions52are for example formed in V-shapes and coupled together so as to form a zigzag shape in the tire circumferential direction. Plural of the zigzag shaped rib-shaped protrusions52are formed at a pitch P in the tire radial direction. A cross-section profile of the rib-shaped protrusions52, and the pitch P between the center of one rib-shaped protrusion52and the center of another rib-shaped protrusion52out of the adjacent rib-shaped protrusions52are the same as the cross-section profile and the pitch P of the first asterisk protrusions34and the second asterisk protrusions36illustrated inFIG. 5.

Note that the cross-section profile of the rib-shaped protrusions52may be different from the cross-section profile of the first asterisk protrusions34and so on. Moreover, the rib-shaped protrusions52do not need to be coupled together in V-shapes, and linear elements of the rib-shaped protrusions52may be arranged independently of one another.

Furthermore, the extension directions of some or all of the respective extension portions of the first asterisk protrusions34of the first patterned regions21are different directions to the directions of the linear elements of the rib-shaped protrusions52of the second patterned region22.

Operation and Advantageous Effects

Explanation follows regarding operation and advantageous effects of the tire according to the present exemplary embodiment.

In the decorative portion14of the tire side portion12, light incident to the first asterisk protrusions34and the second asterisk protrusions36formed at the first patterned regions21hits the side faces34D,36D illustrated inFIG. 5. The incident light then attenuates as it is repeatedly reflected back and forth between the opposing side faces34D,36D before being reflected to the exterior.

Formed at the second patterned region22of the decorative portion14of the tire side portion12. Light incident to the rib-shaped protrusions52similarly attenuates as it is repeatedly reflected back and forth between opposing side faces (not illustrated in the drawings) before being reflected to the exterior.

In the other region18of the tire side portion12that is not formed with protrusions, light incident to the other region18is reflected toward the exterior by an outer face configuring the other region18.

Note that the pitch P between the first asterisk protrusions34and the second asterisk protrusions36formed at the first patterned regions21, and the pitch P between the rib-shaped protrusions52formed at the second patterned region22are both the same prescribed value from 0.1 mm to 1.0 mm. The brightness of these lowered brightness regions appears lower than the brightness of the other region18that is not formed with protrusions. Moreover, since the shapes of the protrusions in the first patterned regions21and the second patterned region22are different from one another as viewed along the direction orthogonal to the base face40, the angle of light incidence differs even when the brightness is the same, such that the first patterned regions21or the second patterned region22can be made to appear to stand out.

In the present exemplary embodiment, the plural zigzagging rib-shaped protrusions52configure a herringbone pattern, such that faces orthogonal to the angle of light incidence and faces parallel to the angle of light incidence are alternately formed. This enables a striped pattern configured of light and dark areas to be expressed by the decorative portion14(FIG. 1andFIG. 2).

The first asterisk protrusions34and the second asterisk protrusions36of the first patterned regions21are configured differently to the rib-shaped protrusions52, and are combined with the second patterned region22including the rib-shaped protrusions52so as to enable a graphic design to be expressed by the difference in reflectivity. In the present exemplary embodiment, the first patterned regions21that express letters stand out from the second patterned region22that acts as a background. As illustrated inFIG. 1andFIG. 2, the appearance varies according to the angle from which the decorative portion14of the tire10is viewed. In this manner, the scope for expression using the decorative portion14including the regions formed with the protrusions on the tire10can be increased.

InFIG. 4, the respective extension portions34E of the first asterisk protrusions34extend along different directions to one another, and the respective extension portions36E of the second asterisk protrusions36extend along different directions to one another. This enables a change in the appearance to be suppressed when the decorative portion14is viewed from different angles.

Each of the first asterisk protrusions34is configured by the six extension portions34E that extend in different directions to one another and are coupled together at the center O1. Each of the second asterisk protrusions36is configured by the six extension portions36E that extend in different directions to one another and are coupled together at the center O2. Both the first asterisk protrusions34and the second asterisk protrusions36are thus less liable to collapse, enabling the durability of both the first asterisk protrusions34and the second asterisk protrusions36to be improved.

Moreover, the first asterisk protrusions34and the second asterisk protrusions36are coupled together in a staircase pattern through the coupled portions34A,34B. The first asterisk protrusions34and the second asterisk protrusions36therefore support each other through the coupled portions34A,34B, thus suppressing the first asterisk protrusions34and the second asterisk protrusions36from collapsing and thereby enabling durability to be improved.

Second Exemplary Embodiment

As illustrated inFIG. 7, in a tire30according to a second exemplary embodiment in the present invention, the decorative portion14is formed at a tread32of the tire30. Specifically, plural circumferential direction grooves42,44that extend in the tire circumferential direction are formed at the tread32of the tire30at intervals in the tire width direction (the arrow W inFIG. 7). The circumferential direction groove42is provided at a tire width direction center portion, and the circumferential direction grooves44are respectively provided on either tire width direction side of the circumferential direction groove42. The decorative portion14is formed at the circumferential direction groove42at the tire width direction center portion, serving as an example of a tire outer face. First patterned regions21, serving as an example of plural first patterned regions, and second patterned regions22are for example arranged alternately around the tire circumferential direction in the decorative portion14. Providing the decorative portion14to the circumferential direction grooves44in this manner enables the scope for expression on the tread32to be increased.

Note that another patterned region (not illustrated in the drawings) may be provided in addition to the first patterned regions21and the second patterned regions22. Moreover, the respective patterned regions may be arranged as desired. For example, the respective patterned regions may be arrayed in the tire width direction, or in an oblique direction that intersects the tire width direction.

Detailed configuration of the first patterned regions21and the second patterned regions22is similar to that in the first exemplary embodiment, and so explanation thereof is omitted.

Other Exemplary Embodiments

Note that exemplary embodiments according to the present invention are not limited to the respective exemplary embodiments described above, and it would be obvious to a person skilled in the art that various other exemplary embodiments may be implemented within the scope of the present invention. For example, although the first asterisk protrusions34and the second asterisk protrusions36are coupled to one another in the first exemplary embodiment, a configuration without such mutual coupling may be applied. Moreover, although the first asterisk protrusions34and the second asterisk protrusions36are provided to the first patterned regions21and the rib-shaped protrusions52are provided to the second patterned region22, the protrusion types may be reversed. Moreover, the protrusions may have a shape other than that of the first asterisk protrusions34, the second asterisk protrusions36, and the rib-shaped protrusions52.

The entire content of the disclosure of Japanese Patent Application No. 2017-237174 filed on Dec. 11, 2017 is incorporated by reference in the present specification.

All cited documents, patent applications, and technical standards mentioned in the present specification are incorporated by reference in the present specification to the same extent as if each individual cited document, patent application, or technical standard was specifically and individually indicated to be incorporated by reference.