JP2017114281A - tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire capable of allowing a tread rubber to sufficiently ground the whole tread surface by further raising the temperature of the tread rubber in early utilization.SOLUTION: A pneumatic tire is equipped with a carcass layer bridged between a pair of beads, and an inner liner arranged inside the carcass layer and excellent in a function which blocks air penetration to retain an air pressure. The tire has a tread rubber having an outer surface in a tire radial direction. The tread rubber has first and second rubbers 4a and 5a having the elastic modulus different from each other, and has a peripheral joint part 33 at which the first and second rubbers are joined in a tire circumferential direction D3.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a tire including a tread rubber having an outer surface in the tire radial direction.

  Conventionally, a tire provided with tread rubber formed from two different rubbers is known as a tire (for example, patent documents 1-3). The tire has a plurality of grooves on the outer surface of the tread rubber, and has an edge effect (effect of generating a grip force on the road surface when the edge scratches the road surface when traveling on the road surface). Yes.

  By the way, in the initial stage of operation (when the temperature of the tire is low), since the temperature of the tread rubber is low, the tread rubber may not be sufficiently elastically deformed. Thereby, for example, since the tread rubber cannot be sufficiently grounded to the ground throughout, the edge effect by the groove may not be sufficiently exhibited.

JP 2006-168564 A JP-A-11-227415 JP 2004-338621 A

  Then, a subject is providing the tire which can raise the temperature of a tread rubber more in the operation | movement initial stage.

  The tire includes a tread rubber having an outer surface in the tire radial direction, and the tread rubber includes a circumferential joint portion where rubbers having different elastic moduli are joined in the tire circumferential direction.

  In the tire, the tread rubber includes a cap rubber having an outer surface in the tire radial direction and a base rubber disposed on the inner side in the tire radial direction of the cap rubber, and the cap rubber has different elasticity. The structure which further has the diameter joining part with which the rubber | gum which has a ratio is joined in a tire radial direction may be sufficient.

  In the tire, at least a part of the tread rubber is formed by spirally winding the first and second ribbon rubbers along the tire circumferential direction, and the ribbon rubbers are arranged in parallel with the tire circumferential direction. The parallel portion to be arranged and the inclined portion arranged to be inclined with respect to the tire circumferential direction are arranged so as to be repeated, and the circumferential joint portion includes the inclined portion and the second portion of the first ribbon rubber. The inclined portion of the ribbon rubber is formed by being joined in the tire circumferential direction.

  As described above, the tire has an excellent effect that the temperature of the tread rubber can be further increased in the initial operation.

Drawing 1 is an important section sectional view in the tire meridian surface of the tire concerning one embodiment. FIG. 2 is a development view of main parts of the tread rubber according to the embodiment. FIG. 3 is a development view of a main part of the cap outer layer of the cap rubber according to the embodiment, and is a view for explaining the arrangement of the rubber. FIG. 4 is a main part development view of the cap inner layer of the cap rubber according to the embodiment, and is a view for explaining the arrangement of the rubber. 5 is an enlarged cross-sectional view taken along line VV in FIG. 6 is an enlarged cross-sectional view of a main part taken along line VI-VI in FIG. FIG. 7 is a schematic diagram for explaining the tire manufacturing method according to the embodiment. FIG. 8 is a schematic view for explaining the tire manufacturing method according to the embodiment. FIG. 9 is a development view of main parts of a tread rubber according to another embodiment, and is a view for explaining the arrangement of the rubber. 10 is an enlarged sectional view taken along line XX in FIG. 11 is an enlarged sectional view taken along line XI-XI in FIG. FIG. 12 is a development view of a main part of a tread rubber according to still another embodiment, and is a view for explaining the arrangement of the rubber. FIG. 13 is a development view of a main part of a tread rubber according to still another embodiment, and is a view for explaining the arrangement of the rubber. FIG. 14 is a schematic diagram illustrating a tire manufacturing method according to still another embodiment. FIG. 15 is a schematic diagram illustrating a tire manufacturing method according to still another embodiment. FIG. 16 is a development view of a main part of a tread rubber according to a comparative example, and is a view for explaining the arrangement of the rubber. FIG. 17 is an evaluation table of examples and comparative examples.

  Hereinafter, an embodiment of a tire will be described with reference to FIGS. In each figure (the same applies to FIGS. 9 to 16), the dimensional ratio of the drawings does not necessarily match the actual dimensional ratio, and the dimensional ratio between the drawings does not necessarily match. Absent.

  As shown in FIG. 1, the tire 1 according to the present embodiment includes a pair of bead portions 11 having beads, sidewall portions 12 extending from the bead portions 11 to the outside in the tire radial direction D2, and a pair of sidewall portions. The tread portion 13 is connected to the outer end portion in the tire radial direction D2 and constitutes a tread surface in contact with the ground. In the present embodiment, the tire 1 is a pneumatic tire in which air is introduced, and is attached to the rim 100.

  Further, the tire 1 includes a carcass layer 14 that is spanned between a pair of beads, and an inner liner 15 that is disposed inside the carcass layer 14 and has an excellent function of preventing gas permeation in order to maintain air pressure. I have. The carcass layer 14 and the inner liner 15 are disposed along the tire inner periphery over the bead portion 11, the sidewall portion 12, and the tread portion 13.

  In FIG. 1 (the same applies to the following drawings), the first direction D1 is the tire width direction D1, and the second direction D2 is the tire radial direction D2, which is the diameter direction of the tire 1, and is not illustrated. However, the third direction D3 is a tire circumferential direction D3 that is a direction around the tire rotation axis. The tire equatorial plane S1 is a plane orthogonal to the tire rotation axis and located in the center of the tire width direction D1, and the tire meridian plane is a plane including the tire rotation axis and orthogonal to the tire equatorial plane S1. Surface.

  The tread portion 13 includes a tread rubber 2 having a tread surface that is an outer surface in the tire radial direction D2, and a belt layer 16 disposed between the tread rubber 2 and the carcass layer 14. The tread rubber 2 includes a cap rubber 3 disposed outside the tire radial direction D2 and a base rubber 17 disposed between the cap rubber 3 and the belt layer 16. Although not shown, the tread rubber 2 (cap rubber 3) has a plurality of circumferential grooves extending along the tire circumferential direction D3 and a plurality of width grooves extending along the tire width direction D1 on the outer surface. I have.

  As shown in FIGS. 2 to 6, the cap rubber 3 is formed by first and second ribbon rubbers 4 and 5 being spirally wound along the tire circumferential direction D <b> 3. The cap rubber 3 is formed by winding the first and second ribbon rubbers 4 and 5 so as to form two layers in the tire radial direction D2. Accordingly, the cap rubber 3 includes a cap outer layer 31 having a tread surface which is an outer surface in the tire radial direction D2, and a cap inner layer 32 disposed between the cap outer layer 31 and the base rubber 17.

  3 shows the arrangement of the first and second ribbon rubbers 4 and 5 of the cap outer layer 31, and FIG. 4 shows the first and second ribbon rubbers 4 and 5 of the cap inner layer 32 at the same position as FIG. Shows the arrangement. 3 and 4 (the same applies to the following drawings), the first ribbon rubber 4 is shown in a shaded area, and the second ribbon rubber 5 is shown in a plain area. 2 to 4 and 6, the plane S <b> 2 is a predetermined tire meridian plane S <b> 2.

  Further, the cross-sectional shapes of the first and second ribbon rubbers 4 and 5 are substantially the same. That is, in the first and second ribbon rubbers 4 and 5, the dimensions in the directions D1 to D3 are substantially the same. In the present embodiment, the cross-sectional shape of the first and second ribbon rubbers 4 and 5 has a substantially triangular shape in which the central portion in the width direction has the maximum thickness, and the thickness gradually decreases from the central portion toward both side ends.

  In addition, the cross-sectional shape of the 1st and 2nd ribbon rubbers 4 and 5 can be made into various cross-sectional shapes according to the form of the tread rubber 2 (cap rubber 3) used as shaping | molding object. For example, the cross-sectional shape of the first and second ribbon rubbers 4 and 5 may be a substantially trapezoidal shape or a flat plate shape. In addition, in the 1st and 2nd ribbon rubber | gum 4,5, the cross-sectional shape and the dimension of each direction D1-D3 may differ.

  The rubber (hereinafter also referred to as “first rubber”) 4a constituting the first ribbon rubber 4 and the rubber (hereinafter also referred to as “second rubber”) 5a constituting the second ribbon rubber 5 are different rubbers. is there. Specifically, the elastic modulus of the first rubber 4a and the elastic modulus of the second rubber 5a are different. In the present embodiment, the elastic modulus is a tensile elastic modulus, which is a value measured at room temperature (25 ° C.) according to the method defined in JIS K6251.

  For example, the elastic modulus of the second rubber 5a is preferably 1.2 to 5.0 times the elastic modulus of the first rubber 4a. For example, the 100% tensile elastic modulus of the first rubber 4a is preferably 0.5 MPa to 3.5 MPa, and the 100% tensile elastic modulus of the second rubber 5a is 0.6 MPa to 17.5 MPa. It is preferable that

  The elastic modulus of the first rubber 4 a and the second rubber 5 a is larger than that of the base rubber 17. The base rubber 17 is formed from one rubber different from the first and second rubbers 4a and 5a.

In the present embodiment, the first rubber 4a and the second rubber 5a are non-conductive rubber. For example, non-conductive rubber refers to rubber having a volume resistivity of 10 ⁸ Ω · cm or more. Note that at least one of the first rubber 4a and the second rubber 5a may be a conductive rubber having a volume resistivity of less than 10 ⁸ Ω · cm.

  Each of the ribbon rubbers 4 and 5 includes parallel portions 41 and 51 disposed in parallel to the tire circumferential direction D3, and inclined portions 42 and 52 disposed to be inclined with respect to the tire circumferential direction D3. The ribbon rubbers 4 and 5 are arranged so as to be connected so that the parallel portions 41 and 51 and the inclined portions 42 and 52 are repeated. Further, the first and second ribbon rubbers 4 and 5 are alternately arranged in the tire width direction D1. In addition, the dimension of the tire circumferential direction D3 of the parallel parts 41 and 51 is larger than the dimension of the tire circumferential direction D3 of the inclined parts 42 and 52.

  The cap rubber 3 includes a plurality of peripheral joint portions 33 formed by joining the first ribbon rubber 4 (first rubber 4a) and the second ribbon rubber 5 (second rubber 5a) in the tire circumferential direction D3. The circumferential joint 33 is formed by joining the inclined portion 42 of the first ribbon rubber 4 and the inclined portion 52 of the second ribbon rubber 5 in the tire circumferential direction D3.

  And the circumferential junction part 33 is arrange | positioned so that it may cross | intersect with respect to the tire circumferential direction D3. Specifically, the circumferential joint portion 33 is disposed so as to incline and intersect with the tire circumferential direction D3. For example, the circumferential joint portion 33 preferably has an intersection angle with the tire circumferential direction D3 of 20 ° or more, more preferably 30 ° or more, and further preferably 45 ° or more. .

  In the present embodiment, the plurality of circumferential joint portions 33 are arranged in parallel in the tire width direction D1 and are respectively disposed at predetermined tire meridian surfaces S2. That is, the first group of the circumferential joint portion 33 is disposed away from the second group of the circumferential joint portion 33 by a distance corresponding to approximately 180 ° in the tire circumferential direction D3.

  The cap rubber 3 includes a plurality of radial joints 34 formed by joining the first ribbon rubber 4 (first rubber 4a) and the second ribbon rubber 5 (second rubber 5a) in the tire radial direction D2. The radial joint 34 is formed by joining at least a part of the parallel part 41 of the first ribbon rubber 4 and at least a part of the parallel part 51 of the second ribbon rubber 5 in the tire radial direction D2 and the first ribbon rubber 4. A part of the inclined part 42 and a part of the inclined part 52 of the second ribbon rubber 5 are joined and formed in the tire radial direction D2.

  And the diameter junction part 34 is arrange | positioned so that it may cross | intersect with respect to the tire radial direction D2. Since the elastic modulus of the first and second rubbers 4a and 5a of the cap inner layer 32 is different from the elastic modulus of the rubber of the base rubber 17, the joint portion between the cap inner layer 32 and the base rubber 17 is also a diameter joint portion. 34 has the same function.

  The cap rubber 3 includes a plurality of width joint portions 35 formed by joining the first ribbon rubber 4 (first rubber 4a) and the second ribbon rubber 5 (second rubber 5a) in the tire width direction D1. The width joining portion 35 is formed by joining the parallel portion 41 of the first ribbon rubber 4 and the parallel portion 51 of the second ribbon rubber 5 in the tire width direction D1.

  And the width | variety junction part 35 is arrange | positioned so that it may cross | intersect with respect to the tire width direction D1. In addition, what is arrange | positioned so that the width | variety junction part 35 may cross | intersect slightly with respect to the tire circumferential direction D3 is also contained. For example, the width joint portion 35 includes one having an intersection angle with the tire circumferential direction D3 of less than 10 °.

  The configuration of the tire 1 according to the present embodiment is as described above. Next, a method for manufacturing the tire 1 according to the present embodiment will be described with reference to FIGS. 7 and 8.

  As shown in FIG. 7, the molding apparatus 70 includes a first extruding portion 71 that extrudes the first rubber 4 a that becomes the first ribbon rubber 4 and a second extruding portion 72 that extrudes the second rubber 5 a that becomes the second ribbon rubber 5. I have. Further, the molding device 70 includes a winding portion 73 around which the string-like ribbon rubbers 4 and 5 formed by being extruded from the extrusion portions 71 and 72 are wound.

  The extruding parts 71 and 72 extrude the rubbers 4a and 5a so that the cross-sectional shapes of the ribbon rubbers 4 and 5 are constant. And the extrusion parts 71 and 72 are extruding rubber | gum 4a, 5a so that the extrusion amount of rubber | gum 4a, 5a per unit time may become fixed. Moreover, the 1st extrusion part 71 and the 2nd extrusion part 72 are arrange | positioned so that the winding part 73 may be interposed and it may oppose in the diameter direction of the winding part 73. FIG.

  The winding part 73 is formed in a columnar shape and can be rotated around the axis (rotation direction D4). Thereby, the winding rubber | gum part 73 is wound, and the ribbon rubbers 4 and 5 extruded and shape | molded are wound around an outer peripheral part. Further, the winding portion 73 can be relatively displaced in the axial direction with respect to the extruding portions 71 and 72. In the present embodiment, the winding part 73 is movable in the axial direction.

  And when the winding part 73 is immovable with respect to the extrusion parts 71 and 72, the parallel parts 41 and 51 of the ribbon rubbers 4 and 5 are formed, and the winding part 73 is a shaft with respect to the extrusion parts 71 and 72. When moving in the direction, the inclined portions 42 and 52 of the ribbon rubbers 4 and 5 are formed. Thereby, as shown in FIG. 8, the ribbon rubbers 4 and 5 are arranged so that the parallel parts 41 and 51 and the inclined parts 42 and 52 are repeated, and the first and second ribbon rubbers 4 and 5 are arranged. Are alternately arranged in the tire width direction D1.

  The inclined portion 42 of the first ribbon rubber 4 and the inclined portion 52 of the second ribbon rubber 5 are bonded together in the tire circumferential direction D3, whereby the circumferential bonded portion 33 is formed. Moreover, the parallel part 41 of the 1st ribbon rubber 4 and the parallel part 51 of the 2nd ribbon rubber 5 are joined by the tire width direction D1, and the width junction part 35 is formed. In addition, the circumferential joining part 33 is spaced apart by a distance corresponding to 180 ° in the tire circumferential direction D3.

  Thereafter, although not shown, the first and second ribbon rubbers 4 and 5 are wound so as to form two layers in the tire radial direction D2. Thereby, the 1st ribbon rubber 4 and the 2nd ribbon rubber 5 are joined by tire radial direction D2, and diameter joint part 34 is formed.

  Then, for example, an unvulcanized tire is formed through a process of expanding the diameter. In addition, in FIG. 8, the member for comprising the structures 11, 12, 14-17 other than the cap rubber 3 is not illustrated. And the vulcanized tire 1 is manufactured by vulcanizing an unvulcanized tire with a vulcanizer.

  As described above, the tire 1 according to the present embodiment includes the tread rubber 2 having the outer surface in the tire radial direction D2, and the tread rubber 2 has the rubbers 4a and 5a having different elastic moduli joined in the tire circumferential direction D3. The circumferential joint 33 is provided.

  According to such a configuration, since the tire 1 receives a force in the tire circumferential direction D3 when the vehicle travels, the circumferential joint portion 33 is elastically deformed in the tire circumferential direction D3. And since the rubber | gum 4a, 5a which has a different elasticity modulus is joined in the tire circumferential direction D3, the circumferential junction part 33 will be elastically deformed so that it may be distorted. Thereby, since heat generate | occur | produces from the periphery junction part 33, the temperature of the tread rubber 2 can be raised more in the operation | movement initial stage.

  Accordingly, for example, since the tread rubber 2 can be sufficiently elastically deformed even in the initial stage of operation, the tread rubber 2 can be grounded to the ground throughout. As a result, for example, the edge effect due to the grooves (circumferential groove and width groove) can be sufficiently exerted, so that the steering stability performance in the initial operation can be improved.

  Further, in the tire 1 according to the present embodiment, the tread rubber 2 includes a cap rubber 3 having an outer surface in the tire radial direction D2, and a base rubber 17 disposed on the inner side of the tire rubber in the tire radial direction D2. The cap rubber 3 may be configured to further include a diameter joining portion 34 to which the rubbers 4a and 5a having different elastic moduli are joined in the tire radial direction D2.

  According to such a configuration, since the tire 1 receives a force in the tire radial direction D2 when the vehicle travels, the radial joint 34 is elastically deformed in the tire radial direction D2. And since the rubber | gum 4a, 5a which has a different elasticity modulus is joined by the tire radial direction D2, the diameter joining part 34 will be elastically deformed so that it may be distorted. Thereby, since heat is generated from the diameter joining portion 34, the temperature of the tread rubber 2 can be further increased in the initial operation.

  Therefore, even in the initial stage of operation, for example, the tread rubber 2 can be further elastically deformed, so that the tread rubber 2 can be grounded to the ground throughout. As a result, for example, the edge effect due to the grooves (circumferential groove, width groove) can be more sufficiently exhibited, and therefore, the steering stability performance in the initial operation can be further improved.

  Further, in the tire 1 according to the present embodiment, at least a part of the tread rubber 2 (a part of the tread rubber 2 in the present embodiment, which is the cap rubber 3), the first and second ribbon rubbers 4 and 5 are arranged around the tire circumference. Each of the ribbon rubbers 4 and 5 is formed by being spirally wound along the direction D3, and the ribbon rubbers 4 and 5 are inclined with respect to the tire circumferential direction D3 and parallel portions 41 and 51 arranged in parallel with the tire circumferential direction D3. The inclined portions 42 and 52 to be arranged are connected so as to be repeated, and the circumferential joint portion 33 includes the inclined portion 42 of the first ribbon rubber 4 and the inclined portion 52 of the second ribbon rubber 5. They are joined and formed in the tire circumferential direction D3.

  In addition, a tire is not limited to the structure of above-described embodiment, Moreover, it is not limited to an above-described effect. Of course, the tire can be variously modified without departing from the gist of the present invention. For example, it is needless to say that one or a plurality of configurations and methods according to various modifications described below may be arbitrarily selected and employed in the configurations and methods according to the above-described embodiments.

  In the tire 1 according to the above-described embodiment, the cap rubber 3 is formed in two layers in the tire radial direction D2 and includes a diameter joining portion 34. However, the tire is not limited to such a configuration. For example, the cap rubber 3 may be configured to be formed in three or more layers in the tire radial direction D2 and provided with the diameter joining portion 34. For example, as shown in FIGS. 9 to 11, the cap rubber 3 may be formed in one layer in the tire radial direction D <b> 2 and not include the diameter joining portion 34.

  Moreover, in the tire 1 which concerns on the said embodiment, it is the structure that the circumferential junction part 33 is arrange | positioned so that it may incline and cross | intersect with respect to the tire circumferential direction D3. However, the tire is not limited to such a configuration. For example, as shown in FIG.12 and FIG.13, the structure that the circumferential junction part 33 is arrange | positioned so that it may cross | intersect orthogonally with respect to the tire circumferential direction D3 may be sufficient.

  In the tire 1 according to the above-described embodiment, the tread rubber 2 (cap rubber 3) is configured to include the width joining portion 35. However, the tire is not limited to such a configuration. For example, as shown in FIG. 13, the tread rubber 2 (cap rubber 3) may not include the width joint portion 35.

  Further, in the tire 1 according to the above-described embodiment, the circumferential joint portion 33 is configured to be spaced apart by a distance corresponding to 180 ° in the tire circumferential direction D3. However, the tire is not limited to such a configuration. For example, the circumferential joint portion 33 may be arranged to be separated from the circumferential joint portion 33 adjacent in the tire circumferential direction D3 by a distance corresponding to 15 ° to 180 ° in the tire circumferential direction D3.

  Further, in the tire 1 according to the embodiment, the tread rubber 2 (cap rubber 3) is wound with the string-like ribbon rubbers 4 and 5 formed by being extruded from the first and second extruding portions 71 and 72. It is the structure of being wound around the part 73 and being formed. However, the tire is not limited to such a configuration.

  For example, as shown in FIG. 14, the tread rubber 2 (cap rubber 3) includes a sheet-like first rubber member 40 made of the first rubber 4a and a sheet-like second rubber member 50 made of the second rubber 5a. However, the structure which is affixed and formed in the winding part 73 may be sufficient. Each rubber member 40, 50 may be ribbon-shaped. Further, each rubber member 40, 50 may be directly attached to the winding part 73, or indirectly to the winding part 73, that is, each component of the tire 1 (for example, the base rubber 17). You may affix from on the member for doing.

  Further, for example, as shown in FIG. 15, the tread rubber 2 (cap rubber 3) is wound around a winding portion 73 by a string-like ribbon rubber 6 in which first rubber 6 a and second rubber 6 b are alternately connected. It is also possible to adopt a configuration in which it is formed. A molding apparatus 70 according to FIG. 15 includes a first extruding part 71 for extruding the first rubber 6a, a second extruding part 72 for extruding the second rubber 6b having an elastic modulus different from the elastic modulus of the first rubber 6a, Of the rubber 6a and the second rubber 6b, a switching unit 74 for forming the ribbon rubber 6 by switching the rubber to be pushed out is provided.

  Further, in the tire 1 according to the above-described embodiment, the circumferential joint portion 33 is configured to be provided in a part of the tread rubber 2, that is, the cap outer layer 31 and the cap inner layer 32 of the cap rubber 3. However, the tire is not limited to such a configuration.

  For example, the circumferential joint 33 may be provided on the entire tread rubber 2 (the cap rubber 3 and the base rubber 17). Further, for example, the circumferential joint 33 may be provided only in the cap outer layer 31 or may be provided only in the cap inner layer 32. Further, for example, the circumferential joint 33 may be provided in at least one of the cap outer layer 31, the cap inner layer 32, and the base rubber 17.

  Moreover, in the tire 1 which concerns on the said embodiment, the cap rubber 3 is the structure that it is formed from two rubber | gum 4a, 5a from which an elasticity modulus differs. However, the tire is not limited to such a configuration. For example, the cap rubber 3 (tread rubber 2) may be formed of three or more rubbers having different elastic moduli.

  The tire 1 includes a tire before vulcanization (unvulcanized tire) and a tire after vulcanization (vulcanized tire). In the tire after vulcanization, the tire 1 is cut with a sharp blade, and the boundary surfaces of the rubbers 4a and 5a (ribbon rubbers 4 and 5) can be observed from the cross section. Thereby, the arrangement state of the rubbers 4a and 5a (ribbon rubbers 4 and 5) can be specified.

  In order to specifically show the structure and effects of the tire, examples of the tire and comparative examples thereof will be described below with reference to FIGS. 2 to 6, 9 to 11, and FIGS. 16 to 17. .

<Rolling resistance>
After assembling each tire on the rim, an internal pressure of 50 psi (air pressure corresponding to the maximum load capacity of a single wheel indicated on the side wall) was filled, and rolling resistance was measured according to international standard ISO28580 (JIS D4234). The result of the comparative example is evaluated with an index of 100, and the smaller the index, the lower the rolling resistance and the better.

<Steering stability>
Each tire was mounted on the vehicle, and during the period from the beginning of operation until the tire reached the saturation temperature, the dry road surface was accelerated, braked, turned, and lane changed. Then, the steering stability performance was evaluated by a sensory test with a driver. The result of the comparative example was evaluated with an index of 100, and the larger the index, the better the steering stability performance.

<Examples 1 and 2>
Example 1 is a tire according to the above-described embodiment according to FIGS. That is, Example 1 is a tire that includes all of the circumferential joint portion 33, the diameter joint portion 34, and the width joint portion 35.
As shown in FIGS. 9 to 11, Example 2 is a tire that is changed to a configuration in which the cap rubber 3 is composed of one layer with respect to the tire according to Example 1. That is, Example 2 is a tire that includes the circumferential joint portion 33 and the width joint portion 35 but does not include the diameter joint portion 34.

<Comparative example>
In the comparative example, as shown in FIG. 16, the cap rubber 3 is composed of one layer and the ribbon rubber is continuously inclined by 2 ° with respect to the tire circumferential direction D3 with respect to the tire according to the first embodiment. It is a tire that has been changed to a configuration that is. In other words, the comparative example is a tire that includes the width joint portion 35 but does not include the circumferential joint portion 33 and the diameter joint portion 34.

<Evaluation results>
As shown in FIG. 17, Examples 1 and 2 can improve the steering stability performance compared to the comparative example. As described above, the tread rubber 2 (cap rubber 3) includes the circumferential joint portion 33 in which the rubbers 4a and 5a having different elastic moduli are joined in the tire circumferential direction D3, thereby improving the steering stability performance. . In Examples 1 and 2, since the weight ratio between the first rubber 4a and the second rubber 5a is substantially the same as that of the comparative example, the rolling resistance can be maintained.

  A more preferred embodiment of the tire will be described below.

  First, in the tire according to the first embodiment, the cap rubber 3 is configured to include the diameter joining portion 34. On the other hand, in the tire according to the second embodiment, the cap rubber 3 has a configuration in which the diameter joining portion 34 is not provided.

  In the tire according to the second embodiment, the steering stability performance can be improved, whereas in the tire according to the first embodiment, the steering stability performance can be effectively improved. . Thereby, in the tire, the configuration in which the cap rubber 3 further includes a diameter joining portion 34 to which the rubbers 4a and 5a having different elastic moduli are joined in the tire radial direction D2.

DESCRIPTION OF SYMBOLS 1 ... Tire, 2 ... Tread rubber, 3 ... Cap rubber, 4 ... 1st ribbon rubber, 4a ... 1st rubber, 5 ... 2nd ribbon rubber, 5a ... 2nd rubber, 6 ... Ribbon rubber, 6a ... 1st rubber, 6b ... 2nd rubber, 11 ... bead part, 12 ... side wall part, 13 ... tread part, 14 ... carcass layer, 15 ... inner liner, 16 ... belt layer, 17 ... base rubber, 31 ... cap outer layer, 32 ... cap inner layer, 33 ... Circumferentially joined portion, 34 ... Diameter joined portion, 35 ... Width joined portion, 40 ... First rubber member, 41 ... Parallel portion, 42 ... Inclined portion, 50 ... Second rubber member, 51 ... Parallel portion, 52 ... Inclined , 70 ... molding device, 71 ... first extrusion part, 72 ... second extrusion part, 73 ... winding part, 74 ... switching part, 100 ... rim, D1 ... tire width direction, D2 ... tire radial direction, D3 ... Tire circumferential direction, D4 ... rotational direction, S1 ... tie Equatorial plane, S2 ... tire meridional

Claims (3)

Comprising a tread rubber having an outer surface in the tire radial direction;
The tread rubber is a tire provided with a circumferential joining portion in which rubbers having different elastic moduli are joined in the tire circumferential direction. The tread rubber includes a cap rubber having an outer surface in the tire radial direction, and a base rubber disposed inside the tire radial direction of the cap rubber,
2. The tire according to claim 1, wherein the cap rubber further includes a diameter joint portion in which rubbers having different elastic moduli are joined in a tire radial direction. At least a part of the tread rubber is formed by spirally winding the first and second ribbon rubbers along the tire circumferential direction,
Each of the ribbon rubbers is arranged in such a manner that a parallel portion arranged parallel to the tire circumferential direction and an inclined portion arranged inclined with respect to the tire circumferential direction are repeated,
The tire according to claim 1 or 2, wherein the circumferential joining portion is formed by joining the inclined portion of the first ribbon rubber and the inclined portion of the second ribbon rubber in a tire circumferential direction.

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