JP5632233B2 - Pneumatic tires for motorcycles - Google Patents

Description

  The present invention relates to a pneumatic tire for motorcycles (hereinafter, also simply referred to as “tire”), and more specifically, a radial tire and a bias tire for motorcycles, and a pneumatic tire for motorcycles suitable as a bias tire for scooters. The present invention relates to the improvement of the tire outer shape.

  In general, when manufacturing a tire, pressure is applied to the inside of the molded green tire so that the outer surface of the green tire is pressed against the inner wall of a heated mold, and the raw rubber is vulcanized with heat and pressure. A sulfur mold is used. Such a mold is usually provided with a number of vent holes that open to a tire molding surface on which the outer surface of the tire is molded. This vent hole communicates with the inside and outside of the mold, and prevents the generation of dents called bears by discharging air between the outer surface of the tire and the tire molding surface to the outside during vulcanization molding. To do.

  FIG. 3 is a schematic view showing an outer shape of a portion connecting a tread portion to a sidewall portion in a conventional motorcycle pneumatic tire. When vulcanizing a pneumatic tire for a motorcycle having an outer shape as shown in the figure, conventionally, venting is performed near the position corresponding to the boundary between the tread portion and the sidewall portion of the mold where air easily collects. A hole was provided and air was extracted through this vent hole to prevent the occurrence of a bear (air trap).

  As an improved technique related to a pneumatic tire for a motorcycle, for example, in Patent Document 1, an annular surface substantially parallel to the equator plane of the tire is formed on the outer edge of the ground contact surface of the shoulder portion of the tire. A pneumatic radial tire is disclosed. Patent Document 2 discloses an automatic machine in which a crossing portion between an outer surface of a sidewall portion extending radially outward from a bead portion and a tread surface is formed by a joint surface formed of a curved portion protruding outward in the tire axial direction. A motorcycle tire is disclosed.

  Furthermore, in Patent Document 3, the tire axial direction of the tread portion can be obtained for the purpose of obtaining a pneumatic tire for a motorcycle that can easily determine the ground contact state during cornering traveling and that has improved cornering force and camber thrust. Projections projecting at a height of 1.0 mm or more and 5.0 mm or less and extending in the tire circumferential direction at a width of 1.0 mm or more and 10 mm or less from the contour curved surface of the tread portion extending from the tire equator on both side edges A technique for forming the portion is disclosed.

JP 59-179406 (Claims) JP 2002-331809 (Claims etc.) JP-A-3-182812 (Claims etc.)

  Conventionally, the vent hole provided in the mold has the effect of extracting the air that exists in the immediate vicinity, but at the boundary between the tread portion and the sidewall portion where air is likely to concentrate, and bear is a concern. It was necessary to install a large number of vent holes in the tire circumferential direction, which was a heavy burden in terms of mold processing man-hours and costs. In particular, the conventional tire shape as shown in FIG. 3 has a problem that it is difficult to ensure an air escape path because the green tire comes into contact with the tread end relatively quickly. Tires with insufficient air removal and bare bearings are defective and reduce product yield, so air can be vented more efficiently during molding vulcanization, There was a need to establish technology that could reduce costs.

  Accordingly, an object of the present invention is to eliminate the above-mentioned problems, and more efficiently bleed air during molding vulcanization, and can reduce the number of man-hours and costs for molding a motorcycle. To provide tires.

  As a result of intensive studies, the present inventors have found that the above problem can be solved by improving the outer shape of the vicinity of the intersection between the tread portion and the sidewall portion of the pneumatic tire for motorcycles, The present invention has been completed.

That is, the pneumatic tire for a motorcycle of the present invention is a pneumatic tire for a motorcycle including a tread portion formed in an annular shape, and a sidewall portion and a bead portion connected to both ends of the tread portion.
The intersection of the virtual extension line of the outline of the tread portion and the sidewall portion is located at the tire maximum width, and a protrusion protruding in the tire width direction is continuously formed in a position including the intersection in the tire circumferential direction. It is characterized by that.

  In the tire of the present invention, it is preferable that the protrusion is smoothly connected to the tread portion and the sidewall portion. The length of the protrusion in the tire radial direction is preferably 1 to 3 mm. Furthermore, the cross-sectional shape of the protrusion may be trapezoidal or semicircular.

  According to the present invention, a pneumatic tire for a motorcycle that can extract air more efficiently at the time of molding and vulcanization, and can reduce the processing man-hours and cost of the mold by adopting the above configuration. It became possible to realize.

FIG. 3 is a cross-sectional view showing an outer shape of a portion connected from a tread portion to a sidewall portion in an example of a pneumatic tire for a motorcycle of the present invention. FIG. 6 is a cross-sectional view showing an outer shape of a portion connecting a tread portion to a sidewall portion in another example of the pneumatic tire for a motorcycle of the present invention. FIG. 6 is a cross-sectional view showing a contour shape of a portion connecting a tread portion to a sidewall portion in a conventional pneumatic tire for a motorcycle.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
The pneumatic tire for a motorcycle according to the present invention includes a tread portion formed in an annular shape, and a sidewall portion and a bead portion connected to both ends of the tread portion. FIG. 1 is a cross-sectional view showing an outer shape of a portion connected from a tread portion to a sidewall portion in an example of a pneumatic tire for a motorcycle of the present invention.

  In the present invention, as shown in the drawing, a protrusion 3 projecting in the tire width direction is continuously provided in the tire circumferential direction at the tire maximum width position including the intersection point P of the outline of the tread portion 1 and the sidewall portion 2. Is formed. By providing such a protrusion 3 in the vicinity of the intersection P of the outer line of the tread portion 1 and the sidewall portion 2, which is the most air collecting portion in the mold during tire vulcanization molding, Since the recess corresponding to the projection 3 serves as a passage for air, air can be efficiently ventilated with a minimum number of vent holes. As a result, it is possible to reduce manufacturing defects of products and improve manufacturing yields, and it is possible to reduce man-hours and costs for mold processing by reducing vent holes. The number of vent holes can be reduced to, for example, about 9-12 from what was conventionally about 16-24. Further, by providing the mold with a vent ridge that communicates with the recess corresponding to the protrusion 3, and further providing a vent hole in the vicinity thereof, it becomes possible to vent air more efficiently. In the present invention, the intersection P of the outline of the tread portion 1 and the sidewall portion 2 means the intersection of the virtual extension lines of the outlines indicated by dotted lines in the drawing.

  The protrusion 3 according to the present invention may be any protrusion that protrudes in the tire width direction and is connected to the tire circumferential direction at the tire maximum width position including the intersection point P. Thus, the remaining of air can be prevented even with a small number of vent holes. The cross-sectional shape of the protrusion 3 is not particularly limited, and for example, a trapezoidal shape as shown in FIG. 1 or a semicircular protrusion 13 as shown in FIG. Moreover, as shown in the figure, the protrusion 3 is preferably connected smoothly to the tread portion 1 and the sidewall portion 2. If there is a corner, cracks and cracks are likely to occur in the recess.

  Further, the length x of the protrusion 3 in the tire radial direction is preferably 1 to 3 mm. If the length x is too short, there is a possibility that air circulation is insufficient and air remains, and if it is too long, no further effect can be obtained. In the present invention, the tire radial direction length x of the protrusion 3 means the distance in the tire radial direction between the contact points of the protrusion 3 and the outline of the tread portion 1 or the sidewall portion 2.

  In the tire of the present invention, only the point of providing the protrusion is important, and the other points can be appropriately configured according to a conventional method and are not particularly limited. For example, the tire of the present invention includes one or more carcass layers straddling a toroid between a pair of bead cores embedded in the bead portions, and usually one or more belts on the outer side in the tire radial direction. Layers are arranged.

  The carcass layer is made of at least one carcass ply formed by arranging relatively highly elastic textile cords in parallel with each other. The number of carcass plies may be one or two, or three or more. The both ends of the carcass layer may be folded around the bead core from the inside of the tire to the outside, or may be sandwiched and locked by bead wires from both sides, and any fixing method may be used. Further, as the belt layer, a spiral belt layer in which the cord direction is substantially the tire circumferential direction can be arranged, or two layers of cord rubberized layers extending obliquely with respect to the tire equatorial plane May be a cross belt layer formed by laminating such that the cord directions intersect with each other across the tire equator plane. Furthermore, although not shown, an inner liner is disposed in the innermost layer of the tire, and a tread pattern is appropriately formed on the tread surface.

Hereinafter, the present invention will be described in more detail with reference to examples.
1-3, a die having nine vent holes in the tire circumferential direction in the vicinity of the boundary between the tread portion and the sidewall portion of the pneumatic tire for motorcycles having a tire size of 120 / 70ZR17 having outer shapes shown in FIGS. Vulcanization molding was performed using In the tire shown in FIGS. 1 and 2, a protrusion protruding in the tire width direction at the tire maximum width position including the intersection of the outline of the tread portion and the sidewall portion under the conditions shown in the following table, It is formed continuously in the tire circumferential direction.

  Twenty tires of each shape were vulcanized, and the number of bares was measured. The results are also shown in the table below.

  As shown in the table above, in the tire maximum width position including the intersection of the outer line of the tread portion and the sidewall portion, a protrusion protruding in the tire width direction is continuously formed in the tire circumferential direction. In the tire, it was confirmed that the number of bears generated can be reduced as compared with a conventional tire having no such protrusion.

1 Tread part 2 Side wall part 3 Protrusion

Claims (4)

In a pneumatic tire for a motorcycle including a tread portion formed in an annular shape, and a sidewall portion and a bead portion continuous to both ends of the tread portion,
Located at the intersection tire maximum width of a virtual extension line of the outline of the tread portion and sidewall portions, a position including the intersection point, projection projecting in the tire width direction, is formed continuously in the tire circumferential direction A pneumatic tire for motorcycles, characterized by   The pneumatic tire for a motorcycle according to claim 1, wherein the protrusion is smoothly connected to the tread portion and the sidewall portion.   The pneumatic tire for a motorcycle according to claim 1 or 2, wherein a length of the protrusion in the tire radial direction is 1 to 3 mm. The pneumatic tire for a motorcycle according to any one of claims 1 to 3, wherein a cross-sectional shape of the protrusion is trapezoidal or semicircular.

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