JP4553678B2 - Pneumatic tires for motorcycles - Google Patents

Description

  The present invention relates to a pneumatic tire for motorcycles, and more particularly to a pneumatic tire for motorcycles that achieves both drainage and wear resistance.

  In recent years, motorcycles for racing are in the direction of higher horsepower and higher torque. For this reason, ensuring the drainage performance in high traction such as rainy weather is a major issue.

Conventionally, there are many tires having a circumferential groove in the crown center in order to ensure drainage performance and contact pressure within the contact surface (see, for example, Patent Document 1). On the other hand, as shown in FIG. 3, the main lug groove that exists at a minute distance from the circumferential groove has a large angle with respect to the tire equatorial plane in order to ensure drainage in the radial direction. .
JP 2000-142031 A

  Thus, since the angle of the main lug groove with respect to the tire equator surface is large, the drainage performance is excellent in the vicinity of the upright, but there are many problems that uneven wear occurs.

  In view of the above problems, an object of the present invention is to provide a pneumatic tire for a motorcycle that has both drainage and wear resistance.

  In order to solve the above-mentioned problem, the feature of the present invention is that it extends in a toroid shape between bead cores embedded in a pair of bead parts, and extends from the inner side to the outer side in the tire width direction along the peripheral surface around the bead core. Alternatively, a carcass composed of at least one carcass ply, which is formed by winding from the outside to the inside, and in which textile cords formed by rubber coating in a range of 70 to 90 ° with respect to the tire equatorial plane are arranged in parallel, For motorcycles having a belt layer composed of at least two belt plies arranged between a carcass and a tread and arranged in parallel with a textile cord formed by rubber coating in a range of 20 to 40 ° with respect to the tire equatorial plane This pneumatic tire has a directional pattern on the tread, and the negative rate of the pattern is 20 to 40%. A central land portion formed by a pair of circumferential grooves in the central region of the tire, and the tread does not open to the pair of circumferential grooves, and extends from the central region toward the shoulder region, and the tire equator surface From the steeply inclined central portion where the inclination angle to the tire is 1 to 10 °, through the gentle inclination intermediate portion where the inclination angle to the tire equator surface is 15 to 50 °, the inclination angle to the tire equator surface is 55 to 90 ° It has an inclined main lug groove composed of an inclined side portion and a plurality of inclined sub lug grooves between the inclined main lug grooves, and the arrangement pitch of the inclined main lug grooves is a tire circumference x 10 to 20%, and The tires are rim-assembled on the rim used, and the ground contact length is 1.5 to 2.5 times that grounds when the used air pressure and load are applied. The groove width of the inclined main lug groove is half of the tread width. If Tr is Tr, it is Tr × 3-6%, and the steep main lug groove is steep The central portion starts from the region of Tr × 5 to 15% from the circumferential groove and ends at the region of Tr × 20 to 40%, and the gently inclined middle portion of the inclined main lug groove is Tr × 45 to 75 from the circumferential groove. The steeply inclined central part of the inclined main lug groove is rim-assembled on the rim used, running on both side edges of the grounding point when the used air pressure, load 2000N, camper angle 0 ° The gist of the invention is that it is a pneumatic tire for motorcycles that is substantially always included.

  According to the pneumatic tire for motorcycles according to the features of the present invention, the angle of the main lug groove with respect to the tire equatorial plane is small near the crown center and large near the shoulder, thereby achieving both drainage and wear resistance. Can do.

  In addition, the inclined secondary lug groove of the pneumatic tire for motorcycles according to the features of the present invention starts from a region of Tr × 0 to 15% from the shoulder side end of the steeply inclined central portion of the inclined main lug groove and reaches the shoulder region. It is preferable.

  Moreover, it is preferable to have one circumferential groove in the central land portion of the pneumatic tire for motorcycles according to the features of the present invention.

  The textile cord used for the carcass of the pneumatic tire for motorcycles according to the feature of the present invention is preferably a high elastic cord having a tensile breaking strength of 4.7 cN · dtex or more.

  The textile cord used for the belt layer of the pneumatic tire for motorcycles according to the features of the present invention is preferably a non-extensible high-elastic cord having a tensile breaking strength of 6.3 cN · dtex or more.

  According to the present invention, it is possible to provide a pneumatic tire for a motorcycle that achieves both drainage and wear resistance.

  Next, embodiments of 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, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(Pneumatic tire structure)
As shown in FIG. 1, the pneumatic tire for a motorcycle according to the embodiment of the present invention extends between the pair of bead portions 1 and the pair of sidewall portions 2 and the sidewall portions 2 with respect to the tire equatorial plane CL. And a tread portion 3 connected in a toroidal shape. In FIG. 1, only the right side is shown, but it is of course that the configuration is usually symmetrical.

  The carcass 5 extends in a toroidal shape between the bead cores 4 embedded in the pair of bead portions 1 and is wound around the bead core along the circumferential surface from the inner side to the outer side in the tire width direction. A toroidal radial carcass that reinforces the portion 2 and the tread portion 3. The carcass may be configured by winding from the outside toward the inside. The carcass 5 is composed of at least one carcass ply in which textile cords coated with rubber in a range of 70 to 90 ° with respect to the tire equatorial plane are arranged in parallel. The textile cord used for the carcass is a highly elastic cord having a tensile breaking strength of 4.7 cN · dtex or more. “Tensile strength at break” is a value measured according to JIS K6251-1993 using a JIS No. 3 dumbbell-shaped test piece.

  The belt layers 6 a and 6 b are disposed between the carcass 5 and the tread portion 3 and reinforce the tread portion 3. The belt layers 6a and 6b are composed of at least two belt plies in which textile cords formed by rubber coating in a range of 20 to 40 ° with respect to the tire equatorial plane are arranged in parallel. The textile cord used for the belt layers 6a and 6b is a non-stretchable highly elastic cord having a tensile breaking strength of 6.3 cN · dtex or more. The widths of the belt layers 6a and 6b are substantially equal to the tread width.

  As shown in FIG. 2, the pneumatic tire for a motorcycle according to the present embodiment has a directional pattern on the tread. The negative rate of the pattern is 20-40%. Further, the rotation direction of the tire is an arrow A direction.

  A central land portion 19 formed by a pair of circumferential grooves 14 is provided in the central region of the tread. The central land portion 19 may have one circumferential groove, although not shown.

  The tread has an inclined main lug groove 16 and a plurality of inclined sub lug grooves 17 between the inclined main lug grooves 16.

  The inclined main lug groove 16 does not open to the pair of circumferential grooves 14 and extends from the central region of the tread toward the shoulder region. Further, the inclined main lug groove 16 is from a steeply inclined central portion S1 having an inclination angle α1 with respect to the tire equator plane CL of 1 to 10 ° to a moderately inclined intermediate portion having an inclination angle α2 with respect to the tire equator surface CL of 15 to 50 °. Through S2, it consists of a slightly inclined side portion S3 having an inclination angle α3 with respect to the tire equatorial plane CL of 55 to 90 °.

  The pitch L of the inclined main lug groove 16 (the circumferential length of the inclined main lug groove 16) is the tire circumferential length × 10 to 20%, and the tire is rim assembled to the used rim, and the used air pressure is set. The circumferential grounding length for grounding in a state where a load is applied is 1.5 to 2.5 times.

  The groove width of the inclined main lug groove 16 is Tr × 3 to 6%, where Tr is half of the tread width.

  Further, the steeply inclined central portion S1 of the inclined main lug groove 16 starts from a region of Tr × 5 to 15% from the circumferential groove 14 and ends in a region of Tr × 20 to 40%. Further, the gently inclined intermediate portion S2 of the inclined main lug groove 16 is disposed in a region of Tr × 45 to 75% from the circumferential groove 14. In addition, the steeply inclined central portion S1 of the inclined main lug groove 16 is substantially always during traveling while the rim is assembled on the rim used, and both side edges of the contact point when the used air pressure, the load is 2000 N, and the camper angle is 0 °. Including.

  Further, the inclined sub lug groove 17 starts from the region of Tr × 0 to 15% from the shoulder side end of the steeply inclined central portion S1 of the inclined main lug groove 16 and reaches the shoulder region.

(Function and effect)
According to the pneumatic tire for a motorcycle according to the present embodiment, the angle of the inclined main lug groove 16 with respect to the tire equator surface is small near the crown center and large near the shoulder, thereby achieving both drainage and wear resistance. be able to.

  Specifically, the inclined main lug groove 16 has a steeply inclined middle portion S2 having an inclination angle with respect to the tire equator plane of 15 to 50 ° from a steeply inclined central portion S1 having an inclination angle with respect to the tire equator surface of 1 to 10 °. And the fine slope side portion S3 having an inclination angle of 55 to 90 ° with respect to the tire equator plane.

  Moreover, drainage improves by the negative rate of a tread pattern being 20 to 40%.

  Further, by having the central land portion 19 formed by the pair of circumferential grooves 14 in the central region of the tread, it is possible to ensure drainage and ground pressure within the ground contact surface.

  In addition, the pitch L of the inclined main lug grooves 16 is the tire circumferential length × 10 to 20%, and the ground is grounded in a state where the tire is rim-assembled on the used rim and loaded with the used air pressure and load. Length x 1.5 to 2.5 times.

  The groove width of the inclined main lug groove 16 is Tr × 3 to 6%, where Tr is half of the tread width. If it is smaller than Tr × 3%, it is difficult to obtain a drainage effect, and if it is larger than Tr × 6%, the rigidity of the tread portion becomes too low.

  The steeply inclined central portion S1 of the inclined main lug groove 16 starts from a region of Tr × 5 to 15% from the circumferential groove 14 and ends in a region of Tr × 20 to 40%. By disposing the steeply inclined central portion S1 in this region, it is possible to obtain block rigidity that can withstand high input near the upright position.

  The moderately inclined intermediate portion S2 of the inclined main lug groove 16 is disposed in a region of Tr × 45 to 75% from the circumferential groove 14. By disposing the gently inclined intermediate portion S2 in this region, it is possible to ensure block rigidity that can withstand the resultant force of the driving force and the lateral force in the middle camber region.

  The steeply inclined central portion S1 of the inclined main lug groove 16 substantially includes both side edges of the ground contact point when the tire is rim-assembled on the used rim and the used air pressure, the load is 2000 N, and the camper angle is 0 ° during traveling. Thus, it is possible to achieve both drainage and wear resistance.

  Further, the inclined sub lug groove 17 starts from the region of Tr × 0 to 15% from the shoulder side end of the steeply inclined central portion S1 of the inclined main lug groove 16 and reaches the shoulder region. By disposing the inclined auxiliary lug groove 17 in this region, it is possible to achieve both drainage and wear resistance in the middle camber region.

  Further, by having one circumferential groove in the central land portion 19, it is possible to further ensure drainage and ground pressure within the ground surface.

  Further, by using a high elastic cord having a tensile breaking strength of 4.7 cN · dtex or more as the textile cord used for the carcass 5, the wear resistance can be improved.

  In addition, wear resistance can be improved by using a non-extensible high-elastic cord having a tensile breaking strength of 6.3 cN · dtex or more as the textile cord used for the belt layers 6a and 6b.

  The pneumatic tire for motorcycles according to this embodiment is excellent in drainage and wear resistance, and is therefore preferably used particularly in a large displacement two-wheeled road race vehicle. Moreover, it can be suitably used even in rainy weather.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.

  In order to confirm the effect of the present invention, a pneumatic tire according to Example 1 and Conventional Example 1 was made as an experiment. The size of each test tire was 190 / 650R16.5. Example 1 was the tread pattern shown in FIG. 2, and Conventional Example 1 was the tread pattern shown in FIG.

  In the test, each test tire was mounted on an actual vehicle, and in rainy weather, drainage feeling evaluation and wear amount were confirmed by a test rider on a circuit. The score is a maximum of 10 points, and a larger value indicates better performance.

(result)
The results are shown in Table 1.

  Compared with Conventional Example 1, Example 1 was superior in drainage and wear resistance in a region that travels straight or has a small camper angle. Further, Example 1 maintained the same performance as Conventional Example 1 in the region having a large camper angle. Therefore, it was found that the pneumatic tire having the tread pattern shown in FIG. 2 can achieve both drainage and wear resistance as compared with the conventional tire.

1 is a cross-sectional view including a tire rotation axis of a pneumatic tire for a motorcycle according to an embodiment. 1 is a plan view of a tread of a pneumatic tire for a motorcycle according to an embodiment. FIG. 6 is a tread plan view of a conventional pneumatic tire for a motorcycle.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Tread part, 2 ... Side wall part, 3 ... Tread part, 4 ... Bead core, 5 ... Carcass, 6a, 6b ... Belt layer, 14 ... Circumferential main groove, 16 ... Inclined main lug groove, 17 ... Inclined sub lug Groove, 19 ... Central land, CL ... Tire equator

Claims (4)

It extends in a toroid shape between bead cores embedded in a pair of bead portions, and is wound around the bead core along its peripheral surface from the inside in the tire width direction to the outside or from the outside to the inside, A carcass composed of at least one carcass ply in which textile cords coated with rubber in a range of 70 to 90 ° with respect to the tire equatorial plane are arranged in parallel;
A motorcycle provided with a belt layer composed of at least two belt plies arranged between the carcass and the tread and arranged in parallel with a textile cord formed by rubber coating in a range of 20 to 40 ° with respect to the tire equatorial plane. Pneumatic tires for
The tread has a directional pattern, and the negative rate of the pattern is 20 to 40%,
In the central region of the tread, it has a central land portion formed by a pair of circumferential grooves,
From the steeply inclined central portion that does not open to the pair of circumferential grooves, extends from the central region toward the shoulder region, and has an inclination angle of 1 to 10 degrees with respect to the tire equator plane, the tire equatorial plane An inclined main lug groove formed of a slightly inclined side portion having an inclination angle with respect to the tire equator plane of 55 to 90 ° through a gentle inclination intermediate portion with an inclination angle with respect to the tire being 15 to 50 ° and a plurality of spaces between the inclined main lug grooves And an inclined sub lug groove
The pitch of the inclined main lug grooves is a tire circumferential length × 10 to 20%, and a circumferential grounding length × 1 in which the tire is rim-assembled on a working rim and is grounded in a state where a working air pressure and a load are applied. .5 to 2.5 times,
The groove width of the inclined main lug groove is Tr × 3 to 6%, where Tr is half of the tread width.
The steeply inclined central portion of the inclined main lug groove starts from a region of Tr × 5 to 15% from the circumferential groove and ends in a region of Tr × 20 to 40%.
The moderately inclined middle part of the inclined main lug groove is disposed in a region of Tr × 45 to 75% from the circumferential groove,
The steeply inclined central portion of the inclined main lug groove substantially includes both side edges of the ground contact point when the tire is rim-assembled on the used rim and the used air pressure, the load is 2000 N, and the camper angle is 0 ° during traveling. A pneumatic tire for motorcycles.   2. The motorcycle according to claim 1, wherein the inclined sub lug groove starts from a region of Tr × 0 to 15% and reaches a shoulder region from a shoulder side end of a steeply inclined central portion of the inclined main lug groove. Pneumatic tires.   The pneumatic tire for a motorcycle according to claim 1 or 2, wherein the central land portion has one circumferential groove.   The pneumatic tire for a motorcycle according to any one of claims 1 to 3, wherein the steeply inclined central portion is linear.

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