JP2010184539A - Pneumatic tire for motorcycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire for a motorcycle, capable of achieving both grip performance and wet performance. <P>SOLUTION: In the pneumatic tire for the motorcycle, a number of first inclined grooves 11 inclining across an equatorial plane E are disposed in the peripheral direction at intervals within the range of grounding surface Q1 during straight travelling, second inclined grooves 12 having the same direction of inclination with respect to the equatorial plane E as that of the first inclined grooves 11 are disposed in a position separated from the first inclined grooves 11 of one outside grounding surface Q2, corresponding to the respective first inclined grooves 11. Both a limited length part 15 of a center line 13 in the width direction of the first inclined grooves 11 and a limited length part 16 of a center line 14 in the width direction of the second inclined grooves 12 are on a common curved line 20 in which the positive/negative direction of curvature is unchangeable. Projection images of the first inclined grooves 11 and the second inclined grooves 12 corresponding thereto on a plane passing a tire axis are separated from each other by a distance α in the tire axis direction, and the projection images of the first inclined grooves 11 and the second inclined grooves 12 corresponding thereto on the equatorial plane E are overlapped over a length β in the tire peripheral direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic tire for a motorcycle in which a large number of inclined grooves are arranged in a tread portion that is connected to a pair of bead portions via a sidewall portion, and in particular, grip performance that enables sporty driving with peace of mind on a circuit or the like. In addition, the present invention relates to a road having a wet performance that can travel safely even on a general road.

  2. Description of the Related Art Conventionally, a pneumatic tire for a motorcycle having a pattern in which a large number of inclined grooves are arranged in a tread portion is known in order to ensure steering stability on a dry road surface and a wet road surface on a general road (for example, , See Patent Document 1).

  However, recently, there is an increasing need to use a pneumatic tire for motorcycles for general road driving also for circuit driving, and if the conventional tire as described above is used for such a purpose, The grip performance required for sporty driving on circuit driving, etc. was not sufficient, and improvements were required.

  On the other hand, as a pneumatic tire for motorcycles dedicated to circuit running, a pneumatic tire for motorcycles having a pattern as shown in FIG. 1 has also been proposed (see, for example, Patent Document 2). When a tire ground contact surface when a tire having a predetermined rim filled with a predetermined internal pressure is traveled straight under a predetermined load is referred to as a straight travel contact surface, the pattern shown in FIG. A first inclined groove 91 that inclines across the equator plane E and a second inclined groove 92 that is provided so as not to cross the equator plane E corresponding to each of the first inclined grooves 91 are provided in Q1. The first inclined groove 91 and the second inclined groove 92 corresponding to the first inclined groove 91 are spaced apart from each other and are opposite to the equatorial plane E. Inclined in the direction. In order to improve the grip performance required for circuit driving, this pattern keeps the ratio of the groove area to the total area of the tread portion extremely low. For this reason, the first inclined groove 91 and the second inclined groove 92 However, there is a problem that the wet performance is not sufficient and it is not possible to run on a general road, because they are not configured to cooperate with each other to enhance drainage performance.

JP 2007-331596 A Design Registration No. 1312918

  The present invention has been made in view of such problems, and is capable of achieving both a grip performance capable of driving in a sporty manner on a circuit or the like and a wet performance capable of traveling on a general road with peace of mind. An object is to provide a pneumatic tire for a motorcycle.

The present invention is a pneumatic tire for a motorcycle in which a large number of inclined grooves are arranged in a tread portion connected to a pair of bead portions via a sidewall portion.
The tire contact surface of the tread when a predetermined rim is filled with a predetermined internal pressure is traveled straight under a predetermined load is referred to as a straight contact surface when traveling straight, and the contact surfaces connected to both sides of the straight contact surface are connected outwardly. When calling the ground, a number of first inclined grooves that are inclined across the equator plane are arranged in the circumferential direction at intervals in the range of the ground contact surface when going straight.
Corresponding to each of the first inclined grooves, a second inclined groove whose inclination direction with respect to the equator plane is the same as that of the first inclined groove is a position on one side of the outer grounding surface away from the first inclined groove. Placed in
Both the finite length portion of the width direction center line of the first inclined groove and the finite length portion of the width direction center line of the second inclined groove are on a common curve in which the positive and negative directions of curvature do not change. And
The projected images of the first inclined groove and the corresponding second inclined groove on the plane passing through the tire axis are separated from each other by a distance α in the tire axial direction, and correspond to the first inclined groove and the corresponding one. An image projected onto the equator plane with the second inclined groove is a pneumatic tire for a motorcycle, characterized in that it overlaps with the length β in the tire circumferential direction.

  According to the present invention, a pair of the first inclined grooves adjacent to each other in the circumferential direction are inclined in directions opposite to each other with respect to the equator plane, and correspond to each of the pair of the first inclined grooves adjacent to each other in the circumferential direction. Preferably, the second inclined grooves are arranged on the outer grounding surfaces on the opposite sides.

  In the present invention, it is preferable that the distance α is 5 to 15 mm and the length β is 5 to 25 mm.

  In the present invention, the ratio of the area of the groove portion to the total area of the tread portion is preferably 10% or less.

  According to the present invention, as will be described in detail later, it is possible to combine a grip performance that allows a sporty run with peace of mind on a circuit or the like, and a wet performance that can run with peace of mind even on a general road.

FIG. 6 is a developed schematic view showing a pattern of a conventional pneumatic tire for motorcycles dedicated to circuit running. 1 is a sectional view showing a pneumatic tire for a motorcycle according to an embodiment of the present invention. 1 is a developed schematic view showing a pattern of a pneumatic tire for a motorcycle according to an embodiment of the present invention. It is a schematic diagram which shows the projection image to the equator surface of the 1st and 2nd inclination groove | channel. It is a schematic diagram which shows the projection image to the plane which passes along the tire axis line of the 1st and 2nd inclination groove | channel.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 2 is a cross-sectional view showing a motorcycle pneumatic tire according to an embodiment of the present invention. The motorcycle pneumatic tire 10 includes a pair of bead portions 1 and sidewalls on each of these bead portions 1. The bead portions 1 are each provided with a bead core 4, and a central portion 5a of a radial carcass 5 made of one or more carcass plies is provided between the bead cores 4. Is extended in a toroidal shape, and the radial carcass 5 is locked to the bead core 4 by folding back both side portions 5 b with the bead core 4.

  The tread portion 3 is provided with a tread rubber 6 that constitutes a ground contact surface during traveling, and a belt 7 composed of one or more belt plies is disposed between the central portion 5a of the radial carcass 5 and the tread rubber 6. Is done. The tread rubber 6 can be composed of a plurality of different types of rubber depending on the axial position thereof. In the illustrated case, the tread rubber 6 is composed of three types of rubber 6a, 6b, 6c having different physical properties. Yes.

FIG. 3 is a developed view showing the ground contact surface Q of the tread portion 3 according to the present invention. The ground contact surface Q is formed with a pattern including a land portion and a groove portion. A large number of first inclined grooves 11 inclined across the equator plane E are arranged in the circumferential direction at intervals within the range of the hourly contact surface Q1.
Corresponding to each of the first inclined grooves 11, the second inclined groove 12 having the same inclination direction as that of the first inclined groove 11 with respect to the equator plane E is a first inclined groove on one side of the outer grounding surface Q2. 11 is located away from
Both the finite length portion 15 of the width direction center line 13 of the first inclined groove 11 and the finite length portion 16 of the width direction center line 14 of the second inclined groove 12 change in the positive and negative direction of curvature. Not on the common curve 20,
Projected images 11a and 12a on the plane passing through the tire axis of the first inclined groove 11 (21) and the corresponding second inclined groove 12 (22) are separated from each other by a distance α in the tire axial direction. The projected images 11b and 12b on the equator plane E of the first inclined groove 11 and the corresponding second inclined groove 12 overlap with each other over the length β in the tire circumferential direction.

  In FIG. 3, the first inclined groove 21 and the second inclined groove 22 have the above-described correspondence, but the other first adjacent to the first inclined groove 21 in the circumferential direction. A similar correspondence is established for the inclined groove 31 and the second inclined groove 32.

  In the pneumatic tire for a motorcycle of the present invention, the second inclined groove 12 corresponding to one first inclined groove 11 has the same inclination direction with respect to the equator plane E as the first inclined groove 11. Moreover, both the finite length portion 15 of the center line 13 in the width direction of the first inclined groove 11 and the finite length portion 16 of the center line 14 in the width direction of the second inclined groove 12 have positive and negative curvatures. Is present on a common curve 20 that does not change (that is, the first inclined groove 11 comes on an extension line of the second inclined groove 12), and as schematically shown in FIG. Projected images 11b and 12b of the first inclined groove 11 and the corresponding second inclined groove 12 on the equator plane E overlap with each other over a length β in the tire circumferential direction (that is, the grooves in the circumferential direction have a groove). This is a pair that corresponds to each other Of the inclined grooves 11 and 12, jointly can improve drainage, in contrast to conventional tire shown in FIG. 1, in general road, it is possible to impart wet performance can travel with confidence.

Further, as schematically shown in FIG. 5, projection images 11a and 12a on the plane passing through the tire axis of the first inclined groove 11 and the corresponding second inclined groove 12 are in the tire axial direction. Since they are separated from each other by a distance α (that is, separated in the tire axial direction), the tread rigidity is not reduced compared to the conventional tire shown in FIG. Grip performance that enables smooth running can be provided.
4 and 5, reference numeral 19 represents the outer surface of the tread.

  Here, a pair of one of the first inclined grooves 21 and a circumferentially adjacent one 31 are inclined in opposite directions with respect to the equator plane E, and the first inclined groove 21 and the The second inclined grooves 22 and 32 respectively corresponding to the circumferentially adjacent ones 31 are preferably arranged on the outer grounding surface Q2 opposite to each other across the grounding grounding surface Q1. The force applied in the tire axial direction can be made equal to the left and right.

  In the present invention, the distance α is preferably 5 to 15 mm, and the length β is preferably 5 to 25 mm. When the distance α is less than 5 mm or when the length β exceeds 25 mm, the tread On the other hand, if the distance α exceeds 5 mm or the length β is less than 25 mm, the drainage performance is not sufficient.

  In the present invention, the ratio of the area of the groove portion to the total area of the tread portion (that is, the negative ratio) is preferably 10% or less, and when this ratio exceeds 10%, the tread rigidity is reduced, the circuit, etc. The grip performance for a sporty run is not sufficient.

  The tires of Examples 1 to 7 having the structure shown in FIG. 2 and the pattern shown in FIG. 3 and only the distances α and β are different from each other, mounted on a motorcycle, and sensory evaluation by a driver. The grip performance and wet performance were compared. The size of the mounted tire is as follows.

(Rear wheel)
Size: MCR190 / 50ZR17M / C
Carcass material: Nylon Belt structure: A belt crossing layer consisting of two layers of nylon belt plies inclined at opposite angles to each other at a low angle with respect to the equatorial plane, and one steel cord in the substantially circumferential direction on the radially outer side Structure with a circumferential reinforcing layer that can be wound.
(front wheel)
Size: MCR120 / 70ZR17M / C
Carcass material: Rayon Belt structure: Same as rear wheel

  As described above, the front wheels and the rear wheels have different sizes, but the patterns including the distances α and β are the same for the front and rear wheels.

  Further, with respect to conventional tires that differ from the examples only in that the pattern is that shown in FIG. 1, these were mounted on a motorcycle and evaluated in the same manner. Table 1 shows the values α and evaluation results of the distances α and β.

  In addition, the numerical value of the sensory evaluation regarding the grip performance and the wet performance in Table 1 is represented by an index with a level that can be satisfied as an absolute level being 100, and the larger the value, the better the performance.

DESCRIPTION OF SYMBOLS 1 Bead part 2 Side wall part 3 Tread part 4 Bead core 5 Radial carcass 5a Radial carcass center part 5b Radial carcass both sides 6 Tread rubber 6a, 6b, 6c Rubber part which comprises tread rubber 7 Belt 10 Pneumatic for motorcycles Tire 11 First inclined groove 12 Second inclined groove 13 Width direction center line of first inclination groove 14 Width direction center line of second inclination groove 15 Finite length of width direction center line of first inclination groove Portion 16 Finite length portion of widthwise center line of second inclined groove 19 Tread outer surface 21 First inclined groove 22 Second inclined groove 31 First inclined groove 32 Second inclined groove E Equatorial plane Q Grounding surface Q1 Grounding surface during straight travel Q2 Outside grounding surface

Claims (4)

In a pneumatic tire for a motorcycle in which a large number of inclined grooves are arranged in a tread portion connected to a pair of bead portions via a sidewall portion,
The tire contact surface of the tread when a predetermined rim is filled with a predetermined internal pressure is traveled straight under a predetermined load is referred to as a straight contact surface when traveling straight, and the contact surfaces connected to both sides of the straight contact surface are connected outwardly. When calling the ground, a number of first inclined grooves that are inclined across the equator plane are arranged in the circumferential direction at intervals in the range of the ground contact surface when going straight.
Corresponding to each of the first inclined grooves, a second inclined groove whose inclination direction with respect to the equator plane is the same as that of the first inclined groove is a position on one side of the outer grounding surface away from the first inclined groove. Placed in
Both the finite length portion of the width direction center line of the first inclined groove and the finite length portion of the width direction center line of the second inclined groove are on a common curve in which the positive and negative directions of curvature do not change. And
The projected images of the first inclined groove and the corresponding second inclined groove on the plane passing through the tire axis are separated from each other by a distance α in the tire axial direction, and correspond to the first inclined groove and the corresponding one. A pneumatic tire for a motorcycle, wherein the projection image on the equator plane with the second inclined groove overlaps with the length β in the tire circumferential direction.   A pair of the first inclined grooves adjacent to each other in the circumferential direction are inclined in directions opposite to each other with respect to the equator plane, and a second pair corresponding to each of the pair of adjacent first circumferential grooves in the circumferential direction is provided. 2. The pneumatic tire for a motorcycle according to claim 1, wherein the inclined grooves are disposed on outer grounding surfaces opposite to each other. 3.   The pneumatic tire for a motorcycle according to claim 1 or 2, wherein the distance α is 5 to 15 mm and the length β is 5 to 25 mm.   The pneumatic tire for a motorcycle according to any one of claims 1 to 3, wherein a ratio of an area of the groove portion to a total area of the tread portion is 10% or less.

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