JP2010120436A - Pneumatic tire for motorcycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire for a motorcycle for improving driving stability in high-speed travelling, traction performance when accelerating from, especially, a deep cornering wherein a vehicle (motorcycle) is tilted large, and stability when tilting a vehicle body. <P>SOLUTION: The pneumatic tire includes an annular tread part 11. The tread part 11 has a spiral belt layer 3 formed at an angle of 0-5 degrees to the tire equator direction and arranged at a width of 0.5-0.8 times the tread width inside in the radial direction of a crown part so that the center in the cross direction of the spiral belt layer 3 coincides with the tire equator. A reinforcing rubber 4 is arranged in a carcass 2 inside in the radial direction of the tire at least over from a tread shoulder part to one part of a sidewall part 12. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic tire for a motorcycle (hereinafter, also simply referred to as “tire”), and more specifically, improves the steering stability performance at high speed, and particularly when accelerating from deep cornering that greatly depresses a vehicle (motorcycle). The present invention relates to a pneumatic tire for a motorcycle that can improve traction performance and stability when the vehicle body is collapsed.

  In high-performance two-wheeled vehicle tires, the rotational speed of the tires is high, and therefore the influence of centrifugal force is large, and the tread portion of the tires expands outward, which may impair steering stability performance. Therefore, a tire structure has been developed in which a reinforcing member (spiral member) made of organic fiber or steel is wound around the tread portion of the tire so as to be substantially parallel to the tire equatorial plane.

  Examples of the spiral member used for the spiral belt layer include nylon fiber, aromatic polyamide (trade name: Kevlar), and steel. Among them, aromatic polyamide and steel have recently been attracting attention because they can suppress expansion of the tread portion without stretching even at high temperatures. When such a spiral member is wound around the crown portion of the tire, a so-called “tangle” effect (the tire crown portion is restrained by the spiral member so that the tire is inflated by centrifugal force even when the tire rotates at a high speed. A number of techniques for improving these spiral members have been proposed so far (for example, Patent Documents 1 to 5). .

It is known that a tire around which these spiral members are wound has excellent steering stability performance at high speed and extremely high traction. However, with regard to the turning performance when the vehicle (motorcycle) is largely tilted, the steering stability performance is not dramatically improved even when the spiral member is wound. For this reason, consumers and riders who are racing may request an improvement in grip performance when the motorcycle is greatly defeated.
JP 2004-067059 A JP 2004-067058 A JP 2003-011614 A JP 2002-316512 A JP 09-226319 A

  In a pneumatic tire for a two-wheeled vehicle, since the two-wheeled vehicle turns while tilting the vehicle body, the place where the tire tread portion is in contact with the ground is different between when going straight and when turning. That is, the center portion of the tread portion is used when going straight, and the end portion of the tread portion is used when turning. Therefore, the shape of the tire is very round compared to the tire for passenger cars. This round crown shape (the shape of the tread portion of the tire is called a crown shape) has the following unique characteristics, particularly during turning.

  In a tire for a motorcycle, particularly with respect to turning performance when the vehicle body is largely tilted, one end of the tread of the tire is grounded to generate a grip. When the vehicle is turned with a large tilt, the grounding state as shown in FIG. 6 is obtained. Considering the ground contact shape at this time, as shown in the drawing, the deformation state of the tread differs between the ground shape near the center and the ground shape near the tread end. Looking at the deformation of the tread in the tire rotation direction (also referred to as the tire equator direction or the tire front-rear direction), it is in a driving state near the tire center and in a braking state near the tire tread end.

  Here, the driving state means that when the wheel is cut along the tire equator direction, the deformation of the tread is caused by the lower surface of the tread (the surface in contact with the skeleton member inside the tire) being sheared rearward in the tire traveling direction. This is a shearing state in which the tread surface that is in contact with the ground is deformed forward in the tire traveling direction, which is a deformation that occurs when a driving force is applied to the tire. On the other hand, the braking state is the reverse of the driving state, and the deformation of the tread is a sheared state in which the tire inner side (belt) is sheared forward, and the tread surface that is in contact with the road surface is deformed rearward, This is the movement of the tire when braking.

  As shown in FIG. 7, when turning with a large camber angle (CA) such as 40 degrees, the ground contact area near the tread center even when the tire does not apply driving force or braking force. The driving state appears at the front and the braking state appears near the tread edge. This is due to the difference in the radius of the belt portion of the tire (diameter difference). In a motorcycle tire, since the tire crown portion is rounded, the distance from the rotating shaft to the belt is greatly different between the tread center portion and the tread end portion. In the case of FIG. 7, the radius R1 at the position near the center of the ground contact shape is clearly larger than the radius R2 at the position near the tread edge of the ground contact shape. Since the angular speed at which the tire rotates is the same, the speed of the belt (when the tire is in contact with the road surface, it means the speed in the tire equator direction along the road surface; the belt radius multiplied by the tire angular speed) is The portion of R1 having a larger radius is faster. The tread surface of the tire is not sheared in the front-rear direction at the moment of contact with the road surface, but proceeds with the rotation of the tire while in contact with the road surface, and undergoes shear deformation in the front-rear direction when leaving the road surface. At this time, the tread near the tire center where the belt speed is fast becomes a shearing deformation in the driving state, and the braking state occurs at the end portion of the tire tread because the belt speed is slow. This is a modification of the tread in the front-rear direction.

  Due to such extra deformation during turning, the tread causes reverse shear deformation in the forward and backward directions, which includes useless behavior and wasteful tire grip force during turning. Ideally, if all the deformations of the tread that are in contact with the ground are the same, the gripping force will be maximum, but the excessive deformation as described above will occur, and depending on the grounding location, the gripping force may be It may not occur. For example, when considering acceleration when the tire is tilted, the driving force is applied to the tire, but the tread near the center already in the driving state exhibits the driving grip as soon as the driving force is applied to the tire. On the other hand, the tread at the tread end already in the braking state cannot easily contribute to the driving force because the braking deformation once returns to neutral and then shifts to the deformation on the driving side. A large traction force is required to bring the tread end into the driving state. When the accelerator is opened and a driving force is applied to the tire to apply such a traction force, the tire center side in the driving state is originally The tread slips easily and falls into an idle state.

  With respect to such a problem, it is considered that if the tread deformation of the tire shoulder portion (tread end portion) originally on the braking side is set to the driving side as much as possible, the traction force can be exerted greatly at the tread end portion. One solution is to increase the belt speed at the tread edge. However, the belt speed is determined by the belt radius as described above, and if the belt radius is increased, the belt cannot be used as a tire for a motorcycle. Therefore, it is conceivable to increase the belt speed by making the belt easily extend in the equator direction at the end of the tread after being grounded. In other words, when turning at a large CA, if the center half of the grounding shape has a structure in which the belt does not extend in the equator direction, and if the belt is extended in the equator direction for the half on the tread end side, then the tread after grounding. By extending the belt on the side, the belt speed on the tread end side is increased, and braking deformation on the tread end side can be reduced. As a result, the traction (acceleration from a turn with a large tilt of the motorcycle) at the time of large CA is improved.

  In conventional motorcycle tires, the spiral belt layer is usually wound around the entire tread region. With such a tire, the belt of the shoulder portion of the tread cannot be extended in the equator direction. Therefore, if the spiral belt layer is arranged only on the center side without being wound around the tread edge, the belt speed at the tread edge increases at the time of large CA, that is, at the time of turning with a large camber angle. Thus, the traction grip can be improved. In addition, when the belt speed of the tread shoulder portion increases at the time of large CA, it means that the belt speed of the tread shoulder portion approaches the belt speed on the tread center side, and this causes an extra movement of the tread that is grounded. It is suppressed. That is, the tread that has been sheared in the reverse direction until now has the shear in the same direction, and unnecessary movement is eliminated, and the occurrence of uneven wear can be suppressed. In addition, since the spiral belt layer is disposed in the tread center portion, it is possible to suppress the expansion due to the centrifugal force of the tire during high speed running (high speed = the motorcycle is upright). Steering stability at high speeds can be maintained at the same level as a tire with a full width spiral belt layer.

  However, if the spiral belt layer is not wound around the end of the tread, the region where there is no spiral belt layer suddenly touches the ground when the vehicle is tilted down, which is a cause of sudden grip changes (changes in rigidity steps). Also, there may be a problem that the rider feels the difference in level of the tires and cannot defeat the car body.

  Accordingly, an object of the present invention is to improve the steering stability performance at high speed, and at the same time, improve the traction performance especially when accelerating from deep cornering that greatly defeats the vehicle (bike) and the stability when the vehicle body is collapsed. The object is to provide a pneumatic tire for a motorcycle.

  From the above viewpoint, as a result of further examination, the present inventors have found that the above-mentioned problem can be solved by increasing the rigidity of the tread portion buttress (the region from the tread shoulder portion to the sidewall portion) where the spiral belt layer is not wound. Thus, 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.
A spiral belt layer having an angle with respect to the tire equator direction of 0 to 5 degrees and an arrangement width of 0.5 to 0.8 times the tread width is provided on the inner side in the tire radial direction of the tread portion. Arranged so that the center of the belt layer in the width direction coincides with the tire equator, and
Reinforcing rubber is disposed on the inner side in the tire radial direction of the carcass at least from the tread shoulder portion to a part of the sidewall portion.

  In the present invention, it is preferable that an arrangement width of the reinforcing rubber is wider than a distance from an end portion of the spiral belt layer to an end portion of the tread portion, and the spiral rubber layer is adjacent to the spiral belt layer. It is preferable that a belt crossing layer made of organic fibers having a width wider than the belt layer and having an angle with respect to the tire equator direction of 30 degrees or more and less than 85 degrees is disposed, and further, the tread layer and the spiral are arranged. Between the belt layers, a belt reinforcing layer made of an organic fiber cord having an angle with respect to the tire equator direction of 85 degrees to 90 degrees is disposed with a width of 90% or more and 110% or less of the tread width in contact with the tread layer. It is preferable that the cushioning layer has a thickness of 0.3 to 1.5 mm on the inner side in the tire radial direction of the belt reinforcing layer and adjacent to the belt reinforcing layer. It is preferable that beam is arranged.

  According to the present invention, the above configuration enhances the steering stability performance at high speeds, and particularly improves the traction performance when accelerating from the deep cornering that greatly defeats the vehicle (bike) and the stability when the vehicle body is collapsed. It becomes possible to provide a pneumatic tire for a motorcycle that can be improved.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view in the width direction of a pneumatic tire for a motorcycle according to a preferred embodiment of the present invention. As shown in the figure, the pneumatic tire for a motorcycle of the present invention includes a tread portion 11 formed in an annular shape, a pair of sidewall portions 12 disposed on the inner side in the tire radial direction from both sides thereof, and the sidewall portions 12. At least 1 that extends between a pair of bead cores 1 (consisting of bead wires 1 in the illustrated example) embedded in the bead portions 13 respectively. One carcass 2 is provided in the illustrated example.

  In the tire of the present invention, as shown in the drawing, the angle with respect to the tire equator direction is 0 ° to 5 ° inside the crown portion tire radial direction of the tread portion 11 and the arrangement width is 0.5 to 0.5 of the tread width. A spiral belt layer 3 that is 0.8 times is disposed. Here, the tread width is the distance of the curved surface from the tread end on one side to the tread end on the opposite side along the surface of the tire. The grounds for setting the width are based on the ground contact portion in the vicinity of 50 degrees CA where the motorcycle falls most, and the ground contact portion at the position where the motorcycle is slightly raised.

  When turning at a CA of 50 degrees, only the tread shoulder portion having a width 0.2 to 0.25 times the entire width of the tread is grounded (see FIG. 7). This is about 1/4 of the total width. As described above, a spiral belt is wound around the tread center portion at the time of large CA to prevent the skeletal member from extending in the equator direction in the ground contact range, and conversely, the skeleton is not wound around the tread end side. There is a demand for positively extending the member in the equator direction. Half of the grounding part at the time of large CA is 0.1 times the width of the tread, and if the spiral belt is not wound around this width, there is no spiral belt in the 0.1 times the width of both ends. The spiral belt layer width is 0.8 times the tread width.

  The above upper limit is an ideal value for ground contact when the motorcycle is most collapsed. However, when the motorcycle accelerates, it has the feature that it starts accelerating from the most collapsed position and gradually raises the vehicle body, that is, the ground contact portion of the tire gradually moves from the center. Further, the motorcycle accelerates most in the range of CA 30 to 45 degrees than in the case of CA 50 degrees when the motorcycle fell most. In consideration of maximizing the traction performance at this time, the spiral belt width is preferably narrower than the 0.8-fold width. Therefore, 0.5 times is set as the lower limit of the spiral belt width. When the spiral belt layer width is 0.5 times the tread width, the end portion of the spiral belt layer is positioned at the center in the width direction of the ground contact portion at CA 30 to 40 degrees. If the spiral belt layer width is less than 0.5 times, the position is shifted from the center in the width direction of the grounding shape of CA 30 to 40 degrees, which is not preferable. That is, the spiral belt layer is too narrow.

  From the above, when the width of the spiral belt layer 3 is 0.8 times the upper limit of the tread width, the end portion of the spy label layer is positioned at the center of the ground contact shape near the CA of 50 degrees where the motorcycle falls most. The grip improvement effect becomes high in the early stage of acceleration. In addition, the effect is high at a low-speed corner where a motorcycle is greatly defeated (it is possible to greatly defeat a motorcycle at a low-speed corner). On the other hand, when the arrangement width of the spiral belt layer 3 is 0.5 times the tread width which is the lower limit, the end of the spiral belt layer can be arranged at the center of the ground shape when the motorcycle is slightly raised (CA30). From ~ 40 degrees), the grip improvement effect can be exhibited in the middle of acceleration when the vehicle body is slightly raised. In addition, it demonstrates the effect of increasing the grip at high-speed corners where the bike is not overwhelmed. In the present invention, the spiral belt layer is arranged so that the center in the width direction coincides with the tire equator. This makes it possible to match the left and right reinforcement directions when the vehicle body is folded down.

  The cord constituting the spiral belt layer 3 may be an organic fiber cord or a steel cord. In the case of organic fiber cords, for example, twisted cords such as aromatic polyamide (trade name: Kevlar), nylon, and aromatic polyketone can be used. In the case of a steel cord, for example, five steel single wires having a wire diameter of 0.2 mm or five steel single wires having a wire diameter of 0.4 mm can be used without being twisted.

  In the present invention, it is important that the reinforcing rubber 4 is disposed on the inner side in the tire radial direction of the carcass 2 at least from the tread shoulder portion to a part of the sidewall portion 12. FIG. 8 is a conceptual diagram showing the distribution of rigidity in the tread portion. The solid line in the graph indicates the change in rigidity when the reinforcing rubber is disposed on the inner side in the tire radial direction of the carcass, and the dotted line indicates the change in rigidity when the reinforcing rubber is not disposed on the inner side in the tire radial direction of the carcass. It is. When there is no reinforcing rubber, the portion where the spiral belt layer is disposed (region from C to L1) maintains a certain rigidity, but the portion between L1 and L2 where the spiral belt layer is not disposed. Stiffness decreases in the region. That is, when the spiral belt layer 3 is narrowed, the spiral belt layer 3 is not suddenly disposed when the vehicle body is tilted (the in-plane shear rigidity) compared to the case where the spiral belt layer 3 has the entire tread width. The point L1 is grounded. Therefore, here, a sudden change in grip occurs when the vehicle body is finished, and there is a problem that the rider feels the level difference of the tire and cannot fall down the vehicle body. In order to solve this problem, the reinforcing rubber 4 is disposed on the inner side in the tire radial direction of the carcass 2 at least from the tread shoulder portion to a part of the sidewall portion 12. Thereby, the rigidity of the area | region of L1 to L2 improves, and the average rigidity in the same ground plane improves. As a result, the steep rigidity step is alleviated, the change of the grip becomes gentle, and the rider can incline the vehicle body without feeling uncomfortable. Further, since the shearing strain applied to the end portion of the spiral belt layer can be reduced by relaxing the rigidity step, it is possible to prevent a crack failure that is likely to occur at the end portion.

  Further, as shown in FIG. 1, the width of the reinforcing rubber 4 is preferably wider than the distance from the end of the spiral belt layer 3 to the end of the tread portion 11. Furthermore, in order to obtain the effect of the present invention more satisfactorily, assuming that the total width of the tread portion 11 is L, the tread portion 11 is positioned from the position of 0.1 L from the end of the spiral belt layer 3 toward the tire center C. It is preferable to be disposed over a position of 0.1 L from the end portion toward the sidewall portion 12, but it may be disposed so as to extend to the bead portion 13 at the maximum.

  In addition, there is no restriction | limiting in particular about the material of the rubber used for the reinforcement rubber 4, The coating rubber etc. which are used for a belt reinforcement layer can be used. In order to obtain the effect of the present invention satisfactorily, the thickness of the reinforcing rubber layer 4 is preferably 1.0 to 5.0 mm.

  FIG. 2 shows a pneumatic tire for a motorcycle according to another preferred embodiment of the present invention. In the present invention, as shown in the figure, adjacent to the spiral belt layer 3, it is wider than the spiral belt layer 3, and is made of an organic fiber having an angle with respect to the tire equator direction of 30 degrees or more and less than 85 degrees. The belt crossing layer 5 is preferably disposed. This is because if the belt crossing layer does not exist at the left and right shoulders where the spiral belt is not wound, the shear rigidity of the belt will decrease, and the belt will be too weak to reduce the grip force when turning. It is to do.

  When the angle of the belt crossing layer 5 arranged in the tread shoulder portion with respect to the equator direction is less than 30 degrees, this is a direction approaching the angle of the spiral belt layer 3, and the belt is difficult to extend in the tire equator direction. Come. This would be contrary to the spirit of the present invention in which the shoulder belt extends in the equator direction in the installation area. Therefore, when the belt is less than 30 degrees, the skeleton member is less likely to extend in the equator direction at the shoulder portion, the belt speed of the shoulder portion does not increase, and the tread of the shoulder portion remains in a braking deformation, thereby obtaining a traction grip. I can't. On the other hand, when the angle is 85 degrees or more, the belt surface of the shoulder portion cannot be sufficiently obtained as a belt crossing layer (the effect of increasing the in-plane shear rigidity of the belt by overlapping the belts in opposite directions to each other). The internal rigidity is insufficient and sufficient turning grip cannot be obtained. In addition, about an angle, Preferably 45 degree | times or more is good because a frame member tends to extend in an equatorial direction. Moreover, it is preferably 80 degrees or less in order to exhibit shear rigidity. Therefore, it is preferably 45 degrees or more and 80 degrees or less.

  An organic fiber cord is used as the material of the belt crossing layer 5. This is because if a cord having rigidity in the compression direction of the cord as in the case of a steel cord is arranged as a skeleton member, the skeleton member has a characteristic that it is difficult to bend out of the plane, the ground contact area is reduced, and the gripping force is reduced. If it is an organic fiber cord, it does not have a great rigidity for compression in the cord direction, it can reduce the out-of-plane rigidity of the skeleton member and increase the ground contact area, and it is very strong in the tension direction of the cord This is because the rigidity can be effectively increased due to the rigidity. In the present invention, the belt crossing layer 5 may be arranged inside the spiral belt layer 3 in the radial direction of the tire as shown in FIG. 2, or may be arranged outside the spiral belt layer 3 in the radial direction. As long as it is arranged (not shown) adjacent to the spiral belt layer 3, there is no particular limitation on the arrangement order.

  Further, in the present invention, as shown in FIG. 3, the angle with respect to the tire equator direction is 85 degrees to 90 degrees between the tread layer of the tread portion 11 and the spiral belt layer 3 and adjacent to the tread layer. It is also preferable to dispose a belt reinforcing layer 6 made of an organic fiber cord. In the tread portion, the rigidity step at the boundary between the portion where the spiral belt layer 3 exists and the portion where the spiral belt layer 3 does not exist is large. In order to alleviate the level difference, the belt reinforcement layer is arranged continuously from the tire center to the tire shoulder as a belt adjacent to the tread layer, that is, as the outermost layer. it can.

  The reason why the angle of the belt reinforcing layer 6 is set to 90 degrees with respect to the tire equator direction is that the step is most effectively prevented from being felt by arranging the cords along the width direction. Here, the reason why the angle is given a width of 85 degrees to 90 degrees includes a manufacturing error. Further, the arrangement width of the belt reinforcing layer 6 is 90% to 110% of the entire width of the tread. The purpose of the belt reinforcing layer 6 is to prevent the step from being felt, that is, the end of the spiral belt is covered with a member so that the outermost belt is not divided. Therefore, it is preferable to widen the arrangement width and cover the entire area of the tread. If the arrangement width is 90% or more of the total tread width L, the step of the spiral belt can be sufficiently covered. In addition, about an upper limit, the tread width L may be exceeded and it may reach a sidewall part. However, if it exceeds 110%, there will also be a 90-degree belt in the sidewall portion of the tire, the sidewall will be difficult to bend and the tire will be hard (that is, the tire will be difficult to bend and ride comfort) There is a risk that performance will deteriorate. Therefore, the upper limit was made 110%.

  The belt reinforcing layer 6 is made of organic fibers because the motorcycle tire has a very round cross section, and if steel with rigidity is used on the compression side of the cord in the tire width direction, the tire will not bend easily. This is because the ground contact area is reduced. Organic fibers have low rigidity on the compression side of the cord, and there is no risk of reducing the ground contact area.

  Since the reason for providing the belt reinforcing layer 6 is to eliminate the step at the end of the spiral belt, the effect cannot be obtained if the diameter of the cord is too thin. On the other hand, if the diameter of the cord is too large, the cord has rigidity on the compression side of the cord even though it is an organic fiber. Therefore, the diameter of the cord of the belt reinforcing layer 6 is preferably 0.5 mm or greater and 1.2 mm or less.

  Here, as described above, since the belt crossing layer 5 may be provided inside or outside the spiral belt layer 3, the belt crossing layer 5 is spiral as the arrangement order of these and the belt reinforcing layer 6. In the case where the belt reinforcement layer 6 is present on the inner side in the tire radial direction than the belt layer 3, the belt reinforcing layer 6 is disposed immediately outside the spiral belt layer 3 in the tire radial direction (see FIG. 3). On the other hand, when the belt crossing layer 5 exists outside the spiral belt layer 3 in the tire radial direction, the belt reinforcing layer 6 is disposed immediately outside the outer belt in the tire radial direction of the two belt crossing layers 5 ( Not shown). In any case, it is necessary to dispose the belt reinforcing layer 6 immediately inside the tread portion 11 in the tire radial direction and adjacent to the tread portion 11.

  FIG. 4 shows a cross-sectional view of a pneumatic tire for motorcycles according to still another preferred embodiment of the present invention. In the present invention, when the belt reinforcing layer 6 is disposed, as shown in the drawing, a buffer having a thickness of 0.3 to 1.5 mm is provided on the inner side in the tire radial direction of the belt reinforcing layer 6 and adjacent to the belt reinforcing layer 6. It is also preferable to dispose the rubber layer 7. The buffer rubber layer 7 has an effect of suppressing wear of the tread of the shoulder portion.

  FIG. 7 shows the behavior in the tread width direction when the tire turns at a CA of 50 degrees. On the other hand, the tread is deformed in the equator direction in the region where the tread is in contact with the road surface. And the tread center area are different. This is because the belt speed is different between the area near the center of the ground contact shape and the area near the tread end of the ground contact shape. The tire of a motorcycle has a large roundness in the cross section in the width direction. Therefore, the belt radius, which is the distance from the rotating shaft to the belt, is larger in the region near the tread center. Therefore, the speed of the belt, that is, the belt speed until the tread moves away from the road surface after the tread comes into contact with the road surface, and the region near the tread center becomes faster. This is because the belt speed is obtained by multiplying the belt radius by the rotational angular velocity of the tire. Due to the speed difference in the equator direction of the belt, the tread is in the driving state near the center of the tire, and the braking state is in the region near the tread end of the tire (described above).

  In the present invention, by reducing the width of the spiral belt layer, the portion of the belt where the spiral belt layer is not disposed extends along the ground in the equator direction, and the belt speed is improved. As described above, the deformation is alleviated. However, reducing the width of the spiral belt layer to alleviate it does not completely eliminate the unnecessary deformation.

  When the shock absorbing rubber layer 7 is provided on the inner side in the tire radial direction of the belt reinforcing layer 6, the shock absorbing rubber layer 7 shears and deforms in the equator direction. The deformation of is further eased. On the other hand, since the shock absorbing rubber layer 7 has the belt reinforcing layer 6 along the tire width direction on the upper surface thereof, it is not easily sheared and deformed in the tire width direction. Therefore, the deformation of the tread is not replaced with respect to the tire width direction, and the transverse shear deformation of the tread remains large even when the buffer rubber layer 7 is disposed. That is, the shock absorbing rubber layer 7 shoulders the deformation only in the tire equator direction and further reduces the tread equator direction deformation to further improve the grip force. On the other hand, the deformation in the tire width direction does not replace the shoulder, The deformation is kept large and the lateral force can be kept high. As in the present invention, when the spiral belt layer width is narrowed and the buffer rubber layer 7 is provided, the tread is further prevented from being deformed in the tire equator direction. preferable. The belt reinforcing layer 6 and the shock absorbing rubber layer 7 are preferably arranged widely, particularly in the range of 90% or more (particularly 110% or less) of the tread width.

  In the tire of the present invention, it is important only to satisfy the above-mentioned condition relating to the reinforcing rubber disposed on the inner side in the tire radial direction of the carcass, and thereby the desired effect of the present invention can be obtained, Other conditions such as the tire structure and material are not particularly limited.

  For example, the carcass 2 that forms the skeleton of the tire of the present invention includes 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. Further, both ends of the carcass 2 may be sandwiched and locked by bead wires from both sides as shown in FIG. 1 or the like, or may be folded around the bead core 1 from the inside of the tire to the outside (not shown). Any fixing method may be used. Further, an inner liner is disposed on the innermost layer of the tire (not shown), and a tread pattern is appropriately formed on the surface of the tread portion 11 (not shown). The present invention is applicable not only to radial tires but also to bias tires.

Hereinafter, the present invention will be specifically described with reference to examples.
(Conventional example 1)
A pneumatic tire for a motorcycle having a cross-sectional structure as shown in FIG. 5 was manufactured with a tire size of 190 / 50ZR17 in accordance with the following conditions. The test tire includes a carcass made of two carcass plies (body plies) extending across a toroid between a pair of bead cores. Here, nylon fiber was used for the carcass ply. The angle of the carcass was the radial direction (the angle with respect to the equator direction was 90 degrees). Further, as shown in the drawing, the end portions of each carcass ply were sandwiched by bead wires from both sides and locked at the bead portions.

  A spiral belt layer was disposed outside the carcass in the radial direction of the tire. The spiral belt layer was formed in a so-called spiral shape in which a steel cord twisted by a 1 × 5 type steel single wire having a diameter of 0.18 mm was spirally wound in the equator direction. The spiral belt layer is a method in which a belt-like body in which a single parallel cord is embedded in a coated rubber is wound in a spiral direction along the tire equator direction in the tire rotation axis direction. Formed with. The total width of the spiral belt layer is 240 mm, which is the same as the total tread width of 240 mm. A tread layer having a thickness of 7 mm is disposed outside the spiral belt layer in the tire radial direction.

Example 1
1 is a pneumatic tire for a motorcycle having a cross-sectional structure as shown in FIG. The width of the spiral belt is 170 mm, which corresponds to 0.71 times the total width of the tread. Further, a reinforcing rubber was provided on the inner side in the tire radial direction of a part of the carcass from the tread shoulder portion. The material of the reinforcing rubber is the same as the coating rubber used for the belt reinforcing layer. The reinforcing rubber was disposed from a position 5 mm in the tire center direction from the end portion L1 of the spiral belt layer to a position 15 mm from the tread end L2 of the sidewall portion. Other than that, the configuration is the same as that of Conventional Example 1.

(Comparative Example 1)
This is a configuration in which the reinforcing rubber is removed from the tire of Example 1.

(Comparative Example 2)
The configuration is the same as that of Example 1 except that the spiral belt layer width is 240 mm.

(Comparative Example 3)
The configuration is the same as in Example 1 except that the spiral belt layer width is 100 mm.

(Conventional example 2)
Fig. 7 is a pneumatic tire for a motorcycle having a cross-sectional structure as shown in Fig. 6. Compared to the conventional example 1, there are two belts that cross each other inside the spiral belt layer in the tire radial direction. The crossing belt is formed by twisting aromatic polyamide fibers to have a diameter of 0.5 mm and driving them in at 50/50 mm. The angle of the crossing layer is 60 degrees with respect to the equator direction, and they cross each other. The width of the crossing belt is 250 mm for the first sheet and 230 mm for the second sheet. One carcass was used, and the angle of the carcass was the radial direction (angle with respect to the equator direction was 90 degrees).

(Example 2)
Compared to Conventional Example 1, the spiral belt width was 170 mm (0.71 times the total tread width). Further, a reinforcing rubber was provided on the inner side in the tire radial direction of a part of the carcass from the tread shoulder portion. The material of the reinforcing rubber is the same as the coating rubber used for the belt reinforcing layer. The reinforcing rubber was disposed from a position 5 mm in the tire center direction from the end portion L1 of the spiral belt layer to a position 15 mm from the tread end L2 of the sidewall portion.

(Example 3)
A tire of Example 3 was produced in the same manner as the tire of Example 2 except that the angle of the crossing belt was 40 degrees.

Example 4
A belt reinforcing layer ("outermost layer reinforcing layer" in Table 1) is arranged outside in the radial direction of the spiral belt layer of the tire of Example 2. The belt reinforcing layer is formed by twisting aromatic polyamide. A cord having a diameter of 0.7 mm is formed by driving 50 cords / 50 mm, and the width of the belt reinforcing layer is 240 mm.

(Example 5)
4 is a pneumatic tire for a motorcycle having a cross-sectional structure as shown in FIG. 4. A shock absorbing rubber layer having a thickness of 0.6 mm (in Table 1, “rubber”) Abbreviated as “layer”). The material of the buffer rubber layer is the same as the coating rubber used for the belt reinforcing layer.

(Comparative Example 4)
This is a structure in which a belt reinforcing layer is arranged on the outer side in the radial direction of the spiral belt layer of the tire of Conventional Example 2. The belt reinforcing layer is a cord formed by twisting aromatic polyamide and having a diameter of 0.7 mm formed by driving 50 cords / 50 mm. The width of the belt reinforcing layer is 240 mm.

(Comparative Example 5)
Comparative Example 5 has the same configuration except that a buffer rubber layer having a thickness of 0.6 mm is disposed on the inner side in the tire radial direction of the belt reinforcing layer. The material of the buffer rubber layer is the same as the coating rubber used for the belt reinforcing layer.

(Example 6)
The thickness of the buffer rubber layer of the tire of Example 5 is 1.5 mm.

(Example 7)
The thickness of the buffer rubber layer of the tire of Example 5 is 1.8 mm.

(Example 8)
A tire of Example 8 was produced in the same manner as the tire of Example 2 except that the angle of the crossing belt was 20 degrees.

  Each of the obtained test tires was subjected to the test specified below. Table 1 summarizes the tire structures of Examples 1 to 8, Comparative Examples 1 to 5, and Conventional Examples 1 and 2.

<Drum test>
First, it was measured using a drum whether the traction when the vehicle body was tilted, which is the main object of the present invention, was improved. The method for measuring traction using a drum is as follows.

  As a testing machine, sandpaper was affixed to a drum having a diameter of 3 m, and the surface of the sandpaper was regarded as a road surface. The drum was rolled at a speed of 80 km / h, and a tire was pressed onto the drum at a CA of 35 degrees and a CA of 50 degrees. Each test tire was filled with an internal pressure of 240 kPa and pressed with a load of 150 kgf. The tire has a chain that transmits power to the rotating shaft, and a driving force can be applied. The driving force was applied using a motor. The tire was rotated at 80 km / h, and driving force was applied to accelerate the tire linearly to 120 km / h in a time of 3 seconds. At this time, since the drum rolls at 80 km / h, the driving force is applied to the tire, and the traction can be measured with the vehicle body tilted.

  The force acting in the direction parallel to the tire rotation axis (that is, the tire width direction) and the force acting in the direction perpendicular to the tire rotation axis are measured by a force sensor installed at the center of the tire wheel, and these forces are measured by the camber. The force in the drum width direction and the drum rotation direction are decomposed according to the angle, the force in the drum width direction is Fy, and the force in the drum rotation direction is Fx (Fx and Fy are coordinates with respect to the ground). That is, Fy indicates a lateral force for turning the motorcycle, and Fx indicates a driving force for accelerating the motorcycle. By drawing these as Fx on the horizontal axis and Fy on the vertical axis, a waveform as shown in FIG. 9 is obtained. Although this is called a friction ellipse, the intercept of Fy at Fx0 indicates a pure lateral force at a driving force of 0, and this is a force called camber thrust. In this test, the grip performance of a tire in a traction state can be evaluated by applying a driving force to the tire to accelerate the rotation of the tire. With time, the waveform of the graph moves in the positive direction of Fx. The maximum value of Fx can be said to be an index of traction grip.

  With the maximum value of Fx in Conventional Example 1 being 100, the performance of the example was evaluated by an index. This was done for two levels of CA 35 degrees and CA 50 degrees. The obtained results are shown in Table 2 below.

<Driving test>
Next, in order to confirm the performance improvement effect of the two-wheeled vehicle tire of the present invention, a result of a steering performance comparison test using an actual vehicle will be described. Since each test tire was a rear tire, an actual vehicle test was performed by exchanging the rear tire alone. The front tire was always fixed with a conventional one. The evaluation method is described below.

  Each test tire was mounted on a 1000cc sports-type motorcycle, and the vehicle was run on a test course. The steering stability (cornering performance) was comprehensively evaluated by a 10-point method based on the feeling of the test rider. On the course, the motorcycle ran intensely in consideration of motorcycle racing, and the maximum speed reached 180 km / h. The test items are low-speed corner traction performance (acceleration performance from a state where the vehicle body is largely defeated at a speed of 50 km / h), high-speed corner traction performance (acceleration performance from a state where the vehicle body is slightly defeated at a speed of 120 km / h), There are three types of grip stability (discontinuity) when the vehicle body is tilted down. The test results obtained are also shown in Table 2.

＊１ カッコ内の数値はトレッド幅に対するスパイラルベルト層の幅の割合である。

* 1 The value in parentheses is the ratio of the width of the spiral belt layer to the tread width.

  It can be seen that in all of the present examples, the steering stability performance (traction performance) at the time of turning when the vehicle body is largely tilted and the stability when the vehicle body is collapsed can be achieved at a high level.

  By comparing Conventional Example 1, Comparative Example 1, and Example 1, it can be seen that the present invention can achieve both steering stability during turning and stability when the vehicle body is collapsed. Moreover, by comparing Comparative Examples 2 and 3, it can be seen that the spiral belt layer width has an appropriate value.

  By comparing Conventional Example 2, Examples 2, 3 and Example 8, when a belt crossing layer is provided, a synergistic effect can be obtained by setting the angle of the belt crossing layer to 30 degrees or more and less than 80 degrees. I understand.

  In addition, by comparing Conventional Example 2, Example 4, and Comparative Example 4, it can be seen that a synergistic effect can be obtained by providing the belt reinforcing layer.

  Further, by comparing Comparative Example 5 and Examples 5, 6, and 7, it can be seen that a synergistic effect is obtained by combination with the buffer rubber layer, and that the thickness of the buffer rubber layer has an appropriate value.

  From the above results, it has been found that according to the present invention, the steering stability performance (traction performance) during turning when the vehicle body is largely tilted and the stability when the vehicle body is collapsed can be achieved at a high level.

1 is a cross-sectional view in a width direction showing a pneumatic tire for a motorcycle according to a preferred example of the present invention. It is a width direction sectional view showing a pneumatic tire for two-wheeled vehicles concerning other suitable examples of the present invention. FIG. 5 is a cross-sectional view in the width direction showing a pneumatic tire for a motorcycle according to still another preferred embodiment of the present invention. FIG. 5 is a cross-sectional view in the width direction showing a pneumatic tire for a motorcycle according to still another preferred embodiment of the present invention. It is sectional drawing of the width direction which shows the pneumatic tire for two-wheeled vehicles which concerns on a prior art example. It is sectional drawing of the width direction which shows the pneumatic tire for two-wheeled vehicles which concerns on the other example of a prior art example. It is sectional drawing which shows the tire just under a load when a two-wheeled vehicle is turning by big CA (CA50 degree | times). It is a conceptual diagram which shows distribution of the rigidity of the tread part of the pneumatic tire for two-wheeled vehicles. It is a graph which shows the friction ellipse which shows the relationship between Fx and Fy.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bead core 2 Carcass 3 Spiral belt layer 4 Reinforcement rubber 5 Belt crossing layer 6 Belt reinforcement layer 7 Buffer rubber layer 11 Tread part 12 Side wall part 13 Bead part

Claims (5)

In a pneumatic tire for a motorcycle including a tread portion formed in an annular shape,
A spiral belt layer having an angle with respect to the tire equator direction of 0 to 5 degrees and an arrangement width of 0.5 to 0.8 times the tread width is provided on the inner side in the tire radial direction of the tread portion. Arranged so that the center of the belt layer in the width direction coincides with the tire equator, and
A pneumatic tire for a motorcycle, wherein a reinforcing rubber is disposed on the inner side in the tire radial direction of the carcass from at least a tread shoulder portion to a part of the sidewall portion.   The pneumatic tire for a motorcycle according to claim 1, wherein a width of the reinforcing rubber is wider than a distance from an end portion of the spiral belt layer to an end portion of the tread portion.   Adjacent to the spiral belt layer, a belt crossing layer made of organic fibers having a width wider than the spiral belt layer and an angle with respect to the tire equator direction of 30 degrees or more and less than 85 degrees is disposed. Item 3. A pneumatic tire for a motorcycle according to item 1 or 2.   Between the tread layer and the spiral belt layer, a belt reinforcing layer made of an organic fiber cord having an angle of 85 degrees to 90 degrees with respect to the tire equator direction in contact with the tread layer is 90% to 110% of the tread width. The pneumatic tire for a motorcycle according to any one of claims 1 to 3, wherein the tire is arranged with the following width.   The pneumatic tire for a motorcycle according to claim 4, wherein a cushioning rubber having a thickness of 0.3 to 1.5 mm is disposed on the inner side in the tire radial direction of the belt reinforcing layer and adjacent to the belt reinforcing layer.

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