JP2008238878A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire for a motorcycle improved in grip performance during cornering traveling by making a belt structure of a tread proper, and enhancing high-speed stability and handling performance during direct-advance traveling. <P>SOLUTION: The pneumatic tire for the motorcycle comprises a carcass 5 composed of a pair of side walls 3 extending from a bead 2 to the outside in a tire diametrical direction and a tread 4 extending between both the side walls 3, and constituted of at least one ply, and a spiral belt layer 6 helically and spirally winding a strip formed by coating a cord with rubber in a tire circumferential direction outside in the tire diametrical direction of the carcass 5. A tilting belt layer 7 is formed inside in the tire diametrical direction or outside in the tire diametrical direction of the spiral belt layer 6. The tilting belt layer 7 is folded to the inside in a tire width direction so as to cover tire width direction both ends 8, 8 of the spiral belt layer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention includes a pair of bead portions in which a bead core is embedded, a pair of sidewall portions extending outward from the bead portion in the tire radial direction, and a tread portion extending between both sidewall portions, and includes at least one ply. A carcass, and at least one spiral belt layer formed by spirally winding a strip formed by rubber coating one or more cords in the tire circumferential direction on the outer side in the tire radial direction of the carcass. The pneumatic tire for motorcycles is intended to improve the high-speed stability during straight running, handling performance, and grip performance during cornering running of the motorcycle pneumatic tire.

  In recent years, two-wheeled vehicles have become lighter and have higher performance, and it has become more important to ensure high-speed stability when traveling straight on a racing course or the like. In particular, a rear tire that is a driving tire to which a large torque is applied is required to improve high-speed stability. From these facts, the belt structure of motorcycle tires is the shape in the tread contact area that contacts the road surface when traveling straight ahead, compared to the inclined belt layer in which the cord direction is inclined at a constant angle with respect to the tire equatorial plane. In many cases, a spiral belt layer having a small change in speed and excellent in high-speed stability is used.

  However, motorcycle tires with a spiral belt layer have improved high-speed stability when traveling straight, but when cornering, the change in the shape of the tread area that contacts the road surface becomes too large. Handling performance and grip performance during cornering running deteriorated, and it was not suitable for cornering running. As a countermeasure, Patent Document 1 discloses that a spiral belt layer is disposed over the entire tread portion, and an inclined belt layer is disposed only in the tread portion region that is in contact with the road surface during cornering traveling. There has been disclosed a pneumatic tire for a motorcycle having improved stability, handling performance and grip performance during cornering.

JP 2002-316512 A

  However, in the pneumatic tire for a motorcycle described in Patent Document 1, since the driving density of the spiral belt layer is constant over the entire tread portion, in order to sufficiently secure high-speed stability during straight running, If the striking density of the layer is increased, the rigidity of the tread contact area that touches the road surface during cornering will become too high, so the grip performance during cornering will decrease, and conversely the grip performance during cornering If the driving density of the spiral belt layer is lowered to ensure sufficient resistance, the rigidity of the tread contact area that touches the road surface during straight running will be too low, so the high-speed stability during straight running is effectively improved. There is a possibility not to. Thus, it can be said that the improvement in high-speed stability during straight traveling and the improvement in grip performance during cornering are in a trade-off relationship. In addition, since the traveling performance is not improved at the same time, the handling performance may not be sufficiently improved.

  Accordingly, an object of the present invention is to optimize the belt structure of the tread portion, and in particular, in a pneumatic tire for motorcycles for race driving, while improving the grip performance during cornering driving, It is to improve the high-speed stability and improve the handling performance.

  In order to achieve the above object, a pneumatic tire for a motorcycle according to the present invention spans between a pair of bead portions in which a bead core is embedded, a pair of sidewall portions extending outward from the bead portion in the tire radial direction, and both sidewall portions. A carcass composed of an extended tread portion and composed of at least one ply, and a strip formed by rubber coating one or a plurality of cords on the outer side in the tire radial direction of the carcass is spirally wound in the tire circumferential direction. And a plurality of cords that are inclined with respect to the tire circumferential direction are covered with rubber on the inner side in the tire radial direction or the outer side in the tire radial direction of the spiral belt layer. At least one inclined belt layer is provided, and at least one of the inclined belt layers is a tire width of the spiral belt layer. Characterized in that it is a belt layer which is folded in the inner side in the tire width direction so as to wrap the direction both end portions. In such a pneumatic tire, at least one of the inclined belt layers is a belt layer that is folded back inward in the tire width direction so as to wrap both ends of the spiral belt layer in the tire width direction. The camber angle at which the vehicle can be banked during traveling is increased, and the turning performance can be improved.

  Further, the cord constituting the inclined belt layer is preferably inclined within a range of 45 ° to 90 ° with respect to the tire circumferential direction, more preferably within a range of 65 ° to 85 °. .

  Furthermore, the cord constituting the spiral belt layer preferably has an initial tensile resistance of 50 cN / string or more, more preferably 400 cN / string or more. Here, “initial tensile resistance” refers to a characteristic value corresponding to the initial elastic modulus measured under the condition of 24 ° C. according to JIS L 1017 in the case of organic fiber cord. In the case of a cord, it refers to a characteristic value corresponding to an initial elastic modulus measured under the condition of 24 ° C. by a method defined in JIS G 3510.

  Furthermore, the cord constituting the spiral belt layer is preferably made of a material selected from the group consisting of steel, glass fiber, aromatic polyamide, polyethylene naphthalate, polyethylene terephthalate, rayon and aliphatic polyamide.

  In addition, the cord constituting the inclined belt layer preferably has an initial tensile resistance of 50 cN / line or more, more preferably 60 cN / line or more.

  In addition, the cord constituting the inclined belt layer is preferably made of a material selected from the group consisting of aromatic polyamide, polyethylene naphthalate, polyethylene terephthalate, rayon and aliphatic polyamide.

  Moreover, it is preferable that the folding | turning edge part of an inclination belt layer is located in the area | region whose tire width direction distance from a tire equator surface is 25% or less of a tread width.

  Further, the folded end portion of the inclined belt layer extends inward in the tire width direction beyond the position of 25% of the distance in the tire width direction from the tire equatorial plane with respect to the tread width, and the tire width at the position of 25% and the folded end portion. The directional distance is less than 25% of the tread width, and the tire width direction distance between both folded ends is preferably in the range of 1 to 50 mm, more preferably in the range of 8 to 30 mm.

  Furthermore, the driving density of the spiral belt layer in the portion up to 25% of the distance in the tire width direction from the tire equatorial plane with respect to the tread width is a range in the portion outside the tire width direction from the position of 25%. It is preferably 1.25 times or more, more preferably 1.5 times or more, the driving density of the spiral belt layer inside.

  According to the present invention, by optimizing the belt structure of the tread portion, particularly in a pneumatic tire for a motorcycle for racing, the grip performance during cornering is improved while the high speed during straight running is improved. Stability can be improved and handling performance can also be improved.

  Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 are sectional views in the tire width direction of a typical pneumatic tire for a motorcycle (hereinafter referred to as “tire”) according to the present invention.

  As shown in FIG. 1, the tire of the present invention spans a pair of bead portions 2 in which a bead core 1 is embedded, a pair of sidewall portions 3 extending from the bead portion 2 outward in the tire radial direction, and both sidewall portions 3. A carcass 5 composed of a tread portion 4 that extends, and a strip formed by rubber coating one or more cords on the outer side in the tire radial direction of the carcass 5 in a tire radial direction. And at least one spiral belt layer 6 formed by turning. The spiral belt layer 6 includes, on the outer side in the tire radial direction, a single inclined belt layer 7 formed by rubber-coating a plurality of cords inclined with respect to the tire circumferential direction. The width of the tire along the outer surface in the tire radial direction of the spiral belt layer is folded so as to wrap around both ends 8 and 8 in the tire width direction, that is, the inclined belt layer is folded at both ends 8 and 8 in the tire width direction of the spiral belt layer. The belt layer is folded inward. The tire having such a configuration can maintain a high tension in the tire radial direction in the entire tread portion by continuously folding and arranging the end portion 8 in the tire width direction of the spiral belt layer by the inclined belt layer 7. The cornering force at the time of banking increases, and the camber angle at which the vehicle can be banked at the time of cornering travel increases, so that it is possible to improve the turning performance.

  Further, the cord constituting the inclined belt layer 7 is preferably inclined within a range of 45 ° to 90 °, more preferably within a range of 65 ° to 85 ° with respect to the tire circumferential direction. Yes. Because, when the cord constituting the inclined belt layer 7 is inclined beyond the range of 45 ° to 90 ° with respect to the tire circumferential direction, the cornering travels from the coordination direction in which the cord is inclined. This is because deformation in the tire width direction of the tread portion 4 cannot be sufficiently suppressed and steering stability may be lowered.

  Furthermore, the cord constituting the spiral belt layer 6 preferably has an initial tensile resistance of 50 cN / string or more, more preferably 400 cN / string or more. This is because when the initial tensile resistance of the cord constituting the spiral belt layer 6 is less than 50 cN / strand, the initial tensile strength of the cord becomes too small. This is because the code can be destroyed without being able to resist.

  Furthermore, the cord constituting the spiral belt layer 6 is preferably made of a material selected from the group consisting of steel, glass fiber, aromatic polyamide, polyethylene naphthalate, polyethylene terephthalate, rayon and aliphatic polyamide. For example, since cords used in passenger car tires do not require such a high rigidity, it is rather important to reduce the weight, and generally the rigidity is not so high but the weight per unit volume is relatively small. It is preferable to use an organic fiber cord having, but since the cord used in heavy duty tires used for buses, trucks, agricultural machinery, construction vehicles, etc. requires high rigidity, the weight per unit volume is generally A steel cord having a large but high rigidity characteristic is preferable.

  In addition, the cord constituting the inclined belt layer 7 preferably has an initial tensile resistance of 50 cN / line or more, more preferably 60 cN / line or more. This is because, when the initial tensile resistance of the cord constituting the inclined belt layer 7 is less than 50 cN / strand, the initial tensile strength of the cord becomes too small. This is because the code can be destroyed without being able to resist.

  In addition, the cord constituting the inclined belt layer 7 is preferably made of a material selected from the group consisting of aromatic polyamide, polyethylene naphthalate, polyethylene terephthalate, rayon and aliphatic polyamide. In addition, when a cord having flexibility and strength according to the vehicle type and use environment is not used, the cord may be broken at the time of tire load rolling.

  Moreover, it is preferable that the folding | turning edge part 9 of an inclined belt layer is located in the area | region whose tire width direction distance from the tire equatorial plane CL is 25% or less of a tread width. This is because, when the folded end portion 9 of the inclined belt layer is located outside the region of 25% or less, there is a region where the inclined belt layer is not disposed in the tread contact area that contacts the road surface during cornering traveling. This is because the grip performance at the time of cornering traveling may not be sufficiently ensured because of excessive expansion.

  Further, the folded end 9 of the inclined belt layer extends inward in the tire width direction beyond the position of 25% of the distance in the tire width direction from the tire equatorial plane CL with respect to the tread width, and the position of the folded end 9 and the folded end 9 The distance in the tire width direction is less than 25% of the tread width, and the distance in the tire width direction between the folded end portions 9 and 9 is preferably in the range of 1 to 50 mm, more preferably in the range of 8 to 30 mm. It is in. This is because the folded end portion 9 of the inclined belt layer extends inward in the tire width direction beyond the position of 25%, and the distance between the 25% position and the folded end portion 9 in the tire width direction is less than 25% of the tread width. When the distance in the tire width direction between the folded-back end portions 9 and 9 is less than 1 mm, the folded-back end portions 9 come into contact with each other during rolling of the tire load, and the tread portion 4 is broken due to friction between the cords. On the other hand, the folded end portion 9 of the inclined belt layer extends inward in the tire width direction beyond the position of 25%, and the distance between the 25% position and the folded end portion 9 in the tire width direction is the tread width. However, when the distance in the tire width direction of both folded ends 9 exceeds 50 mm, an inclined belt layer that is folded back in the tread contact area that contacts the road surface during cornering traveling is disposed. No area is large Since too no longer, because grip performance during cornering may not be sufficiently ensured.

  Furthermore, as shown in FIG. 2, the driving density of the spiral belt layer 6 in the portion up to the position of 25% of the distance in the tire width direction from the tire equatorial plane CL with respect to the tread width is from the position of 25%. It is preferably 1.25 times or more, more preferably 1.5 or more times the driving density of the spiral belt layer 6 within the range in the outer portion in the tire width direction. This is because when the driving density of the spiral belt layer 6 in the portion up to the position of 25% is less than 1.25 times the driving density of the spiral belt layer 6 within the range outside the tire width direction from the position of 25%. Because, even if the rigidity of the spiral belt layer in the tread contact area that contacts the road surface during cornering is sufficiently secured, the driving density of the spiral belt layer in the tread contact area that contacts the road surface during straight traveling is too small. This is because the rigidity of the tread portion that contacts the road surface during straight traveling cannot be sufficiently ensured, and the high-speed stability during straight traveling may not be sufficiently improved. On the contrary, as in the present invention, when the driving density is 1.25 times or more, the grip performance during cornering traveling is sufficiently ensured, and the high-speed stability during straight traveling is sufficiently improved. Therefore, handling performance is also effectively improved. Moreover, as shown in FIG. 3, as shown in FIG. 4, the driving density of the spiral belt layer can be reduced from the tire equatorial plane CL to the outer side in the tire radial direction in three steps as long as the above conditions are satisfied. In addition, the driving density of the spiral belt layer can be gradually decreased from the tire equatorial plane CL toward the outer side in the tire radial direction.

  The above description shows only a part of the embodiment of the present invention, and these configurations can be combined alternately or various changes can be made without departing from the gist of the present invention. For example, as shown in FIG. 5, an inclined belt layer 7 is disposed outside the spiral belt layer 6 in the tire radial direction, and the inclined belt layer 7 is wrapped around both ends 8 and 8 in the tire width direction of the spiral belt layer 6. It is also possible to make the tire folded back inward in the tire width direction. Moreover, as shown in FIG. 6, it is also possible to set it as the tire which becomes the structure similar to the tire shown in FIG. 1 except having arrange | positioned the carcass 5 comprised by laminating | stacking two plies.

  Next, tires having conventional belt layers (conventional tires 1 and 2) and tires having inclined belt layers and spiral belt layers according to the present invention (example tires 1 and 2) are tire sizes 190 / 50ZR17. Each of these was prototyped and their performance was evaluated, and will be described below.

  As shown in FIG. 7, the conventional tire 1 includes a spiral belt layer and an inclined belt layer over the entire tread portion, and the conventional tire 2 includes the spiral belt layer over the entire tread portion as shown in FIG. It is a tire for a passenger car having an inclined belt layer divided into two on the outer side in the tire radial direction.

  As shown in FIG. 8, the example tire 1 includes a spiral belt layer and an inclined belt layer. The inclined belt layer 7 on the outer side in the tire radial direction of the spiral belt layer has both ends in the tire width direction of the spiral belt layer. The belt layer is folded back inward in the tire width direction so as to wrap the portion. An example tire 2 shown in FIG. 2 is a tire having the same configuration as that of the example tire except that the driving density of the spiral belt layer is reduced on the inner side in the tire width direction. The example tires 1 and 2 have the specifications shown in Table 1, respectively.

  Each of these test tires was attached to a rim of size MT 6.00 × 17 to form a tire wheel, and was applied to a motorcycle as a rear tire under the condition that air pressure: 290 kPa (relative pressure) was applied. The handling performance and grip performance during cornering were evaluated. As for the front tire, a passenger car tire of size 120 / 70ZR17 was attached to a rim of size MT3.50 × 17 and mounted on the vehicle under the condition that air pressure: 250 kPa (relative pressure) was applied.

  High-speed stability during straight running is evaluated when a professional rider goes straight over a distance of 1.5 km at a speed of 270 km / h on a circuit with each tire wheel mounted on a 1000 cc motorcycle. Was measured. In addition, the anti-shimmy performance that prevents the steering wheel from moving to the left or right due to cornering force, self-aligning torque, etc. It was measured by evaluating the feeling when it was run. Handling performance is a professional rider with regard to nimbleness (an index of ease of switching between cornering and straight running) and neutrality (an index of ease of running while maintaining a desired driving state). Measured by running a motorcycle on the circuit and evaluating the feeling. In addition, grip performance during cornering was measured by examining the limit height during cornering and evaluating the slip control by a professional rider. At this time, the evaluation of the conventional tire 1 is indexed with respect to each performance as 100, and various performances in other tires are shown as relative values. In addition, it represents that those performance is so high that a numerical value is large. Various evaluation results are shown in Table 2.

  As is clear from the results in Table 2, the example tire 1 is improved only in the limit height as compared with the conventional tire 2. In addition, compared with the conventional tire 1, the example tire 1 has the same shimmy prevention performance, but the high-speed stability, neutrality, and slip control during straight running are reduced, and on the contrary, the lightness, The critical height has improved. On the other hand, the tire 2 of the example has the same anti-shimmy performance as the tires 1 and 2 of the prior art, but all of the high-speed stability, lightness, neutrality, and limit height when traveling straight ahead. Compared to conventional tires. Therefore, in the example tire 2 in which the driving density of the spiral belt layer is reduced on the inner side in the tire width direction, the high-speed stability during straight traveling, the handling performance, and the grip performance during cornering traveling are remarkably improved. all right.

  As is clear from the above, by optimizing the belt structure of the tread part, while improving the grip performance during cornering traveling, the high-speed stability during straight traveling is improved, and handling performance is also improved. It has become possible to provide an improved pneumatic tire for motorcycles.

1 is a sectional view in the tire width direction of a typical tire according to the present invention. FIG. 5 is a sectional view in the tire width direction of another typical tire according to the present invention. FIG. 5 is a sectional view in the tire width direction of another typical tire according to the present invention. FIG. 5 is a sectional view in the tire width direction of another typical tire according to the present invention. FIG. 5 is a sectional view in the tire width direction of another typical tire according to the present invention. FIG. 5 is a sectional view in the tire width direction of another typical tire according to the present invention. It is tire width direction sectional drawing of the conventional example tire according to a prior art. It is tire width direction sectional drawing of the conventional example tire according to a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bead core 2 Bead part 3 Shoulder part 4 Tread part 5 Carcass 6 Spiral belt layer 7 Inclined belt layer 8 Spiral belt layer End part 9 of a tire width direction 9 Folding end part of an inclined belt layer

Claims (9)

A carcass composed of at least one ply, comprising a pair of bead portions with embedded bead cores, a pair of sidewall portions extending outward from the bead portion in the tire radial direction, and a tread portion extending between both sidewall portions. A motorcycle having at least one spiral belt layer formed by spirally winding a strip formed by rubber coating one or more cords in the tire circumferential direction on the outer side in the tire radial direction of the carcass For pneumatic tires
Including at least one inclined belt layer formed by rubber-coating a plurality of cords inclined with respect to the tire circumferential direction on the tire radial direction inner side or the tire radial direction outer side of the spiral belt layer,
A pneumatic tire for a motorcycle, wherein at least one of the inclined belt layers is a belt layer folded back inward in the tire width direction so as to wrap around both ends of the spiral belt layer in the tire width direction.   The pneumatic tire for a motorcycle according to claim 1, wherein the cord constituting the inclined belt layer is inclined within a range of 45 ° to 90 ° with respect to a tire circumferential direction.   The pneumatic tire for a motorcycle according to claim 1 or 2, wherein the cord constituting the spiral belt layer has an initial tensile resistance of 50 cN / piece or more.   The cord constituting the spiral belt layer is made of a material selected from the group consisting of steel, glass fiber, aromatic polyamide, polyethylene naphthalate, polyethylene terephthalate, rayon, and aliphatic polyamide. The pneumatic tire for motorcycles according to any one of the above.   The pneumatic tire for a motorcycle according to any one of claims 1 to 4, wherein the cord constituting the inclined belt layer has an initial tensile resistance of 50 cN / piece or more.   The cord constituting the inclined belt layer is made of a material selected from the group consisting of aromatic polyamide, polyethylene naphthalate, polyethylene terephthalate, rayon and aliphatic polyamide, according to any one of claims 1 to 5. The pneumatic tire for motorcycles described.   The motorcycle tire according to any one of claims 1 to 6, wherein the folded end portion of the inclined belt layer is located in a region where a distance in a tire width direction from the tire equatorial plane is 25% or less of a tread width.   The folded end portion of the inclined belt layer extends inward in the tire width direction over a position of 25% of the distance in the tire width direction from the tire equatorial plane with respect to the tread width, and the 25% position and the tire width at the folded end portion. The pneumatic tire for a motorcycle according to any one of claims 1 to 7, wherein the directional distance is less than 25% of the tread width, and the tire width direction distance between both folded ends is in the range of 1 to 50 mm. tire.   The driving density of the spiral belt layer in the portion up to 25% of the distance in the tire width direction from the tire equatorial plane with respect to the tread width is within the range in the portion outside the tire width direction from the 25% position. The pneumatic tire for a motorcycle according to any one of claims 1 to 8, wherein the pneumatic tire is at least 1.25 times the driving density of the spiral belt layer.

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