JP2008260348A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of attaining enhancement of steering stability at high load when a belt layer is made to a fall dead structure while suppressing increase of weight. <P>SOLUTION: The belt layer 20 is made to the fall dead structure, and is further formed by aramid, i.e., a high elastic non-metal fiber. Thereby, cornering power at a low load area can be enhanced while attaining light weight of the belt layer 20. Further, a belt reinforcement layer 30 having a belt reinforcement layer cord inclined relative to a tire circumferential direction within a range of 50°-90° is arranged at an inner side in the tire radial direction of the belt layer 20. Thereby, compression rigidity in the tire width direction can be enhanced, and generation of buckling can be suppressed when the high load is applied. As a result, while suppressing increase of weight, enhancement of steering stability at high load when the belt layer 20 is made to the fall dead structure can be attained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire. In particular, the present invention relates to a pneumatic tire having a folded structure belt layer.

  Some conventional pneumatic tires have improved handling stability even in pneumatic tires as the performance of vehicles increases. For example, in the pneumatic radial tire described in Patent Document 1, the inner belt positioned relatively inward in the tire radial direction in the belt layer in which a plurality of layers are stacked in the tire radial direction is the tire radial direction of the inner belt. The outer belt is folded outward in the tire radial direction so as to wrap around both ends of the outer belt located outside. That is, the belt layer has a folded structure. Thereby, the tension | tensile_strength of the edge part of the belt layer in a tire width direction is securable. Furthermore, in the pneumatic radial tire described in Patent Document 1, a reinforcing belt is disposed outside the inner belt and the outer belt in the tire radial direction so that the inner belt covers the inner end portion in the tire width direction of the folded portion. ing. Thereby, since the level | step difference of the rigidity distribution in a tire width direction becomes loose, a ground contact property can be improved. As a result, steering stability can be improved.

JP 2000-6614 A

  However, when the belt layer has a folded structure, the belt layer has a lower rigidity in the vicinity of the center than both ends in the tire width direction. For this reason, the belt layer may bend in the tire radial direction in the vicinity of the center portion in the tire width direction at high load, and so-called buckling may occur. Thus, when buckling occurs, the tread surface that is in contact with the road surface does not contact the center of the tread surface in the tire width direction, or the contact pressure becomes low, and the cornering power may decrease.

  In order to suppress a decrease in cornering power due to such buckling, it is conceivable to improve rigidity by forming all belt layers from a metal material such as steel. However, when the belt layer is formed of a metal material, the weight of the belt layer increases and the weight of the pneumatic tire may increase. Therefore, it has been very difficult to suppress a decrease in handling stability at a high load when the belt layer has a folded structure while suppressing an increase in the weight of the pneumatic tire.

  The present invention has been made in view of the above, and is a pneumatic tire capable of improving the handling stability at high loads when the belt layer has a folded structure while suppressing an increase in weight. The purpose is to provide.

  In order to solve the above-described problems and achieve the object, a pneumatic tire according to the present invention includes at least two belt layers, and at least one of the belt layers in the tire width direction of the belt layer. In a pneumatic tire that wraps around both end portions of the other belt layer by folding back the portion, at least one of the belt layers is made of a highly elastic non-metallic fiber, and the tire radial direction of the belt layer A belt reinforcing layer having a cord inclined within a range of 50 ° to 90 ° with respect to the tire circumferential direction is disposed on the inner side.

  In the present invention, the belt layer has a folded structure in which at least one belt layer wraps both ends of the other belt layer, and at least one belt layer is formed of a highly elastic non-metallic fiber. As described above, the belt layer is formed of a highly elastic non-metallic fiber and has a folded structure, so that it is possible to secure the tension near both ends in the tire width direction while reducing the weight of the belt layer, and in a low load region. Cornering power can be improved. Furthermore, a belt reinforcing layer having a cord inclined within a range of 50 ° to 90 ° with respect to the tire circumferential direction is disposed on the inner side in the tire radial direction of the belt layer. The compression rigidity in the width direction can be improved. Therefore, by utilizing the compression rigidity of the belt reinforcing layer in the tire width direction, occurrence of buckling when a high load is applied can be suppressed, and cornering power in a high load region can be secured. As a result, it is possible to improve the handling stability at high loads when the belt layer has a folded structure while suppressing an increase in weight.

  In the pneumatic tire according to the present invention, the cord included in the belt reinforcing layer is a steel cord.

  In this invention, since the cord of the belt reinforcing layer is formed of a steel cord, the compression rigidity of the belt reinforcing layer in the tire width direction can be improved more reliably, and cornering in the high load region can be performed more effectively. Power can be improved. As a result, it is possible to improve the handling stability at high loads more reliably.

  In the pneumatic tire according to the present invention, the end of the belt reinforcing layer in the tire width direction is positioned closer to the tire equator line than the end of the belt layer in the tire width direction. .

  In this invention, the end of the belt reinforcing layer in the tire width direction is positioned closer to the tire equator line than the end of the belt layer in the tire width direction, so the belt reinforcing layer on the inner side in the tire radial direction of the belt layer. Tread rubber can be located on both sides of the tire width direction. Thereby, since it can suppress that the rigidity of belt layer edge part vicinity becomes high too much, it can receive a bigger load and can improve cornering power. As a result, the steering stability can be improved more reliably.

  The pneumatic tire according to the present invention has an effect that it is possible to improve the handling stability under a high load when the belt layer has a folded structure while suppressing an increase in weight.

  Hereinafter, an embodiment of a pneumatic tire according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

(Embodiment)
In the following description, the tire width direction refers to a direction parallel to the rotation axis of the pneumatic tire, the inner side in the tire width direction is the direction toward the tire equator line in the tire width direction, and the outer side in the tire width direction is The direction opposite to the direction toward the tire equator line in the tire width direction. Further, the tire radial direction means a direction orthogonal to the rotation axis, the tire radial inner direction means the direction toward the rotation axis in the tire radial direction, and the tire radial direction outward means away from the rotation axis in the tire radial direction. The direction. Further, the tire circumferential direction refers to the direction of rotation with the rotation axis as the axis serving as the center of rotation.

  FIG. 1 is a meridional cross-sectional view showing a main part of a pneumatic tire according to the present invention. The pneumatic tire 1 shown in the figure has a tread portion 5 provided at the outermost portion in the tire radial direction when viewed in a meridional section. Further, a sidewall portion 7 is provided from the end of the tread portion 5 in the tire width direction, that is, from the vicinity of the shoulder portion 8 to a predetermined position on the inner side in the tire radial direction, and the sidewall portion is further provided. 7 is provided with a bead portion 16 on the inner side in the tire radial direction. The bead portions 16 are provided at two locations of the pneumatic tire 1, and are also provided on the opposite side of the tire equator line 3 so as to be symmetric with respect to the tire equator line 3. A bead core 17 is provided in the bead portion 16, and a bead filler 18 is provided on the outer side of the bead core 17 in the tire radial direction.

  A plurality of belt layers 20 are provided on the inner side of the tread portion 5 in the tire radial direction. A carcass 10 is continuously provided on the inner side in the tire radial direction of the belt layer 20 and on the tire equator line 3 side of the sidewall portion 7. The carcass 10 is folded back outward in the tire width direction along the bead core 17 at the bead portion 16. An inner liner 15 is formed along the carcass 10 on the inner side of the carcass 10 or on the inner side of the carcass 10 in the pneumatic tire 1.

  The plurality of belt layers 20 includes two belt layers 20 stacked in the tire radial direction. Of the two belt layers 20, the belt layer 20 positioned on the outer side in the tire radial direction is an outer belt. The belt layer 20 located on the inner side of the outer belt 23 in the tire radial direction is an inner belt 25. Both the inner belt 25 and the outer belt 23 are formed by winding a cord (not shown) made of a highly elastic non-metallic fiber such as aramid at a predetermined angle with respect to the tire circumferential direction or the tire circumferential direction. .

  Of the outer belt 23 and the inner belt 25, the inner belt 25 has both end portions in the tire width direction folded back outward in the tire radial direction, and the folded portion becomes a folded portion 26. Yes. Specifically, the folded portion 26 of the inner belt 25 is folded back outward in the tire radial direction in the vicinity of both ends of the outer belt 23 in the tire width direction. Is turned back toward the direction of the tire equator line 3. That is, the folded portion 26 is laminated on the outer side in the tire radial direction in the vicinity of both ends of the outer belt 23 in the tire width direction. In other words, the inner belt 25 wraps both ends in the tire width direction of the outer belt 23 by folding back both ends in the tire width direction, and the belt layer 20 is formed in a so-called folded structure. .

  A belt reinforcing layer 30 is disposed on the inner side of the belt layer 20 in the tire radial direction. The belt reinforcing layer end 31 which is the end of the belt reinforcing layer 30 in the tire width direction is located closer to the tire equator line 3 than the belt layer end 21 which is the end of the belt layer 20 in the tire width direction. Yes. That is, the width in the tire width direction of the belt reinforcing layer 30 is narrower than the width in the tire width direction of the belt layer 20 in a state in which both end portions of the inner belt 25 are folded and the folded portions 26 are laminated on the outer belt 23. Yes.

  Here, the belt layer end portion 21 is an end portion in the tire width direction of the inner belt 25 in a state in which both end portions of the inner belt 25 are folded and the folded portion 26 is formed. The distance D between the belt reinforcing layer end 31 and the belt layer end 21 in the belt reinforcing layer 30 is preferably at least 10 mm or more. Specifically, it is preferable to dispose rubber layers having a maximum thickness portion gauge of at least 1 mm at positions 5 mm on both sides of the belt reinforcing layer end portion 31 in the tire width direction.

  FIG. 2 is a cross-sectional view taken along the line AA of FIG. The belt reinforcing layer 30 includes a belt reinforcing layer cord 32 that is a cord forming the belt reinforcing layer 30. The belt reinforcing layer cord 32 is a metallic cord such as a steel cord. The belt reinforcing layer cord 32 of the belt reinforcing layer 30 is inclined within a range of 50 ° to 90 ° with respect to the tire circumferential direction, and the belt reinforcing layer 30 is thus inclined with respect to the tire circumferential direction. The plurality of belt reinforcing layer cords 32 are formed by being wound substantially in parallel. That is, the belt reinforcing layer cord 32 is formed so that the angle θ with respect to the tire equator line 3 is in the range of 50 ° to 90 °.

  When this pneumatic tire 1 is mounted on a vehicle (not shown) and travels, a load acts on the surface of the tread portion 5, that is, the tread surface 6 that is a surface that contacts the road surface due to the weight of the vehicle. When a load is applied to the tread surface 6, the load is transmitted to each portion located inward in the tire radial direction of the tread portion 5, and therefore also to the belt layer 20 provided on the inner side in the tire radial direction of the tread portion 5. Communicated. The belt layer 20 has a folded structure, and the inner belt 25 wraps both ends of the outer belt 23 in the tire width direction by forming a folded portion 26. Thereby, the restraining force in the tire width direction of the inner side belt 25 and the outer side belt 23 can be heightened, and the tension | tensile_strength of the both ends vicinity in the tire width direction of the belt layer 20 can be ensured. Therefore, the cornering power in the low load region can be improved.

  Moreover, both the inner side belt 25 and the outer side belt 23 are formed with the code | cord which consists of highly elastic nonmetallic fibers, such as an aramid. Since such a highly elastic non-metallic fiber is lighter than a metal, the tread portion including the belt layer 20 is formed by forming the belt layer 20 with a cord made of the highly elastic non-metallic fiber. 5 can be reduced in weight.

  In addition, a belt reinforcing layer 30 having a belt reinforcing layer cord 32 inclined within a range of 50 ° to 90 ° with respect to the tire circumferential direction is disposed on the inner side in the tire radial direction of the belt layer 20. The belt reinforcing layer 30 has a compression rigidity in the tire width direction by inclining the belt reinforcing layer cord 32 forming the belt layer 20 in the range of 50 ° to 90 ° with respect to the tire circumferential direction. Can be high. That is, by inclining the belt reinforcing layer cord 32 at an angle of 50 ° or more with respect to the tire circumferential direction, the belt reinforcing layer cord 32 becomes closer to the direction along the tire width direction, so that compression in the tire width direction is performed. Increases rigidity. For this reason, it is possible to increase the compression rigidity of the belt reinforcing layer in the tire width direction by inclining the belt reinforcing layer cord 32 within a range of 50 ° to 90 ° with respect to the tire circumferential direction. Therefore, by providing the belt reinforcing layer 30 on the inner side in the tire width direction of the belt layer 20, the compression rigidity in the tire width direction can be improved.

  Thus, by improving the compression rigidity in the tire width direction, even when a high load acts on the tread surface 6 and this load is received by the belt layer 20, the compression force in the tire width direction due to the high load is applied to the belt. It can be received by the reinforcing layer 30. As a result, the belt layer 20 can be prevented from being deformed in the tire radial direction by the compressive force in the tire width direction, and the contact area of the tread surface 6 can be secured, so that cornering power can be secured. That is, by using the compression rigidity of the belt reinforcing layer 30 in the tire width direction, occurrence of buckling when a high load is applied can be suppressed, and cornering power in a high load region can be secured. As a result, it is possible to improve the handling stability at high loads when the belt layer 20 has a folded structure while suppressing an increase in weight.

  In addition, since the belt reinforcement layer cord 32, which is the cord of the belt reinforcement layer 30, is formed of a steel cord, the compression rigidity of the belt reinforcement layer 30 in the tire width direction can be improved more reliably. That is, since the steel cord has higher rigidity than non-metallic fibers such as aramid, the belt reinforcing layer cord 32 is formed of the steel cord, so that the belt reinforcing layer 30 is more reliably compressed in the tire width direction. Stiffness can be improved. Thereby, the cornering power of a high load area can be improved more effectively. As a result, it is possible to improve the handling stability at high loads more reliably.

  Further, since the belt reinforcement layer end 31 is positioned closer to the tire equator line 3 than the belt layer end 21, the belt reinforcement layer 30 on both sides in the tire width direction of the belt layer 20 in the tire radial direction, A tread rubber that is a rubber material forming the tread portion 5 can be positioned. Thereby, since it can suppress that the rigidity of the belt layer edge part 21 vicinity becomes high too much, it can receive a bigger load and can improve cornering power. As a result, the steering stability can be improved more reliably.

  In particular, the cornering power can be improved more reliably by setting the distance D between the belt reinforcing layer end portion 31 and the belt layer end portion 21 to 10 mm or more. That is, by setting the distance D between the belt reinforcing layer end portion 31 and the belt layer end portion 21 to 10 mm or more, the rigidity in the vicinity of the belt layer end portion 21 is more reliably provided on both sides of the belt reinforcing layer 30 in the tire width direction. An amount of tread rubber can be provided that can be prevented from becoming too high. Thereby, it can receive a big load more reliably and can improve cornering power. As a result, the steering stability can be improved more reliably. In particular, a rubber layer having a maximum thickness gauge of at least 1 mm is disposed at positions 5 mm on both sides of the belt reinforcing layer end 31 in the tire width direction, so that a cushioning effect can be obtained more reliably and steering stability. It is possible to improve the performance.

  In the pneumatic tire 1 described above, the belt layer 20 is formed by two layers of the outer belt 23 and the inner belt 25, but the belt layer 20 may be three or more layers. The belt layer 20 includes at least two layers, and at least one belt layer 20 of the belt layers 20 is folded at both ends in the tire width direction so that both ends of the other belt layers 20 are folded. It only has to be wrapped. That is, the number of the belt layers 20 is not limited as long as the belt layer 20 has a folded structure.

  The outer belt 23 and the inner belt 25 are both formed of a cord made of a highly elastic nonmetallic fiber such as aramid, but both may not be formed of a cord made of a highly elastic nonmetallic fiber. Of the plurality of belt layers 20, at least one belt layer 20 may be formed of highly elastic non-metallic fibers. The high-elasticity non-metallic fiber forming the belt layer 20 may be a material other than aramid, such as nylon, a composite material of nylon and aramid, or an organic fiber such as polyolefin ketone or heat-resistant polyester. May be used. By forming at least one belt layer 20 with such highly elastic non-metallic fibers, it is possible to reduce the weight of the tread portion 5 on which the belt layer 20 is provided.

  In the belt reinforcing layer 30, the belt reinforcing layer cord 32 forming the belt reinforcing layer 30 is formed of a steel cord. However, the belt reinforcing layer cord 32 may be other than a steel cord, and may be made of a metallic material. What is necessary is just to be formed with the code | cord | chord. By forming the belt reinforcing layer cord 32 with a metallic cord, the compression rigidity in the tire width direction is increased, so that the cornering power in the high load region can be improved more effectively and more reliably at high loads. The steering stability can be improved.

  Hereinafter, the evaluation test of the performance performed about the pneumatic tire 1 of this invention and the pneumatic tire of the comparative example compared with the pneumatic tire of this invention about said pneumatic tire 1 is demonstrated. In the performance evaluation test, two items of the cornering power and the weight of the tread portion 5 were performed.

  This performance evaluation test was performed by mounting the 225 / 45R17 size pneumatic tire 1 on a 17 × 8 J rim wheel and adjusting the internal pressure to 200 kPa. As for the evaluation method of each test item, in the performance test for cornering power, the load is 3.0 kN when the pneumatic tire 1 to be tested is run by an indoor flat belt type testing machine at a speed of 10 km / h. The cornering power at 0 kN was measured. The evaluation is indicated by an index with the measured value of Comparative Example 1 described later as 100, and the larger the index value, the larger the cornering power and the better the performance with respect to the cornering power.

  Further, regarding the evaluation of the weight of the tread portion 5, each pneumatic tire 1 to be tested is different only in the form of the belt layer 20 and the belt reinforcing layer 30 provided in the tread portion 5, and therefore each pneumatic tire 1 1 was measured, and the difference was defined as the difference in the weight of the tread portion 5. The evaluation of the weight of the tread portion 5 is indicated by an index with a measured value of Comparative Example 1 described later as 100, and the larger the index value, the lighter the tread portion 5 is. It should be noted that the weight index of the tread portion 5 is not substantially different up to 4 points, and even if the index falls below 4 points, there is no substantial increase in weight.

  In these tests, Comparative Examples 1 to 5 and Inventions 1 to 6 to be compared with the pneumatic tire 1 according to the present invention are tested by the above-described methods. In the pneumatic tire 1 for performing this test, the belt layer 20 is entirely composed of the two belt layers 20 of the inner belt 25 and the outer belt 23. Among these pneumatic tires 1 to be tested, in the present inventions 1 to 6 and Comparative Examples 2, 3, and 4, the belt layer 20 has a folded structure, and in Comparative Examples 1 and 5, the belt layer 20 has a folded structure. It does not have a folded structure, but has a normal step structure in which a plurality of belt layers 20 are laminated.

  Further, in the first to sixth aspects of the invention and the comparative examples 2 and 3, the cord of at least one of the belt layers 20 of the inner belt 25 and the outer belt 23 is formed of aramid, In 4 and 5, the cords of the inner belt 25 and the outer belt 23 are both made of steel. In the inventions 1 to 6 and the comparative examples 3 to 5, the belt reinforcing layer 30 is disposed on the inner side in the tire radial direction of the belt layer 20, and in the comparative examples 1 and 2, the belt reinforcing layer 30 is provided. Is not provided.

  Moreover, among the pneumatic tires 1 in which the belt reinforcing layer 30 is provided, in the present inventions 1 to 6 and Comparative Examples 4 and 5, the inclination angle of the belt reinforcing layer cord 32 with respect to the tire circumferential direction is in the range of 50 ° to 90 °. In Comparative Example 3, the inclination angle of the belt reinforcing layer cord 32 with respect to the tire circumferential direction is 45 °, that is, less than 50 °. Moreover, among the pneumatic tires 1 in which the belt reinforcing layer 30 is provided, the widths of the belt reinforcing layer 30 in the present inventions 1 to 5 and Comparative Examples 2 to 5 are larger than the width of the belt layer 20 in the tire width direction. In the sixth aspect of the present invention, the width of the belt reinforcing layer 30 is wider than the width of the belt layer 20.

  These comparative examples 1 to 5 and pneumatic tires 1 of the present invention 1 to 6 are subjected to an evaluation test by the above method, and the obtained results are shown in Table 1-1 and Table 1-2. Among these Table 1-1 and Table 1-2, Table 1-1 has displayed the result of the evaluation test of Comparative Examples 1-5, and Table 1-2 is the result of the evaluation test of this invention 1-6. Is displayed.

  As apparent from the above test results shown in Table 1-1 and Table 1-2, the belt layer 20 has a folded structure, and the belt reinforcing layer cord 32 is provided on the inner side in the tire radial direction of the belt layer 20. By disposing the belt reinforcing layer 30 inclined within the range of 50 ° to 90 ° with respect to the circumferential direction, the cornering power in both the low load region and the high load region can be improved. In particular, when the belt reinforcing layer cord 32 is formed of a steel cord and the angle of the belt reinforcing layer cord 32 with respect to the tire circumferential direction is 90 °, the compression rigidity of the belt reinforcing layer 30 in the tire width direction is significantly increased. Therefore, the cornering power in the high load range can be improved more reliably (Invention 1, 4, 6).

  In addition, by forming at least one of the cords of the inner belt 25 and the outer belt 23 with aramid, the tread portion 5 can be reduced in weight. That is, as is clear from the test results, at least one of the plurality of belt layers 20 is formed of a highly elastic non-metallic fiber such as aramid so that the belt layer 20 has a folded structure, and the inner side of the belt layer 20 in the tire radial direction. On the side, the belt reinforcement layer 30 is provided with the belt reinforcement layer cord 32 inclined within a range of 50 ° to 90 ° with respect to the tire circumferential direction, so that the belt layer 20 is folded while suppressing an increase in weight. When the structure is adopted, it is possible to improve the handling stability at the time of high load.

  As described above, the pneumatic tire according to the present invention is useful when the belt layer is formed in a folded structure, and is particularly suitable for a pneumatic tire used even in a high load range.

It is a meridional sectional view showing the main part of the pneumatic tire according to the present invention. It is AA sectional drawing of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 3 Tire equatorial line 5 Tread part 6 Tread surface 7 Side wall part 8 Shoulder part 10 Carcass 15 Inner liner 16 Bead part 17 Bead core 20 Belt layer 21 Belt layer end part 23 Outer belt 25 Inner belt 26 Folding part 30 Belt Reinforcing layer 31 Belt reinforcing layer end 32 Belt reinforcing layer cord

Claims (3)

In a pneumatic tire comprising at least two belt layers, and wrapping both ends of the other belt layer by folding back both ends in the tire width direction of the belt layer of at least one of the belt layers,
At least one of the belt layers is made of a highly elastic non-metallic fiber,
A pneumatic tire is characterized in that a belt reinforcing layer having a cord inclined within a range of 50 ° to 90 ° with respect to the tire circumferential direction is disposed on the inner side in the tire radial direction of the belt layer. .   The pneumatic tire according to claim 1, wherein the cord included in the belt reinforcing layer is a steel cord.   The pneumatic tire according to claim 1 or 2, wherein an end portion of the belt reinforcing layer in the tire width direction is located closer to a tire equator line than an end portion of the belt layer in the tire width direction. .

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