JP5076322B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire that achieves both steering stability and road noise.

  One of noises caused by pneumatic tires is road noise. This road noise is a noise having a relatively low frequency generated in the passenger compartment when the vehicle travels on a rough road surface, and is one of the factors that greatly affect the vibration characteristics of the tire. Conventionally, by increasing the thickness of the tread rubber or reducing the spring constant of the tire, the vibration input of the tread portion due to road surface unevenness is reduced to reduce road noise.

  However, when the tread rubber is thickened, there arises a problem that steering stability is lowered in addition to an increase in tire mass and rolling resistance. On the other hand, when the spring constant is reduced, steering stability is deteriorated due to a decrease in tire side rigidity, and it is difficult to achieve both steering stability and road noise.

2. Description of the Related Art Conventionally, as a pneumatic tire mounted on a high-performance vehicle, a tire in which two carcass layers are extended between left and right bead portions so as to exhibit high exercise performance is known (for example, Patent Documents). 1). As described above, pneumatic tires mounted on high-performance vehicles having two carcass layers also have a problem that steering stability deteriorates when trying to improve road noise as described above, and countermeasures have been demanded. .
JP 2001-354017 A

  An object of the present invention is to provide a pneumatic tire in which two carcass layers are extended between left and right bead portions and which can achieve both steering stability and road noise.

In the pneumatic tire of the present invention that achieves the above object, bead cores are embedded in the left and right bead portions, bead fillers are arranged on the outer peripheral side of the bead core, and the two carcass layers are divided into the left and right without dividing the tread portion. In a pneumatic tire that extends continuously between bead portions and has a belt layer disposed on the outer peripheral side of the carcass layer of the tread portion, the reinforcing cord in which each carcass layer extends while being inclined with respect to the tire radial direction is provided in the tire. The two carcass layers are arranged at predetermined intervals in the circumferential direction, and the reinforcing cords that are inclined between the layers are configured such that the reinforcing cords that are inclined between the layers intersect with each other with the inclination direction with respect to the tire radial direction being opposite to each other. One of the carcass layers is arranged inside the tire from the other carcass layer, and both ends of the one carcass layer are folded around the bead core from the inside of the tire to the outside. Together with the outer peripheral edge of the bead filler extending to a position in the tire radial direction inner side, the carcass layer of the one extending the ends of the other carcass layer to a position in contact with the tire radial direction inner side of the bead core The bead core is engaged from the inside of the tire so as to be sandwiched between the bead core and the bead core and is not folded back around the bead core.

  According to the above-described present invention, since the bead filler is not completely enclosed by the end portions of the two carcass layers, vibration input transmitted from the road surface to the bead filler via the belt layer and the carcass layer can be reduced. Is possible. As a result, vibration transmitted from the bead filler to the bead core, that is, vibration transmitted to the vehicle body via the bead core can be suppressed, and road noise can be improved.

  Further, the reinforcing cords that incline the two carcass layers between the layers have a half radial structure in which the inclining direction with respect to the tire radial direction is reversed and intersect with each other, while the end portions of the two carcass layers are respectively as described above By engaging around the bead core, the rigidity of the side portion can be ensured, so that deterioration in steering stability can be suppressed. Therefore, even if the road noise is improved, the steering stability is not greatly deteriorated as in the prior art, and it is possible to achieve both the steering stability and the road noise.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings . FIG. 1 shows a basic form of a pneumatic tire according to the present invention, where 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion.

  A bead core 4 is embedded in each of the left and right bead portions 3, and a bead filler 5 having a triangular cross section extending to the sidewall portion 2 is disposed on the outer periphery of the bead core 4. The bead filler 5 has a height measured along the tire radial direction of approximately 15 to 50 mm.

  Two carcass layers 6, 7 extend between the left and right bead portions 3, and a plurality of belt layers 8 (two layers are illustrated in the figure) are provided on the outer peripheral side of the carcass layers 6, 7 of the tread portion 1. Is provided. A plurality of belt cover layers 9 in which organic fiber cords such as nylon cords are spirally wound in the tire circumferential direction are disposed on the outer peripheral side of the belt layer 8. The belt cover layer 9 includes a belt full cover layer 9 </ b> A that covers the entire belt layer 8, and a belt edge cover layer 9 </ b> B that covers both ends of the belt layer 8.

  As shown in FIG. 2, the carcass layers 6 and 7 have reinforcing cords f1 and f2 made of organic fiber cords such as nylon cords and polyester cords extending obliquely with respect to the tire radial direction TR. Are arranged at predetermined intervals and embedded in the rubber layers r1 and r2. In addition, the two carcass layers 6 and 7 are configured such that reinforcing cords f1 and f2 inclined between the layers intersect each other with the inclination direction with respect to the tire radial direction TR being opposite.

  Of the two carcass layers 6, 7, both end portions 6 a of one carcass layer 6 disposed on the inner side are folded around the bead core 4 from the tire inner side (one side) and beaded along the bead filler 5. The filler 5 extends from the outer peripheral end 5a to a position on the inner side in the tire radial direction. Both end portions 7a of the other outer carcass layer 7 are configured to engage only around the bead core 4 from the inner side of the tire and are not folded back around the bead core 4. The parts 6a and 7a prevent the bead filler 5 from being completely wrapped.

In FIG. 1, each end 7a of the carcass layer 7 is engaged around the bead core 4 so as to be in contact only with the tire axial direction inner side surface 4a of the bead core 4, but in the present invention, it is shown in FIG. as such, that extends to a position in contact with the tire radially inner surface 4b of the bead core 4 match engages around the bead core 4.

  According to the above-described present invention, the end portions 6a and 7a of the two carcass layers 6 and 7 do not completely enclose the bead filler 5 as described above, so that the belt layer 8 and the carcass layer are formed from the road surface. Since vibration input transmitted to the bead filler 5 through 6 and 7 can be reduced, vibration transmitted from the bead filler 5 to the vehicle body side via the bead core 4 is suppressed, and road noise is improved. Can do.

  On the other hand, the reinforcing cords f1 and f2 that incline the two carcass layers 6 and 7 between the layers have a half radial structure in which the inclination directions with respect to the tire radial direction TR are reversed and intersect with each other, and the end portions of the carcass layers 6 and 7 By engaging the 6a and 7a around the bead core 4 as described above, it is possible to ensure the rigidity of the side portion, so that it is possible to suppress deterioration in steering stability. Therefore, even if the road noise is improved, the steering stability is not greatly deteriorated as in the prior art, and it is possible to achieve both the steering stability and the road noise.

  In the present invention, the inclination angles A and B of the reinforcing cords f1 and f2 of the carcass layers 6 and 7 with respect to the tire circumferential direction TC are preferably in the range of 60 ° to 88 °. Even if the inclination angles A and B are smaller than 60 ° or exceed 88 °, the steering stability is lowered, which is not preferable. More preferably, it is 70 ° to 85 °.

  Each end portion 6a of the carcass layer 6 folded around the bead core 4 is preferably at or below the position P where the edge 6e is 20 mm outward from the inner peripheral end 4e of the bead core 4 in the tire radial direction (is the same as the position P or not)? It is preferable to be located on the inner side in the tire radial direction from the position P) and on the outer side in the tire radial direction from the outer peripheral end 4f of the bead core 4.

  Since this position P is generally the upper limit position that contacts the rim flange when the rim is assembled in a passenger car tire, the edge 6e can be pressed by the rim flange by setting the position P or less. Generation of separation and cracks at the edge 6e can be effectively suppressed. More preferably, the edge 6e is positioned within a range of 13 to 17 mm from the inner peripheral end 4e of the bead core 4 to the outer side in the tire radial direction.

  The present invention can be preferably used particularly for a pneumatic tire for a passenger car in which two carcass layers 6 and 7 are extended between the left and right bead portions 3.

The tire size is the same for 205 / 55R16 89V, and the basic structure shown in FIG. 1 (the inclination angles A and B of the reinforcing cords f1 and f2 are both 84 °, the edge 6e is the tire radial direction from the inner peripheral end 4e of the bead core 4) in 17mm positions) on the outside, the present invention tires were extended to both ends of the outer carcass layer to the tire radial direction inner side of the bead core as shown in FIG. 3, the outer carcass 4 layer 7 comparison tire except that the both end portions 7a is engaged from the tire outer side around the bead core 4 having the same structure as the underlying structure, both end portions 6a of the carcass layer 6 and 7 as shown in FIG. 5 and 7a folded outwardly from the tire inside around the bead core 4, the conventional tire having the same structure other is the underlying structure which is adapted to wrap the bead core 4 completely by the end 6a of the carcass layer 6 , And in the conventional tire 1 was prepared inclination angle A of the reinforcing cords of the carcass layer, B together 90 ° in the conventional tire 2, respectively.

  Each of these test tires is mounted on a rim having a rim size of 16 × 7 JJ, mounted on a vehicle (FR vehicle) having a displacement of 3000 cc with an air pressure of 230 kPa, and under the same load conditions as when two people are riding, When the steering stability and road noise were evaluated, the results shown in Table 1 were obtained.

Steering stability In the dry road test course, a feeling test by a test driver was performed, and the evaluation result was shown by a five-point method with the conventional tire 2 as three points. The higher this score, the better the steering stability.

Road noise Sensory evaluation was performed by a test driver on the in-vehicle noise when driving straight on a rough test road surface at a speed of 100 km / h, and the evaluation result was shown by a five-point method with three points for the conventional tire 2. The higher the score, the lower the road noise.

  In addition, together with sensory evaluation, vehicle interior noise is measured with a measuring instrument placed in the driver's seat of the test vehicle, and the difference in sound pressure level at the peak frequency (160 Hz) is defined as the reference [0 (dB)] for the conventional tire 2. Show. The greater the minus value, the lower the sound pressure level and the better the road noise.

  From Table 1, the tire of the present invention can obtain higher steering stability and road noise resistance than the conventional tire 2, while the road noise does not deteriorate as in the conventional tire 1 with higher steering stability. It can be seen that both stability and road noise can be achieved.

1 is a cross-sectional view of a main part of a tire meridian showing a form serving as a basis of a pneumatic tire of the present invention. It is explanatory drawing of the carcass layer of FIG. The main part of the implementation form of the pneumatic tire of the present invention is a schematic diagram showing in cross-section. It is the schematic which shows the principal part of a comparative tire in a cross section. It is the schematic which shows the principal part of the conventional tire 1 in a cross section.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Bead core 4e Inner peripheral end 4f Outer peripheral end 5 Bead filler 5a Outer peripheral end 6 Carcass layer 6X Carcass division | segmentation layer 6a End part 6e Edge 7 Carcass layer 7a End part 8 Belt layer A, B inclination Angle M Overlapping width P Position TC Tire circumferential direction TR Tire radial direction f1, f2 Reinforcement cord

Claims (4)

A bead core is embedded in the left and right bead portions, a bead filler is disposed on the outer periphery of the bead core, and the two carcass layers are extended so as to be continuous between the left and right bead portions without being divided at the tread portion. In a pneumatic tire in which a belt layer is arranged on the outer peripheral side of the carcass layer of the part,
Each of the carcass layers has a configuration in which reinforcing cords that are inclined and extend with respect to the tire radial direction are arranged at predetermined intervals in the tire circumferential direction, and the reinforcing cords that the two carcass layers are inclined between the layers are tires. The two carcass layers are arranged so as to cross each other with the inclination direction with respect to the radial direction being reversed, and one of the two carcass layers is disposed on the inner side of the tire than the other carcass layer, and both ends of the one carcass layer The portion is folded back from the inside of the tire around the bead core to the outside, and extends from the outer peripheral end of the bead filler to a position radially inward of the tire, and both ends of the other carcass layer are connected to the inner side surface of the bead core in the tire radial direction. contact position to extend engages the inside of the tire around the bead core so as to sandwich between one carcass layer and the bead core above and around the bead core Pneumatic tire is not folded configuration.   The pneumatic tire according to claim 1, wherein an inclination angle of the reinforcing cord of each carcass layer with respect to the tire circumferential direction is 60 ° to 88 °.   The pneumatic tire according to claim 2, wherein the inclination angle is 70 ° to 85 °.   The edge of the both ends of said one carcass layer is located below 20 mm from the inner peripheral end of the bead core to the outer side in the tire radial direction, and positioned at the outer side in the tire radial direction from the outer peripheral end of the bead core. Pneumatic tire described in 2.

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