JP2013184533A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively reduce columnar resonant sounds in a vehicle imparted with a negative camber.SOLUTION: In a pneumatic tire 1 for which a mounting direction to the inside and outside of a vehicle when being mounted to the vehicle is specified and which includes at least one layer of a carcass layer, side rubber S mounted to the outside in a tire width direction of the carcass layer 6 including a tire width direction maximum width position is provided, at least two layers of the side rubber S are mounted in the vehicle in the tire width direction, and with respect to the side rubber S1 outermost in the tire width direction at the inside of the vehicle, the side rubber S2 innermost in the tire width direction at the inside of the vehicle, and the side rubber S3 outside the vehicle, a loss tangent tanδ at a temperatures of 60°C has a relation of tanδS2>tanδS1≥tanδS3.

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire that reduces cavity resonance noise.

  One of noises generated by a pneumatic tire is cavity resonance sound (also referred to as cavity noise) due to vibration of air filled in the tire. This cavity resonance sound is an air column resonance generated when the tread portion is repeatedly deformed when the tire rolls to vibrate the internal air and the air moves as an air column through an annular lumen. .

  Conventionally, for example, in the pneumatic tire described in Patent Document 1, in order to reduce road noise in the vicinity of 250 Hz generated by the cavity resonance phenomenon caused by the length of the circular tube of the tire, the inner side of the inner liner or the carcass layer and the inner side of the tire is reduced. It is shown that a damping rubber layer having a loss tangent tan δ larger than that of the outer rubber layer positioned outside the tire with the carcass layer interposed therebetween is provided between the liner and the liner.

JP 2000-127709 A

  The pneumatic tire described in Patent Document 1 described above is devised to reduce noise caused by air column resonance by disposing a damping rubber in the tire. This pneumatic tire is a negative camber. This does not consider application to vehicles to which

  This invention is made in view of the above, Comprising: It aims at providing the pneumatic tire which can reduce air column resonance sound effectively with respect to the vehicle provided with the negative camber.

  In order to solve the above-described problems and achieve the object, the pneumatic tire according to the present invention is a pneumatic tire including at least one carcass layer in which a direction inside and outside the vehicle is specified when the vehicle is mounted. The side rubber provided at the outer side in the tire width direction and including the tire maximum width position is provided with at least two layers of the side rubber in the tire width direction on the inner side of the vehicle. The loss tangent tan δ at 60 ° C. of the side rubber S1, the innermost side rubber S2 in the tire width direction inside the vehicle, and the side rubber S3 outside the vehicle has a relationship of tan δS2> tan δS1 ≧ tan δS3.

  When mounted on a vehicle provided with a negative camber, the amount of deflection of the side rubber inside the vehicle is greater than that of the side rubber outside the vehicle. In this regard, according to the pneumatic tire of the present invention, the loss tangent tan δS1 at 60 ° C. of the side rubber S1 inside the vehicle is equal to or greater than the loss tangent tan δS3 at 60 ° C. of the side rubber S3 outside the vehicle, and 60 ° C. of the side rubber S2 inside the vehicle. Is made higher than the loss tangent tan δS3 at 60 ° C. of the side rubber S3 on the outside of the vehicle, thereby converting the kinetic energy of the sidewall portion into thermal energy and suppressing vibration transmission. As a result, air column resonance can be effectively reduced.

  Moreover, some side rubbers have a very large cross-sectional area in the meridional section depending on the tire size. When only the side rubber is made extremely high tan δ, the hysteresis loss of the entire tire becomes excessive, rolling resistance deteriorates, and high-speed durability is achieved. It can be a factor that leads to a decline in sex. In this regard, according to the pneumatic tire of the present invention, the side rubbers S1 and S2 inside the vehicle including the tire maximum width position are formed of a plurality of layers, and the vicinity of the tire maximum width position is made high tan δ. Reduction and other performance can be achieved. On the other hand, by reducing the tan δ of the side rubber S3 outside the vehicle including the tire maximum width position, it is possible to reduce cornering power under a high load and maximum cornering force, and to improve rollover resistance.

  In the pneumatic tire of the present invention, the loss tangent tan δS1 at 60 ° C. of the side rubber S1 is in the range of 0.15 or more and 0.25 or less, and the loss tangent tan δS2 at 60 ° C. of the side rubber S2 is 0.18. It is the range of 0.35 or less.

  According to this pneumatic tire, by defining the range of the loss tangents tan δ S1 and tan δ S2 of the side rubbers S1 and S2 at 60 ° C., the effect of reducing the air column resonance noise and the effect of achieving compatibility with other performances are remarkably obtained. be able to.

  In the pneumatic tire of the present invention, the loss tangent tan δS3 at 60 ° C. of the side rubber S3 is in the range of 0.05 or more and 0.10 or less.

  According to this pneumatic tire, by defining the range of the loss tangent tan δS3 at 60 ° C. of the side rubber S3, the effect of improving the rollover resistance can be remarkably obtained.

  The pneumatic tire according to the present invention can effectively reduce air column resonance noise with respect to a vehicle provided with a negative camber.

FIG. 1 is a meridional sectional view of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a chart showing the results of the performance test of the pneumatic tire according to the example of the present invention.

  Embodiments of the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. The constituent elements of this embodiment include those that can be easily replaced by those skilled in the art or those that are substantially the same. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

  FIG. 1 is a meridional sectional view of a pneumatic tire 1 according to the present embodiment. In the following description, the tire radial direction refers to a direction orthogonal to the rotation axis (not shown) of the pneumatic tire 1, and the tire radial direction inner side refers to the side toward the rotation axis in the tire radial direction, the tire radial direction outer side. Means the side away from the rotation axis in the tire radial direction. Further, the tire circumferential direction refers to a direction around the rotation axis as a central axis. Further, the tire width direction means a direction parallel to the rotation axis, the inner side in the tire width direction means the side toward the tire equator plane (tire equator line) CL in the tire width direction, and the outer side in the tire width direction means the tire width direction. Is the side away from the tire equatorial plane CL. The tire equatorial plane CL is a plane that is orthogonal to the rotation axis of the pneumatic tire 1 and passes through the center of the tire width of the pneumatic tire 1. The tire width is the width in the tire width direction between the portions located outside in the tire width direction, that is, the distance between the portions farthest from the tire equatorial plane CL in the tire width direction. The tire equator line is a line along the tire circumferential direction of the pneumatic tire 1 on the tire equator plane CL. In the present embodiment, the same sign “CL” as that of the tire equator plane is attached to the tire equator line.

  As shown in FIG. 1, the pneumatic tire 1 according to the present embodiment includes a tread portion 2, shoulder portions 3 on both sides thereof, and a sidewall portion 4 and a bead portion 5 that are sequentially continuous from the shoulder portions 3. ing. The pneumatic tire 1 includes a carcass layer 6, a belt layer 7, and a belt reinforcing layer 8.

  The tread portion 2 is made of a rubber material (tread rubber), is exposed at the outermost side in the tire radial direction of the pneumatic tire 1, and the surface thereof is the contour of the pneumatic tire 1. A tread surface 21 is formed on the outer peripheral surface of the tread portion 2, that is, on the tread surface that contacts the road surface during traveling. The tread surface 21 is provided with a plurality of (four in this embodiment) main grooves 22 that are straight main grooves extending along the tire circumferential direction and parallel to the tire equator line CL. The tread surface 21 extends along the tire circumferential direction by the plurality of main grooves 22, and a plurality of rib-like land portions 23 parallel to the tire equator line CL are formed. Although not shown in the figure, the tread surface 21 is provided with a lug groove that intersects the main groove 22 in each land portion 23. The land portion 23 is divided into a plurality of portions in the tire circumferential direction by lug grooves. Further, the lug groove is formed to open to the outer side in the tire width direction on the outermost side in the tire width direction of the tread portion 2. Note that the lug groove may have either a form communicating with the main groove 22 or a form not communicating with the main groove 22.

  The shoulder portion 3 is a portion on both outer sides in the tire width direction of the tread portion 2. Further, the sidewall portion 4 is exposed at the outermost side in the tire width direction of the pneumatic tire 1. The bead unit 5 includes a bead core 51 and a bead filler 52. The bead core 51 is formed by winding a bead wire, which is a steel wire, in a ring shape. The bead filler 52 is a rubber material disposed in a space formed by folding the end portion in the tire width direction of the carcass layer 6 at the position of the bead core 51.

  The carcass layer 6 is configured such that each tire width direction end portion is folded back from the tire width direction inner side to the tire width direction outer side by a pair of bead cores 51 and is wound around in a toroidal shape in the tire circumferential direction. It is. The carcass layer 6 is formed by coating a plurality of carcass cords (not shown) arranged in parallel at an angle in the tire circumferential direction with an angle with respect to the tire circumferential direction being along the tire meridian direction. The carcass cord is made of organic fibers (polyester, rayon, nylon, etc.). The carcass layer 6 is shown in FIG. 1 as being provided with two layers, but is provided with at least one layer.

  The belt layer 7 has a multilayer structure in which at least two belts 71 and 72 are laminated, and is disposed on the outer side in the tire radial direction which is the outer periphery of the carcass layer 6 in the tread portion 2 and covers the carcass layer 6 in the tire circumferential direction. It is. The belts 71 and 72 are made by coating a plurality of cords (not shown) arranged in parallel at a predetermined angle (for example, 20 degrees to 30 degrees) with a coat rubber with respect to the tire circumferential direction. The cord is made of steel or organic fiber (polyester, rayon, nylon, etc.). Further, the overlapping belts 71 and 72 are arranged so that the cords intersect each other.

  The belt reinforcing layer 8 is disposed on the outer side in the tire radial direction which is the outer periphery of the belt layer 7 and covers the belt layer 7 in the tire circumferential direction. The belt reinforcing layer 8 in the present embodiment has reinforcing layers 81 and 82 arranged in two layers so as to cover the outer periphery of the belt layer 7. The reinforcing layers 81 and 82 are made by coating a plurality of cords (not shown) arranged in parallel in the tire circumferential direction (± 5 degrees) in the tire width direction with a coat rubber. The cord is made of steel or organic fiber (polyester, rayon, nylon, etc.). The belt reinforcement layer 8 shown in FIG. 1 is arranged so that the reinforcement layer 81 on the belt layer 7 side is formed larger in the tire width direction than the belt layer 7 so as to cover the entire belt layer 7. The outer reinforcing layer 82 is disposed only at the end portion in the tire width direction of the reinforcing layer 81 so as to cover the end portion in the tire width direction of the belt layer 7. The configuration of the belt reinforcing layer 8 is not limited to the above, and is not clearly shown in the drawing, but the reinforcing layers 81 and 82 are both formed larger in the tire width direction than the belt layer 7 and are arranged so as to cover the entire belt layer 7. Alternatively, the reinforcing layer 81 and the reinforcing layer 82 may be arranged so as to cover only the end portion in the tire width direction of the belt layer 7. Further, the belt reinforcing layer 8 may be configured by any one of the reinforcing layers 81 and 82. That is, the belt reinforcing layer 8 overlaps at least the end portion in the tire width direction of the belt layer 7. The belt reinforcing layer 8 (reinforcing layers 81 and 82) is provided by winding a strip-shaped strip material (for example, a width of 10 [mm]) in the tire circumferential direction.

  Moreover, when the pneumatic tire 1 of this Embodiment is mounted | worn with a vehicle (not shown), the direction with respect to the inner side and the outer side of a vehicle is designated in the tire width direction. The designation of the direction is not clearly shown in the figure, but is indicated by, for example, an index provided on the sidewall portion 4. Hereinafter, the side facing the inside of the vehicle when mounted on the vehicle is referred to as the inside of the vehicle, and the side facing the outside of the vehicle is referred to as the outside of the vehicle. The designation of the vehicle inner side and the vehicle outer side is not limited to the case where the vehicle is mounted. For example, when the rim is assembled, the direction of the rim with respect to the inside and outside of the vehicle is determined in the tire width direction. For this reason, when the rim is assembled, the pneumatic tire 1 is designated with respect to the inner side (vehicle inner side) and the outer side (vehicle outer side) of the vehicle in the tire width direction.

  In the pneumatic tire 1 configured as described above, the side rubber S is provided so as to include the tire maximum width position P outside the carcass layer 6 in the tire width direction. The side rubber S constitutes the sidewall portion 4. And on the vehicle inner side, it is composed of at least two layers of side rubbers S1 and S2, and on the vehicle outer side, it is composed of side rubber S3. In the side rubber S, the loss tangent tan δS1 at 60 ° C. of the side rubber S1, the loss tangent tan δS2 at 60 ° C. of the side rubber S2, and the loss tangent tan δS3 of the side rubber S3 at 60 ° C. have a relationship of tan δS2> tan δS1 ≧ tan δS3.

  Here, when the side rubber S is composed of three or more layers in the tire width direction on the inner side of the vehicle, the outermost side in the tire width direction on the inner side of the vehicle corresponds to the side rubber S1, and the innermost side in the tire width direction on the inner side of the vehicle. It corresponds to the side rubber S2. Further, on the vehicle outer side, the side rubber is composed of a single layer or a plurality of layers in the tire width direction, and tan δS3 in the case of a plurality of layers is an average of the respective layers.

  Thus, in the pneumatic tire 1 of the present embodiment, the side rubber S provided outside the carcass layer 6 in the tire width direction and including the tire maximum width position P is at least in the tire width direction on the vehicle inner side. Two layers are provided, and the loss tangent tan δ at 60 ° C. of the side rubber S1 at the outermost side in the tire width direction inside the vehicle, the side rubber S2 at the innermost side in the tire width direction at the inner side of the vehicle, and the side rubber S3 at the outer side of the vehicle is tanδS2> tanδS1 ≧ tanδS3.

  When mounted on a vehicle provided with a negative camber, the side rubber S on the inner side of the vehicle has a larger amount of deflection than the side rubber S on the outer side of the vehicle. In this regard, according to the pneumatic tire 1 of the present embodiment, the loss tangent tan δS1 at 60 ° C. of the side rubber (S1) inside the vehicle is equal to or greater than the loss tangent tan δ S3 at 60 ° C. of the side rubber (S3) outside the vehicle. By making the loss tangent tan δS2 of the inner side rubber (S2) at 60 ° C. higher than the loss tangent tan δS3 of the side rubber (S3) of the vehicle outside at 60 ° C., the kinetic energy of the sidewall portion 4 is converted into thermal energy, and vibration is generated. Suppress transmission. As a result, air column resonance can be effectively reduced.

  Moreover, the side rubber S has a very large cross-sectional area in the meridional section depending on the tire size, and when only the side rubber S is made extremely high tan δ, the hysteresis loss is excessive as a whole tire, the rolling resistance is deteriorated, It can be a factor that leads to a decrease in high-speed durability. In this regard, the pneumatic tire 1 of the present embodiment is configured such that the vehicle-side side rubber S (S1, S2) including the tire maximum width position P is composed of a plurality of layers, and the vicinity of the tire maximum width position P is increased to tan δ. Thus, it is possible to achieve both reduction of air column resonance and other performance. On the other hand, by reducing the tan δ of the side rubber S (S3) outside the vehicle including the tire maximum width position P, it is possible to reduce cornering power and maximum cornering force under high load and improve rollover resistance. Become.

  Further, the loss tangent tan δS1 at 60 ° C. of the side rubber S1 is in the range of 0.15 to 0.25, and the loss tangent tan δS2 of the side rubber S2 at 60 ° C. is in the range of 0.18 to 0.35. Is preferred.

  According to the pneumatic tire 1, as described above, by defining the range of the loss tangent tan δ S1 and tan δ S2 of the side rubbers S1 and S2 at 60 ° C., the effect of reducing air column resonance noise and the effect of achieving compatibility with other performances Can be obtained remarkably.

  The loss tangent tan δS3 at 60 ° C. of the side rubber S3 is preferably in the range of 0.05 or more and 0.10 or less.

  According to the pneumatic tire 1, as described above, by defining the range of the loss tangent tan δS3 at 60 ° C. of the side rubber S3, the effect of improving the rollover resistance can be remarkably obtained.

  In this example, performance tests regarding air column resonance (cavity noise), road noise, and rollover resistance performance were performed on a plurality of types of pneumatic tires with different conditions (see FIG. 2).

  In this performance test, a pneumatic tire having a tire size of 215 / 55R17 is assembled on a regular rim (17 × 7J), filled with a regular internal pressure (230 [kPa]), and a test vehicle having a displacement of 2500 [cc]. It was mounted on a domestic minivan type vehicle.

  The regular rim is “standard rim” defined by JATMA, “Design Rim” defined by TRA, or “Measuring Rim” defined by ETRTO. The normal internal pressure is “maximum air pressure” defined by JATMA, the maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO.

  The evaluation method of the air column resonance sound is that the above test vehicle is driven at a speed of 60 [km / h] on the test course, the sound pressure level of the vehicle sound is measured, and the cavity resonance in a narrow-band waveform near 200 to 250 Hz is measured. The peak level [dB] of the sound was measured. This measured value indicates that the columnar resonance is reduced as the numerical value is smaller.

  The road noise is evaluated by sensory evaluation by one skilled test driver with respect to in-vehicle noise that travels on the test course at 60 [km / h] on the test vehicle. This sensory evaluation uses a conventional pneumatic tire as a reference (3), and performs a five-step evaluation in 0.125 increments. This evaluation shows that road noise is reduced as the value increases.

  The rollover resistance evaluation method is as follows. In the above test vehicle, the travel road A is 10.0 [m] in width 3 [m], and 1 [m] in width 13.5 [m] ahead of the travel road A. From a traveling route B having a width of 3 [m] and a length of 11.0 [m] with a distance from each other, from a traveling route C arranged 12.5 [m] ahead of the traveling route A in a straight line. In accordance with the Doyle Elk test course, an elk test that enters the road A at 100 [km] per hour and turns off the accelerator and passes through the road A → the road B → the road C is performed by one skilled test driver. Perform by sensory evaluation. This sensory evaluation is indicated by an index based on a conventional pneumatic tire as a reference (100), and the higher the index, the better the rollover resistance.

  In FIG. 2, the pneumatic tire of the conventional example has a single side rubber (S1, S3) in the tire width direction on both the vehicle inner side and the vehicle outer side. In the pneumatic tires of the comparative example and the example, the side rubber inside the vehicle has two layers (S1, S2), and the side rubber outside the vehicle has a single layer (S3).

  In the conventional pneumatic tire, the loss tangent tan δS1 of the side rubber S1 at 60 ° C. and the loss tangent tan δS3 of the side rubber S3 at 60 ° C. are the same. Further, the pneumatic tire of Comparative Example 1 has the loss tangent tan δS1 at 60 ° C. of the side rubber S1 and the loss tangent tan δS3 at 60 ° C. of the side rubber S3, and the loss tangent tan δS2 of the side rubber S2 at 60 ° C. is higher than these. It is low. In the pneumatic tire of Comparative Example 2, the loss tangent tan δS2 of the side rubber S2 at 60 ° C. is the same as the loss tangent tan δS3 of the side rubber S3 at 60 ° C., and the loss tangent tan δS1 of the side rubber S1 at 60 ° C. is lower than these. doing.

  On the other hand, in the pneumatic tires of Examples 1 to 8, the loss tangent tan δS1 of the side rubber S1 at 60 ° C., the loss tangent tan δS2 of the side rubber S2 at 60 ° C., and the loss tangent tan δS3 of the side rubber S3 at 60 ° C. > Tan δS1 ≧ tan δS3. In the pneumatic tires of Examples 2 to 4, the loss tangents tan δS1 and tan δS2 are set within a specified range. In the pneumatic tire of Example 5, the loss tangent tan δS3 is set within a specified range. Further, in the pneumatic tires of Examples 6 to 8, loss tangents tan δS1, tan δS2, and tan δS3 are set within a specified range.

  As shown in the test results of FIG. 2, the pneumatic tires of Examples 1 to 8 have reduced air column resonance sound (cavity noise) and road noise, and improved rollover resistance. I understand.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 4 Side wall part P Tire maximum width position S (S1, S2, S3) Side rubber

Claims (3)

In a pneumatic tire provided with at least one carcass layer in which the direction inside and outside the vehicle is specified when the vehicle is mounted,
Regarding the side rubber provided outside the carcass layer in the tire width direction and including the tire maximum width position, at least two layers of the side rubber are provided in the tire width direction inside the vehicle, and the tire width direction inside the vehicle The loss tangent tan δ at 60 ° C. of the outermost side rubber S1, the innermost side rubber S2 in the tire width direction on the inner side of the vehicle, and the side rubber S3 on the outer side of the vehicle has a relationship of tan δS2> tan δS1 ≧ tan δS3. Pneumatic tire.   The loss tangent tan δS1 at 60 ° C. of the side rubber S1 is in the range of 0.15 to 0.25, and the loss tangent tan δS2 of the side rubber S2 at 60 ° C. is in the range of 0.18 to 0.35. The pneumatic tire according to claim 1.   The pneumatic tire according to claim 1 or 2, wherein the loss tangent tan δS3 at 60 ° C of the side rubber S3 is in a range of 0.05 to 0.10.