JP2013095233A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of reducing cavity resonance sound and tire mass without degrading rolling resistance and riding comfort.SOLUTION: A side rubber layer 20 positioned at the outside of a carcass layer 4 in the tire width direction in a sidewall section 2 is divided into an outer layer 20A, a middle layer 20B and an inner layer 20C. The tanδand the hardness of a rubber composition contained in the middle layer 20B are set to be higher than those of a rubber composition contained in the outer layer 20A and the inner layer 20C. The tanδ and the hardness of the rubber composition contained in the middle layer 20B is set to be not less than 0.17 and not less than 58, respectively. The tanδ and the hardness of the rubber composition contained in the outer layer 20A and the inner layer 20C are set to be not less than 0.05 but not more than 0.20, and not less than 40 but not more than 60, respectively.

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can reduce cavity resonance noise and tire mass without deteriorating rolling resistance and riding comfort.

  In a pneumatic tire, one of the causes for generating noise is cavity resonance sound caused by vibration of air filled in the tire. The cavity resonance sound is generated when the tread portion vibrates due to road surface irregularities when the tire rolls, and the vibration of the tread portion vibrates the air inside the tire.

  Conventionally, as a technique for reducing such cavity resonance noise, it has been proposed to install a sound absorbing material made of a porous material on the inner surface of a tread portion of a pneumatic tire (see, for example, Patent Document 1). However, the method of installing such a sound absorbing material does not suppress the cavity resonance phenomenon itself, but absorbs the cavity resonance sound generated by the cavity resonance phenomenon. Even if it was possible, it was not the fundamental solution to the cavity resonance phenomenon. Further, since it is essential to add a sound absorbing material as a new member to the tire, there is a problem that an increase in tire mass, a reduction in uniformity, an increase in cost, and the like occur.

  Alternatively, as a technique for reducing the cavity resonance without using the sound absorbing material as described above, it has been proposed to make the rubber thickness and density near the tire maximum width larger than other parts (for example, Patent Document 2). reference). That is, by increasing the rubber thickness and density, the vibration of the sidewall part that causes the cavity resonance noise is suppressed. However, when the rubber thickness and density are increased in this way, there is a problem that the tire mass increases or the ride comfort and rolling resistance deteriorate due to the increase in the longitudinal rigidity accompanying the increase in the rubber thickness and density. .

Japanese Patent No. 4148777 JP-A-4-43107

  An object of the present invention is to solve the above-mentioned problems, and to provide a pneumatic tire that can reduce cavity resonance noise and tire mass without deteriorating rolling resistance and riding comfort. is there.

  In order to achieve the above object, the pneumatic tire of the present invention includes a pair of bead portions, sidewall portions extending radially outward from the bead portions, and a cylindrical shape connecting the radially outer sides of the sidewall portions. A tread portion, and at least one carcass layer is mounted between the pair of bead portions, and both ends of the carcass layer are wound from the inside of the tire to the outside so as to sandwich a bead filler around the bead core. In the pneumatic tire, a side rubber layer positioned on the outer side in the tire width direction of the carcass layer in the sidewall portion is between an outer layer positioned on the outer side in the tire radial direction, an inner layer positioned on the inner side in the tire radial direction, the outer layer, and the inner layer. And the tan δ at 60 ° C. of the rubber composition contained in the intermediate layer is divided into the outer layer and the intermediate layer The rubber composition contained in the layer is higher than tan δ at 60 ° C., and the hardness of the rubber composition contained in the intermediate layer at 20 ° C. is higher than the hardness of the rubber composition contained in the outer layer and the inner layer at 20 ° C. The tan δ at 60 ° C. of the rubber composition contained in the middle layer is 0.17 or more and the hardness at 20 ° C. is 58 or more, and the tan δ at 60 ° C. of the rubber composition contained in the outer layer and the inner layer is increased. The hardness is 0.05 or more and 0.20 or less, and the hardness at 20 ° C. is 40 or more and 60 or less.

  In the present invention, as described above, the side rubber layer constituting the sidewall portion is divided into three layers laminated in the tire radial direction, and tan δ at 60 ° C. of the rubber composition contained in the middle layer is contained in the outer layer and the inner layer. Since the hardness at 20 ° C. of the rubber composition contained in the middle layer is higher than the hardness at 20 ° C. of the rubber composition contained in the outer layer and the inner layer, the rolling resistance is higher. In addition, the cavity resonance noise and the tire mass can be reduced without deteriorating riding comfort. Specifically, by setting the middle layer to high tan δ and high hardness, the middle layer has high hysteresis loss and high rigidity, so that the middle layer, which has a large contribution to the cavity resonance sound, is less likely to vibrate, and vibration is generated. However, since the vibration can be absorbed, the cavity resonance can be effectively suppressed. In addition, there is a concern that rolling resistance and riding comfort may deteriorate due to high tan δ and high hardness, but the region where high tan δ and high hardness are limited to the middle layer, and the outer and inner layers are relatively low tan δ and low. Since the hardness is set, it is possible to offset the deterioration of rolling resistance and riding comfort due to high tan δ and high hardness of the middle layer, and to improve rolling resistance and riding comfort. Furthermore, because it corresponds to the cavity resonance sound, rolling resistance, and riding comfort only by the physical properties of the rubber composition of the side rubber layer, it is possible to add a new sound absorbing material or increase the thickness and density of the rubber. Compared with the tire, the mass of the tire can be reduced. In particular, since the tan δ and hardness of the rubber composition contained in each layer are set in the above ranges, the above-described tire performance can be highly compatible.

In the present invention, the height H _Li of the boundary Li between the middle layer and the inner layer is set in the range of 20% to 25% of the tire sectional height SH, and the height H _Lo of the boundary Lo between the middle layer and the outer layer is set to the tire cross section. and 45% to 50% of the height SH, and it is preferable that the height H _P of the tire maximum width position P in the range of 30% to 40% of the tire section height SH.

By thus setting the height H _P of the height H _Lo and maximum tire width position P of the boundary Lo between the height H _Li and middle and outer boundaries Li between middle and inner layer, the deflection of the tire Since the maximum tire width position P, which is the maximum portion, is arranged at a low position in the tire radial direction, and the maximum tire width position P is located near the center in the tire radial direction of the middle layer, the cavity resonance noise is further reduced. I can do it.

In the present invention, it is preferable that the height H _F of the tire radial direction outer end of the bead filler in the range of 25% to 45% of the tire section height SH.

By thus setting the height H _F of the tire radial direction outer end of the bead filler, placing the tire radial direction outer end of the bead filler in the tire radial direction inside part from the tire maximum width position P of the middle layer Therefore, it is possible to further improve the riding comfort and reduce the tire mass while keeping the cavity resonance sound low.

  In the present invention, the flatness is preferably 50% or more. If the tire has a high aspect ratio of 50% or more, the tire cross-section height SH increases, so the cross-sectional area of the side rubber layer that greatly contributes to each tire performance increases, and the above-mentioned tire performance is further enhanced. Can be compatible.

  In the present invention, tan δ at 60 ° C. is based on JIS K6394, using a viscoelastic spectrometer (manufactured by Toyo Seiki Seisakusho), temperature 60 ° C., frequency 20 Hz, static strain 10%, dynamic strain ± 2 % Is a conditional value. Moreover, the hardness as used in the field of this invention is the durometer hardness prescribed | regulated to JISK6253, Comprising: It is the hardness measured in the temperature of 20 degreeC with the type A durometer.

It is a meridian half section view showing a pneumatic tire according to an embodiment of the present invention.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.

  In FIG. 1, 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion. A carcass layer 4 is mounted between the pair of left and right bead portions 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction, and is folded from the tire inner side to the outer side around the bead core 5 disposed in each bead portion 3. A bead filler 6 is disposed on the outer periphery of the bead core 5, and the bead filler 6 is wrapped by the main body portion and the folded portion of the carcass layer 4.

  On the other hand, a plurality of belt layers 7 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. These belt layers 7 include a plurality of reinforcing cords inclined with respect to the tire circumferential direction, and are arranged so that the reinforcing cords cross each other between the layers. In the belt layer 7, the inclination angle of the reinforcing cord with respect to the tire circumferential direction is set in a range of, for example, 10 ° to 40 °. Further, a belt reinforcing layer 8 is provided on the outer peripheral side of the belt layer 7. The cord angle of the belt reinforcing layer 8 with respect to the tire circumferential direction is 5 ° or less, more preferably 3 ° or less.

  In addition, in this invention, the cross-sectional shape of a tire is not limited to the aspect of FIG. 1, What kind of thing may be used if it is a general pneumatic tire.

  In the present invention, the side rubber layer 20 positioned on the outer side in the tire width direction of the carcass layer 4 in the sidewall portion 2 is divided into three, an outer layer 20A positioned on the outer side in the tire radial direction, and an inner layer 20C positioned on the inner side in the tire radial direction. The intermediate layer 20B is located between the outer layer 20A and the inner layer 20C. The tan δ at 60 ° C. of the rubber composition contained in the middle layer 20B is higher than the tan δ at 60 ° C. of the rubber compositions contained in the outer layer 20A and the inner layer 20C, and the hardness at 20 ° C. of the rubber composition contained in the middle layer 20B. Is set higher than the hardness at 20 ° C. of the rubber composition contained in the outer layer 20A and the inner layer 20C.

  By making the middle layer 20B of the side rubber layer 20 relatively high tan δ and high hardness in this way, the middle layer 20B has high hysteresis loss and high rigidity, and therefore, the middle layer 20B that greatly contributes to the cavity resonance sound hardly vibrates. Furthermore, even if vibration occurs, the vibration can be absorbed, so that the cavity resonance can be effectively suppressed. In addition, there is a concern that rolling resistance and ride comfort may deteriorate due to high tan δ and high hardness, but the region where high tan δ and high hardness are limited to the middle layer 20B, and the outer layer 20A and the inner layer 20C are relatively low. Since the tan δ is low and the hardness is low, the deterioration of the rolling resistance and riding comfort due to the high tan δ and high hardness of the middle layer 20B can be offset, and the rolling resistance and riding comfort can be improved. Furthermore, since only the physical properties of the rubber composition of the side rubber layer 20 correspond to cavity resonance sound, rolling resistance, and riding comfort, a conventional tire that newly adds a sound absorbing material or increases the thickness and density of the rubber. The mass of the tire can be reduced as compared with. Thus, while improving rolling resistance and riding comfort, cavity resonance sound and tire mass can be reduced and these tire performances can be made compatible. At this time, if the magnitude relationship between tan δ and hardness is reversed, rolling resistance and riding comfort deteriorate, and cavity resonance noise cannot be reduced.

  In the present invention, the tan δ at 60 ° C. of the rubber composition contained in the intermediate layer 20B is set to 0.17 or more and the hardness at 20 ° C. is set to 58 or more in the above-described relationship between tan δ and hardness. Further, the tan δ at 60 ° C. of the rubber composition contained in the outer layer 20A and the inner layer 20C is set to 0.05 to 0.20, and the hardness at 20 ° C. is set to 40 to 60.

  Thereby, the above-mentioned tire performance can be more highly compatible. If the tan δ at 60 ° C. of the rubber composition contained in the middle layer 20B is less than 0.17, the middle layer 20B cannot be made sufficiently high in hysteresis loss, and cavity resonance noise cannot be reduced sufficiently. Similarly, if the hardness at 20 ° C. of the rubber composition contained in the middle layer 20B is less than 58, the middle layer 20B cannot be made sufficiently rigid, and the effect of reducing cavity resonance noise cannot be obtained sufficiently. In practice, the rubber composition contained in the middle layer 20B preferably has a tan δ at 60 ° C. of 0.30 or less and a hardness at 20 ° C. of 70 or less.

  If the tan δ at 60 ° C. of the rubber composition contained in the outer layer 20A and the inner layer 20C is smaller than 0.05, the hysteresis loss of the outer layer 20A and the inner layer 20C becomes too low, so that sufficient breaking strength cannot be obtained. Conversely, if the tan δ at 60 ° C. of the rubber composition contained in the outer layer 20A and the inner layer 20C is greater than 0.20, the hysteresis loss of the outer layer 20A and the inner layer 20C cannot be sufficiently reduced, and the rolling resistance and multiplication are reduced. Comfort deteriorates. If the hardness at 20 ° C. of the rubber composition contained in the outer layer 20A and the inner layer 20C is less than 40, the rigidity of the outer layer 20A and the inner layer 20C becomes too low, and the durability of the tire decreases. Conversely, if the hardness at 20 ° C. of the rubber composition contained in the outer layer 20A and the inner layer 20C is greater than 60, the rigidity of the outer layer 20A and the inner layer 20C cannot be sufficiently lowered, and rolling resistance and riding comfort are reduced. Getting worse.

  In particular, after setting the tan δ and hardness of each layer within the above ranges, tan δ at 60 ° C. of the rubber composition contained in the middle layer 20B and tan δ at 60 ° C. of the rubber compositions contained in the outer layer 20A and the inner layer 20C. Is preferably set in a range of 0.1 to 0.2. Similarly, the difference between the hardness at 20 ° C. of the rubber composition contained in the middle layer 20B and the hardness at 20 ° C. of the rubber compositions contained in the outer layer 20A and the inner layer 20C is preferably set in the range of 5-15. In this manner, by reducing the difference in tan δ and hardness of each layer within a specific range, it is possible to achieve both a reduction in cavity resonance noise and an improvement in rolling resistance and riding comfort.

Here, although the middle layer 20B is disposed between the outer layer 20A and the inner layer 20C, the height H _Li of the boundary Li between the middle layer 20B and the inner layer 20C is set within a range of 20% to 25% of the tire cross-section height SH. At the same time, the height H _Lo of the boundary Lo between the middle layer 20B and the outer layer 20A is preferably in the range of 45% to 50% of the tire cross-section height SH. Furthermore, with respect to this arrangement the intermediate layer 20B, it is preferable that the height H _P of the maximum width position P tire in the range of 30% to 40% of the tire section height SH. The heights H _Li and H _Lo are the heights from the bead heel to the boundaries Li and Lo. When the boundaries Li and Lo are inclined with respect to the tire axial direction, the heights H _Li and H _Lo are , The height of the midpoint of each of the boundaries Li and Lo.

By thus setting the height H _P of the height H _Lo and maximum tire width position P of the boundary Lo between the height H _Li and intermediate 20B and an outer layer 20A of the border Li of the middle 20B and the inner layer 20C, Since the tire maximum width position P, which is the portion where the tire deflection is maximized, is disposed at a position lower in the tire radial direction, and the tire maximum width position P is located near the center of the middle layer 20B, the cavity resonance sound is further increased. Can be reduced. Therefore, the height H _P of the maximum width position P tire as about 35% of the tire section height SH, it is particularly preferable to arrange the position coincident with the center of the tire radial direction of the middle 20B arranged within the above range .

At this time, 20 percent and less than the height H _Li tire section height SH of the boundary Li, rolling resistance and ride comfort properties for middle 20B is increased on the inner side in the tire radial direction is high hysteresis loss and high rigidity deteriorate To do. On the contrary, if the height H _Li of the boundary Li is larger than 25% of the tire cross-section height SH, the middle layer 20B having high hysteresis loss and high rigidity is reduced, so that the effect of reducing the cavity resonance noise cannot be sufficiently obtained. . Further, 45% and smaller than the height H _Lo tire section height SH of the boundary Lo, can not be obtained sufficiently effect of reducing the cavity resonance for middle 20B decreases a high hysteresis loss and high rigidity. Conversely, 50% larger than the height H _Lo tire section height SH of the boundary Lo, rolling resistance and ride comfort properties for middle 20B is increased outward in the tire radial direction is high hysteresis loss and high rigidity deteriorate To do. Furthermore, the height H _P of the maximum width position P tire is less than 30% of the tire section height SH, rigidity of the vicinity of the tire maximum width position P by force occurs in the carcass line is reduced. Conversely, when the height H _P of the maximum width position P tire is greater than 40% of the tire section height SH, cavity resonance for eccentric deformation increases is deteriorated.

  In addition, after setting the position of the middle layer 20B as described above, the height of the outer end 20Ao in the tire radial direction of the outer layer 20A is set to a range of 75% to 85% of the tire cross-section height, and the inner layer 20C The height of the tire radial direction inner end 20Ci can be in the range of 10% to 15% of the tire cross-section height.

In the present invention, it is preferable that the height H _F of the tire radially outer end 6o of the bead filler 6 to the range of 25% to 45% of the tire section height SH. By thus setting the height H _F of the tire radially outer end 6o of the bead filler 6, the tire radial direction outer end of the bead filler 6 to the tire radial direction inside part from the tire maximum width position P of the middle layer 20B Since the portion 6o can be disposed, the riding comfort can be further improved and the tire mass can be reduced while keeping the cavity resonance sound low.

At this time, the height H _F of the tire radially outer end 6o of the bead filler 6 is less than 25% of the tire section height SH, rigidity of the vicinity of the tire maximum width position P is lowered, cavity resonance is degraded . Conversely, the height H _F of the tire radially outer end 6o of the bead filler 6 is greater than 45% of the tire section height SH, it is impossible to suppress the amount of the bead filler 6, sufficient tire mass It cannot be reduced.

In the present invention, the middle layer 20B and the thickness G _B with thinner than the thickness G _C thickness G _A and the inner layer 20C of the outer layer 20A, the thickness G _A of the outer layer 20A below 3.0mm or 6.0mm the thickness G _B of the middle layer 20B to 1.0mm or 4.0mm or less, it is preferable that the thickness G _C of the inner layer 20C below 3.0mm or 6.0 mm.

Thus, by setting the rubber thicknesses G _A , G _B , and G _C of the respective layers 20A, 20B, and 20C in the side rubber layer 20, the amount of rubber used in each layer is balanced, and the above-described tire performance is improved. Can be compatible. In particular, the tire mass can be reduced. The thickness G _A of the outer layer 20A is deteriorated is 3.0mm smaller than cut resistance. Conversely, the rubber thickness G _A of the outer layer 20A is larger than 6.0 mm, it can not be sufficiently reduced tire weight. Further, to reduce the 1.0mm smaller than the thickness G _B of the middle layer 20B, the rubber composition is high tanδ and high hardness contained in the middle layer 20B is reduced, the cavity resonance to suppress sufficiently vibrate The effect is not obtained. Conversely, and 4.0mm larger than the thickness G _B of the intermediate layer 20B, it is impossible to sufficiently reduce the tire weight. Furthermore, if the thickness G _C of the inner layer 20C is smaller than 3.0 mm, the cavity resonance sound cannot be sufficiently reduced. Conversely, if the thickness G _C of the inner layer 20C is greater than 6.0 mm, the tire mass cannot be reduced sufficiently. The thicknesses G _A , G _B , and G _C of the layers 20A, 20B, and 20C in the side rubber layer 20 are the thicknesses of the side rubber layers measured perpendicular to the carcass layer 4, and the layers 20A, 20B , 20C within the maximum value.

  In the present invention, the flatness of the tire is preferably 50% or more. If the tire has a high flatness ratio of 50% or more, the tire cross-section height SH increases, so the cross-sectional area of the side rubber layer that greatly contributes to each tire performance increases, and the above-mentioned tire performance is further enhanced. Can be compatible.

In a pneumatic tire having a tire size of 205 / 60R16 92V, presence or absence of division of the side rubber layer, tan δ at 60 ° C., hardness at 20 ° C., thickness G _A , G of the rubber composition contained in each of the outer layer, the middle layer, and the inner layer _B , G _C , the height of the end or boundary, the height of the tire maximum width position, and the height of the bead filler outer end as shown in Tables 1 and 2, and Comparative Example 1 and Comparative Examples 1 to 5. Twenty kinds of test tires of Examples 1 to 14 were manufactured.

  About these 20 types of test tires, tire mass, rolling resistance, riding comfort, and cavity resonance sound were evaluated by the following evaluation methods, and the results are also shown in Tables 1 and 2.

Tire Mass The weight of each test tire was measured. The evaluation results are shown as an index with the conventional example 1 as 100, using the reciprocal of the measured value. A larger index value means a lighter tire weight.

Rolling resistance Each test tire is mounted on an aluminum wheel with a rim size of 16 x 6.5 J, filled with air pressure of 230 kPa, and a drum tester with a drum diameter of 1707.6 mm is used according to ISO 28580. Maximum load specified by JATMA The rolling resistance at the time of traveling at a speed of 80 km / h was measured with a load of 70% of the capacity. The evaluation results are shown as an index with the conventional example 1 as 100, using the reciprocal of the measured value. It means that rolling resistance is so low that this index value is large.

Ride comfort Each test tire is assembled on an aluminum wheel with a rim size of 16 x 6.5 J, filled with air pressure of 230 kPa, mounted on an FF minivan with a displacement of 2.0 liters, and a speed of 50 km on a test course partially including uneven surfaces. The vehicle was run at / h, and sensory evaluation was conducted by one panelist. The evaluation results are shown as an index with Conventional Example 1 as 100. It means that riding comfort is excellent, so that this index value is large.

Cavity resonance sound Each test tire is assembled on an aluminum wheel with a rim size of 16 × 6.5J, filled with air pressure of 230 kPa, mounted on an FF minivan with a displacement of 2.0 liters, running on a concrete road at a speed of 40 km / h, and a driver's seat The vehicle interior noise was measured at the position of, and the peak level (narrow band) (dB) of the cavity resonance sound near the frequency of 225 Hz was obtained. The evaluation result was shown by the difference of the measured real value (difference with the prior art example 1). The smaller this value, the smaller the cavity resonance sound.

  As can be seen from Tables 1 and 2, Examples 1 to 14 all reduced tire mass, improved rolling resistance and riding comfort, and reduced cavity resonance noise. In particular, Examples 5, 9, and 11 in which the height of the tire maximum width position and / or the height of the outer end portion of the bead filler were set in a preferable range achieved both of these performances at a higher level.

  On the other hand, Comparative Examples 1 and 2 in which the side rubber layer is not divided into three layers of the outer layer, the middle layer, and the inner layer, and Comparative Examples 3 and 4 in which the magnitude relationship between tan δ and hardness of each layer is out of the definition of the present invention reduce tire mass. However, any or all of rolling resistance, riding comfort, and cavity resonance sound deteriorated.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Carcass layer 5 Bead core 6 Bead filler 7 Belt layer 8 Belt cover layer 20 Side rubber layer 20A Outer layer 20B Middle layer 20C Inner layer

Claims (4)

A pair of bead portions, sidewall portions extending radially outward from the bead portions, and a cylindrical tread portion connecting the radially outer sides of the sidewall portions, and at least between the pair of bead portions. In a pneumatic tire in which one carcass layer is mounted and both ends of the carcass layer are wound up from the inside of the tire so as to sandwich the bead filler around the bead core,
A side rubber layer positioned on the outer side in the tire width direction of the carcass layer in the sidewall portion; an outer layer positioned on the outer side in the tire radial direction; an inner layer positioned on the inner side in the tire radial direction; an intermediate layer positioned between the outer layer and the inner layer; And the tan δ at 60 ° C. of the rubber composition contained in the middle layer is higher than the tan δ at 60 ° C. of the rubber composition contained in the outer layer and the inner layer, and 20 of the rubber composition contained in the middle layer. The hardness at 20 ° C. is higher than the hardness at 20 ° C. of the rubber composition contained in the outer layer and the inner layer, and the tan δ at 60 ° C. of the rubber composition contained in the intermediate layer is 0.17 or more and the hardness at 20 ° C. And the tan δ at 60 ° C. of the rubber composition contained in the outer layer and the inner layer is from 0.05 to 0.20, and A pneumatic tire, characterized in that the hardness at 20 ° C. in 40 to 60 below. The height H _Li of the boundary Li between the middle layer and the inner layer is set in the range of 20% to 25% of the tire sectional height SH, and the height H _Lo of the boundary Lo between the middle layer and the outer layer is set to the tire sectional height. is the 45% to 50% of SH, and pneumatic described height H _P of the tire maximum width position P to claim 1, characterized in that the range of 30% to 40% of the tire section height SH tire. The pneumatic tire according to claim 1 or 2, characterized in that the height H _F of the tire radial direction outer end of the bead filler in the range of 25% to 45% of the tire section height SH.   4. The pneumatic tire according to claim 1, wherein the flatness is 50% or more.

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