JP6038574B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire.

  As a method for improving ride comfort and in-vehicle noise, a study has been made on reinforcing materials and their arrangement in the tire structure. For example, Patent Document 1 and Patent Document 2 below propose that an organic fiber cord oriented in the tire circumferential direction is disposed in a buttress portion of a tire.

  On the other hand, although it is not a technique regarding vehicle interior noise, Patent Document 3 below discloses that an organic fiber cord reinforcing layer is provided from the bead portion to the sidewall portion in order to prevent the occurrence of a flat spot. Patent Document 4 below discloses disposing an organic fiber cord oriented in the tire circumferential direction in a portion including the tire maximum width position of the sidewall portion in order to improve steering stability. .

  By the way, in order to improve the vibration and noise performance of the vehicle, it is important to suppress the force transmitted from the tire to the axle. Each vibration mode of the tire contributes to the transmission of force in the front / rear, left / right and up / down directions of the vehicle, and the suspension also has a frequency characteristic of how to transmit the input in each direction to the vehicle interior. Focusing on this point, the following Non-Patent Document 1 attempts to reduce vehicle interior noise by controlling the eigenvalues of the tire modes corresponding to the suspension characteristics.

JP 2010-274812 A JP-A-6-24214 JP-A-10-297223 JP 2001-277820 A

Eihito Miyama et al., “Development of tire eigenvalue control technology for road noise spectrum optimization”, 200-20095194, Japan Society for Automotive Engineers, Academic Lecture Preprint No. 41-09, pp. 17-22, May 2009

  When controlling the eigenvalue of each mode of the tire in order to reduce the vehicle interior noise, it is desirable to increase the eigenvalue in the lateral bending tertiary mode of the tire and lower it in the upper and lower primary mode. Here, the tire lateral bending mode is a mode in which the tread portion is deformed so as to collapse in the tire lateral direction (width direction), and the tertiary mode is a mode in which the tire is laterally deformed at three locations on the circumference of the tire. . The tire up / down mode is a mode in which the tire is deformed so as to bend in the up / down direction.

  However, for example, in the means for increasing the rigidity of the entire tire by increasing the rigidity of the carcass ply, not only the eigenvalue of the transverse bending third-order mode but also other eigenvalues including the upper and lower first-order modes follow and rise. For this reason, in order to efficiently control the emphasis on the eigenvalue of the transverse bending third-order mode, it is desirable to control the rigidity of the portion deeply related to the transverse bending mode deformation by reinforcement. Further, in the eigenvalue operation by reinforcement, there is a possibility that the riding comfort is deteriorated due to an increase in tire rigidity.

  Therefore, an object of the present invention is to provide a pneumatic tire that can reduce in-vehicle sound by an eigenvalue operation while suppressing the influence on the ride comfort.

A pneumatic tire according to the present invention includes a carcass ply that is locked at a bead portion from a tread portion through a buttress portion and a sidewall portion, and a belt that is disposed on an outer peripheral side of the carcass ply in the tread portion. A second reinforcement including a fiber material oriented in a tire meridian direction, wherein a first reinforcing layer including a fiber material oriented in a tire circumferential direction is provided outside the main body portion of the carcass ply in the buttress portion. A layer is provided outside the main body portion of the carcass ply in a region from the bead portion to the sidewall portion, and the first reinforcing layer and the second reinforcing layer are disposed with a gap in the tire meridian direction. It is a thing. The second reinforcing layer is provided from the bead portion to the sidewall portion, and an upper end of the second reinforcing layer is at a position of 40 to 60% of a tire cross-sectional height, and the first reinforcing layer is It is provided from the widthwise end portion of the belt toward the sidewall portion, and the gap between the lower end of the first reinforcing layer and the upper end of the second reinforcing layer is 10 to 10 times the tire cross-sectional height in the tire radial direction. It is set to 20%.

  According to the present invention, the in-vehicle sound can be reduced by increasing the eigenvalue difference of the lateral bending third-order mode with respect to the up-and-down first-order mode while suppressing the influence on the ride comfort.

1 is a half sectional view of a pneumatic tire according to an embodiment. It is the side schematic diagram which showed the structure of the reinforcement layer in this pneumatic tire.

  Hereinafter, embodiments will be described with reference to the drawings.

  FIG. 1 is a right half sectional view of a structure of a pneumatic tire 10 according to an embodiment, cut along a meridian section including a tire axis. Here, since the tire is symmetrical, the left half is not shown.

  A pneumatic tire 10 in FIG. 1 includes a pair of left and right bead portions 12, a pair of left and right sidewall portions 14 extending radially outward from the bead portion 12, a tread portion 16 constituting a ground contact surface, and a tread portion 16. A pair of left and right buttress portions 18 connecting the sidewall portions 14 on both sides in the width direction are provided. Here, the buttress portion 18 is a boundary region between the tread portion 16 and the sidewall portion 14, and is provided between the tread portion 16 and the sidewall portion 14.

  The pneumatic tire 10 includes a carcass ply 20 provided in a toroidal shape between a pair of bead portions 12. A ring-shaped bead core 22 is embedded in each of the pair of bead portions 12. The carcass ply 20 passes from the tread portion 16 through the buttress portion 18 and the sidewall portion 14, and is locked by the bead core 22 at the bead portion 12, and reinforces the respective portions 12, 14, 16, and 18. In this example, the carcass ply 20 is locked by folding both ends around the bead core 22 from the inner side to the outer side in the tire width direction. Therefore, the carcass ply 20 includes a main body portion 20A spanned in a toroidal shape along the inner liner 24 on the inner surface of the tire, and folded portions 20B at both ends.

  The carcass ply 20 includes at least one ply in which an organic fiber cord is arranged at an angle of 70 ° to 90 ° with respect to the tire circumferential direction and is covered with a topping rubber. In this example, the carcass ply 20 includes one ply. Yes. As the cord constituting the carcass ply 20, for example, an organic fiber cord such as polyester fiber, rayon fiber, aramid fiber, nylon fiber or the like is preferably used.

  A belt 26 is disposed on the outer peripheral side of the carcass ply 20 in the tread portion 16. That is, the belt 26 is provided between the carcass ply 20 and the tread rubber 28 in the tread portion 16. The belt 26 includes at least two cross belt plies in which belt cords are arranged at an angle of 10 ° to 35 ° with respect to the tire circumferential direction. As the belt cord, a steel cord or an organic fiber cord having a high tension is used. In this example, the belt 26 has a two-layer structure of a first belt 26A disposed on the inner side in the tire radial direction and a second belt 26B disposed on the outer peripheral side thereof. The first belt 26A has the largest width. It is a wide maximum width belt.

  In the buttress portion 18, a rubber member called a belt lower pad 30 is provided on the inner side in the tire radial direction at the end portion in the width direction of the belt 26. The belt lower pad 30 is disposed in a gap between the width direction end portion 26A1 of the first belt 26A and the main body portion 20A of the carcass ply 20, and has a substantially triangular cross section. A sidewall rubber 32 is provided outside the carcass ply 20 (that is, on the tire outer surface side) in the sidewall portion 14. Further, in the bead portion 12, a bead filler 34 made of a hard rubber material that tapers outwardly in the tire radial direction between the main body portion 20 </ b> A and the folded portion 20 </ b> B of the carcass ply 20 on the outer peripheral side of the bead core 22. Is arranged.

  As shown in FIG. 1, the buttress portion 18 is provided with a first reinforcing layer 36 as a high-rigidity member on the outer side of the main body portion 20 </ b> A of the carcass ply 20 (that is, on the tire outer surface side). The 1st reinforcement layer 36 is a reinforcement layer which has high rigidity in the tire circumferential direction A by including the fiber material orientated in the tire circumferential direction A (refer FIG. 2). Specifically, the first reinforcing layer 36 includes organic fiber cords 38 (see FIG. 2) oriented in the tire circumferential direction A as the fiber material, and the organic fiber cords 38 are arranged at predetermined intervals. Although not shown, the organic fiber cord 38 is usually covered with a topping rubber.

  In the first reinforcing layer 36, the orientation direction of the fiber material, specifically, the organic fiber cord 38, is not necessarily limited to the case where it is strictly parallel to the tire circumferential direction A, and is slightly inclined with respect to the tire circumferential direction A. It is also assumed that the tire is oriented in the tire circumferential direction A. The angle of the organic fiber cord 38 oriented in the tire circumferential direction A in the first reinforcing layer 36 is preferably 15 ° or less (that is, 0 ° to 15 °) as an absolute value of the angle with respect to the tire circumferential direction A. Preferably, it is 0 ° to 10 °.

  The first reinforcing layer 36 is provided from the width direction end portion 26A1 of the first belt 26A toward the sidewall portion 14. In this example, the upper end 36A of the first reinforcing layer 36 is placed on the tire outer surface side of the width direction end portion 26A1 so as to cover the width direction end portion 26A1 of the first belt 26A. The first reinforcing layer 36 is provided adjacent to the belt lower pad 30 and the outside of the main body portion 20A of the carcass ply 20 from the width direction end portion 26A1. The lower end 36B of the first reinforcing layer 36 is, for example, 55 to 75% of the tire cross-section height H so as to be disposed with a gap 44 in the tire meridian direction C with respect to the second reinforcing layer 40 described later. In other words, the height H1 from the bead heel E to the lower end 36B is preferably 55 to 75% of the tire cross-section height H.

  For example, the first reinforcing layer 36 is formed by aligning a plurality of organic fiber cords with a predetermined number of ends (the number of driven ends), covering both sides with a topping rubber, and processing the topping reversely. You may form by installing over the perimeter of the tire circumferential direction A so that it may orient in the direction A. In particular, the first reinforcing layer 36 oriented substantially at 0 ° with respect to the tire circumferential direction A is formed, for example, by winding one or a plurality of alignment cords in a spiral around the tire axis. May be.

  In the region from the bead portion 12 to the sidewall portion 14, a second reinforcing layer 40 as a highly rigid member is provided outside the main body portion 20 </ b> A of the carcass ply 20 (that is, on the tire outer surface side). The second reinforcing layer 40 is a reinforcing layer having high rigidity in the tire meridian direction C or the radial direction B by including a fiber material oriented in the tire meridian direction C. Specifically, the second reinforcing layer 40 includes organic fiber cords 42 (see FIG. 2) oriented in the tire meridian direction C as the fiber material, and the organic fiber cords 42 are arranged at predetermined intervals. Although not shown, the organic fiber cord 42 is usually covered with a topping rubber.

  In the second reinforcing layer 40, the orientation direction of the fiber material, specifically, the organic fiber cord 42, is not necessarily limited to the case where it is strictly parallel to the tire meridian direction C, and is slightly inclined with respect to the tire meridian direction C. Those that are also oriented in the tire meridian direction C. The angle of the organic fiber cord 42 oriented in the tire meridian direction C in the second reinforcing layer 40 is preferably 75 to 90 ° as an absolute value with respect to the tire circumferential direction A, more preferably 80 to 90 °. is there.

  The second reinforcing layer 40 is provided from the bead portion 12 to the sidewall portion 14. The second reinforcing layer 40 is disposed between the bead filler 34 and the folded portion 20B of the carcass ply 20, and is sandwiched between the outer surface of the bead filler 34 and the inner surface of the folded portion 20B. In this example, the lower end 40 </ b> B of the second reinforcing layer 40 is located near the boundary surface between the bead core 22 and the bead filler 34. The second reinforcing layer 40 extends upward from the lower end of the bead filler 34 along the outer surface of the bead filler 34, exceeds the upper end (radially outer end) of the bead filler 34, and then reaches the main portion 20 </ b> A of the carcass ply 20. It is provided adjacent to the outside. Thereby, it reinforces from the bead part 12 to the sidewall part 14.

  The upper end 40A of the second reinforcing layer 40 is located at 40-60% of the tire cross-section height H, that is, the height H2 from the bead heel E to the upper end 40A is set to 40-60% of the tire cross-section height H. Has been. By setting the height H2 to 40% or more of the tire cross-section height H, the reinforcing effect by the second reinforcing layer 40 can be enhanced. By setting the height H2 to be 60% or less of the tire cross-section height H, it is easy to sufficiently secure the gap 44 between the first reinforcing layer 36 and suppress deterioration in ride comfort.

  For example, the second reinforcing layer 40 is formed by aligning a plurality of organic fiber cords with a predetermined number of ends (the number of driven ends), covering both sides with topping rubber, and processing the topside of the cord, and the cord is a tire meridian You may form by installing over the perimeter of the tire circumferential direction A so that it may orient in the direction C.

  The first reinforcing layer 36 and the second reinforcing layer 40 are disposed with a gap 44 in the tire meridian direction C. Specifically, the gap 44 between the lower end 36B of the first reinforcing layer 36 and the upper end 40A of the second reinforcing layer 40 has a height (gap amount) S in the tire radial direction B of 10 to 20 of the tire cross-sectional height H. % Is set. The gap amount S is 10% or more, which is advantageous in reducing the influence on the ride comfort. In addition, since the gap amount S is 20% or less, the size of the first reinforcing layer 36 and the second reinforcing layer 40 can be secured and the effect of reducing the vehicle interior sound can be enhanced.

  Each dimension value in the present embodiment is in a normal state with no load in which a tire is mounted on a regular rim and filled with a regular internal pressure. A regular rim is a rim determined for each tire in a standard system including a standard on which a tire is based. For example, a standard rim for JATMA, a “Design Rim” for TRA, or a rim for ETRTO. "Measuring Rim". In addition, the normal internal pressure is the air pressure defined by each standard for each tire in the standard system. If it is JATMA, it is the maximum air pressure. If the maximum value is ETRTO, "INFLATION PRESSURE" is assumed. The tire cross-section height H is a vertical height from the bead heel E to the tread surface, and is ½ of the difference between the tire outer diameter and the rim diameter.

  Examples of the fiber material constituting the first reinforcing layer 36 and the second reinforcing layer 40 include aramid fibers, polyethylene naphthalate fibers, nylon fibers, polyester fibers, rayon fibers, or a composite of two or more of these. . Preferably, organic fibers having higher strength than the carcass ply 20 are used, and for example, aramid fibers, polyethylene naphthalate fibers, or composites thereof are preferably used.

  In the present embodiment, the first reinforcing layer 36 and the second reinforcing layer 40 are set to have higher tensile rigidity than the carcass ply 20. For the first reinforcing layer 36 and the second reinforcing layer 40, it is preferable to set the tensile rigidity of the first reinforcing layer 36 to be equal to or higher than the tensile rigidity of the second reinforcing layer 40, more preferably the first reinforcing layer 36. However, the tensile rigidity is higher than that of the second reinforcing layer 40.

  Here, the tensile rigidity is a modulus at 2% extension in the cord orientation direction as each ply of the carcass ply 20, the first reinforcing layer 36, and the second reinforcing layer 40, and the modulus at the time of 2% extension of the cord Modulus at 2% extension per predetermined width of each ply, which can be calculated by multiplying the number of ends. The modulus at 2% elongation of the cord is a value (LASE 2%) obtained by reading the load at the time of 2% elongation when a tensile test according to JIS L1017 is performed at room temperature.

  As a means for setting the tensile rigidity in this way, in addition to using high-strength organic fibers as the constituent fiber material, the tensile rigidity may be adjusted by the fineness and the number of ends of the organic fiber cords in each ply. For example, in order to make the tensile rigidity of the first reinforcing layer 36 equal to or higher than the tensile rigidity of the second reinforcing layer 40, the fineness and the number of ends of the organic fiber cords 38, 42 constituting these reinforcing layers 36, 40 are set as follows. Can be set as follows. That is, the number of ends of the organic fiber cord 38 in the first reinforcing layer 36 is set to be equal to or more than the number of ends of the organic fiber cord 42 in the second reinforcing layer 40, and the fineness of the organic fiber cord 38 in the first reinforcing layer 36 is set. The fineness of the organic fiber cord 42 in the second reinforcing layer 40 is equal to or greater.

  The number of ends and the fineness of the organic fiber cords 38 and 42 constituting the first reinforcing layer 36 and the second reinforcing layer 40 are not particularly limited, but the number of ends is preferably 15 to 38/25 mm, and the fineness is It is preferable that it is 2000-6700 dtex, and it is preferable to select so that the said magnitude relationship may be satisfy | filled from these ranges. By setting the number of ends to 15/25 mm or more, the reinforcing effect can be enhanced. The number of ends is the number of cross sections per 25 mm width of the organic fiber cords confirmed in a cross section obtained by cutting each reinforcing layer perpendicularly to the longitudinal direction of the organic fiber cords. Here, the number of ends of the second reinforcing layer 40 is the number of ends measured at an intermediate position in the height direction of the second reinforcing layer 40. The number of ends of the carcass ply 20 is the number of ends measured around the bead portion. The fineness is a nominal fineness (also referred to as display fineness).

  Next, the operation of the pneumatic tire according to this embodiment will be described.

  The tire lateral bending mode is a mode in which the tread portion 16 of the tire fixed by the rim in the bead portion 12 is deformed so as to fall in the tire lateral direction (width direction) D. Therefore, as a feature of the deformation in the lateral bending mode, (a) the tread portion 16 moves in a undulating manner in the tire circumferential direction A, so that the circumferential length of the buttress portion 18 changes greatly, and (b) the tread. The buttress portion 18 pulls and compresses the region from the sidewall portion 14 to the bead portion 12 (hereinafter referred to as the side-bead portion) in order to make the portion 16 fall in the tire width direction D. Is mentioned.

  According to the present embodiment, with respect to the phenomenon (a), the first reinforcing layer 36 increases the circumferential rigidity of the buttress portion 18, so that the change in the circumferential length of the buttress portion 18 can be reduced. it can. Further, with respect to the phenomenon (b), the second reinforcing layer 40 increases the rigidity in the tire radial direction at the side-bead portion, so that the tension / compression motion of this portion can be reduced. Thus, since the reinforcement specialized for the transverse bending mode is performed, the eigenvalue of the transverse bending tertiary mode can be increased efficiently. Further, since the first reinforcing layer 36 and the second reinforcing layer 40 do not overlap with each other and a gap 44 is provided in the tire meridian direction C, and the rigidity of the entire tire side portion is not improved, the vertical direction It is possible to suppress an increase in the eigenvalue of the upper and lower first-order modes due to the bending deformation. In addition, since the up / down primary mode performs an eccentric motion in which the tread circumference does not change, the eigenvalue of the up / down primary mode can be lowered by reducing the rigidity of the carcass ply 20. Thus, it is possible to balance the eigenvalues of the up-and-down primary mode and the transverse bending tertiary mode, and the eigenvalues of the transverse bending tertiary mode can be increased efficiently.

  Further, according to the present embodiment, an increase in tire longitudinal rigidity can be suppressed by the gap 44 provided between the first reinforcing layer 36 and the second reinforcing layer 40, so that deterioration in riding comfort can be reduced. Can do. As described above, it is possible to reduce the noise in the passenger compartment by increasing the eigenvalue difference of the lateral bending tertiary mode with respect to the upper and lower primary modes while suppressing the influence on the riding comfort.

  In the present embodiment, the second reinforcing layer 40 is also disposed between the bead filler 34 and the folded portion 20 </ b> B of the carcass ply 20. By arranging the second reinforcing layer 40 on the outer side with respect to the bead filler 34 in this way, in-plane bending rigidity in the tire cross section can be ensured. That is, since the main body portion 20A of the carcass ply 20 exists inside the bead filler 34, the bending rigidity can be improved by sandwiching the bead filler 34 between the main body portion 20A and the second reinforcing layer 40. Therefore, the reinforcement effect with respect to the transverse bending mode can be further enhanced. In the present invention, the second reinforcing layer 40 may be disposed between the main body portion 20A of the carcass ply 20 and the bead filler 34, or may be attached to the outside of the folded portion 20B of the carcass ply 20. You may arrange.

  In the present embodiment, since the first reinforcing layer 36 is provided so as to cover the width direction end portion 26A1 of the first belt 26A which is the maximum width belt, the reinforcing effect for the phenomenon (a) is further enhanced. Can be increased.

  In the present embodiment, since the second reinforcing layer 40 provided from the bead portion 12 to the sidewall portion 14 is oriented in the tire meridian direction C, the ride comfort tends to be deteriorated due to an increase in tire longitudinal rigidity. On the other hand, since the first reinforcing layer 36 provided in the buttress portion 18 is oriented in the tire circumferential direction A, the influence on the tire longitudinal rigidity is small. Therefore, by making the tensile rigidity of the first reinforcing layer 36 larger than the tensile rigidity of the second reinforcing layer 40, the rigidity of the portion deeply related to the lateral bending mode deformation is effectively reduced while reducing the influence on the riding comfort. It is possible to improve the eigenvalue of the transverse bending tertiary mode efficiently.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to this embodiment, A various change is possible unless it deviates from the meaning.

  As for a pneumatic radial tire having a tire size of 225 / 50R18, a tire having no first and second reinforcing layers as a conventional example is a control tire, and the control tire is shown in FIG. For each tire of the example and the comparative example provided with the first reinforcing layer 36 and / or the second reinforcing layer 40 shown in FIG. 1, the eigenvalue analysis by FEM was performed, and the sound pressure evaluation and the riding comfort evaluation were performed on the prototype tire. . In addition, the cord angle about the 1st and 2nd reinforcement layer in Table 1 is an angle of the organic fiber cord with respect to the tire circumferential direction A, and the fineness is the fineness of the organic fiber cord. Moreover, aramid means an aramid fiber and PEN means a polyethylene naphthalate fiber.

  In each of the tires of the conventional example, the example, and the comparative example, a carcass ply having a 2350 dtex polyester fiber cord (PET fiber cord) arranged at 28 ends / 25 mm and having a tensile rigidity of 25 N is used. It was.

  In each of the first reinforcing layers 36, the position of the upper end 36A is the end 26A1 in the width direction of the first belt 26A shown in FIG. In each of the second reinforcing layers 40, the position of the lower end 40B is set in the vicinity of the boundary surface between the bead core 22 and the bead filler 34 shown in FIG. Table 1 shows the height H2 of the upper end 40A of the second reinforcing layer 40 and the gap amount S, which is the height in the tire radial direction B of the gap 44 between the first reinforcing layer 36 and the second reinforcing layer 40. (The values in the table are ratios to the tire cross-section height H).

  In the eigenvalue analysis by FEM, the eigenvalues of the transverse bending third-order mode and the upper-lower first-order mode are calculated under the conditions of rim size: 18 × 7.5JJ, air pressure: 230 kPa, load: 4.5 kN. The index is shown with an example of 100.

  For sound pressure evaluation, a rim size of 18 x 7.5 JJ and air pressure of 230 kPa, mounted on a 3000 cc rear wheel drive car sedan, running on the test road surface at 60 km / h, and attached to the ear position of the driver's seat Then, the sound pressure was measured. The sound pressure measurement result was subjected to 1/3 octave band analysis, and the power spectrum of 125 to 200 Hz was evaluated. The evaluation uses the reciprocal of the measured value, indexed the result of the conventional example as 100, and indicates that the larger the value, the lower the sound pressure energy at the medium frequency and the better the effect of reducing the cabin sound.

  As for the ride comfort evaluation, the feeling evaluation by running the actual vehicle when traveling on the test road surface is performed in the same way as the sound pressure evaluation, and the equivalent one is “± 0” based on the ride comfort of the conventional example, which is inferior Was evaluated as minus (−). In the case of a negative value, the larger the absolute value, the greater the deterioration of the ride comfort. This indicates that there is a slight change at -0.5. Is a level.

  The results are as shown in Table 1. Compared to the conventional example, in Comparative Example 1 in which only the first reinforcing layer is provided, the difference between the eigenvalues of the transverse bending tertiary mode with respect to the upper and lower primary modes cannot be sufficiently increased, and the effect of reducing the sound pressure energy is achieved. It was small and inferior in the sound reduction effect of the passenger compartment. Further, in Comparative Example 2 in which only the second reinforcing layer was provided, the difference in eigenvalue was larger than that in Comparative Example 1, but it was not sufficient and was inferior in the effect of reducing vehicle interior noise. Moreover, although both the first reinforcing layer and the second reinforcing layer were provided, the comparative example 3 in which both were partially overlapped with no gap had a large eigenvalue difference and was excellent in the effect of reducing vehicle interior noise. The comfort was getting worse.

  On the other hand, in the tire of the example in which both the first reinforcing layer and the second reinforcing layer are provided and a gap is provided between them, the difference in eigenvalue of the lateral bending tertiary mode with respect to the upper and lower primary modes is large. The effect of reducing sound pressure energy was great, and the effect of reducing vehicle interior sound was excellent. Moreover, the influence on riding comfort was also able to be suppressed with respect to Comparative Example 3.

  Specifically, in the second embodiment, the noise reduction effect is slightly reduced by changing the cord material of the second reinforcing layer from the aramid to the PEN as compared with the first embodiment, but the decrease in riding comfort is suppressed. did it. In Example 3, compared with Example 1, the number of ends of the first reinforcing layer was increased and the number of ends of the second reinforcing layer was decreased, so that the first reinforcing layer was pulled more than the second reinforcing layer. By increasing the rigidity, it was possible to further improve the noise reduction effect while suppressing a decrease in riding comfort.

  In Examples 4 and 5, the cord angle of the first reinforcing layer is changed with respect to Example 1, and the effect of reducing in-vehicle sound is slightly reduced by providing an angle with respect to the tire circumferential direction. The decrease in was also slightly reduced. In Example 6, the cord angle of the second reinforcing layer was changed with respect to Example 1, and a slight decrease was observed in the effect of reducing vehicle interior noise by providing an angle with respect to the tire meridian direction.

  In Example 7, the amount of the first reinforcing layer was increased by reducing the gap amount S between the reinforcing layers as compared with Example 1, and the effect of reducing the cabin noise was slightly improved, but the riding comfort was reduced. In Example 8, the gap amount S between the reinforcing layers was increased compared to Example 1, but the amount of the first reinforcing layer was reduced and the effect of reducing the cabin noise was slightly reduced, but the riding comfort was improved. .

  The present invention can be used for various types of pneumatic tires, and is particularly preferably applied to passenger car pneumatic tires.

DESCRIPTION OF SYMBOLS 10 ... Pneumatic tire 12 ... Bead part 14 ... Side wall part 16 ... Tread part 18 ... Buttress part 20 ... Carcass ply 20A ... Main-body part 20B ... Folding part 22 ... Bead core 26 ... Belt 26A ... 1st belt 34 ... Bead filler 36 ... 1st reinforcement layer 38 ... Organic fiber cord 40 ... 2nd reinforcement layer 42 ... Organic fiber cord 44 ... Crevice A ... Tire circumferential direction B ... Tire radial direction C ... Tire meridian direction H ... Tire cross-sectional height

Claims (5)

In a pneumatic tire including a carcass ply that is locked at a bead portion from a tread portion through a buttress portion and a sidewall portion, and a belt disposed on an outer peripheral side of the carcass ply in the tread portion,
A first reinforcing layer including a fiber material oriented in the tire circumferential direction is provided outside the main body portion of the carcass ply in the buttress portion, and a second reinforcing layer containing a fiber material oriented in the tire meridian direction is In the region from the bead portion to the sidewall portion, provided outside the main body portion of the carcass ply, the first reinforcing layer and the second reinforcing layer are arranged with a gap in the tire meridian direction ,
The second reinforcing layer is provided from the bead portion to the sidewall portion, and an upper end of the second reinforcing layer is at a position of 40 to 60% of a tire cross-sectional height, and the first reinforcing layer is It is provided from the widthwise end portion of the belt toward the sidewall portion, and the gap between the lower end of the first reinforcing layer and the upper end of the second reinforcing layer is 10 to 10 times the tire cross-sectional height in the tire radial direction. A pneumatic tire characterized by being set to 20% . The carcass ply is locked by folding back around the bead core embedded in the bead portion from the inside to the outside, and the bead portion includes a body portion and a folded portion of the carcass ply on the outer peripheral side of the bead core. The pneumatic tire according to claim 1, wherein a bead filler is disposed therebetween, and the second reinforcing layer is disposed between the bead filler and the folded portion. The pneumatic tire according to claim 1 or 2, wherein the first reinforcing layer and the second reinforcing layer have higher tensile rigidity than the carcass ply. The pneumatic tire according to claim 3, wherein the first reinforcing layer has higher tensile rigidity than the second reinforcing layer. The first reinforcing layer includes an organic fiber cord oriented in a tire circumferential direction as the fiber material, and an absolute value of an angle of the organic fiber cord with respect to the tire circumferential direction is 15 ° or less,
The second reinforcing layer includes an organic fiber cord oriented in a tire meridian direction as the fiber material, and an absolute value of an angle of the organic fiber cord with respect to a tire circumferential direction is 75 ° to 90 °. Item 5. The pneumatic tire according to any one of Items 1 to 4 .

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