JP2013035428A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce road noise while improving controllability and stability.SOLUTION: In a pneumatic tire with a pair of bead cores 51, a carcass layer 6 disposed between the bead cores 51, a bead filler 52 disposed outside each bead core 51 in a tire radial direction, and a belt layer 7 disposed outside the carcass layer 6 in the tire radial direction in which a direction of the inside or outside of a vehicle at a mount time is indicated, a cross sectional area of the bead filler 52 at a meridian cross section is set larger at an outer mount side than at an inner mount side. A steel reinforcement layer 9 is disposed where steel cords of substantially 90 degrees with respect to the tire circumferential direction are provided in parallel between the inner most belt 71 of the belt layers 7 in a tire circumferential direction, and the carcass layer 6, and a dimension in a tire width direction is 10% or larger and 50% or smaller of an effective belt width of the belt layer 7.

Description

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

  In recent years, in order to reduce the fuel consumption of a vehicle equipped with a pneumatic tire, in order to reduce the rolling resistance of the pneumatic tire, it has been studied to increase the working air pressure. However, increasing the operating air pressure increases the input from the road surface, which increases road noise. In addition, the diameter growth in the center region, which is the center in the tire width direction, tends to increase due to the increase in the air pressure used, and the cornering power and self-aligning torque at low loads are reduced accordingly. There arises a problem that the performance is lowered.

  Conventionally, it has been disclosed that the rigidity of the right and left bead portions is asymmetrical with the aim of increasing the lateral rigidity without impairing the ride comfort (see, for example, Patent Document 1).

Japanese Utility Model Publication No. 64-30704

  According to the inventor's study, the cross-sectional area of the bead filler in the meridional section is configured to be larger on the outer side of the vehicle than on the inner side of the vehicle, so that the vibration mode becomes asymmetrical inside and outside the vehicle. It was discovered that it can be reduced. However, as in the pneumatic tire described in Patent Document 1 described above, if the rigidity of the left and right bead portions is asymmetric, the ground contact state becomes asymmetric (for example, the meridional section is deformed into a trapezoidal shape), and the steering stability is increased. It is difficult to improve the performance.

  This invention is made | formed in view of the above, Comprising: It aims at providing the pneumatic tire which can reduce road noise, improving steering stability.

  In order to solve the above-described problems and achieve the object, the pneumatic tire of the present invention includes a pair of left and right bead cores, a carcass layer disposed between each of the bead cores, and a tire radial outside of each of the bead cores. In a pneumatic tire comprising a bead filler disposed and a belt layer disposed on the outer side in the tire radial direction of the carcass layer, a meridian of the bead filler in a pneumatic tire in which a direction inside and outside the vehicle when the vehicle is mounted is specified. The cross-sectional area of the cross section is configured so that the vehicle mounting outer side is larger than the vehicle mounting inner side, and between the belt innermost belt in the tire radial direction of the belt layer and the carcass layer, substantially 90 [ Steel cords of [degree] are juxtaposed in the tire circumferential direction, and the steel width direction dimension is 10% to 50% of the effective belt width of the belt layer. Characterized by disposing the reinforcing layer.

  According to this pneumatic tire, when the cross-sectional area of the bead filler in the meridional section is configured to be larger on the vehicle mounting outer side than on the vehicle mounting inner side, the vibration mode that contributes to road noise is in a state where the rim is assembled. Asymmetrical between the vehicle mounting inner side and the vehicle mounting outer side. For this reason, the rigidity of the entire tire is ensured by making the rigidity of the bead portion outside the vehicle mounting, which has a high contribution of bending rigidity in the tire width direction, relatively low and the rigidity of the bead portion inside the vehicle mounting relatively low. However, road noise can be reduced. Moreover, according to this pneumatic tire, by arranging the steel reinforcing layer, the compression deformation rigidity of the tread portion can be improved and the ground contact state can be suitably maintained, and the steering stability can be improved. .

  In the pneumatic tire according to the present invention, a difference in cross-sectional area between the vehicle mounting outer side and the vehicle mounting inner side of the bead filler is 10% to 80% of the total cross-sectional area.

  If the cross-sectional area difference of the bead filler is 10% or more of the total cross-sectional area, the effect of reducing road noise due to asymmetry can be obtained remarkably. On the other hand, if the difference in the cross-sectional area of the bead filler is 80% or less of the total cross-sectional area, in order to prevent the carcass layer from greatly differing in the strained state on the left and right, maintaining the elastic force inside and outside the vehicle, the steering stability It is possible to suppress the deterioration. Therefore, according to this pneumatic tire, the effect of reducing road noise while improving steering stability can be obtained remarkably.

  Further, the pneumatic tire of the present invention has a tire cross-section in a state in which a tire radial dimension difference between the bead filler on the vehicle mounting outer side and the vehicle mounting inner side is incorporated in a normal rim and filled with 5% of the normal internal pressure. The height is 5% or more and 60% or less.

  If the tire radial direction dimensional difference of the bead filler is 5% or more of the tire cross-sectional height, the effect of reducing road noise due to asymmetry is remarkably obtained. On the other hand, if the dimensional difference in the tire radial direction of the bead filler is equal to or less than 60% of the tire cross-section height, in order to prevent the distortion state of the carcass layer from greatly differing from left to right, the elastic force inside and outside the vehicle is maintained. It is possible to suppress the deterioration of steering stability. Therefore, according to this pneumatic tire, the effect of reducing road noise while improving steering stability can be obtained remarkably.

  In the pneumatic tire of the present invention, the steel reinforcing layer is mounted on the vehicle with respect to the tire equatorial plane in the range of 0.5 [%] to 15 [%] of the effective belt width at the center position in the tire width direction. It is arranged close to the inside.

  According to this pneumatic tire, with respect to the asymmetry of the tread portion, the mass sensitivity is larger than the bending rigidity, so that the larger deformation side becomes lighter, so that the effective belt width is 0.5 [%] or more and 15 [%]. In the following range, by arranging the center position of the steel reinforcing layer in the tire width direction at a position closer to the inside of the vehicle than the tire equator plane, the contact shape can be optimized.

  In the pneumatic tire of the present invention, the steel reinforcing layer is a non-twisted monofilament having a diameter of 0.27 [mm] to 0.45 [mm] in the steel cord.

  According to this pneumatic tire, an increase in tire mass can be suppressed by employing a monofilament.

In the pneumatic tire of the present invention, the steel reinforcing layer has a product of one cross-sectional area of the steel cord and the number of driven portions per 50 [mm] of 4.5 [mm ² ] or more and 6.8 [ mm ² ] or less and the strength is 3200 [MPa].

According to this pneumatic tire, if the product of the cross-sectional area of one steel cord and the number of driven portions per 50 [mm] is 4.5 [mm ² ] or more, the rigidity is increased and the durability is improved. . Also, if the product of the cross-sectional area of one steel cord and the number of driven wires per 50 [mm] is 6.8 [mm ² ] or less, the cord spacing is not close and the adhesion to other layers (durability) Improved).

  The pneumatic tire of the present invention has a main groove extending in the tire circumferential direction on a tread surface of a tread portion disposed on the outer side in the tire radial direction of the belt layer, and the tire of the steel reinforcing layer The main groove disposed on the radially outer side has a groove width smaller than that of the other main grooves.

  According to this pneumatic tire, by making the groove width of the main groove disposed on the outer side in the tire radial direction of the steel reinforcing layer smaller than the groove width of the other main groove, the bending rigidity of the tread portion is further improved, The effect of reducing road noise can be obtained remarkably.

  The pneumatic tire of the present invention is characterized by being applied to a pneumatic tire for passenger cars having a high internal pressure.

  Increasing the operating air pressure increases the input from the road surface, so road noise increases and the diameter growth in the center region, which is the center in the tire width direction, tends to increase and steering stability tends to decrease. . According to this pneumatic tire, in such a pneumatic tire for passenger cars with a high internal pressure, it is possible to significantly obtain the effect of reducing road noise while improving steering stability.

  The pneumatic tire according to the present invention can reduce road noise while improving steering stability.

FIG. 1 is a meridional sectional view of a pneumatic tire according to an embodiment of the present invention. FIG. 2-1 is a schematic diagram showing the presence and arrangement of a steel reinforcing layer. FIG. 2-2 is a schematic view showing the presence and arrangement of a steel reinforcing layer. FIG. 2-3 is a schematic view showing the presence and arrangement of a steel reinforcing layer. FIG. 2-4 is a schematic diagram showing the presence and arrangement of a steel reinforcing layer. FIG. 3-1 is a diagram illustrating cornering power at the normal internal pressure in the form of the steel reinforcing layer of FIGS. 2-1 to 2-4. FIG. 3-2 is a diagram illustrating cornering power at high pressure in the form of the steel reinforcing layer of FIGS. 2-1 and 2-4. FIG. 4-1 is a diagram showing a self-aligning torque at the time of normal internal pressure in the form of the steel reinforcing layer of FIGS. 2-1 to 2-4. FIG. 4-2 is a diagram showing a self-aligning torque at high pressure in the form of the steel reinforcing layer of FIGS. 2-1 and 2-4. FIG. 5 is a diagram showing a change in sound pressure level in the form of the steel reinforcing layer of FIGS. 2-1 and 2-4. FIG. 6 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 according to the present embodiment. In the following description, the tire radial direction refers to a direction orthogonal to the rotational axis (not shown) of the pneumatic tire, and the tire radial inner side refers to the side toward the rotational axis in the tire radial direction, the tire radial outer side, and 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 rotational axis of the pneumatic tire and passes through the center of the tire width of the pneumatic tire. 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 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 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. Yes. The pneumatic tire 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), and is exposed at the outermost side in the tire radial direction of the pneumatic tire, and the surface thereof is the contour of the pneumatic tire. 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. The sidewall portion 4 is exposed at the outermost side in the tire width direction of the pneumatic tire. 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. This carcass layer 6 has a 90 ° (± 5 °) angle with respect to the tire circumferential direction, and a plurality of carcass cords (not shown) arranged in the tire circumferential direction along the tire meridian direction and covered with a coat rubber. It is. The carcass cord is made of organic fibers (polyester, rayon, nylon, etc.). The carcass layer 6 is provided as 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 has reinforcing layers 81 and 82 arranged in at least 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 width direction (± 5 degrees) in the tire circumferential direction with a coat rubber. The cord is made of steel or organic fiber (polyester, rayon, nylon, etc.). The belt reinforcing layer 8 shown in FIG. 1 is disposed so that the reinforcing layer 81 and the reinforcing layer 82 cover only the end portion of the belt layer 7 in the tire width direction. 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. The reinforcing layer 81 on the belt layer 7 side is formed to be larger in the tire width direction than the belt layer 7 so as to cover the entire belt layer 7, and the reinforcing layer 82 on the outer side in the tire radial direction of the reinforcing layer 81. May be disposed only at the end portion of the reinforcing layer 81 in the tire width direction so as to cover the end portion of the belt layer 7 in the tire width direction. That is, the belt reinforcing layer 8 overlaps at least 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. The belt reinforcing layer 8 (reinforcing layers 81 and 82) is provided by winding a strip-like strip material (for example, a width of 10 [mm]) in the tire circumferential direction.

  In addition, when the pneumatic tire of the present embodiment is mounted on a vehicle (not shown), the direction with respect to the inner side and the outer side of the vehicle is specified 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 that is the side surface of the tire. Hereinafter, the side facing the inside of the vehicle when mounted on the vehicle is referred to as the vehicle mounting inside, and the side facing the outside of the vehicle is referred to as the vehicle mounting outside. In addition, designation | designated of vehicle mounting inside and vehicle mounting outside is not restricted to the case where it mounts on a vehicle. 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 is designated in the tire width direction with respect to the inner side (vehicle mounting inner side) and the outer side (vehicle mounting outer side) of the vehicle. In FIG. 1, the right side from the tire equator plane CL is the vehicle mounting outside, and the left side from the tire equator plane CL is the vehicle mounting inside.

  In the pneumatic tire configured in this manner, the cross-sectional area of the bead filler 52 in the meridian cross section is configured to be larger on the vehicle mounting outer side than on the vehicle mounting inner side.

  The pneumatic tire includes a steel reinforcing layer 9. The steel reinforcing layer 9 is disposed between the innermost belt 71 in the tire radial direction of the belt layer 7 and the carcass layer 6. The steel reinforcing layer 9 has a steel cord (not shown) arranged in parallel in the tire circumferential direction at an angle of 90 degrees (including an error of ± 5 degrees) with respect to the tire circumferential direction, and is coated with a coat rubber. Yes. The steel reinforcing layer 9 is formed such that the tire width direction dimension W1 is 10% or more and 50% or less of the effective belt width W of the belt layer 7. The steel reinforcing layer 9 is not divided in the tire width direction, and is disposed on the tire equatorial plane CL that is the center position in the tire width direction of the pneumatic tire. The steel cord (metal cord) of the steel reinforcing layer 9 is made of, for example, steel or carbon steel.

  The effective belt width W of the belt layer 7 indicates the tire width direction dimension of the belt (the belt 72 in the present embodiment) having the shortest tire width direction dimension in the belt layer 7.

  In the pneumatic tire according to the present embodiment, the vibration mode is asymmetrical inside and outside the vehicle when the cross-sectional area of the bead filler 52 in the meridional section is configured to be larger on the outside of the vehicle than on the inside of the vehicle. Therefore, the sound pressure level in the 315 Hz band is lowered.

  When the cross-sectional area of the bead filler 52 in the meridional section is configured to be larger on the outer side of the vehicle than on the inner side of the vehicle, vibration modes having a high contribution to road noise are generated when the rim is assembled. Becomes asymmetric. For this reason, the rigidity of the entire tire is reduced by relatively increasing the rigidity of the bead portion 5 on the outer side of the vehicle mounting, which has a high contribution of bending rigidity in the tire width direction, and relatively lowering the rigidity of the bead portion 5 on the inner side of the vehicle mounting. It is possible to reduce road noise while ensuring the above.

  On the other hand, if the cross-sectional area at the meridional section of the bead filler 52 is made different between the vehicle mounting inner side and the vehicle mounting outer side, the ground contact state becomes asymmetric (for example, the meridian cross section is deformed into a trapezoidal shape), Stability tends to deteriorate.

  Therefore, in the pneumatic tire according to the present embodiment, the difference in cross-sectional area of the bead filler 52 is provided inside and outside the vehicle, and the tire circumference is between the belt 71 on the inner side in the tire radial direction of the belt layer 7 and the carcass layer 6. Steel cords of substantially 90 [degrees] with respect to the direction were juxtaposed in the tire circumferential direction, and the tire width direction dimension W1 was formed to be 10 [%] or more and 50 [%] or less of the effective belt width W of the belt layer 7. A steel reinforcing layer 9 is arranged. For this reason, the compression deformation rigidity of the tread portion 2 can be improved and the ground contact state can be suitably maintained, and the steering stability can be improved.

  The action of the steel reinforcing layer 9 will be specifically described. FIGS. 2-1 to 2-4 are schematic views showing the presence and arrangement of a steel reinforcing layer, and FIG. 3-1 is a diagram of the steel reinforcing layer in FIGS. 2-1 to 2-4 at normal internal pressure. FIG. 3-2 is a diagram showing cornering power at (for example, 230 [kPa]), and FIG. 3-2 is a diagram at the time of high pressure in the form of the steel reinforcing layer in FIGS. 230 [kPa], the shape of FIG. 2-4 is a diagram showing the cornering power at 300 [kPa], FIG. 4-1 is a normal in the form of the steel reinforcing layer of FIGS. 2-1 to 2-4 It is a figure which shows the self-aligning torque at the time of internal pressure (for example, 230 [kPa]), FIG. 4-2 is the time of the high pressure (for example, FIG. 2-) in the form of the steel reinforcement layer of FIGS. 1 is 230 [kPa] and FIG. 2-4 is 300 [kPa] ]) Is a diagram showing the self-aligning torque in FIG. 5 is a diagram showing a sound pressure level changes in the form of the steel reinforcing layer in Figure 2-1 and Figure 2-4.

  In FIGS. 2-1 to 2-4, the cross-sectional area of the bead filler 52 is not different between the vehicle mounting inner side and the vehicle mounting outer side, the carcass layer 6 is not shown, and the belt layer 7 (belts 71 and 72). ) And the belt reinforcing layer 8 (one reinforcing layer). And FIG. 2-1 is a form which does not have the steel reinforcement layer 9. FIG. FIG. 2B shows a form in which the steel reinforcing layer 9 is provided but the tire width direction dimension is 90% of the effective belt width of the belt layer 7. FIG. 2-3 has the steel reinforcing layer 9 and the tire width direction dimension is 45 [%] of the effective belt width of the belt layer 7, but is arranged on both sides in the tire width direction. FIG. 2-4 shows a form in which the steel reinforcing layer 9 is provided, the tire width direction dimension is 45 [%] of the effective belt width of the belt layer 7, and the tire width direction dimension is arranged at the center position in the tire width direction. Further, in FIGS. 3-1 and 4-1, the form of FIG. 2-1 is a thick broken line, the form of FIG. 2-2 is an alternate long and short dash line, the form of FIG. 2-3 is a thin broken line, and the form of FIG. 3-2 and FIG. 4-2, the form of FIG. 2-1 is shown by a thick broken line, the form of FIG. 2-4 is shown by a solid line, and in FIG. 5, the form of FIG. The form 2-4 is indicated by a circle.

  As shown in FIG. 3A, at normal internal pressure, the cornering power is relatively high at a low load (1 [kN] to 3 [kN]), and the cornering power at a high load (3 [kN] or more). Is not too high in order to improve steering stability. In this regard, a configuration (see FIGS. 2-3 and 2-4) having the steel reinforcing layer 9 in which the tire width direction dimension is 45% of the effective belt width of the belt layer 7 and the steel reinforcing layer 9 are The form (see FIG. 2-1) that does not have the cornering power is not too high at a high load. On the other hand, in the embodiment having the steel reinforcing layer 9 whose tire width direction dimension is 90% of the effective belt width of the belt layer 7 (see FIG. 2-2), the cornering power is too high at a high load.

  Further, as shown in FIG. 3-2, at high pressure, it is preferable that the cornering power does not decrease at low load in order to improve the steering stability. In this regard, the embodiment having the steel reinforcing layer 9 in which the tire width direction dimension is 45% of the effective belt width of the belt layer 7 (see FIG. 2-4) does not have the steel reinforcing layer 9. A decrease in cornering power is not seen as in (refer to FIG. 2-1). In addition, the form (refer FIG. 2-4) which has the steel reinforcement layer 9 which made the tire width direction dimension 45% of the effective belt width of the belt layer 7 does not reduce cornering power in high load.

  Further, as shown in FIG. 4A, it is preferable that the self-aligning torque is relatively high at the normal internal pressure in order to improve the steering stability. In this regard, a configuration (see FIGS. 2-3 and 2-4) having the steel reinforcing layer 9 in which the tire width direction dimension is 45% of the effective belt width of the belt layer 7 and the steel reinforcing layer 9 are The form that does not have (see FIG. 2-1) has a relatively high self-aligning torque. On the other hand, the self-aligning torque is relatively low in the embodiment having the steel reinforcing layer 9 in which the tire width direction dimension is 90% of the effective belt width of the belt layer 7 (see FIG. 2-2).

  Further, as shown in FIG. 4B, in the case of high pressure, the embodiment has the steel reinforcing layer 9 whose tire width direction dimension is 45% of the effective belt width of the belt layer 7 (see FIG. 2-4). No decrease in self-aligning torque is observed in the same manner as in the embodiment without the steel reinforcing layer 9 (see FIG. 2-1).

  That is, from the action shown in FIGS. 3 and 4, when the tire width direction dimension of the steel reinforcing layer 9 exceeds 50 [%] of the effective belt width, the compression rigidity of the tread surface 21 at the time of ground deformation becomes too high. Since the self-aligning torque is reduced, it is not expected to improve the handling stability. Further, when the tire width direction dimension W1 of the steel reinforcing layer 9 is less than 10% of the effective belt width W, the ground contact state cannot be suitably maintained, and improvement in handling stability cannot be expected. In addition, it is preferable to form the tire width direction dimension W1 of the steel reinforcing layer 9 in the range of 20% to 45% of the effective belt width W of the belt layer 7 in order to improve steering stability.

  Moreover, as shown in FIG. 5, with respect to the vehicle interior sound (road noise) on the driver's seat window side when traveling on a paved road at 60 [km / h], the tire width direction dimension W1 is set to the effective belt width W of the belt layer 7. The sound pressure level is lower in the form having the steel reinforcement layer 9 of 45% (see FIG. 2-4) than in the form not having the steel reinforcement layer 9 (see FIG. 2-1). Tend to.

  Thus, according to the pneumatic tire of the present embodiment, the cross-sectional area of the bead filler 52 in the meridional section is configured such that the outer side of the vehicle mounting is larger than the inner side of the mounting of the vehicle, and Between the inner belt 71 and the carcass layer 6, steel cords of substantially 90 degrees with respect to the tire circumferential direction are juxtaposed in the tire circumferential direction, and the tire width direction dimension W1 is the effective belt width W of the belt layer 7. By disposing the steel reinforcing layer 9 formed at 10 [%] to 50 [%], road noise can be reduced while improving steering stability.

  Further, in the pneumatic tire according to the present embodiment, the difference in cross-sectional area between the vehicle mounting outer side and the vehicle mounting inner side of the bead filler 52 (vehicle mounting outer side-vehicle mounting inner side) is 10 [%] or more and 80 [ %] Or less is preferable.

  When the cross-sectional area difference of the bead filler 52 is 10% or more of the total cross-sectional area, the effect of reducing road noise due to asymmetry can be obtained remarkably. On the other hand, if the difference in the cross-sectional area of the bead filler 52 is 80% or less of the total cross-sectional area, in order to prevent the carcass layer 6 from having a greatly different strain state on the left and right, control is performed while maintaining the elastic force inside and outside the vehicle. It is possible to suppress deterioration of stability. Therefore, according to this pneumatic tire, the difference in cross-sectional area of the bead filler 52 is set to 10% to 80% of the total cross-sectional area, thereby improving the driving stability and reducing road noise. Can be obtained remarkably.

  Further, in the pneumatic tire according to the present embodiment, the tire radial direction difference between the vehicle mounting outer side and the vehicle mounting inner side of the bead filler 52 (vehicle mounting outer dimension Hout−vehicle mounting inner dimension Hin) is incorporated in the regular rim. In a state where 5% of the normal internal pressure is filled, the tire cross-section height H is preferably 5% or more and 60% or less.

  Here, 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 tire cross-section height H is ½ of the difference between the tire outer diameter and the rim diameter. In the present embodiment, the outer diameter of the tire is the outer diameter of the tire in the no-load state (the maximum dimension in the tire radial direction) that is mounted in a normal rim and filled with 5% of the normal internal pressure. .

  If the tire radial direction dimensional difference of the bead filler 52 is 5 [%] or more of the tire cross-section height H, the effect of reducing road noise due to asymmetry is remarkably obtained. On the other hand, if the dimensional difference in the tire radial direction of the bead filler 52 is 60 [%] or less of the tire cross-sectional height H, in order to prevent the distortion state of the carcass layer 6 from greatly differing from left to right, elasticity inside and outside the vehicle is mounted. It is possible to maintain the power and suppress the deterioration of steering stability. Therefore, according to this pneumatic tire, road noise is improved while improving steering stability by setting the tire radial direction dimensional difference of the bead filler 52 to 5 [%] or more and 60 [%] or less of the tire cross-section height H. It is possible to obtain a remarkable effect of reducing.

  Further, in the pneumatic tire of the present embodiment, the steel reinforcing layer 9 has the tire equatorial plane CL at the center position in the tire width direction within a range S of 0.5 [%] to 15 [%] of the effective belt width W. On the other hand, it is preferable to offset the vehicle toward the inside of the vehicle.

  Regarding the asymmetry of the tread portion 2, since the mass sensitivity is larger than the bending rigidity, the effective belt width W is within a range S of 0.5% to 15% so that the large deformation side is lightened. By arranging the center position in the tire width direction of the steel reinforcing layer 9 at a position closer to the vehicle mounting side than the tire equatorial plane CL, the ground contact shape can be optimized and road noise can be reduced. The offset range S is preferably 2% or more and 8% or less of the effective belt width W in order to obtain the effect of reducing road noise while improving steering stability. In addition, since the sensitivity of conicity is larger in the tread portion 2, it is desirable to make the offset range S smaller than the cross-sectional area difference between the inside and outside of the bead filler 52 mounted on the vehicle.

  In the pneumatic tire of the present embodiment, the steel reinforcing layer 9 is preferably a non-twisted monofilament with a steel cord having a diameter of 0.27 [mm] or more and 0.45 [mm] or less.

  The steel reinforcing layer 9 improves the compression deformation rigidity of the tread portion 2, but it is preferable to employ a monofilament in order not to increase the tire mass. And in order to improve the compression deformation rigidity of the tread part 2 in the monofilament, it is desirable that the diameter is 0.27 [mm] or more and 0.45 [mm] or less.

Further, in the pneumatic tire of the present embodiment, the steel reinforcing layer 9 has a product of one cross-sectional area of the steel cord and the number of driven portions per 50 [mm] of 4.5 [mm ² ] or more and 6.8. [Mm ² ] or less and the strength is preferably 3200 [MPa].

If the product of the cross-sectional area of one steel cord and the number of driven wires per 50 [mm] is 4.5 [mm ² ] or more, the rigidity is increased and the durability is improved. Also, if the product of the cross-sectional area of one steel cord and the number of driven wires per 50 [mm] is 6.8 [mm ² ] or less, the cord spacing is not close and the adhesion to other layers (durability) Improved).

  The pneumatic tire of the present embodiment has a main groove 22 extending in the tire circumferential direction on the tread surface 21 of the tread portion 2 disposed on the outer side in the tire radial direction of the belt layer 7, and steel. The groove width D1 of the main groove 22 disposed on the outer side in the tire radial direction of the reinforcing layer 9 is preferably smaller than the groove width D2 of the main groove 22 disposed elsewhere.

  By making the groove width D1 of the main groove 22 disposed on the outer side in the tire radial direction of the steel reinforcing layer 9 smaller than the groove width D2 of the other main grooves 22, the bending rigidity of the tread portion 2 is further improved, and road noise It is possible to obtain a significant reduction effect.

  Moreover, it is preferable that the pneumatic tire of this Embodiment is applied to the pneumatic tire for passenger cars with a high internal pressure. Here, the high internal pressure indicates an internal pressure in a range of 280 [kPa] to 350 [kPa].

  In order to reduce the fuel consumption of passenger vehicles equipped with pneumatic tires, it is effective to increase the operating air pressure in order to reduce the rolling resistance of pneumatic tires. Since the input is increased, road noise increases, and the diameter growth of the center region, which is the center in the tire width direction, tends to increase, and the steering stability tends to decrease. According to this pneumatic tire, in such a pneumatic tire for passenger cars having a high internal pressure, it is possible to significantly obtain the effect of reducing road noise while improving steering stability.

  In this example, performance tests on road noise, steering stability, and conicity were performed on a plurality of types of pneumatic tires having different conditions (see FIG. 6).

  In this performance test, a pneumatic tire having a tire size of 195 / 65R15 (effective belt width 134 [mm], cross-sectional height 128 [mm]) is assembled on a regular rim (15 × 6JJ aluminum wheel) with a regular internal pressure. (230 [kPa]) was charged.

  The road noise is evaluated by mounting the pneumatic tire on a test vehicle of a 1500 [cc] front-drive passenger car, attaching a microphone to the driver's seat window side of the test vehicle, and having an uneven road surface at 60 [km / h]. Measure the sound inside the car when driving. Specifically, the sound pressure level in the center frequency 315 Hz band of the 1/3 octave band waveform is measured. And based on this measurement result, a pneumatic tire is made into a reference | standard (100), and sound pressure level difference is exponentially evaluated. This index evaluation shows that road noise is reduced as the numerical value is smaller.

  The steering stability is evaluated by mounting the pneumatic tire on a test vehicle of a 1500 [cc] front-drive passenger car, traveling on a dry test road with the test vehicle, steering performance during lane change and cornering, For straight running stability, the average value of 10 sensory evaluations by 5 test drivers is performed. Based on this sensory evaluation, index evaluation is performed with the conventional pneumatic tire as a reference (100). This index evaluation shows that the larger the value, the better the steering stability.

  The evaluation method of conicity is a tire generated when the pneumatic tire is rotated at a speed of 10 [km / h] under a load of 4.5 [kN] on a uniformity testing machine having a drum diameter of 854 [mm]. Measure the average lateral force generated in the axial direction. In this case, the index is based on the conventional pneumatic tire as a reference (100), and the smaller the index, the better the conicity.

  In FIG. 6, the conventional pneumatic tire does not have a steel reinforcing layer (see FIG. 2-1), and the cross-sectional area of the bead filler is the same inside and outside the vehicle. The pneumatic tire of Comparative Example 1 does not have a steel reinforcing layer, and the cross-sectional area of the bead filler is large on the vehicle mounting outer side. The pneumatic tire of Comparative Example 2 has a steel reinforcing layer (see FIG. 2-2), but the cross-sectional area of the bead filler is the same inside and outside the vehicle. The pneumatic tire of Comparative Example 3 has a steel reinforcing layer (see FIG. 2-3), but the cross-sectional area of the bead filler is the same inside and outside the vehicle. The pneumatic tire of Comparative Example 4 has a steel reinforcing layer (see FIG. 2-4), but the cross-sectional area of the bead filler is the same inside and outside the vehicle.

  Moreover, in FIG. 6, the pneumatic tires of Examples 1 to 11 have a steel reinforcing layer (Example 1: see FIG. 2-3, Examples 2 to 11: see FIG. 2-4). The cross-sectional area of the bead filler is larger on the vehicle mounting outer side than on the vehicle mounting inner side. In the pneumatic tires of Examples 9 to 11, the positions of the steel reinforcing layers are arranged close to the vehicle mounting inner side. In the pneumatic tires of Example 10 and Example 11, the steel cord is a non-twisted monofilament. Further, in the pneumatic tires of Examples 5 to 11, the difference in cross-sectional area between the vehicle mounting outside and the vehicle mounting inside of the bead filler is in the range of 10 [%] to 80 [%] of the total cross-sectional area. ing. In addition, the pneumatic tires of Examples 6 to 11 have a tire radial dimension difference between the vehicle mounting outer side and the vehicle mounting inner side of the bead filler in a state where the pneumatic tire is assembled in a normal rim and filled with 5% of the normal internal pressure. Is in the range of 5 [%] to 60 [%] of the tire cross-section height.

  And as shown to the test result of FIG. 6, it turns out that the road noise of the pneumatic tire of Example 1- Example 11 is reduced, improving steering stability.

2 Tread portion 21 Tread surface 22 Main groove 23 Land portion 3 Shoulder portion 4 Side wall portion 5 Bead portion 51 Bead core 52 Bead filler 6 Carcass layer 7 Belt layers 71, 72 Belt 8 Belt reinforcing layer 81, 82 Reinforcing layer 9 Steel reinforcing layer CL tire equator surface (tire equator line)

Claims (8)

A pair of left and right bead cores, a carcass layer disposed between the bead cores, a bead filler disposed on the outer side in the tire radial direction of each bead core, and a belt layer disposed on the outer side in the tire radial direction of the carcass layer; In a pneumatic tire in which the orientation inside and outside the vehicle is specified when the vehicle is mounted,
The cross-sectional area of the bead filler in the meridional section is configured such that the outer side of the vehicle is larger than the inner side of the vehicle, and between the innermost belt in the tire radial direction of the belt layer and the carcass layer in the tire circumferential direction. On the other hand, a steel reinforcing layer in which steel cords of substantially 90 degrees are juxtaposed in the tire circumferential direction, and the tire width direction dimension is 10% to 50% of the effective belt width of the belt layer. A pneumatic tire characterized by being arranged.   2. The pneumatic tire according to claim 1, wherein a difference in cross-sectional area between the vehicle mounting outer side and the vehicle mounting inner side of the bead filler is 10% to 80% of the total cross-sectional area.   In the state where the tire radial dimension difference between the vehicle mounting outer side and the vehicle mounting inner side of the bead filler is incorporated in a normal rim and filled with 5 [%] of the normal internal pressure, the tire cross-section height is 5 [%] or more and 60 [ %] Or less. The pneumatic tire according to claim 1 or 2, wherein:   The steel reinforcing layer is arranged such that the center position in the tire width direction is arranged closer to the vehicle mounting inner side with respect to the tire equatorial plane in a range of 0.5 [%] to 15 [%] of the effective belt width. The pneumatic tire according to any one of claims 1 to 3.   5. The steel reinforcement layer according to claim 1, wherein the steel cord is a non-twisted monofilament having a diameter of 0.27 [mm] or more and 0.45 [mm] or less. Pneumatic tire. The steel reinforcing layer has a product of one cross-sectional area of the steel cord and the number of driven portions per 50 [mm] of 4.5 [mm ² ] or more and 6.8 [mm ² ] or less, and has a strength. The pneumatic tire according to any one of claims 1 to 5, wherein the pneumatic tire is 3200 [MPa].   The tread surface of the tread portion disposed on the outer side in the tire radial direction of the belt layer has a main groove extending in the tire circumferential direction, and the main groove disposed on the outer side in the tire radial direction of the steel reinforcing layer is The pneumatic tire according to any one of claims 1 to 6, wherein a groove width is smaller than that of a main groove arranged in other than that.   The pneumatic tire according to any one of claims 1 to 7, which is applied to a pneumatic tire for a passenger car having a high internal pressure.

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