JP5257185B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that improves rolling resistance.

  As part of environmental measures, there is a need to improve vehicle fuel efficiency. One countermeasure is to reduce rolling resistance in pneumatic tires. Conventionally, as a technique for reducing the rolling resistance of a pneumatic tire, for example, the rolling resistance is reduced by reducing the weight of the tire, or by reducing the heat generation of the rubber by reducing the tread rubber layer. A technique for reducing this is known (for example, Patent Document 1).

  However, due to the recent increase in environmental awareness, further improvements in vehicle fuel efficiency have been demanded, and further improvements in rolling resistance have been demanded for pneumatic tires.

JP-A-2005-22430

  An object of the present invention is to provide a pneumatic tire that contributes to an improvement in rolling resistance.

  The pneumatic tire of the present invention that achieves the above object is a pneumatic tire in which a carcass layer is extended between left and right bead portions, and a plurality of belt layers are disposed on the outer periphery side of the carcass layer in a tread portion. In the state where the air pressure corresponding to is filled, the intersection of the straight line M passing through the tire maximum width position A of the sidewall portion and parallel to the tire axis and the carcass layer is A ′, and the tire radial direction from the tire maximum width position A is The intersection of the straight line N extending in parallel with the tire axis and the carcass layer through the position B separated by a distance of 10% of the tire cross-section height H on the inner side of the tire is B ′, from the tire maximum width position A along the tire radial direction. Assuming that the intersection of the straight line Q extending parallel to the tire axis and the carcass layer through the position C separated by 10% of the tire cross-section height H on the outer side of the tire is C ′, the intersection between the intersection B ′ and the intersection A ′ Mosquito The angle θ inside the tire formed by the debris layer portion and the carcass layer portion between the intersection point A ′ and the intersection point C ′ satisfies 90 ° ≦ θ ≦ 110 ° in the tire meridian section, and the tire maximum width position from the rim diameter position RP The tire radial height SWH up to A satisfies 0.45 ≦ SWH / H ≦ 0.55 in relation to the tire cross-section height H, and the tire cross-section width SW between the left and right tire maximum width positions A is the rim width. It is characterized in that 0.55 ≦ RW / SW ≦ 0.78 is satisfied in relation to RW.

In the pneumatic tire of the present invention that achieves the above object, the mounting direction of the front and back of the tire with respect to the vehicle is specified, a carcass layer is extended between the left and right bead parts, and the carcass layer outer peripheral side of the tread part is provided. a pneumatic tire in which a plurality of belt layers, in a state filled with air pressure corresponding to 5% of the 180 kPa, for the sidewall portion on the vehicle inner side, and street tire axial tire maximum width position a ₁ of the side wall portions The intersection point of the straight line M ₁ extending in parallel with the carcass layer is A ₁ ′, and the position B ₁ that is separated from the maximum tire width position A ₁ by a distance of 10% of the tire cross-section height H along the tire radial direction inside the tire. linear N ₁ and B ₁ the intersection of the carcass layer extending parallel to the street tire axis', a distance of 10% of the tire section height H to the outer tire along the tire maximum width position a ₁ in the tire radial direction 'When the intersection B _1' only the intersection of the straight line Q _1, a carcass layer extending in parallel to the remote location C ₁ street tire axis C ₁ and the intersection A ₁ 'carcass layer portion and the intersection A ₁ between' The angle θ ₁ inside the tire formed by the carcass layer portion between the intersections C ₁ ′ satisfies 90 ° ≦ θ ₁ ≦ 110 ° in the tire meridian cross section, and the tire from the rim diameter position RP to the tire maximum width position A ₁ The radial height SWH ₁ satisfies 0.45 ≦ SWH ₁ /H≦0.55 in relation to the tire cross-section height H, and the tire maximum width position A ₁ inside the vehicle from the center position P ₀ in the tread width direction. The tire cross-section half width SW _{1 up} to the above satisfies 0.55 ≦ (RW / 2) / SW ₁ ≦ 0.78 in relation to the rim width RW.

In particular, in the case of a pneumatic tire in which the mounting direction of the tire front and back with respect to the vehicle is specified, the tire maximum width position of the sidewall portion with respect to the sidewall portion outside the vehicle in a state in which the air pressure corresponding to 5% of 180 kPa is filled. The intersection of the straight line M ₂ passing through A ₂ and extending parallel to the tire axis and the carcass layer is A ₂ ′, and a distance of 10% of the tire cross-section height H from the tire maximum width position A ₂ to the tire inner side along the tire radial direction. The intersection of the straight line N ₂ extending parallel to the tire axis and the carcass layer through the position B ₂ away from the carcass layer is B ₂ ′, and the tire cross-sectional height H is from the tire maximum width position A ₂ to the tire outer side along the tire radial direction. If the intersection of the straight line Q ₂ extending through the position C ₂ separated by 10% and extending parallel to the tire axis and the carcass layer is C ₂ ′, the carcass layer portion and the intersection between the intersection B ₂ ′ and the intersection A ₂ ′ A ₂ 'and intersection C ₂ Angle theta ₂ is ₂ theta in the tire meridian section of the tire inside which forms' and the carcass layer portion between the> 110 ° satisfy tire radial height from the rim diameter position RP to the tire maximum width position A ₂ SWH ₂ Satisfies the relationship 0.45 ≦ SWH ₂ /H≦0.55 in relation to the tire cross-section height H, and the tire cross-section half-width SW from the center position P ₀ in the tread width direction to the tire maximum width position A ₂ outside the vehicle. ₂ preferably satisfies (RW / 2) / SW ₂ > 0.78 in relation to the rim width RW.

  According to the present invention, by defining the angle θ of the carcass layer in the region of the maximum tire width and the height in the tire radial direction up to the maximum tire width position A in the above range, Since bending deformation that absorbs bending deformation can be performed, bending deformation of the tread portion is suppressed, and rolling resistance can be improved.

  Further, by setting the tire cross-sectional width SW between the tire maximum width positions A within the above range, a rim defined in JATMA can be used, and it is not necessary to newly prepare a special-spec rim.

In a pneumatic tire in which the orientation of the front and back of the tire with respect to the vehicle is specified, the carcass layer angle θ ₁ in the tire maximum width region and the tire radial direction to the tire maximum width position A _{1 with} respect to the sidewall portion inside the vehicle By defining the height within the above range, it becomes possible for the sidewall portion to bend and deform so as to absorb the bending deformation of the tread portion at the time of ground contact. Resistance can be improved. On the other hand, with respect to the sidewall portion outside the vehicle, the rolling resistance is determined by defining the angle θ ₂ of the carcass layer in the tire maximum width region and the height in the tire radial direction up to the tire maximum width position A ₂ in the above range. The cornering performance can be improved while maintaining the reduction of the above.

In this case, the tire from the tire section half width SW ₁ and the center position P ₀ of the tread width direction from the center position P ₀ of the tread width direction to the tire maximum width position A ₁ of the vehicle inner side to the tire maximum width position A ₂ of the vehicle outer side By setting the cross-sectional half width SW ₂ in the above range, a rim defined in JATMA can be used, and it is not necessary to newly prepare a special-spec rim.

In the present invention, the tread rubber gauge at the center P ₀ of the tread width direction D _0, away from the center position P ₀ by 15% of the distance of the belt width BW of the widest belt layer toward the outer side in the tire axial direction When the tread rubber gauge at the position P ₁ is D ₁ , it is desirable that the tread rubber gauge D ₀ satisfies 1.1 ≦ D ₀ / D ₁ ≦ 1.3 with respect to the tread rubber gauge D ₁ .

By thus larger than the tread rubber gauge D ₁ of the tread rubber gauge D ₀ at the center position P ₀ of the tread width direction in its outer position P _1, while maintaining the reduction of the rolling resistance, the center position It is possible to secure a sufficient contact length at P ₀ and improve cornering performance.

1 is a schematic cross-sectional view showing an embodiment of a pneumatic tire of the present invention. It is a principal part expanded sectional view of FIG. It is an expanded sectional view showing the modification of the tread part in the pneumatic tire of the present invention. It is an expanded sectional view showing other modifications of a tread part in a pneumatic tire of the present invention. It is a schematic sectional drawing which shows other embodiment of the pneumatic tire of this invention. It is an expanded sectional view which shows the side wall part inside a vehicle in FIG. FIG. 6 is an enlarged cross-sectional view showing a sidewall portion on the vehicle outer side in FIG. 5.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. 1 and 2 show an embodiment of the pneumatic tire of the present invention, where 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion.

  A carcass layer 4 in which reinforcing cords made of organic fiber cords extending in the tire radial direction are arranged at predetermined intervals in the tire circumferential direction and embedded in the rubber layer is extended between the left and right bead portions 3, and both end portions thereof are The bead filler 6 is folded back from the inner side in the tire axial direction so as to sandwich the bead filler 6 around the bead core 5 embedded in the bead part 3.

  The carcass layer 4 includes a main body portion 4A extending between the bead cores 5 and folded both end portions 4B, and both end portions 4B are extended to a position exceeding the tire maximum width position A on the outer side in the tire radial direction. . The bead filler 6 disposed on the outer peripheral side of the bead core 5 extends from the bead portion 3 toward the sidewall portion 2, and the outer peripheral end 6 </ b> A is disposed on the inner side in the tire radial direction from the tire maximum width position A.

  On the outer peripheral side of the carcass layer 4 of the tread portion 1, reinforcing cords such as steel cords are arranged to be inclined with respect to the tire circumferential direction, and embedded in the rubber layer with the inclination direction with respect to the tire circumferential direction being reversed between the layers. Layer (s) of belt layers 7 and 8 are provided. The belt layer 7 disposed on the inner side is wider than the belt layer 8 disposed on the outer side.

  The tire meridian cross-sectional shape of the carcass layer 4 is such that the intersection point between the straight line M passing through the tire maximum width position A located on the surface of the sidewall portion 2 and parallel to the tire axis and the main body portion 4A of the carcass layer 4 is A ′. An intersection of a straight line N extending parallel to the tire axis and a main body portion 4A of the carcass layer 4 through a position B separated from the maximum width position A along the tire radial direction by a distance of 10% of the tire cross-section height H along the tire radial direction. Of the carcass layer 4 and the straight line Q extending parallel to the tire axis through a position C that is separated from the tire maximum width position A by a distance of 10% of the tire cross-section height H along the tire radial direction from the tire maximum width position A. Assuming that the intersection point with the portion 4A is C ′, the angle θ inside the tire formed by the carcass layer portion 4A1 between the intersection point B ′ and the intersection point A ′ and the carcass layer portion 4A2 between the intersection point A ′ and the intersection point C ′ is Odor in meridian section And it is configured so as to satisfy the relationship of 90 ° ≦ θ ≦ 110 °.

  Further, the tire radial height SWH from the rim diameter position RP to the tire maximum width position A satisfies 0.45 ≦ SWH / H ≦ 0.55 in relation to the tire cross-section height H.

  As a result of intensive studies on the rolling resistance of tires, the present inventor has found the following. That is, the rolling resistance of the tire is greatly affected by the bending deformation of the tread portion. When the bending deformation of the tread portion increases at the time of ground contact, the heat generation inside the tire increases and the rolling resistance tends to increase. Conversely, when the bending deformation of the tread portion at the time of ground contact decreases, the rolling resistance tends to decrease.

  Therefore, attention was paid to the sidewall portion connected to the tread portion. Since the sidewall portion supports the tread portion, the bending deformation of the tread portion is affected by the bending deformation of the sidewall portion. The sidewall portion is bent and deformed with the tire maximum width position as a bending point at the time of ground contact. Therefore, when the cross-sectional shape of the carcass layer in the region of the bending point of the side wall portion is changed and the state of bending deformation of the tread portion is examined, the above-described angle θ is specified in the above range, thereby determining the tread portion. It has been found that the side wall portion exhibits a bending deformation behavior that absorbs the bending deformation of the (shoulder region), thereby suppressing the bending deformation of the tread portion and improving the rolling resistance. It has also been found that the tire maximum width position serving as the bending point should be the central portion of the tire cross-section height H shown in the above-described range.

  Therefore, in the present invention, the angle θ is 90 ° ≦ θ ≦ 110 ° and the tire radial height SWH from the rim diameter position RP to the tire maximum width position A is 0 in relation to the tire cross-section height H as described above. .45 ≦ SWH / H ≦ 0.55. Thereby, bending deformation of the tread portion 1 at the time of grounding can be suppressed, and rolling resistance can be improved. Therefore, by combining with other technologies for improving rolling resistance, it becomes possible to further improve rolling resistance, which greatly contributes to the improvement of fuel consumption of the vehicle.

  In the present invention, the tire cross-sectional width SW between the left and right tire maximum width positions A satisfies 0.55 ≦ RW / SW ≦ 0.78 in relation to the width (rim width) RW of the rim to be mounted. Yes. This makes it possible to use the rim prescribed in JATMA, and avoids newly creating a specially-designed rim.

  If the angle θ is smaller than 90 °, the bending deformation of the tread portion 1 tends to increase, and the rolling resistance is deteriorated. If the angle θ exceeds 110 °, the bending deformation suppressing effect of the tread portion 1 cannot be obtained, and the rolling resistance cannot be improved. The angle θ is preferably in the range of 95 to 105 °.

  Even if SWH / H is smaller than 0.45 or larger than 0.55, the bending deformation suppressing effect of the tread portion 1 cannot be obtained, and it becomes difficult to improve the rolling resistance.

  If RW / SW is less than 0.55, a special rim is required. Even if RW / SW exceeds 0.78, it is outside the JATMA stipulated rim and a special rim is required.

  In the present invention, the tire cross-sectional width SW satisfies BW / SW ≦ 0.70 in relation to the belt width BW of the belt layer 7 having the widest width. It is preferable for improving rolling resistance by reducing the distortion of the tread portion 1. The lower limit value of BW / SW is preferably 0.60 ≦ BW / SW from the viewpoint of making the distortion of the tread portion 1 appropriate.

  It is preferable from the viewpoint of durability that the both end portions 4B of the carcass layer 4 extend to the position beyond the tire maximum width position A on the outer side in the tire radial direction as described above. More preferably, extending from the rim diameter position RP to a height of 0.80H at least 80% of the tire cross-section height H is good in terms of rolling resistance and durability. The upper limit value is preferably from the point of rolling resistance to a position at a height of 0.90H, which is 90% of the tire cross-section height H.

  The bead filler 6 having a hardness higher than that of the surrounding rubber is preferably a region in which the outer peripheral end 6A is located on the inner side in the tire radial direction from the position G of 0.25H, which is 25% of the tire cross-section height H, from the rim diameter position RP. It is preferable to arrange them in terms of rolling resistance (optimization of bending deformation of the sidewall portion 2). The lower limit value is desirably 10% of the tire cross-section height H from the viewpoint of preventing the bending deformation of the sidewall portion 2 from becoming excessively large.

  As shown in FIG. 2, in the side rubber layer 9 disposed on the side wall portion 2, the rubber portion 9A including the tire maximum width position A is preferably made of rubber having a tan δ at 60 ° C. of 0.10 or less. Therefore, the heat generation of the sidewall portion 2 can be suppressed, which is preferable from the viewpoint of rolling resistance and durability. The lower limit of tan δ at 60 ° C. is desirably 0.01 or more from the viewpoint of the viscoelastic properties of rubber. The tan δ at 60 ° C. is measured using a viscoelastic spectrometer (manufactured by Toyo Seiki Seisakusho) under the conditions of a frequency of 20 Hz, an initial strain of 10% and a dynamic strain of ± 2% in an atmosphere of 60 ° C. is there.

  The region X where the rubber portion 9A is located should preferably be in the range of 40 to 60% of the tire cross-section height H from the rim diameter position RP, thereby effectively suppressing heat generation when the side rubber layer 9 is deformed. Can do.

FIG. 3 shows a modification of the tread portion in the pneumatic tire of the present invention. As shown in FIG. 3, the tread rubber gauge at the center position P ₀ in the tread width direction is D ₀ , and 15% of the belt width BW of the belt layer 7 having the widest width from the center position P ₀ toward the outer side in the tire axial direction. tread when the rubber gauge was D _1, the tread rubber gauge D ₀ satisfies the _{1.1 ≦ D 0 / D 1 ≦} 1.3 with respect to the tread rubber gauge D ₁ of the in the distance away P ₁ ing. Here, the tread rubber gauge D ₀ means an average rubber gauge in a region of 10% of the belt width BW centering on the center position P ₀ in the tread width direction, and the tread rubber gauge D ₁ is centered on the position P _1. Means an average rubber gauge in the region of 10% of the belt width BW.

By thus larger than the tread rubber gauge D ₁ of the tread rubber gauge D ₀ at the center position P ₀ of the tread width direction in its outer position P _1, while maintaining the reduction of the rolling resistance, the center position It is possible to secure a sufficient contact length at P ₀ and improve cornering performance. If D ₀ / D ₁ is less than 1.1, the contact length is insufficient, so the effect of improving the cornering performance cannot be obtained. It can no longer be obtained.

FIG. 4 shows another modification of the tread portion in the pneumatic tire of the present invention. In FIG. 3, the value of D ₀ / D ₁ is set in the above range by causing the center position P ₀ in the tread width direction to protrude from the other part of the tread surface. In FIG. The value of D ₀ / D ₁ is set in the above range by indenting inward in the tire radial direction at the center in the direction. Even with such a configuration, it is possible to secure a sufficient contact length at the center position P ₀ in the tread width direction and improve cornering performance.

  5 to 7 show other embodiments of the pneumatic tire of the present invention. In this pneumatic tire, the mounting direction of the tire front and back with respect to the vehicle is designated, and the inside of the vehicle is indicated by IN and the outside of the vehicle is indicated by OUT.

  5-7, 1 is a tread part, 2 is a side wall part, 3 is a bead part. A carcass layer 4 in which reinforcing cords made of organic fiber cords extending in the tire radial direction are arranged at predetermined intervals in the tire circumferential direction and embedded in the rubber layer is extended between the left and right bead portions 3, and both end portions thereof are The bead filler 6 is folded back from the inner side in the tire axial direction so as to sandwich the bead filler 6 around the bead core 5 embedded in the bead part 3.

The carcass layer 4 is composed of a main body portion 4A extending between the bead cores 5 and folded both end portions 4B. Both end portions 4B extend outward in the tire radial direction to positions exceeding the tire maximum width positions A ₁ and A _2. It is installed. The bead filler 6 disposed on the outer peripheral side of the bead core 5 extends from the bead portion 3 toward the sidewall portion 2, and the outer peripheral end 6A is disposed on the inner side in the tire radial direction from the tire maximum width positions A ₁ and A _2. ing.

  On the outer peripheral side of the carcass layer 4 of the tread portion 1, reinforcing cords such as steel cords are arranged to be inclined with respect to the tire circumferential direction, and embedded in the rubber layer with the inclination direction with respect to the tire circumferential direction being reversed between the layers. Layer (s) of belt layers 7 and 8 are provided. The belt layer 7 disposed on the inner side is wider than the belt layer 8 disposed on the outer side.

The tire meridian cross-sectional shape of the carcass layer 4 is asymmetric on both sides of the center position P _{0 in} the tread width direction. In other words, in the sidewall portion 2 inside the vehicle, the intersection of the straight line M ₁ passing through the tire maximum width position A ₁ located on the surface of the sidewall portion 2 and extending parallel to the tire axis, and the main body portion 4 A of the carcass layer 4. A ₁ ′, a straight line N ₁ extending in parallel with the tire axis through the position B ₁ that is separated from the maximum tire width position A ₁ by a distance of 10% of the tire cross-section height H along the tire radial direction along the tire radial direction, and the carcass The intersection of the layer 4 with the main body 4A is B ₁ ', and the tire shaft passes through a position C ₁ that is separated from the tire maximum width position A ₁ by a distance of 10% of the tire cross-section height H along the tire radial direction. Assuming that the intersection of the straight line Q ₁ extending in parallel with the main body 4A of the carcass layer 4 is C ₁ ′, the carcass layer portion 411 between the intersection B ₁ ′ and the intersection A ₁ ′, the intersection A ₁ ′, and the intersection C ₁ ′ The angle θ inside the tire formed by the carcass layer portion 412 therebetween ₁ is configured to satisfy the relationship of 90 ° ≦ θ ₁ ≦ 110 ° in the tire meridian cross section.

Further, the tire radial height SWH ₁ from the rim diameter position RP to the tire maximum width position A ₁ satisfies 0.45 ≦ SWH ₁ /H≦0.55 in relation to the tire cross-section height H. It has become.

On the other hand, in the sidewall portion 2 outside the vehicle, the intersection of the straight line M ₂ extending through the tire maximum width position A ₂ located on the surface of the sidewall portion 2 and parallel to the tire axis, and the main body portion 4 A of the carcass layer 4. A ₂ ′, a straight line N ₂ extending in parallel with the tire axis through a position B ₂ separated from the maximum tire width position A ₂ by a distance of 10% of the tire cross-section height H along the tire radial direction along the tire radial direction, and the carcass The intersection of the layer 4 with the main body 4A is B ₂ ′, and the tire shaft passes through a position C ₂ away from the tire maximum width position A ₂ by a distance of 10% of the tire cross-section height H along the tire radial direction. Assuming that the intersection of the straight line Q ₂ extending in parallel with the main body 4A of the carcass layer 4 is C ₂ ′, the carcass layer portion 421 between the intersection B ₂ ′ and the intersection A ₂ ′, the intersection A ₂ ′, and the intersection C ₂ ′ angle theta ₂ of the tire inside formed by the carcass layer portion 422 between It is configured so as to satisfy θ _2> 110 ° in the tire meridian section.

Further, the tire radial height SWH ₂ from the rim diameter position RP to the tire maximum width position A ₂ satisfies 0.45 ≦ SWH ₂ /H≦0.55 in relation to the tire cross-section height H. It has become.

As described above, in the pneumatic tire in which the orientation of the front and back of the tire with respect to the vehicle is specified, the angle θ ₁ is 90 ° ≦ θ ₁ ≦ 110 ° and the tire from the rim diameter position RP with respect to the sidewall portion 2 inside the vehicle. by the range of 0.45 ≦ SWH ₁ /H≦0.55 in relation to the tire radial height SWH ₁ to the maximum width position a ₁ tire section height H, at the time of grounding of the tread portion 1 Bending deformation can be suppressed and rolling resistance can be improved. Therefore, by combining with other technologies for improving rolling resistance, it becomes possible to further improve rolling resistance, which greatly contributes to the improvement of fuel consumption of the vehicle.

On the other hand, for the sidewall portion 2 outside the vehicle, the angle θ ₂ is θ ₂ > 110 °, and the tire radial height SWH ₂ from the rim diameter position RP to the tire maximum width position A ₂ is related to the tire cross-section height H. In the range of 0.45 ≦ SWH ₂ /H≦0.55, cornering performance can be improved while maintaining a reduction in rolling resistance.

Here, when the angle θ ₁ is smaller than 90 °, the bending deformation of the tread portion 1 tends to increase, and the rolling resistance is deteriorated. When the angle θ ₁ exceeds 110 °, the bending deformation suppressing effect of the tread portion 1 cannot be obtained, and the rolling resistance cannot be improved. The angle θ ₁ is preferably in the range of 95 to 105 °. If the angle θ ₂ is 110 ° or less, the effect of improving the cornering performance decreases. The upper limit value of the angle θ ₂ is preferably 160 °.

Even if SWH ₁ / H and SWH ₂ / H are smaller than 0.45 or larger than 0.55, the bending deformation suppressing effect of the tread portion 1 cannot be obtained, and it becomes difficult to improve the rolling resistance.

In the pneumatic tire, the tire cross-section half width SW ₁ from the center position P _{0 in the} tread width direction to the tire maximum width position A _{1 on the} vehicle inner side is 0.55 ≦ (RW / 2) / in relation to the rim width RW. SW ₁ ≦ 0.78 is satisfied, and the tire cross-section half width SW ₂ from the center position P _{0 in the} tread width direction to the tire maximum width position A _{2 on the} outer side of the vehicle is related to the rim width RW (RW / 2 ) / SW ₂ > 0.78 is satisfied. This makes it possible to use a rim defined in JATMA and avoids newly creating a specially-designed rim.

Here, if (RW / 2) / SW ₁ is smaller than 0.55, a specially designed rim is required. Even if (RW / 2) / SW ₁ exceeds 0.78, the rim is outside the JATMA prescribed rim, and a special rim is required. Further, if (RW / 2) / SW ₂ is 0.78 or less, a specially designed rim is required. The upper limit value of (RW / 2) / SW ₂ is preferably 0.88.

In the pneumatic tire, the tire cross-section half width SW ₁ satisfies (BW / 2) / SW ₁ ≦ 0.70 in relation to the belt width BW of the widest belt layer 7. It is preferable in order to improve the rolling resistance by reducing the distortion of the edge part, that is, reducing the distortion of the tread part 1. The lower limit of _{(BW / 2) / SW 1} , 0.60 ≦ a view to a proper distortion of the tread portion 1 (BW / 2) / SW better to the _1. On the other hand, the tire cross-section half width SW ₂ should satisfy (BW / 2) / SW ₂ > 0.70 in relation to the belt width BW of the belt layer 7 having the widest width. The upper limit value of (BW / 2) / SW ₂ is preferably 0.80.

It is preferable from the viewpoint of durability that the both end portions 4B of the carcass layer 4 extend outward in the tire radial direction to positions exceeding the tire maximum width positions A ₁ and A ₂ as described above. More preferably, extending from the rim diameter position RP to a height of 0.80H at least 80% of the tire cross-section height H is good in terms of rolling resistance and durability. The upper limit value is preferably from the point of rolling resistance to a position at a height of 0.90H, which is 90% of the tire cross-section height H.

  The bead filler 6 having a hardness higher than that of the surrounding rubber is preferably a region in which the outer peripheral end 6A is located on the inner side in the tire radial direction from the position G of 0.25H, which is 25% of the tire cross-section height H, from the rim diameter position RP. It is preferable to arrange them in terms of rolling resistance (optimization of bending deformation of the sidewall portion 2). The lower limit value is desirably 10% of the tire cross-section height H from the viewpoint of preventing the bending deformation of the sidewall portion 2 from becoming excessively large.

As shown in FIGS. 6 and 7, in the side rubber layer 9 arranged on the sidewall portion 2, the rubber portions 9A ₁ and 9A ₂ including the tire maximum width positions A ₁ and A ₂ respectively have a tan δ of 0.10 of 0.10. It is preferable that the rubber is composed of the following rubber, and heat generation of the sidewall portion 2 can be suppressed, which is preferable from the viewpoint of rolling resistance and durability. The lower limit of tan δ at 60 ° C. is desirably 0.01 or more from the viewpoint of the viscoelastic properties of rubber.

The region X in which the rubber portions 9A ₁ and 9A ₂ are located should preferably be in the range of 40 to 60% of the tire cross-section height H from the rim diameter position RP, thereby effecting heat generation when the side rubber layer 9 is deformed. Can be suppressed.

In the pneumatic tire described above, in order to ensure cornering performance, the angle θ _{2 is set} to θ ₂ > 110 ° with respect to the sidewall portion 2 on the outside of the vehicle. However, similarly to the inside of the vehicle, 90 ° ≦ θ ₂ ≦ It can also be set to 110 °. In this case, the sidewall portions 2 on the vehicle inner side and the vehicle outer side may have a symmetric structure or an asymmetric structure.

  The present invention can be preferably used for a pneumatic tire for a passenger car having a relatively high flatness ratio of 55% or more where the height of the sidewall portion 2 is relatively high.

  In the present invention, each position and each dimension defined in the tire meridian section are in a state in which the pneumatic tire mounted on the applicable rim is filled with an air pressure equivalent to 5% of 180 kPa.

  Tires 1 to 7 according to the present invention having a flatness ratio of 60% shown in FIG. 1 in which tire sizes are common to 215 / 60R15 and angles θ, SWH / H, and RW / SW are as shown in Table 1 (Examples 1 to 7) ) And Comparative Tires 1 to 4 (Comparative Examples 1 to 4) and Conventional Tire 1 (Conventional Example 1) were produced as test tires, respectively.

  For each test tire, BW / SW is 0.74, the edge position of both ends of the carcass layer with respect to the tire cross-section height H is 0.6H, the position of the outer peripheral edge of the bead filler with respect to the tire cross-section height H is 0.35H, side rubber The tan δ at 60 ° C. of the rubber of the rubber part located in the range of 40 to 60% of the tire cross-sectional height H of the layer is 0.20, and is common.

  When each of these test tires was subjected to a rolling resistance evaluation test by the following method, the results shown in Table 1 were obtained.

Rolling resistance:
Each test tire was mounted on an applicable rim, and the air pressure was set to 230 kPa and attached to a measuring drum testing machine, and a resistance value was measured under conditions of a load load of 4.5 kN and a speed of 80 km / h. The evaluation result is indicated by an index value where the conventional tire 1 is 100. The larger this value, the smaller the rolling resistance, which means that the rolling resistance has been improved.

  From Table 1, it can be seen that the present invention can improve rolling resistance.

  Next, the tire size is the same as in Example 1, the angle θ, SWH / H, RW / SW, BW / SW, edge positions at both ends of the carcass layer with respect to the tire cross-section height H, bead filler with respect to the tire cross-section height H Of the structure shown in FIG. 1 in which the tan δ at 60 ° C. of the rubber of the rubber part located in the range of 40 to 60% of the tire cross-section height H of the side rubber layer is 60% in the configuration shown in FIG. Tires 8 to 11 of the present invention (Examples 8 to 11) were prepared as test tires.

  When each of these test tires was subjected to a rolling resistance evaluation test in the same manner as in Example 1, the results shown in Table 2 were obtained.

  From Table 2, the edge position of both ends of the carcass layer with respect to BW / SW, the tire cross-section height H, the position of the outer peripheral edge of the bead filler with respect to the tire cross-section height H, and 40-60% of the tire cross-section height H of the side rubber layer It can be seen that the rolling resistance can be further improved by changing the tan δ at 60 ° C. of the rubber in the rubber portion located in the range.

Next, the tire size is made common to 215 / 60R15, and the angle θ, SWH / H, BW / SW, RW / SW, D ₀ / D ₁ , and the tire cross-section height H of the side rubber layer are in the range of 40 to 60%. The tires 12 to 17 (Examples 12 to 17) of the present invention and the conventional tire 2 (Conventional Example 2) having a flatness ratio of 60% as shown in FIG. ) Were prepared as test tires.

  Each test tire has a common edge position at both ends of the carcass layer with respect to the tire cross-section height H of 0.6H and a position of the outer peripheral edge of the bead filler with respect to the tire cross-section height H of 0.35H.

  For each of these test tires, a rolling resistance evaluation test was performed by the same method as described above, and a cornering performance evaluation test was performed by the following method. The results shown in Table 3 were obtained. However, the evaluation result of rolling resistance is an index value with the conventional tire 2 being 100.

Cornering performance:
Each test tire was mounted on an applicable rim, and the air pressure was set to 230 kPa and attached to a flat belt type tire characteristic tester. The cornering force was measured under the conditions of a load of 4.5 kN, a speed of 10 km / h, and a slip angle of 1 °. The evaluation result is shown as an index value with the conventional example 2 as 100. The larger the value, the larger the cornering force and the better the cornering performance.

From Table 3, it can be seen that by changing D ₀ / D ₁ , cornering performance can be improved while maintaining a reduction in rolling resistance.

Next, in the pneumatic tire in which the orientation of the front and back of the tire with respect to the vehicle is specified, the tire size is made common at 215 / 60R15, and the vehicle interior angle θ ₁ , (BW / 2) / SW ₁ , (RW / 2) / SW ₁ , angle θ _{2 on} the outside of the vehicle, (BW / 2) / SW ₂ , (RW / 2) / SW ₂ , of the rubber portion located in the range of 40 to 60% of the tire cross-section height H of the side rubber layer Inventive tires 18 to 21 (Examples 18 to 21) having a flatness ratio of 60% and having a structure shown in FIG.

For each test tire, SWH ₁ / H and SWH ₂ / H are 0.5, the edge positions of both ends of the carcass layer with respect to the tire cross-section height H are 0.6 H, and the position of the outer peripheral edge of the bead filler with respect to the tire cross-section height H Is common at 0.35H.

  Each of these test tires was subjected to a rolling resistance and cornering performance evaluation test in the same manner as described above, and the results shown in Table 4 were obtained. However, the evaluation results of rolling resistance and cornering performance are index values with the tire 18 of the present invention as 100.

From Table 4, in the pneumatic tire in which the orientation of the front and back of the tire with respect to the vehicle is specified, with respect to the sidewall portion inside the vehicle, the angle θ ₁ of the carcass layer in the tire maximum width region and the tire maximum width position A ₁ It can be seen that the rolling resistance can be improved by defining the tire radial height SWH ₁ . Further, by defining the angle θ ₂ of the carcass layer in the tire maximum width region and the tire radial height SWH ₂ up to the tire maximum width position A ₂ for the sidewall portion outside the vehicle, the rolling resistance is reduced. It can be seen that the cornering performance can be improved while maintaining the above.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Carcass layer 4A Main body part 4A1, 4A2 Carcass layer part 4B End part 5 Bead core 6 Bead filler 6A Outer peripheral edge 7,8 Belt layer 9 Side rubber layer 9A Rubber part

Claims (20)

In a pneumatic tire in which a carcass layer is extended between the left and right bead portions, and a plurality of belt layers are arranged on the outer periphery side of the carcass layer of the tread portion,
With the air pressure equivalent to 5% of 180 kPa filled, the intersection of the straight line M passing through the tire maximum width position A of the sidewall portion and extending parallel to the tire axis and the carcass layer is A ′, and the tire from the tire maximum width position A The intersection of the straight line N extending in parallel with the tire axis and the carcass layer through the position B separated by 10% of the tire cross-section height H along the radial direction inside the tire along the radial direction B ′, the tire from the tire maximum width position A If the intersection point between the carcass layer and the straight line Q passing through the position C separated by 10% of the tire cross-sectional height H along the radial direction and extending parallel to the tire axis is C ′, the intersection point B ′ The angle θ inside the tire formed by the carcass layer portion between A ′ and the carcass layer portion between the intersection A ′ and the intersection C ′ satisfies 90 ° ≦ θ ≦ 110 ° in the tire meridian cross section, and from the rim diameter position RP Maximum tire width position A The tire radial direction height SWH satisfies 0.45 ≦ SWH / H ≦ 0.55 in relation to the tire cross-sectional height H, and the tire cross-sectional width SW between the left and right tire maximum width positions A is the rim width RW. Therefore, a pneumatic tire satisfying 0.55 ≦ RW / SW ≦ 0.78.   The pneumatic tire according to claim 1, wherein the tire cross-sectional width SW satisfies 0.60 ≦ BW / SW ≦ 0.70 in relation to the belt width BW of the widest belt layer.   3. The air according to claim 1, wherein both ends of the carcass layer are folded back around the bead core embedded in the bead portion from the inner side in the tire axial direction to the outer side and extend outward in the tire radial direction to a position exceeding the tire maximum width position A. Enter tire.   The pneumatic tire according to claim 3, wherein both end portions of the carcass layer are extended from the rim diameter position RP to at least 80% of the tire cross-section height H.   It has a bead filler extended toward a side wall part from a bead part, and the perimeter edge of this bead filler is arranged in the tire diameter direction inside from tire maximum width position A. Pneumatic tires.   The pneumatic tire according to claim 5, wherein the outer peripheral end of the bead filler is disposed in a region located on the inner side in the tire radial direction from a position of 25% of the tire cross-section height H from the rim diameter position RP.   The pneumatic tire according to any one of claims 1 to 6, wherein a rubber portion including a tire maximum width position A in the side rubber layer of the side wall portion is made of rubber having a tan δ of 60 ° C of 0.10 or less.   The pneumatic tire according to claim 7, wherein the rubber portion is located in a range of 40 to 60% of the tire cross-section height H from the rim diameter position RP. In the pneumatic tire in which the mounting direction of the tire front and back with respect to the vehicle is specified, a carcass layer is extended between the left and right bead portions, and a plurality of belt layers are arranged on the outer periphery side of the carcass layer of the tread portion.
With the air pressure corresponding to 5% of 180 kPa filled, the intersection of the carcass layer with the straight line M ₁ extending parallel to the tire axis through the tire maximum width position A ₁ of the side wall portion of the side wall portion of the vehicle A ₁ ′, a straight line N ₁ extending in parallel with the tire axis through the position B ₁ that is separated from the maximum tire width position A ₁ by a distance of 10% of the tire cross-section height H along the tire radial direction along the tire radial direction, and the carcass The intersection point with the layer is B ₁ ′, a straight line extending in parallel with the tire axis through a position C ₁ that is separated from the tire maximum width position A ₁ by a distance of 10% of the tire cross-section height H along the tire radial direction. If the intersection of Q ₁ and the carcass layer is C ₁ ′, the inside of the tire formed by the carcass layer portion between the intersection B ₁ ′ and the intersection A ₁ ′ and the carcass layer portion between the intersection A ₁ ′ and the intersection C ₁ ′ angle theta ₁ is in the tire meridian section 9 ° ≦ theta ₁ satisfies _{≦ 110 °, 0.45 ≦ SWH 1} / H ≦ tire radial height SWH ₁ from the rim diameter position RP to the tire maximum width position A ₁ is in relation to the tire section height H 0.55 is satisfied, and the tire cross-section half width SW ₁ from the center position P ₀ in the tread width direction to the tire maximum width position A ₁ inside the vehicle is 0.55 ≦ (RW / 2) / in relation to the rim width RW. A pneumatic tire satisfying SW ₁ ≦ 0.78. The pneumatic tire according to claim 9, wherein the tire cross-sectional half width SW ₁ satisfies 0.60 ≦ (BW / 2) / SW ₁ ≦ 0.70 in relation to the belt width BW of the widest belt layer. The intersection of the carcass layer with the straight line M ₂ extending parallel to the tire axis through the maximum tire width position A ₂ of the sidewall portion of the sidewall portion outside the vehicle in a state where the air pressure corresponding to 5% of 180 kPa is filled. A ₂ ′, a straight line N ₂ extending in parallel with the tire axis through a position B ₂ separated from the maximum tire width position A ₂ by a distance of 10% of the tire cross-section height H along the tire radial direction along the tire radial direction, and the carcass The intersection point with the layer is B ₂ ′, a straight line extending in parallel with the tire axis through a position C ₂ away from the tire maximum width position A ₂ by a distance of 10% of the tire cross-section height H along the tire radial direction. If the intersection of Q ₂ and the carcass layer is C ₂ ′, the inside of the tire formed by the carcass layer portion between the intersection B ₂ ′ and the intersection A ₂ ′ and the carcass layer portion between the intersection A ₂ ′ and the intersection C ₂ ′ in the angle theta ₂ tire meridian section theta ₂ > 110 ° is satisfied, and the tire radial height SWH ₂ from the rim diameter position RP to the tire maximum width position A ₂ is 0.45 ≦ SWH ₂ /H≦0.55 in relation to the tire cross-section height H. Satisfactory, the tire cross-section half width SW ₂ from the center position P ₀ in the tread width direction to the tire maximum width position A ₂ outside the vehicle satisfies (RW / 2) / SW ₂ > 0.78 in relation to the rim width RW. The pneumatic tire according to claim 9 or 10. The pneumatic tire according to claim 11, wherein the tire cross-sectional half width SW ₂ satisfies (BW / 2) / SW ₂ > 0.70 in relation to the belt width BW of the widest belt layer.   The carcass layer according to any one of claims 9 to 12, wherein both ends of the carcass layer are folded back around the bead core embedded in the bead portion from the inner side in the tire axial direction to the outer side and extend outward in the tire radial direction to a position exceeding the tire maximum width position. Pneumatic tire described in 2.   The pneumatic tire according to claim 13, wherein both ends of the carcass layer are extended from the rim diameter position RP to a height of at least 80% of the tire cross-section height H.   It has a bead filler extended toward a sidewall part from a bead part, and the perimeter end of this bead filler is arranged in the tire diameter direction inner side from the tire maximum width position. Pneumatic tire.   The pneumatic tire according to claim 15, wherein the outer peripheral end of the bead filler is arranged in a region located on the inner side in the tire radial direction from a position of 25% of the tire cross-section height H from the rim diameter position RP.   The pneumatic tire according to any one of claims 9 to 16, wherein in the side rubber layer of the sidewall portion, the rubber portion including the tire maximum width position is made of rubber having a tan δ of 60 ° C of 0.10 or less.   The pneumatic tire according to claim 17, wherein the rubber portion is located in a range of 40 to 60% of the tire cross-section height H from the rim diameter position RP. The tread rubber gauge at the center position P ₀ in the tread width direction is D ₀ , and the position P ₁ is separated from the center position P _{0 by} a distance of 15% of the belt width BW of the widest belt layer toward the outer side in the tire axial direction. when the tread rubber gauge was D ₁ of the in any one of claims 1 to 18 tread rubber gauge D ₀ satisfies _{1.1 ≦ D 0 / D 1 ≦} 1.3 with respect to the tread rubber gauge D ₁ The pneumatic tire according to item 1.   The pneumatic tire according to any one of claims 1 to 19, wherein the flatness is 55% or more.

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