Tire

Abstract

In a cross-sectional view in the meridian direction of the tire in an unloaded state in which the tire (1) is attached to a predetermined rim and an internal pressure of 230 [kPa] is applied, the radial distance (D3) from the point (P1) to the point (T3) is in the range of 0.05 < = D3 / D1 < = 0.15 with respect to the radial distance (D1) from the point (P1) to the point (T1). In addition, the radial distance (D6) from the point (P1) to the point (T6) is within the range of 3.00 < = D6 / D3 < = 6.00 from the point (P1) to the radial distance (D3). The radius of curvature (R1) of the first arc passing through the points (T3, T4, and T5) is in the range of 0.40 < = R1 / R2 < = 1.00 with respect to the radius of curvature (R2) of the second arc passing through the points (T1, T6, and T7).

Description

Technical Field

[0001] The present invention relates to a tire, and more particularly to a tire capable of achieving both low rolling resistance performance and wet performance of the tire under use conditions at a high internal pressure. Background Art

[0002] In recent years, tires have adopted a structure in which the profile from the tread portion to the sidewall portion is optimized in order to reduce the rolling resistance of the tire. As a conventional tire adopting such a structure, the technology described in Patent Document 1 is known.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2015-113008 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In recent years, in order to reduce the rolling resistance of tires, it is envisaged to use tires at an internal pressure higher than a specified internal pressure. Even under such high internal pressure usage conditions, it is required to ensure an appropriate tire contact shape and ensure wet performance of the tire.

[0008] Therefore, the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a tire capable of achieving both low rolling resistance performance and wet performance of the tire under usage conditions at high internal pressure.

[0009] Technical means of solving problems

[0010] In order to achieve the above-mentioned purpose, the tire of the present invention comprises a carcass layer, a belt layer formed by stacking a pair of cross belts, a tread rubber and a sidewall rubber, and is characterized in that, in a cross-sectional view in the meridian direction of the tire in a no-load state in which the tire is mounted on a specified rim and an internal pressure of 230 [kPa] is applied, the maximum diameter position of the tire contour is defined as point P1, the maximum width position of the tire contour is defined as point T1, the intersection of a straight line passing through point T1 and parallel to the tire width direction and the tire equatorial plane is defined as point T2, the position of 30 [%] of the distance from point T1 to point T2 is defined as point T3, the position of 20 [%] of the distance from point T1 to point T2 is defined as point T4, and the position of 15 [%] of the distance from point T1 to point T2 is defined as point T5. ] is defined as point T5, the position of 10[%] of the distance from point T1 to point T2 is defined as point T6, and the position of 3[%] of the distance from point T1 to point T2 is defined as point T7, the radial distance D3 from point P1 to point T3 is in the range of 0.05≤D3 / D1≤0.15 relative to the radial distance D1 from point P1 to point T1, the radial distance D6 from point P1 to point T6 is in the range of 3.00≤D6 / D3≤6.00 relative to the radial distance D3 from point P1, and the curvature radius R1 of the first arc passing through points T3, T4 and T5 is in the range of 0.40≤R1 / R2≤1.00 relative to the curvature radius R2 of the second arc passing through points T1, T6 and T7.

[0011] Effects of the Invention

[0012] In the tire of the present invention, since the D3 / D1 ratio, D6 / D3 ratio and R1 / R2 ratio become appropriate under the use conditions of high internal pressure, the tire has the advantage of having both low rolling resistance performance and wet performance. Specifically, (1) the lower limit of the D3 / D1 ratio suppresses the deterioration of the tire rolling resistance due to excessive ground contact pressure in the shoulder area of ​​the tread. In addition, the upper limit of the D3 / D1 ratio ensures the ground contact length of the shoulder area of ​​the tread, thereby ensuring the wet performance of the tire. In addition, (2) the lower limit of the D6 / D3 ratio suppresses the reduction of the tire ground contact area due to excessive radial distance D3 from point P1 to point T3, thereby ensuring the wet performance of the tire. In addition, the upper limit of the D6 / D3 ratio suppresses the deterioration of the tire rolling resistance due to excessive rubber volume of the support wall. In addition, (3) by the lower limit of the R1 / R2 ratio, the uniformity of the ground contact pressure distribution on the tire contact surface is ensured, and the energy loss when the tire rotates is reduced. As a result, the rolling resistance of the tire is reduced. In addition, by the upper limit of the R1 / R2 ratio, the tension of the carcass layer 13 is ensured, thereby ensuring the rigidity of the tire. As a result, an appropriate tire contact shape is ensured, thereby ensuring the wet performance of the tire. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a cross-sectional view in the tire meridian direction showing a tire according to an embodiment of the present invention.

[0014] Figure 2 Yes means Figure 1 Illustration of the outline of the described tire.

[0015] Figure 3 Yes means Figure 2 An enlarged view of the main part of the profile of the described tire.

[0016] Figure 4 Yes means Figure 1 An explanatory diagram of the tread portion of the tire described.

[0017] Figure 5 Yes means Figure 4 An explanatory diagram of an improved example of the described tire.

[0018] Figure 6 Yes means Figure 1 An enlarged view of the tread portion of the tire described.

[0019] Figure 7 This is a graph showing the performance test results of the tire according to the embodiment of the present invention.

[0020] Figure 8 This is a graph showing the performance test results of the tire according to the embodiment of the present invention.

[0021] Fig. 9 This is a graph showing the performance test results of the tire according to the embodiment of the present invention. DETAILED DESCRIPTION

[0022] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the present invention is not limited to the present embodiment. In addition, the constituent elements of the present embodiment include elements that are replaceable while maintaining the identity of the invention and that are obvious to replace. In addition, the multiple improved examples described in the present embodiment can be arbitrarily combined within a range that is obvious to those skilled in the art.

[0023] [tire]

[0024] Figure 1 1 is a cross-sectional view of a tire 1 according to an embodiment of the present invention in the tire meridian direction. This figure shows a cross-sectional view of a single side region in the tire radial direction. In this embodiment, a pneumatic radial tire for a passenger car is described as an example of a tire.

[0025] In this figure, the cross section in the tire meridian direction is defined as the cross section after cutting the tire on a plane including the tire rotation axis (not shown). In addition, the tire equatorial plane CL is defined as a plane passing through the midpoint of the tire section width specified by JATMA and perpendicular to the tire rotation axis. In addition, the tire width direction is defined as a direction parallel to the tire rotation axis, and the tire radial direction is defined as a direction perpendicular to the tire rotation axis.

[0026] The tire 1 has an annular structure centered on the tire rotation axis, and includes: a pair of bead cores 11, 11; a pair of bead cores 12, 12; a carcass layer 13; a belt layer 14; a tread rubber 15; a pair of sidewall rubbers 16, 16; and a pair of rim rubbers 17, 17 (see Figure 1 ).

[0027] A pair of bead cores 11, 11 are formed by winding one or more bead wires made of steel in a ring shape and multiple times, and are buried in the bead portion to form the core of the left and right bead portions. A pair of bead edge cores 12, 12 are respectively arranged on the tire radial outer periphery of the pair of bead cores 11, 11 to reinforce the bead portion.

[0028] The carcass layer 13 has a single-layer structure formed by a layer of carcass ply or a multi-layer structure formed by stacking multiple carcass ply layers, and is annularly erected between the left and right bead cores 11, 11 to form the skeleton of the tire. In addition, the two ends of the carcass layer 13 are rolled back in a manner to wrap the bead core 11 and the bead core 12 and are fixed to the outside in the tire width direction. In addition, the carcass ply of the carcass layer 13 is formed by coating a plurality of ply cords made of steel or an organic fiber material (for example, aramid, nylon, polyester, rayon, etc.) with a coating rubber and rolling them, and has a cord angle of 80 [deg] or more and 100 [deg] or less (defined as the inclination angle of the length direction of the ply cord relative to the circumferential direction of the tire).

[0029] The belt layer 14 is formed by laminating a plurality of belt plies 141 to 143, and is disposed around the outer circumference of the carcass layer 13. The belt plies 141 to 143 include a pair of cross belts 141 and 142 and a belt cover layer 143.

[0030] A pair of cross belts 141, 142 is formed by coating a plurality of belt layer cords made of steel or organic fiber material with coating rubber and rolling, and has a cord angle of 15 [deg] or more and 55 [deg] or less in absolute value (defined as the inclination angle of the length direction of the belt layer cord relative to the circumferential direction of the tire). In addition, the pair of cross belts 141, 142 have cord angles of opposite signs, so that the length directions of the belt layer cords are mutually crossed and stacked (the so-called cross-ply structure). In addition, the pair of cross belts 141, 142 are stacked and arranged on the radially outer side of the tire of the carcass layer 13. Here, the cross belt 141 located on the radially inner side of the tire is defined as the inner cross belt, and the cross belt 142 located on the radially outer side of the tire is defined as the outer cross belt.

[0031] The belt cover layer 143 is formed by covering a belt cover layer cord made of steel or organic fiber material with a coating rubber, and has a cord angle of 0 [deg] or more and 10 [deg] or less in absolute value. In addition, the belt cover layer 143 is, for example, a strip-shaped profile formed by covering one or more belt cover layer cords with a coating rubber, and is formed by spirally winding the strip-shaped profile on the outer peripheral surface of the cross belts 141, 142 multiple times in the tire circumferential direction. In addition, the belt cover layer 143 is arranged to cover the entire area of ​​the cross belts 141, 142.

[0032] The tread rubber 15 is arranged on the tire radial outer periphery of the carcass layer 13 and the belt layer 14 to form the tread portion of the tire 1. A pair of sidewall rubbers 16, 16 are respectively arranged on the tire width direction outer side of the carcass layer 13 to form the left and right sidewall portions. A pair of rim rubbers 17, 17 extend from the tire radial inner side of the left and right bead cores 11, 11 and the turned-back portion of the carcass layer 13 to the tire width direction outer side to form the rim fitting surface of the bead portion.

[0033] [Tire profile]

[0034] Figure 2 Yes means Figure 1 An explanatory diagram of the profile of the tire 1 described. The figure shows the profile from the tire equatorial plane CL to the tire maximum width position T1. Here, since the tire profile has a bilaterally symmetrical structure centered on the tire equatorial plane CL, the single-side area with the tire equatorial plane CL as the boundary is described in detail.

[0035] exist Figure 1 and Figure 2 In the cross-sectional view of the tire meridian direction in the tire mounted on a predetermined rim and under an unloaded state with an internal pressure of 230 [kPa], the maximum diameter position of the tire profile is defined as point P1. In addition, the maximum width position of the tire profile is defined as point T1.

[0036] The prescribed rim refers to the "standard rim" prescribed by JATMA, the "design rim" prescribed by TRA, or the "measuring rim" prescribed by ETRTO. In addition, the prescribed internal pressure mentioned later refers to the "maximum air pressure" prescribed by JATMA, the maximum value of the "tire load limits at various cold inflation pressures" prescribed by TRA, or the "inflation pressures" prescribed by ETRTO. In addition, the prescribed load refers to the "maximum load capacity" prescribed by JATMA, the maximum value of the "tire load limits at various cold inflation pressures" prescribed by TRA, or the "load capacity" prescribed by ETRTO. However, in JATMA, when the tire is a passenger car tire, the prescribed internal pressure is an air pressure of 180 [kPa], and the prescribed load is 88 [%] of the maximum load capacity under the prescribed internal pressure.

[0037] A point P1 of the maximum diameter position of the tire profile is defined as an intersection of the tire profile and the tire equatorial plane CL in a cross-sectional view in the tire meridian direction.

[0038] Point T1 of the maximum width position of the tire profile is defined as the end point of the tire section width DW. In addition, the radial distance D1 from point P1 to point T1 is within the range of 0.15≤D1 / (OD / 2)≤0.20 relative to the tire outer diameter OD (not shown).

[0039] The tire section width DW is measured as the straight-line distance between the sidewalls excluding patterns and characters on the tire side when the tire is mounted on a predetermined rim and an internal pressure of 230 [kPa] is applied and the tire is in an unloaded state.

[0040] In addition, the intersection of a straight line passing through point T1 and parallel to the tire width direction and the tire equatorial plane CL is defined as point T2. In addition, a position at 30[%] of the distance from point T1 to point T2 is defined as point T3. In addition, a position at 20[%] of the distance from point T1 to point T2 is defined as point T4. In addition, a position at 15[%] of the distance from point T1 to point T2 is defined as point T5. In addition, a position at 10[%] of the distance from point T1 to point T2 is defined as point T6. In addition, a position at 3[%] of the distance from point T1 to point T2 is defined as point T7.

[0041] At this time, the radial distance D3 from the point P1 to the point T3 is within the range of 0.05≤D3 / D1≤0.15, preferably within the range of 0.10≤D3 / D1≤0.13, relative to the radial distance D1 from the point P1 to the point T1.

[0042] Furthermore, the radial distance D6 from point P1 to point T6 is within the range of 3.00≤D6 / D3≤6.00 relative to the radial distance D3 from point P1, preferably within the range of 3.20≤D6 / D3≤5.00, and more preferably within the range of 3.50≤D6 / D3≤4.50.

[0043] In addition, the radius of curvature R1 of the first arc passing through the points T3, T4 and T5 is within the range of 0.40≤R1 / R2≤1.00, preferably within the range of 0.45≤R1 / R2≤0.85, and more preferably within the range of 0.50≤R1 / R2≤0.70 relative to the radius of curvature R2 of the second arc passing through the points T1, T6 and T7. In addition, the radius of curvature R1 is within the range of 20 [mm] ≤R1 ≤50 [mm], and more preferably within the range of 22 [mm] ≤R1 ≤35 [mm].

[0044] In the structure, since the D3 / D1 ratio, the D6 / D3 ratio and the R1 / R2 ratio under the use condition of high internal pressure become appropriate, the low rolling resistance performance and wet performance of the tire are taken into account. Specifically, (1) by the lower limit of the D3 / D1 ratio, the deterioration of the tire rolling resistance due to the excessive ground contact pressure in the shoulder area of ​​the tread portion is suppressed. In addition, by the upper limit of the D3 / D1 ratio, the ground contact length of the shoulder area of ​​the tread portion is ensured, thereby ensuring the wet performance of the tire. In addition, (2) by the lower limit of the D6 / D3 ratio, the reduction of the tire ground contact area due to the excessive radial distance D3 from point P1 to point T3 is suppressed, thereby ensuring the wet performance of the tire. In addition, by the upper limit of the D6 / D3 ratio, the deterioration of the tire rolling resistance due to the excessive rubber volume of the supporting wall portion is suppressed. In addition, (3) by the lower limit of the R1 / R2 ratio, the uniformity of the ground contact pressure distribution on the tire ground contact surface is ensured, and the energy loss when the tire rotates is reduced. Thus, the rolling resistance of the tire is reduced. In addition, the tension of the carcass layer 13 is ensured by the upper limit of the R1 / R2 ratio, thereby ensuring the rigidity of the tire. Thus, an appropriate tire contact shape is ensured, thereby ensuring the wet performance of the tire.

[0045] In addition, Figure 2, the radial distance D5 from point P1 to point T5 is within the range of 0.20≤D5 / D1≤0.40 relative to the radial distance D1 to point T1, preferably within the range of 0.30≤D5 / D1≤0.35. Thus, an appropriate tire contact shape is ensured. Specifically, the lower limit suppresses the deterioration of the tire rolling resistance due to excessive ground contact pressure in the shoulder area of ​​the tread portion. The upper limit suppresses the reduction of the tire contact area due to excessive curvature radius of the profile from point T3 to point T5, thereby ensuring the wet performance of the tire.

[0046] In addition, the tire contact end (illustration symbol omitted) when the 230 [kPa] internal pressure and the specified internal pressure are applied is located at 25 [%] to 35 [%] of the distance from the point T1 to the point T2, preferably at 26 [%] to 33 [%]. Furthermore, the distance in the tire width direction from the tire contact end to the point T3 (illustration symbol omitted) is preferably within the range of ±5 [%] relative to the distance from the point T1 to the point T2. Therefore, the tire contact end is preferably located at approximately the same position relative to the point T3. In addition, the tire contact end may be located at a position further inward in the tire width direction than the point T3, or may be located further outward in the tire width direction (illustration omitted).

[0047] In order to obtain an appropriate profile at the internal pressure of 230 [kPa], the tire 1 is made to have the following profile at a predetermined internal pressure.

[0048] First, in a cross-sectional view of the tire meridian direction in an unloaded state in which the tire is mounted on a predetermined rim and a predetermined internal pressure is applied, the maximum diameter position of the tire profile is defined as point P1′ (not shown. See Figure 2 ). In addition, the maximum width position of the tire profile is defined as point T1′. In addition, the intersection of a straight line passing through point T1′ and parallel to the tire width direction and the tire equatorial plane CL is defined as point T2′. In addition, the position of 30[%] of the distance from point T1′ to point T2' is defined as point T3'. In addition, the position of 20[%] of the distance from point T1′ to point T2' is defined as point T4'. In addition, the position of 15[%] of the distance from point T1′ to point T2' is defined as point T5'. In addition, the position of 10[%] of the distance from point T1′ to point T2' is defined as point T6. In addition, the position of 3[%] of the distance from point T1′ to point T2' is defined as point T7′.

[0049] At this time, the radial distance D3' from point P1' to point T3' is within the range of 0.05≤D3' / D1'≤0.15 relative to the radial distance D1' from point P1' to point T1', and preferably within the range of 0.08≤D3' / D1'≤0.13 (illustration omitted). In addition, the radial distance D6' from point P1' to point T6' is within the range of 3.20≤D6' / D3'≤5.00 relative to the radial distance D3' from point P1' to point T3', and preferably within the range of 3.20≤D6' / D3'≤4.50. In addition, the curvature radius R1' of the first arc passing through the points T3', T4' and T5' is within the range of 0.20≤R1' / R2'≤0.80, preferably within the range of 0.25≤R1' / R2'≤0.75, and more preferably within the range of 0.28≤R1' / R2'≤0.58 (illustration omitted). Thus, an appropriate tire profile is ensured at the high internal pressure of 230 [kPa].

[0050] Figure 3 Yes means Figure 2 An enlarged view of the main part of the tire profile described.

[0051] exist Figure 2 In the embodiment, the radial distance Da from point T3 to point T4 is within the range of 0.20≤Da / Db≤1.30 relative to the radial distance Db from point T4 to point T5, preferably within the range of 0.40≤Da / Db≤1.10. Thus, an appropriate tire contact shape is ensured. Specifically, Figure 3 As shown, the smaller the Da / Db ratio is, the smaller the curvature radius R1 (see Figure 2 ) is smaller, the ground contact pressure in the shoulder area of ​​the tread portion is greater. Therefore, by means of the lower limit of the Da / Db ratio, the situation where the ground contact pressure in the shoulder area of ​​the tread portion becomes too large is suppressed, thereby ensuring the uniformity of the ground contact pressure distribution on the tire ground contact surface. As a result, the rolling resistance of the tire is suppressed from being deteriorated. On the other hand, the larger the Da / Db ratio is, the larger the radius of curvature R1 of the first arc is, and the more the ground contact area of ​​the tire is reduced. Therefore, by means of the upper limit of the Da / Db ratio, the ground contact area of ​​the tire is ensured, thereby ensuring the wet performance of the tire. In addition, the radial distance Da is preferably in the range of 2.0[mm]≤Da≤7.0[mm].

[0052] Figure 4 Yes means Figure 1 An explanatory diagram of the tread portion of the tire 1 described above. Figure 5 Yes means Figure 4 An explanatory diagram of an improved example of the tire 1 described above.

[0053] exist Figure 1 In the structure, the tire 1 has a plurality of circumferential main grooves 2c, 2s in the contact area of ​​the tread. Here, the circumferential main groove 2c closest to the tire equatorial plane CL among these circumferential main grooves 2c, 2s is defined as a central main groove, and the circumferential main groove located at the outermost side in the tire width direction is defined as a shoulder main groove.

[0054] exist Figure 1 In the structure of Figure 4 As shown in FIG. 1 , the central main groove 2c is located on the tire equatorial plane CL. However, this is not limited to this. Figure 5 As shown, the central main groove 2c may be arranged at a position away from the tire equatorial plane CL.

[0055] In addition, Figure 1 In the structure of the tire 1, the tire 1 has three circumferential main grooves consisting of a single central main groove 2c and a pair of shoulder main grooves 2s, 2s. However, the tire 1 is not limited thereto, and the tire 1 may also have four or more circumferential main grooves (omitted from the illustration). For example, the pair of central main grooves 2c, 2c may be arranged on the left and right of the tire equatorial plane CL, or an intermediate main groove (omitted from the illustration) may be arranged between the central main groove 2c and the shoulder main groove 2s.

[0056] Here, if Figure 4 As shown, an intersection point P2 of a straight line passing through point P1 and parallel to the tire width direction and a straight line passing through intersection point T5 and parallel to the tire radial direction is defined.

[0057] At this time, the groove cross-sectional area Ac of the central main groove 2c in the cross-sectional view in the meridian direction of the tire is within the range of 0.30≤Ac / At≤1.00 relative to the area At of the area enclosed by point P2, point T3, point T5 and the first arc passing through the points T3, T4 and T5, and is preferably within the range of 0.40≤Ac / At≤0.70. As a result, the groove cross-sectional area Ac of the central main groove 2c is made appropriate. That is, the smaller the groove cross-sectional area Ac of the central main groove 2c, the smaller the groove area of ​​the tire contact area, thereby reducing the wet performance of the tire. In addition, the larger the area At of the area, the larger the radius of curvature R1 of the first arc formed by points T3, T4 and T5 (see Figure 2), the more uneven the ground contact pressure distribution on the tire contact surface, and the worse the rolling resistance of the tire. Therefore, by the lower limit of the Ac / At ratio, the wet performance of the tire is ensured and the rolling resistance of the tire is reduced. In addition, the larger the groove cross-sectional area Ac of the central main groove 2c, the more the ground contact area of ​​the central area of ​​the tread portion will be reduced, thereby worsening the rolling resistance of the tire. In addition, the smaller the area At of the area, the smaller the radius of curvature R1 of the first arc formed by points T3, T4 and T5, the greater the ground contact pressure in the shoulder area of ​​the tread portion, and the worse the rolling resistance of the tire. Therefore, by the upper limit of the Ac / At ratio, the deterioration of the rolling resistance of the tire is suppressed.

[0058] In addition, the groove cross-sectional area Ac of the central main groove 2c in the cross-sectional view in the tire meridian direction is within the range of 1.05≤Ac / As≤1.80 relative to the groove cross-sectional area As of the shoulder main groove 2s, preferably within the range of 1.05≤Ac / As≤1.55. Thus, the groove cross-sectional area ratio Ac / As of the central main groove 2c and the shoulder main groove 2s becomes appropriate. That is, since the central main groove 2c has a high contribution to drainage, the larger the groove cross-sectional area Ac of the central main groove 2c, the more the wet performance of the tire will be improved. On the other hand, the larger the groove cross-sectional area Ac of the central main groove 2c, the more the ground contact area of ​​the central area of ​​the tread will be reduced, thereby making the rolling resistance of the tire worse. In addition, the larger the groove cross-sectional area As of the shoulder main groove 2s, the more uneven the ground contact pressure distribution on the tire ground contact surface, and the worse the rolling resistance of the tire will be. Therefore, by the lower limit, the groove cross-sectional area Ac of the central main groove 2c, which has a high contribution to drainage, is ensured, thereby ensuring the wet performance of the tire. In addition, by the upper limit, the groove cross-sectional area As of the shoulder main groove 2s is suppressed from becoming too large, thereby suppressing the deterioration of the rolling resistance of the tire.

[0059] The groove cross-sectional areas Ac and As of the main grooves 2c and 2s are measured as the area of ​​the region surrounded by the groove wall surface of the main groove and the tire contour in the cross-sectional view in the tire meridian direction in the tire mounted on the specified rim and under the unloaded state of 230 [kPa] internal pressure. In addition, in the structure (omitted in the figure) in which the main groove has a chamfered portion at the groove opening, the groove cross-sectional areas Ac and As are calculated by adding the areas of the chamfered portions. On the other hand, in the structure (omitted in the figure) in which the main groove has decorative concave and convex portions on the groove wall, the groove cross-sectional areas Ac and As are calculated using the groove wall surface excluding these concave and convex portions. In addition, in the structure (omitted in the figure) in which the groove area of ​​the main groove changes in the tire circumferential direction, the maximum value of the groove cross-sectional area over the entire circumference of the tire is used as the groove cross-sectional areas Ac and As.

[0060] Figure 6 Yes means Figure 1An enlarged view of the tread portion of the tire 1. This view shows the tread portion of a single side region bordered by the tire equatorial plane CL.

[0061] exist Figure 6 In the embodiment, the distance Ds from the tire equatorial plane CL to the shoulder main groove 2s is within the range of 0.03≤Ds / DW≤0.20 relative to the tire section width DW, preferably within the range of 0.10≤Ds / DW≤0.20. Thus, the position of the shoulder main groove 2s is made appropriate. Specifically, the rigidity of the central area of ​​the tread is ensured by the lower limit, and the rolling resistance of the tire is reduced. The drainage effect achieved by the shoulder main groove 2s is ensured by the upper limit, thereby ensuring the wet performance of the tire.

[0062] The distance Ds to the shoulder main groove 2s is measured with the groove center line of the shoulder main groove 2s as the end point when the tire is mounted on a predetermined rim and an internal pressure of 230 [kPa] is applied and there is no load.

[0063] The groove centerline of the shoulder main groove 2s is defined as a virtual line connecting the midpoints of the end points of the groove width. In a structure where the groove centerline has a sawtooth shape or a wavy shape, the virtual line of the groove centerline is defined as a straight line passing through the center line of the amplitude and parallel to the tire equatorial plane.

[0064] Furthermore, the tire cross-sectional width DW is within the range of DW / OD ≤ 0.40 with respect to the tire outer diameter OD (not shown), and preferably within the range of DW / OD ≤ 0.35.

[0065] In addition, Figure 1 In the pair of cross belts 141, 142, the wider cross belt (in Figure 1 The belt width Wb1 of the inner diameter side cross belt 141 is within the range of 0.60≤Wb1 / DW≤0.90, preferably within the range of 0.70≤Wb1 / DW≤0.85 with respect to the tire cross-sectional width DW. Thus, the belt width Wb1 becomes appropriate.

[0066] The belt ply width Wb1 is the distance in the tire width direction between the left and right end points of the belt ply (more specifically, the outermost belt ply cords in the tire width direction), and is measured when the tire is mounted on a specified rim and an internal pressure of 230 [kPa] is applied and the tire is in a no-load state.

[0067] For example, in Figure 1 In the structure, the inner diameter side cross belt 141 and the outer diameter side cross belt 142 of the belt layer 14 have a bilaterally symmetrical structure centered on the tire equatorial plane CL. In addition, the inner diameter side cross belt 141 is wider than the outer diameter side cross belt 142. In addition, as Figure 6As shown, the edge portion of the radially inner cross belt 141 is located between point T3 and point T4 in the tire width direction.

[0068] In addition, Figure 6 The thickness Ga3 from point T3 to the outer diameter side cross belt 142 is within the range of 0.70≤Ga3 / Ga1≤0.98, preferably within the range of 0.80≤Ga3 / Ga1≤0.98 relative to the thickness Ga1 from point P1 to the outer diameter side cross belt 142. Thus, the tread thickness in the shoulder area of ​​the tread portion becomes appropriate, reducing the rolling resistance of the tire.

[0069] The thicknesses Gal and Ga3 of the outer diameter side cross belt 142 are measured by the length of the perpendicular line from each point P1 and T3 on the tire profile to the outer surface of the outer diameter side cross belt 142. The outer surface of the outer diameter side cross belt 142 is defined as a virtual line (not shown) connecting the outer ends of the belt layer cords constituting the outer diameter side cross belt 142.

[0070] In addition, Figure 6 The thickness Gb3 from point T3 to the inner surface of the tire is within the range of 0.80≤Gb3 / Gb1≤1.10 relative to the thickness Gb1 from point P1 to the inner surface of the tire, preferably within the range of 0.90≤Gb3 / Gb1≤1.10. Thus, the total thickness of the tread shoulder region becomes appropriate, reducing the rolling resistance of the tire.

[0071] In addition, Figure 6 The thickness Gb4 from point T4 to the inner surface of the tire is within the range of 0.70≤Gb4 / Gb3≤1.10 relative to the thickness Gb3 from point T3 to the inner surface of the tire, preferably within the range of 0.75≤Gb4 / Gb3≤1.05. Thus, the contact shape of the shoulder area of ​​the tread portion becomes appropriate, the wet performance of the tire is improved, and the rolling resistance of the tire is reduced.

[0072] The thicknesses Gb1, Gb3, and Gb4 to the inner surface of the tire are measured by the length of the perpendicular line from each point P1, T3 on the tire profile to the inner surface of the tire.

[0073] [Effect]

[0074] As described above, [1] the tire 1 includes a carcass layer 13, a belt layer 14 formed by laminating a pair of cross belts 141 and 142, a tread rubber 15, and a sidewall rubber 16 (see Figure 1). In addition, in the cross-sectional view in the meridian direction of the tire in the unloaded state where the tire 1 is mounted on a specified rim and an internal pressure of 230 [kPa] is applied, the maximum diameter position of the tire contour is defined as point P1, the maximum width position of the tire contour is defined as point T1, the intersection of a straight line passing through point T1 and parallel to the tire width direction and the tire equatorial plane is defined as point T2, the position of 30 [%] of the distance from point T1 to point T2 is defined as point T3, the position of 20 [%] of the distance from point T1 to point T2 is defined as point T4, the position of 15 [%] of the distance from point T1 to point T2 is defined as point T5, the position of 10 [%] of the distance from point T1 to point T2 is defined as point T6, and the position of 3 [%] of the distance from point T1 to point T2 is defined as point T7 (see Figure 2 ). At this time, the radial distance D3 from point P1 to point T3 is within the range of 0.05≤D3 / D1≤0.15 relative to the radial distance D1 from point P1 to point T1. In addition, the radial distance D6 from point P1 to point T6 is within the range of 3.00≤D6 / D3≤6.00 relative to the radial distance D3 from point P1. In addition, the curvature radius R1 of the first arc passing through points T3, T4 and T5 is within the range of 0.40≤R1 / R2≤1.00 relative to the curvature radius R2 of the second arc passing through points T1, T6 and T7.

[0075] In this structure, since the D3 / D1 ratio, the D6 / D3 ratio and the R1 / R2 ratio become appropriate under the use condition of high internal pressure, the advantages of low rolling resistance performance and wet performance of the tire are achieved. Specifically, (1) by the lower limit of the D3 / D1 ratio, the deterioration of the tire rolling resistance due to excessive ground contact pressure in the shoulder area of ​​the tread portion is suppressed. In addition, by the upper limit of the D3 / D1 ratio, the ground contact length of the shoulder area of ​​the tread portion is ensured, thereby ensuring the wet performance of the tire. (2) by the lower limit of the D6 / D3 ratio, the reduction of the tire ground contact area due to excessive radial distance D3 from point P1 to point T3 is suppressed, thereby ensuring the wet performance of the tire. In addition, by the upper limit of the D6 / D3 ratio, the deterioration of the tire rolling resistance due to excessive rubber volume of the support wall portion is suppressed. In addition, (3) by the lower limit of the R1 / R2 ratio, the uniformity of ground contact pressure distribution on the tire ground contact surface is ensured, reducing the energy loss when the tire rotates. Thus, the rolling resistance of the tire is reduced. In addition, the tension of the carcass layer 13 is ensured by the upper limit of the R1 / R2 ratio, thereby ensuring the rigidity of the tire. Thus, an appropriate tire contact shape is ensured, thereby ensuring the wet performance of the tire.

[0076] [2] In the above [1], in the tire 1, the radial distance D5 from the point P1 to the point T5 is within the range of 0.20≤D5 / D1≤0.40 relative to the radial distance D1 from the point P1 to the point T1 (see Figure 2 ). This has the advantage of ensuring an appropriate tire contact patch shape.

[0077] [3] In the above [1] or [2], in the tire 1, the radial distance Da from the point T3 to T4 is within the range of 0.20≤Da / Db≤1.30 relative to the radial distance Db from the point T4 to T5 (see Figure 2 ). This has the advantage of ensuring an appropriate tire contact patch shape.

[0078] [4] In any one of [1] to [3], in the tire 1, the curvature radius R1 of the first arc is in the range of 20 [mm] ≤ R1 ≤ 50 [mm] (see Figure 2 ). This has the advantage of ensuring an appropriate tire contact patch shape.

[0079] [5] In any one of the above [1] to [4], the tire 1 includes a plurality of circumferential main grooves 2c, 2s (see Figure 1 ). In addition, when defining the intersection point P2 of the straight line passing through the point P1 and parallel to the tire width direction and the straight line passing through the point T5 and parallel to the tire radial direction, the groove cross-sectional area Ac of the central main groove 2c in the cross-sectional view in the tire meridian direction is within the range of 0.30≤Ac / At≤1.00 relative to the area At of the area surrounded by the intersection point P2, point T3, point T5 and the first arc. Thus, there is an advantage that the groove cross-sectional area Ac of the central main groove 2c becomes appropriate.

[0080] [6] In the above [5], in the tire 1, the groove cross-sectional area Ac of the center main groove 2c relative to the groove cross-sectional area As of the shoulder main groove 2s in the cross-sectional view of the tire meridian direction is within the range of 1.05≤Ac / As≤1.80 (see Figure 4 ). Thus, there is an advantage that the groove cross-sectional area ratio Ac / As of the center main groove 2c and the shoulder main groove 2s becomes appropriate.

[0081] [7] In any one of the above [1] to [6], in the tire 1, the distance Ds (see Figure 6 ) relative to the tire section width DW (see Figure 1) is within the range of 0.03≤Ds / DW≤0.20. Thus, there is an advantage that the position of the shoulder main groove 2s becomes appropriate. By the lower limit, the rigidity of the central area of ​​the tread is ensured, and the rolling resistance of the tire is reduced. By the upper limit, the drainage effect achieved by the shoulder main groove 2s is ensured, thereby ensuring the wet performance of the tire.

[0082] [8] In any one of [1] to [7], in the tire 1, the tire cross-sectional width DW (see Figure 1 ) is within the range of DW / OD≤0.40 relative to the tire outer diameter OD. This has the advantage of making the tire section width DW appropriate.

[0083] [9] In any one of the above [1] to [8], in the tire 1, the wider cross belt (in Figure 1 In the embodiment, the belt width Wb1 of the inner diameter side cross belt 141 is within the range of 0.60≤Wb1 / DW≤0.90 with respect to the tire cross-sectional width DW. This has the advantage of making the belt width Wb1 appropriate.

[0084]

[10] In any one of the above [1] to [9], in the tire 1, the thickness Ga3 of the cross belt 142 on the outer diameter side of the pair of cross belts 141 and 142 from the point T3 is within the range of 0.70≤Ga3 / Ga1≤0.98 relative to the thickness Ga1 of the cross belt 142 on the outer diameter side from the point P1 (see Figure 6 ). Thus, there is an advantage that the tread thickness in the shoulder area of ​​the tread portion becomes appropriate.

[0085]

[11] In any one of [1] to

[10] , in the tire 1, the thickness Gb3 from point T3 to the tire inner surface is within the range of 0.80≤Gb3 / Gbl≤1.10 relative to the thickness Gb1 from point P1 to the tire inner surface (see Figure 6 ). Thus, there is an advantage that the total thickness of the tread shoulder region becomes appropriate.

[0086]

[12] In any one of [1] to

[11] , in the tire 1, the thickness Gb4 from point T4 to the tire inner surface is within the range of 0.70 ≤ Gb4 / Gb3 ≤ 1.10 relative to the thickness Gb3 from point T3 to the tire inner surface (see Figure 6 ). This has the advantage of making the ground contact shape of the tread shoulder region appropriate.

[0087] Example

[0088] Figure 7 to Figure 9 This is a graph showing the performance test results of the tire according to the embodiment of the present invention.

[0089] In this performance test, various test tires were evaluated with respect to (1) low rolling resistance performance and (2) wet performance.

[0090] In the evaluation of (1) low rolling resistance performance, a test tire with a tire size of 195 / 65R15 was assembled on a rim with a rim size of 15×6, and an internal pressure of 230 [kPa] and a load of 4.82 [kN] were applied to the test tire. In addition, a drum tester with a drum diameter of 1707 [mm] was used to calculate the reciprocal of the rolling resistance coefficient of the test tire at a speed of 80 [km / h] in accordance with ISO28580 for evaluation. The evaluation was performed by an index evaluation with the comparative example as the reference (100), and the larger the value, the better.

[0091] In the evaluation of (2) wet performance, a test tire with a tire size of 195 / 65R15 was assembled on a rim with a rim size of 15×6, and an internal pressure of 230 [kPa] and a load of 4.1 [kN] were applied to the test tire. In addition, the test vehicle was driven on an asphalt road sprinkled with water with a depth of 1 [mm], and the braking distance from an initial speed of 40 [km / h] was measured. Then, based on the measurement results, an index evaluation was performed with the comparative example as the reference (100). The larger the value, the better the evaluation result.

[0092] The test tires of the embodiment and the comparative example have Figure 1 and Figure 2 In addition, the tire outer diameter OD (not shown) is 640 [mm], and the tire section width DW (see Figure 1 ) is 211 [mm]. In addition, the radial distance D1 from point P1 to point T1 is 63 [mm].

[0093] As shown in the test results, it is found that the test tires of the examples can achieve both low rolling resistance performance and wet performance of the tire under usage conditions at high internal pressure.

[0094] Description of Reference Numerals

[0095] 1: tire; 2s: shoulder main groove; 2c: central main groove; 11: bead core; 12: bead core; 13: carcass layer; 14: belt layer; 141: inner diameter side cross belt; 142: outer diameter side cross belt; 143: belt cover layer; 15: tread rubber; 16: sidewall rubber; 17: rim rubber

Claims

1. A tire, the tire comprising a carcass ply, a belt ply formed by laminating a pair of crossed belt plies, a tread rubber, and a sidewall rubber, characterized in that, In the cross-sectional view in the meridian direction of a tire in a non-loaded state where the tire is mounted on a specified rim and an internal pressure of 230 [kPa] is applied, the position of the maximum diameter of the tire contour is defined as point P1, the position of the maximum width of the tire contour is defined as point T1, the intersection of the straight line passing through point T1 and parallel to the tire width direction with the tire equatorial plane is defined as point T2, the position at 30 [%] of the distance from point T1 to point T2 is defined as point T3, the position at 20 [%] of the distance from point T1 to point T2 is defined as point T4, the position at 15 [%] of the distance from point T1 to point T2 is defined as point T5, the position at 10 [%] of the distance from point T1 to point T2 is defined as point T6, and the position at 3 [%] of the distance from point T1 to point T2 is defined as point T7, the radial distance D3 from point P1 to point T3 is in the range of 0.05 < D3 / D1 ≤ 0.15 with respect to the radial distance D1 from point P1 to point T1, the radial distance D6 from point P1 to point T6 is in the range of 3.00 < D6 / D3 < 6.00 with respect to the radial distance D3 starting from point P1, and the radius of curvature R1 of the first circular arc passing through points T3, T4, and T5 is in the range of 0.40 < R1 / R2 < 1.00 with respect to the radius of curvature R2 of the second circular arc passing through points T1, T6, and T7.

2. The tire according to claim 1, wherein, the radial distance D5 from point P1 to point T5 is in the range of 0.20 < D5 / D1 < 0.40 with respect to the radial distance D1 from point P1 to point T1.

3. The tire according to claim 1 or 2, wherein, the radial distance Da from point T3 to T4 is in the range of 0.20 < Da / Db < 1.30 with respect to the radial distance Db from point T4 to T5.

4. The tire according to any one of claims 1 to 3, wherein, the radius of curvature R1 of the first circular arc is in the range of 20 [mm] ≤ R1 < 50 [mm].

5. The tire according to any one of claims 1 to 4, the tire comprising a plurality of circumferential main grooves, defining the circumferential main groove closest to the tire equatorial plane among the plurality of circumferential main grooves as the central main groove, defining the intersection point P2 of the straight line passing through point P1 and parallel to the tire width direction and the straight line passing through point T5 and parallel to the tire radial direction, and the groove cross-sectional area Ac of the central main groove in the cross-sectional view in the tire meridian direction is in the range of 0.30 < Ac / At ≤ 1.00 with respect to the area At of the region surrounded by the intersection point P2, point T3, point T5, and the first circular arc.

6. The tire according to any one of claims 1 to 5, the tire comprising a plurality of circumferential main grooves, defining the circumferential main groove located at the outermost side in the tire width direction among the plurality of circumferential main grooves as the shoulder main groove, and the groove cross-sectional area Ac of the central main groove in the cross-sectional view in the tire meridian direction is in the range of 1.05 ≤ Ac / As ≤ 1.80 with respect to the groove cross-sectional area As of the shoulder main groove.

7. The tire according to any one of claims 1 to 6, the tire comprising a plurality of circumferential main grooves, defining the circumferential main groove located at the outermost side in the tire width direction among the plurality of circumferential main grooves as the shoulder main groove, and the distance Ds from the tire equatorial plane to the shoulder main groove is in the range of 0.03 ≤ Ds / DW ≤ 0.20 with respect to the tire cross-sectional width DW.

8. The tire according to any one of claims 1 to 7, wherein, the tire cross-sectional width DW is in the range of DW / OD < 0.40 with respect to the tire outer diameter OD.

9. The tire according to any one of claims 1 to 8, wherein, the belt width Wb1 of the wider cross belt in the pair of cross belts is in the range of 0.60 < Wb1 / DW < 0.90 with respect to the tire cross-sectional width DW.

10. The tire according to any one of claims 1 to 9, wherein, the thickness Ga3 from point T3 to the outer diameter side cross belt in the pair of cross belts is in the range of 0.70 < Ga3 / Ga1 < 0.98 with respect to the thickness Gal from point P1 to the outer diameter side cross belt.

11. The tire according to any one of claims 1 to 10, wherein: the thickness Gb3 from point T3 to the tire inner surface is in the range of 0.80 < Gb3 / Gb1 < 1.10 with respect to the thickness Gb1 from point P1 to the tire inner surface.

12. The tire according to any one of claims 1 to 11, wherein: the thickness Gb4 from point T4 to the tire inner surface is in the range of 0.70 < Gb4 / Gb3 < 1.10 with respect to the thickness Gb3 from point T3 to the tire inner surface.

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