WO2015019818A1 - 空気入りタイヤ - Google Patents
空気入りタイヤ Download PDFInfo
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- WO2015019818A1 WO2015019818A1 PCT/JP2014/068981 JP2014068981W WO2015019818A1 WO 2015019818 A1 WO2015019818 A1 WO 2015019818A1 JP 2014068981 W JP2014068981 W JP 2014068981W WO 2015019818 A1 WO2015019818 A1 WO 2015019818A1
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- tire
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- ply
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- cord
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C3/00—Tyres characterised by the transverse section
- B60C3/04—Tyres characterised by the transverse section characterised by the relative dimensions of the section, e.g. low profile
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C15/00—Tyre beads, e.g. ply turn-up or overlap
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
- B60C9/02—Carcasses
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
- B60C9/18—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers
- B60C9/20—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
- B60C9/18—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers
- B60C9/20—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel
- B60C9/2003—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel characterised by the materials of the belt cords
- B60C9/2009—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel characterised by the materials of the belt cords comprising plies of different materials
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
- B60C9/18—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers
- B60C9/20—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel
- B60C9/22—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel the plies being arranged with all cords disposed along the circumference of the tyre
- B60C9/2204—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel the plies being arranged with all cords disposed along the circumference of the tyre obtained by circumferentially narrow strip winding
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
- B60C2009/0071—Reinforcements or ply arrangement of pneumatic tyres characterised by special physical properties of the reinforcements
- B60C2009/0078—Modulus
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
- B60C9/18—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers
- B60C2009/1828—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers characterised by special physical properties of the belt ply
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
- B60C9/18—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers
- B60C9/20—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel
- B60C2009/2012—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel with particular configuration of the belt cords in the respective belt layers
- B60C2009/2019—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel with particular configuration of the belt cords in the respective belt layers comprising cords at an angle of 30 to 60 degrees to the circumferential direction
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
- B60C9/18—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers
- B60C9/20—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel
- B60C2009/2048—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel characterised by special physical properties of the belt plies
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
- B60C9/18—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers
- B60C9/20—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel
- B60C2009/2048—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel characterised by special physical properties of the belt plies
- B60C2009/2051—Modulus of the ply
- B60C2009/2058—Modulus of the ply being different between adjacent plies
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
- B60C9/18—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers
- B60C9/20—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel
- B60C2009/2074—Physical properties or dimension of the belt cord
- B60C2009/208—Modulus of the cords
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
- B60C9/18—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers
- B60C9/20—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel
- B60C2009/2074—Physical properties or dimension of the belt cord
- B60C2009/2083—Density in width direction
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
- B60C9/18—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers
- B60C9/20—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel
- B60C2009/2074—Physical properties or dimension of the belt cord
- B60C2009/2093—Elongation of the reinforcements at break point
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
- B60C9/18—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers
- B60C9/20—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel
- B60C9/22—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel the plies being arranged with all cords disposed along the circumference of the tyre
- B60C2009/2228—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel the plies being arranged with all cords disposed along the circumference of the tyre characterised by special physical properties of the zero degree plies
Definitions
- the present invention relates to a pneumatic tire with improved fuel efficiency.
- Tire factors in vehicle fuel efficiency include tire rolling resistance and air resistance.
- the rolling resistance of the tire is mainly caused by energy loss due to repeated deformation of rubber during running.
- a rubber having a small energy loss small tan ⁇ is used for the tread rubber.
- a narrow and large bead diameter tire with a reduced tire cross-section width and a larger bead diameter reduces energy loss at the tread and sidewalls and reduces tire mass. It has been found that fuel efficiency is greatly improved by reducing air resistance.
- the angle of the belt cord is set to a small angle, for example, about 30 °.
- the improvement cost due to the structure is better than the deterioration due to the tread profile, and the effect of further reducing the rolling resistance is exhibited. I was able to find out what would be done.
- the present invention relates to a tire having a narrow and large bead diameter, based on the fact that the angle of the belt cord is set to a value larger than 35 ° and not more than 55 °, which is larger than the conventional one.
- An object of the present invention is to provide a pneumatic tire that can further improve the fuel efficiency improvement effect.
- the present invention is a carcass that leads from the tread portion to the bead core of the bead portion through the sidewall portion, A belt layer composed of two belt plies arranged radially outside the carcass and inside the tread portion, and having a belt cord inclined at an angle ⁇ opposite to the tire equator; A pneumatic tire comprising a band layer composed of a single band ply that is disposed radially outside the belt layer and inside the tread portion, and a band cord is spirally wound in the tire circumferential direction.
- the angle ⁇ of the belt cord is 45 ° to 55 °.
- the tensile rigidity in the range of 0.4% to 1.0% of elongation per belt cord is Ea
- the belt cord in the first and second belt plies is perpendicular to the belt cord.
- the ply rigidity of the belt ply which is the product of the tensile rigidity Ea and the number of driven Na (Ea ⁇ Na) is 14000 to 20000 N / mm. It is preferable.
- the tensile rigidity in the range of 3% to 5% of elongation per band cord is Eb
- the band cord per 1 mm of ply width in the direction perpendicular to the band cord in the band ply is Eb
- the ply rigidity of the band ply which is the product of the tensile rigidity Eb and the driving number Nb (Eb ⁇ Nb)
- the tire outer diameter Dt (unit: mm) satisfies the following expressions (4) and (5).
- each part of the tire is values specified when the bead part is held in accordance with the rim width defined by the tire size in a non-rim assembled state. Further, in this specification, in the range of T1 or more and T2 or less, it is expressed as T1 to T2.
- the pneumatic tire of the present invention is formed as a tire having a narrow and large bead diameter in which the tire cross-sectional width Wt satisfies the expressions (1) and (2). Therefore, it is possible to achieve a reduction in the amount of energy loss in the tread portion and the sidewall portion, a reduction in tire mass, and a reduction in air resistance, thereby improving fuel efficiency.
- the belt cord angle ⁇ is set in the range of 35 ° to 55 °. This makes it possible to further improve the rolling resistance while suppressing crack damage TGC (Tread Groove Cracking) at the groove bottom of the lug groove provided in the tread portion, as described in the “Mode for Carrying Out the Invention” section. Become.
- (A), (B) is a graph which shows the distortion of the tire axial direction of the tread rubber in a tire equator at the time of tire rolling, and the distortion of the tire axial direction of a belt layer.
- (A), (B) is a graph which shows the distortion of the tire axial direction of the tread rubber in a tread shoulder at the time of tire rolling, and the distortion of the tire axial direction of a belt layer. It is a graph of "elongation-load curve" explaining the tensile rigidity of a cord. It is a graph which shows the relationship between band ply rigidity and belt layer ply rigidity, and the amount of energy loss of a tread rubber and a topping rubber.
- the pneumatic tire 1 of the present embodiment includes a carcass 6 that extends from a tread portion 2 through a sidewall portion 3 to a bead core 5 of a bead portion 4, a radially outer side of the carcass 6, and a tread portion. 2 and a belt layer 7 and a band layer 9 disposed radially outside the belt layer 7 and inside the tread portion 2.
- the pneumatic tire 1 is a radial tire for a passenger car is shown.
- the tire cross-sectional width Wt satisfies the following expressions (1) and (2). It is formed as a tire with a narrow and large bead diameter. Wt ⁇ ⁇ 0.7257 ⁇ (Db) 2 + 42.763 ⁇ Db ⁇ 339.67 ⁇ (1) Wt ⁇ ⁇ 0.7257 ⁇ (Db) 2 + 48.568 ⁇ Db ⁇ 552.33 ⁇ (2)
- the region Y1 satisfying the expressions (1) and (2) is outside the range of the conventional tire indicated by the plot, and the average relation Ka indicated by the expression (A) is expressed by the tire cross-sectional width. It is arranged at a position where Wt is translated in a small direction and bead diameter Db is translated in a large direction. That is, a tire satisfying the above formulas (1) and (2) has a narrow and large bead diameter in which the tire cross-sectional width Wt is reduced and the bead diameter Db is increased as compared with a conventional tire having the same tire outer diameter. Tire.
- Such a tire has a narrow tread width due to a narrow tire cross-sectional width, and accordingly, a rubber amount of the tread rubber also decreases. Therefore, the amount of energy loss due to the tread rubber is relatively reduced, and the tire mass is also reduced.
- the exposed area of the tire exposed downward from the lower end of the bumper is also reduced with the tire cross-sectional width. Therefore, the air resistance of the tire during traveling can be reduced.
- the bead diameter is larger than that of a conventional tire having the same tire outer diameter, the side wall region where the deformation during running is large is narrowed. As a result, the amount of energy loss in the sidewall portion 3 is reduced, and the tire mass is also reduced.
- the fuel consumption performance of the tire can be improved by reducing the energy loss in the tread portion 2 and the sidewall portion 3, reducing the tire mass, and reducing the air resistance.
- the tire outer diameter Dt (unit: mm) satisfies the following expressions (4) and (5).
- the average relationship Kb shown in the expression (B) is arranged at a position where the tire outer diameter Dt is translated in the large direction. Is done.
- a tire that further satisfies the expressions (4) and (5) is a tire having a narrow width, a large bead diameter, and a large tire outer diameter Dt.
- the tire T1 having a relatively large tire outer diameter Dt has less bending deformation in the circumferential direction at the contact portion than the tire T2 having a small tire outer diameter Dt. Therefore, the amount of energy loss is small, and it is effective in reducing rolling resistance.
- decrease of the said rolling resistance by tire diameter increase cannot be anticipated.
- the tire flatness is preferably in the range of 55% to 70%. If the tire flatness is less than 55%, the tread width is widened, and tread members such as tread rubber are increased accordingly, leading to an increase in energy loss. Conversely, when the tire flatness ratio exceeds 70%, the ratio of the sidewall members increases, thereby causing an increase in energy loss.
- the road index LI of the pneumatic tire 1 of this example is set in a range of +3 to ⁇ 10 with respect to the load index LI 0 of the reference tire.
- the tire width Wt 0 of the reference tire is defined as the nominal width closest to the value W calculated by the following equation (6) using the tire flatness ratio H.
- W 0.0098 ⁇ H 2 ⁇ 2.9758 ⁇ H + 343.69 ⁇ (6)
- the rim diameter Dr 0 of the reference tire is defined as an integer closest to the value Dr calculated by the following equation (7) using the tire flatness ratio H (unit:%).
- Dr 0.002 ⁇ H 2 ⁇ 0.3547 ⁇ H + 29.783 ⁇ (7)
- the tire width Wt 0 is defined as 205 which is the nominal width closest to 203.
- the road index LI 0 of the reference tire is a road index described in a tire size specified by TATMA, and when there are a plurality of road indexes LI 0 , the lowest value is adopted.
- the carcass 6 of the pneumatic tire 1 includes one or more carcass cords in which a carcass cord is arranged at an angle of, for example, 75 to 90 ° with respect to the tire equator Co, in this example, one carcass. It is formed from ply 6A.
- the carcass ply 6 ⁇ / b> A has ply folding portions 6 b that are folded from the inner side to the outer side in the tire axial direction around the bead core 5 at both ends of the toroidal ply main body portion 6 a straddling the bead cores 5 and 5.
- a bead apex rubber 8 for bead reinforcement that extends from the bead core 5 outward in the tire radial direction is disposed.
- the belt layer 7 is formed of two belt plies 7A and 7B in which a belt cord 7c is inclinedly arranged in opposite directions with respect to the tire equator Co. That is, the belt layer 7 has a bias structure in which the belt cords cross each other between the plies, and strongly reinforces almost the entire width of the tread portion 2.
- the angle ⁇ of the belt cord 7c with respect to the tire equator Co is set to 35 to 55 °, which is larger than the conventional angle.
- FIG. 6A shows the relationship between the angle ⁇ of the belt cord 7c and the shear rigidity of the belt layer 7.
- FIG. 6B shows the relationship between the angle ⁇ of the belt cord 7 c and the Poisson's ratio of the belt layer 7.
- the Poisson's ratio means a ratio between a deformation amount in the tire circumferential direction and a deformation amount in the tire axial direction (width direction) when the belt layer 7 is pulled in the tire circumferential direction.
- the belt layer 7 is pulled in the tire circumferential direction at the time of ground contact.
- the Poisson's ratio is larger, the behavior of the tread portion 2 in the tire axial direction becomes large, and the amount of energy loss is increased. Therefore, it is preferable that the Poisson's ratio is smaller from the viewpoint of rolling resistance.
- the Poisson's ratio has a maximum value when ⁇ 15 °, and from the maximum value, the Poisson's ratio decreases as ⁇ increases.
- the inclination is steep between 20 ° and 35 °, and gradually decreases from 35 °.
- the range of 35 to 55 ° is a region where the shear rigidity is large and the Poisson's ratio is small, and the effect of reducing rolling resistance can be exhibited.
- the range of 35 to 55 ° is as large as the range of 50 to 55 ° for shear rigidity, but the Poisson's ratio is relatively large. Therefore, the behavior of the tread portion 2 in the tire axial direction is slightly large, and the effect of reducing rolling resistance is relatively low. Therefore, in the range of 35 to 55 °, a range larger than 40 ° where the Poisson's ratio is smaller, particularly a range of 45 ° or more is more preferable.
- the angle ⁇ exceeds 55 °, although the Poisson's ratio is small, the shear rigidity itself is excessively reduced, so that the effect of reducing the rolling resistance is not sufficiently exhibited.
- the protrusion of the tread portion 2 toward the outside in the radial direction increases due to the decrease in shear rigidity. Therefore, when the lug groove is formed in the tread portion 2, it tends to cause crack damage such as a crack in the groove bottom.
- a tire for a passenger car (tire size 165 / 65R19) having the structure shown in FIG.
- the distortion in the direction and the distortion in the tire axial direction of the belt layer 7 were calculated by the finite element method, and the results are shown in FIGS. 7 (A) and 7 (B).
- the tread rubber strain calculation position is the center of the tread rubber thickness
- the belt layer 7 strain calculation position is the position between the belt plies 7A and 7B.
- the distortion in the tire axial direction of the tread rubber at the position P (shown in FIG. 1) on the tread shoulder and the distortion in the tire axial direction of the belt layer 7 are measured. The results are shown in FIGS. 8 (A) and 8 (B).
- the ply stiffness (hereinafter sometimes referred to as “belt ply stiffness”) in the belt plies 7A and 7B is preferably in the range of 14000 to 20000 N / mm.
- the ply stiffness (hereinafter sometimes referred to as “band ply stiffness”) in the band ply 9A is preferably in the range of 1600 to 2500 N / mm.
- the belt ply rigidity is defined by the product (Ea ⁇ Na) of the tensile rigidity Ea per belt cord and the number Na of belt cords to be driven.
- the driving number Na means the driving number of belt cords per 1 mm of the ply width of the belt ply in the direction perpendicular to the belt cords.
- the tensile rigidity Ea is the tensile rigidity in the range of 0.4% to 1.0% of the cord elongation. As illustrated in FIG. 9, the tensile rigidity Ea is expressed as a load per 1% of the elongation amount from an inclination between 0.4% and 1.0% of elongation in the “elongation-load curve” of the cord. Desired.
- the band ply rigidity is defined by the product (Eb ⁇ Nb) of the tensile rigidity Eb per band cord and the number Nb of band cords to be driven.
- the driving number Nb means the number of band cords driven per 1 mm of the ply width of the band ply in the direction perpendicular to the band cords.
- the tensile stiffness Eb is the tensile stiffness in the range of 3% to 5% of the cord elongation.
- the tensile rigidity Ea is obtained as a load per 1% of the elongation amount from an inclination between 3% and 5% of elongation in the “elongation-load curve” of the cord.
- the cause is estimated as follows.
- the belt layer 7 is bent in the circumferential direction, a force is generated in the length direction of the belt cord, and shear deformation is generated in the belt layer.
- the belt ply rigidity is small, it is presumed that the shear deformation of the belt layer 7 is also small, and the behavior of the tread rubber on the belt layer 7 is reduced.
- the belt cord angle ⁇ is set to 35 ° or more. Therefore, the behavior in the tire axial direction in the tread portion 2 is reduced as compared with the conventional case. Therefore, distortion at the bottom of the lug groove is reduced, and crack damage is suppressed. That is, by setting the belt cord angle ⁇ to 35 ° or more, the belt ply rigidity can be made lower than the conventional one. Therefore, the effect of reducing the rolling resistance due to the angle ⁇ and the effect of reducing the rolling resistance due to the belt ply rigidity can be activated.
- the rolling resistance reduction effect will not be exhibited effectively. Conversely, if it is less than 15000 N / mm, although it is preferable for rolling resistance, it becomes difficult to suppress crack damage at the bottom of the lug groove.
- the tread portion 2 enters the ground contact region, the tread portion 2 is bent in the circumferential direction, so that the band layer 9 is deformed to the tension side and the belt layer 7 is deformed to the compression side. Therefore, when the band ply rigidity is large, the force is more likely to act on the belt layer 7. Therefore, the deformation of the topping rubber of the belt layer 7 becomes large, and the amount of energy loss increases. However, the deformation of the band layer 9 itself is suppressed because the band ply rigidity is increased, and the amount of energy loss of the tread rubber disposed thereon is reduced. That is, when the band ply rigidity increases, the energy loss amount of the topping of the belt layer 7 increases, but the energy loss amount of the tread rubber decreases conversely.
- the band ply rigidity has an appropriate range for reducing the sum of the energy loss amount of the tread rubber and the energy loss amount of the topping. If the appropriate range is 1600 to 2500 N / mm and the band ply rigidity is out of the above range, the total energy loss becomes large, which is disadvantageous for rolling resistance. Moreover, when the band ply rigidity is less than 1600 N / mm, the tagging effect is insufficient, which causes a disadvantage in crack damage at the bottom of the lug groove.
- FIG. 10 shows a tread rubber and a topping rubber (belt layer and belt) in a tire in which five types of band layers having different band ply stiffnesses B1 to B5 and three types of belt layers having different belt ply stiffnesses A1 to A3 are combined. It is the calculation result which calculated
- the values of the band ply stiffnesses B1 to B5, the values of the belt ply stiffnesses A1 to A3, the value of the energy loss amount of the tread rubber, and the value of the energy loss amount of the topping rubber in the drawing are indicated by indices.
- a pneumatic tire having the internal structure shown in FIG. 1 was prototyped according to the specifications shown in Table 1, and the rolling resistance, air resistance, and riding comfort performance of each sample tire were tested.
- Example 2 (165 / 65R19) in Table 1 is a standard tire (corresponding to Example 3A in Table 2), and only the belt cord angle ⁇ , belt ply stiffness Ea / Na, and band ply stiffness Eb / Nb are shown. Tires changed according to the specifications of No. 2 were manufactured, and the rolling resistance at that time and the crack damage (TGC) at the bottom of the groove were tested.
- TGC crack damage
- ⁇ TGC> Make a cut scratch with a depth of 2mm and a length of 8mm with a razor blade with a thickness of 0.25mm at the bottom of the circumferential groove and lug groove arranged in the tread, and mold the mouth opening shape. measure. Also, the tire was run on a drum for 10000 km with a rim (5.0 J ⁇ 19), internal pressure (310 kPa), and load (4.8 kN), and the cut flaw size before running and cut flaw after running The reciprocal of the increase was shown as an index with the standard tire as 100. The larger the value, the better the crack damage resistance.
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Abstract
Description
該カーカスの半径方向外側かつトレッド部の内部に配され、かつベルトコードがタイヤ赤道に対して互いに逆向きの角度θで傾斜配列された2枚のベルトプライからなるベルト層と、
該ベルト層の半径方向外側かつトレッド部の内部に配され、かつバンドコードがタイヤ周方向に螺旋状に巻回された1枚のバンドプライからなるバンド層とを具えた空気入りタイヤであって、
タイヤ断面巾をWt(単位:mm)、ビード径をDb(単位:インチ)としたとき、前記タイヤ断面巾Wtが次式(1)、(2)を充足するとともに、前記ベルトコードの角度θを35~55°の範囲としたことを特徴としている。
Wt≦ -0.7257×(Db)2 + 42.763×Db - 339.67 ---(1)
Wt≧ -0.7257×(Db)2 + 48.568×Db - 552.33 ---(2)
Dt≦ 59.078×Wt0.498 ---(4)
Dt≧ 59.078×Wt0.467 ---(5)
Wt≦ -0.7257×(Db)2 + 42.763×Db - 339.67 ---(1)
Wt≧ -0.7257×(Db)2 + 48.568×Db - 552.33 ---(2)
Wt=-0.7257×(Db)2 + 39.134×Db - 217.30 ---(A)
Dt≦ 59.078×Wt0.498 ---(4)
Dt≧ 59.078×Wt0.467 ---(5)
Dt= 59.078×Wt0.448 ---(B)
W=0.0098×H2-2.9758×H+343.69 ---(6)
又基準タイヤのリム径Dr0は、タイヤ扁平率H(単位:%)を用いて次式(7)で計算される値Drに最も近い整数として定義される。
Dr=0.002×H2-0.3547×H+29.783 ---(7)
W=0.0098×602-2.9758×60+343.69 = 203
である。従って、タイヤ巾Wt0は、203に最も近い呼び幅である205として定義される。
又式(7)から、
Dr=0.002×602-0.3547×60+29.783 = 15.7
である。従って、リム径Dr0は、15.7に最も近い整数である16として定義される。即ち、基準タイヤのタイヤサイズは、203/60R16となる。
前記打ち込み本数Nbは、バンドコードと直角方向のバンドプライのプライ巾1mm当たりのバンドコードの打ち込み本数を意味する。又前記引張り剛性Ebは、コードの伸び3%~5%の範囲における引張り剛性である。前記引張り剛性Eaは、コードの「伸び-荷重曲線」における、伸び3%と5%との間の傾きから、伸び量1%当たりの荷重として求められる。
転がり抵抗試験機を用い、下記の条件にて、タイヤの転がり抵抗(単位N)を測定し、その逆数を比較例1を100とする指数で示している。数値が大なほど転がり抵抗が少なく良好である。
温度:20℃、
荷重:4.8kN
内圧:表1に記載
リム:正規リム
速度:80km/h
実験室にて、バンパー下端からの露出高さを140mmとし、走行速度100km/hに相当する空気をタイヤの露出面に送風し、そのときタイヤが受ける空気力を測定した。評価は、測定値の逆数を、比較例1を100とする指数で示し、数値が大なほど空気抵抗が小さく良好である。
試供タイヤの縦バネ定数を測定し、その逆数を比較例1を100とする指数で示した。数値が大なほど、乗り心地性能に優れている。
表1の実施例2(165/65R19)を標準タイヤ(表2の実施例3Aに相当する。)とし、ベルトコードの角度θ、ベルトプライ剛性Ea/Na、バンドプライ剛性Eb/Nbのみを表2の仕様で変化させたタイヤを試作し、そのときの転がり抵抗と、ラブ溝溝底での亀裂損傷性(TGC)とをテストした。
トレッド部に配される周方向溝とラグ溝の溝底に、厚さ0.25mm のかみそりの刃で、深さ2mm、長さ8mm のカット傷を入れ、その口開き形状を型取りして計測する。又前記タイヤをリム(5.0J×19)、内圧(310kPa)、荷重(4.8kN)にてドラム上を10000km走行させ、型取りした走行前のカット傷の寸法と、走行後のカット傷の寸法とを比較し、増加量の逆数を、標準タイヤを100とする指数で示した。数値が大なほど耐亀裂損傷性に優れている。
2 トレッド部
3 サイドウォール部
4 ビード部
5 ビードコア
6 カーカス
7 ベルト層
7A、7B ベルトプライ
7c ベルトコード
9 バンド層
9A バンドプライ
Co タイヤ赤道面
Pm 最大幅位置
Claims (5)
- トレッド部からサイドウォール部をへてビード部のビードコアに至るカーカスと、
該カーカスの半径方向外側かつトレッド部の内部に配され、かつベルトコードがタイヤ赤道に対して互いに逆向きの角度θで傾斜配列された2枚のベルトプライからなるベルト層と、
該ベルト層の半径方向外側かつトレッド部の内部に配され、かつバンドコードがタイヤ周方向に螺旋状に巻回された1枚のバンドプライからなるバンド層とを具えた空気入りタイヤであって、
タイヤ断面巾をWt(単位:mm)、ビード径をDb(単位:インチ)としたとき、前記タイヤ断面巾Wtが次式(1)、(2)を充足するとともに、前記ベルトコードの角度θを35~55°の範囲としたことを特徴とする空気入りタイヤ。
Wt≦ -0.7257×(Db)2 + 42.763×Db - 339.67 ---(1)
Wt≧ -0.7257×(Db)2 + 48.568×Db - 552.33 ---(2) - 前記ベルトコードの角度θは、45~55°であることを特徴とする請求項1記載の空気入りタイヤ。
- 前記ベルトコード1本当たりの、伸び0.4%~1.0%の範囲における引張り剛性をEa、前記第1、第2のベルトプライにおけるベルトコードと直角方向のプライ巾1mm当たりのベルトコードの打ち込み本数をNaとしたとき、前記引っ張り剛性Eaと打ち込み本数Naとの積(Ea×Na)であるベルトプライのプライ剛性は、14000~20000N/mmであることを特徴とする請求項1又は2記載の空気入りタイヤ。
- 前記バンドコード1本当たりの、伸び3%~5%の範囲における引張り剛性をEb、前記バンドプライにおけるバンドコードと直角方向のプライ巾1mm当たりのバンドコードの打ち込み本数をNbとしたとき、前記引っ張り剛性Ebと打ち込み本数Nbとの積(Eb×Nb)であるバンドプライのプライ剛性は、1600~2500N/mmであることを特徴とする請求項3記載の空気入りタイヤ。
- タイヤ外径Dt(単位:mm)は、次式(4)、(5)を充足することを特徴とする請求項1~4の何れかに記載の空気入りタイヤ。
Dt≦ 59.078×Wt0.498 ---(4)
Dt≧ 59.078×Wt0.467 ---(5)
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JP6694805B2 (ja) * | 2016-12-09 | 2020-05-20 | 株式会社ブリヂストン | 重荷重用タイヤ |
EP3768526B1 (fr) * | 2018-03-20 | 2024-05-22 | Compagnie Generale Des Etablissements Michelin | Pneumatique comprenant une unique nappe de carcasse avec une profondeur de déformation dans le flanc améliorée après rodage |
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WO2011161854A1 (ja) * | 2010-06-21 | 2011-12-29 | 株式会社ブリヂストン | 乗用車用空気入りラジアルタイヤ |
WO2013065318A1 (ja) * | 2011-11-02 | 2013-05-10 | 株式会社ブリヂストン | 乗用車用空気入りラジアルタイヤ |
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JP4266053B2 (ja) * | 1998-12-28 | 2009-05-20 | 株式会社ブリヂストン | 空気入りタイヤ |
JP2007168711A (ja) * | 2005-12-26 | 2007-07-05 | Bridgestone Corp | 重荷重用空気入りラジアルタイヤ |
WO2010071883A1 (en) * | 2008-12-19 | 2010-06-24 | Michelin Recherche Et Technique S.A. | Improved hydroplaning performance for a tire |
EP2774780B1 (en) * | 2011-11-02 | 2016-04-27 | Bridgestone Corporation | Pneumatic radial tire for passenger car |
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JP2003019762A (ja) * | 2001-07-06 | 2003-01-21 | Sumitomo Rubber Ind Ltd | 空気入りラジアルタイヤの製造方法及びそれにより製造された空気入りラジアルタイヤ |
WO2011161854A1 (ja) * | 2010-06-21 | 2011-12-29 | 株式会社ブリヂストン | 乗用車用空気入りラジアルタイヤ |
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