WO2020122250A1 - Pneumatic tyre - Google Patents

Pneumatic tyre Download PDF

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Publication number
WO2020122250A1
WO2020122250A1 PCT/JP2019/049038 JP2019049038W WO2020122250A1 WO 2020122250 A1 WO2020122250 A1 WO 2020122250A1 JP 2019049038 W JP2019049038 W JP 2019049038W WO 2020122250 A1 WO2020122250 A1 WO 2020122250A1
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WO
WIPO (PCT)
Prior art keywords
elastic modulus
cord
bead
carcass
tire
Prior art date
Application number
PCT/JP2019/049038
Other languages
French (fr)
Japanese (ja)
Inventor
大澤　靖雄
拓也 吉見
Original Assignee
株式会社ブリヂストン
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP2019097826A external-priority patent/JP7177750B2/en
Application filed by 株式会社ブリヂストン filed Critical 株式会社ブリヂストン
Publication of WO2020122250A1 publication Critical patent/WO2020122250A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D30/00—Producing pneumatic or solid tyres or parts thereof
    • B29D30/06—Pneumatic tyres or parts thereof (e.g. produced by casting, moulding, compression moulding, injection moulding, centrifugal casting)
    • B29D30/08—Building tyres
    • B29D30/20—Building tyres by the flat-tyre method, i.e. building on cylindrical drums
    • B29D30/30—Applying the layers; Guiding or stretching the layers during application
    • 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
    • B60C15/06—Flipper strips, fillers, or chafing strips and reinforcing layers for the construction of the bead
    • 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

Definitions

  • the present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that achieves both a high level of riding comfort and steering stability.
  • a reinforcing layer made of fiber cords or steel cords is arranged over the entire circumference of the tire from the bead portion to the sidewall portion, and the cord angle of the reinforcing layer is made substantially perpendicular to the carcass cord of the carcass layer.
  • Patent Document 1 It is described in Patent Document 1 that the reinforcing layer can increase the circumferential rigidity without changing the vertical rigidity, so that the steering stability and the braking/driving performance can be improved without impairing the riding comfort performance.
  • Patent Document 1 has a poorer riding comfort than the comparative example having no reinforcing layer when viewed from the examples, and thus the riding comfort and the steering stability are actually reduced. It was not possible to achieve both.
  • an object of the present invention is to provide a pneumatic tire that achieves a high level of both riding comfort and steering stability.
  • the pneumatic tire of the present invention includes a pair of bead portions each having a bead core, a pair of sidewall portions which are continuous with each of the pair of bead portions and extend outward in the radial direction, and outer peripheral ends of the pair of sidewall portions.
  • Both end portions are carcasses that are moored to the bead cores in the pair of bead portions and have a toroidal shape from the sidewall portion to the tread portion,
  • a belt provided outside the crown portion of the carcass,
  • a cord is provided on at least a part from the bead portion to the sidewall portion at an angle of 0 to 10° with respect to a circumferential direction, and the cord has an inflection point in a stress-strain curve. It is characterized in that it has a low elastic modulus in a low strain region below the inflection point and a high elastic modulus in a high strain region above the inflection point.
  • the pneumatic tire of the present invention may have a structure in which the cord is made of two or more kinds of fibers made of different materials, and the fibers are made of organic fibers or inorganic fibers. Further, the cord, in the case of a pneumatic tire having a structure in which the carcass is folded back at the bead core to include a main body portion and a folded back portion, and a bead filler is provided between the main body portion and the folded back portion. It may be arranged between the main body ply of the carcass and the bead filler, or may be arranged between the bead filler and the folded ply of the carcass, or the folded back of the carcass. It may be arranged outside the partial ply in the tire radial direction.
  • the cord is located outside the carcass in the tire radial direction. It may be arranged at.
  • the material of the cord preferably contains at least aramid or polyethylene terephthalate.
  • the inflection point is preferably in the range of tensile strain of 1 to 8%, and the elastic modulus of the low strain region is in the range of 10 to 90% with respect to the elastic modulus of the high strain region. It is preferable.
  • the method for producing a pneumatic tire of the present invention is a method for producing the above pneumatic tire
  • the non-linear elastic modulus code is prepared by preparing one or more non-linear elastic modulus codes having a non-linear elastic modulus and applying different tensions to the non-linear elastic modulus code depending on the position in the tire in the tire molding process. It is characterized in that the elastic modulus is controlled so that more kinds of nonlinear elastic modulus characteristic codes than the prepared nonlinear elastic modulus codes are formed in the tire.
  • FIG. 4 is a cross-sectional view in the width direction of the pneumatic tire showing a deformed state when going straight.
  • FIG. 4 is a cross-sectional view in the width direction of the pneumatic tire showing a deformed state during cornering. It is a graph which shows the stress-strain curve of a nonlinear elastic modulus code.
  • FIG. 5 is a partial cross-sectional view in the width direction of a pneumatic tire showing a non-linear elastic modulus cord arrangement, FIG. 5( a) being an example arranged between a main body ply of a carcass and a bead filler, FIG. 5( b ).
  • FIG. 5(c) is an example arranged outside the folded back ply of the carcass in the tire radial direction. It is a partial width direction sectional view of the pneumatic tire of another embodiment of the present invention.
  • FIG. 1 shows a cross-sectional view in the width direction of a pneumatic tire 1 according to an embodiment of the present invention in a state of being assembled to a wheel rim R.
  • a pneumatic tire 1 includes a pair of bead portions 2, a pair of sidewall portions 3 respectively connected to the bead portions 2, and a tread portion 4 connecting outer peripheral ends of the pair of sidewall portions 3. Is equipped with.
  • the bead portion 2 has a bead core 5 formed by winding a bead wire.
  • a bead filler 6 made of hard rubber is arranged adjacent to the bead core.
  • the bead portion 2 includes a pair in the width direction of the pneumatic tire 1, and is anchored to the bead core 5 of one bead portion 2 by arranging one end of the carcass 7 so as to be folded back, and the other bead portion.
  • the carcass 7 is anchored to the second bead core 5 such that the other end of the carcass 7 is folded back.
  • the carcass 7 has a toroidal shape from the pair of sidewall portions 3 connected to the pair of bead portions 2 to the tread portion 4.
  • the carcass 7 is made of a carcass ply in which a carcass cord is covered with rubber, and serves as a skeleton for maintaining the tire shape of the pneumatic tire 1.
  • the carcass cord of the carcass 7 extends in the tire radial direction (radial direction).
  • a belt 8 composed of one or more belt plies is arranged on the outer peripheral side of the crown portion of the carcass 7.
  • the cord 9 is provided on at least a part from the bead portion 2 to the sidewall portion 3.
  • the cord 9 forms an angle of 0 to 10° with respect to the tire circumferential direction.
  • This code 9 has an inflection point in the stress-strain curve, and the tensile strain-stress curve has a low strain region from the origin to the inflection point, and a region having a larger tensile strain than the inflection point is a high strain region. Then, it has a low elastic modulus in a low strain region below the inflection point and a high elastic modulus in a high strain region beyond the inflection point.
  • a cord having a low elastic modulus in a low strain region below the inflection point and a high elastic modulus in a high strain region exceeding the inflection point is referred to as a "non-linear elastic modulus code" in this specification.
  • the cord 9 has a body portion 7a and a bead filler when the carcass 7 is divided into a body portion 7a and a folded portion 7b which is a portion folded back by the bead core 5. It is arranged between 6 and.
  • FIG. 2 is a sectional view in the tire width direction showing a deformed state seen in a vertical section including the tire rotation axis when a load is applied to the tire 1.
  • the deformed state shown in FIG. 2 is the same as the deformed state in which the vehicle is traveling straight ahead.
  • FIG. 3 is a cross-sectional view in the tire width direction showing a tire deformed state as seen in a vertical section including the tire rotation axis when the tire 1 is being subjected to cornering under load.
  • the bead portion 2 inside the corner is deformed outward as indicated by the arrow, but the bead portion 2 outside the corner is less deformed than when traveling straight in FIG. This deformation will be described in more detail.
  • a lateral force is applied to the ground contact surface of the tire 1 from the outside to the inside of the corner. Therefore, compared to the tire deformation at the time of straight traveling shown in FIG.
  • the sidewall portion outside the corner is deformed so that the outward bulge is reduced, and the sidewall portion 3 inside the corner is deformed such that the outward bulge is increased.
  • the bending deformation is reduced in the bead portion 2 located outside the corner of the pair of bead portions 2, and the bending deformation is reduced in the bead portion 2 located inside the corner. Will increase.
  • the pneumatic tire of the present embodiment has a non-linear angle of 0 to 10° with respect to the circumferential direction.
  • the effect of the elastic modulus code 9 will be described in comparison with some comparative tires.
  • the vertical spring coefficient (spring constant in the tire radial direction) becomes large, in other words, the vertical rigidity becomes high, and the riding comfort deteriorates.
  • suppressing the bending deformation of the bead portion by the cord not only suppresses the deformation in the vertical direction (tire radial direction) but also suppresses the deformation in the lateral direction (tire width direction). Therefore, the lateral spring coefficient of the tire (spring constant in the tire width direction) becomes large, in other words, the lateral rigidity becomes high, and steering stability is improved.
  • a cord having a small angle with respect to the circumferential direction (that makes an angle of 0 to 10° with respect to the circumferential direction) in at least a part from the bead portion to the sidewall portion is not a non-linear elastic modulus cord.
  • a cord having a small angle with respect to the circumferential direction is provided in the bead portion as in the comparative tire, the elastic modulus is low against the force of bending deformation of the bead portion in the tire width direction cross section during straight traveling. Since the rubber between the cords is stretched and deformed, there is no influence of the cords.
  • the bulging deformation force of the sidewall portion distorts the cord having a high elastic modulus at an angle close to the circumferential direction, and the cord is hard to extend, so that the rigidity of the tire is increased. Therefore, in the comparative tire, the longitudinal spring coefficient is not affected by the cord provided in the bead portion, but is increased due to the influence of the cord provided in the sidewall portion.
  • cords having a small angle with respect to the circumferential direction are provided in at least a part from the bead portion to the sidewall portion, between cords having a low elastic modulus against the bending deformation force of the bead portion in the tire width direction cross section. There is no effect because the rubber stretches and deforms. Further, with respect to the force of the bulging deformation of the sidewall portion, the portion of the pair of sidewall portions where the bulging deformation is reduced in the sidewall portion outside the corner is close to the circumferential direction, which has a high elastic modulus. Although the cord with the angle is provided, the cord is not affected by the force because the bulging deformation is reduced.
  • the cord having a high elastic modulus and having an angle close to the circumferential direction is distorted, and the cord is hard to extend, so that the tire rigidity can be increased. Therefore, it has been newly found by the study by the inventors that the lateral spring coefficient of the tire is not affected by the cords on the bead portion and the cords on the outside of the corner, but is increased by the influence of the cord on the inside of the corner.
  • the tire longitudinal spring coefficient when going straight affects the riding comfort
  • the tire lateral spring coefficient when cornering affects the steering stability. Therefore, in order to improve the ride comfort by suppressing the increase of the tire vertical springs when going straight, and to increase the increase of the lateral spring coefficient when cornering to improve the steering stability, at least a part from the bead to the sidewall is required.
  • the cord with a small angle to the circumferential direction which has a small angle to the circumferential direction, should have a low cord rigidity at the time of a small deformation during straight running and a high code rigidity at the time of a large deformation during cornering.
  • the inventors have found that such a cord characteristic can be realized by using a non-linear elastic modulus cord for the cord provided in at least a part from the bead portion to the sidewall portion.
  • FIG. 4 is a graph showing an example of the elastic stress-strain curve of the nonlinear elastic modulus code.
  • the nonlinear elastic modulus code has a low elastic modulus in a low strain region divided by an inflection point and a high elastic modulus in a high strain region with respect to the elastic modulus indicated by the slope of the curve in FIG. It has a characteristic of nonlinear elastic modulus.
  • the deformation state of the tire of the present embodiment in which the non-linear elastic modulus cord shown in FIG. 4 is provided at least at a part from the bead portion to the sidewall portion at a low angle with respect to the circumferential direction during straight running and cornering will be described.
  • the bead portion is bent and deformed, and the sidewall portion is bulged and deformed as described with reference to FIG. 2, and the nonlinear elastic modulus cord is distorted by the force of the bulged deformation of the sidewall portion. It takes. Since the strain applied to the non-linear elastic modulus code at this time is in a low strain region smaller than the inflection point of the curve shown in FIG. 4, the cord has a force in the low elastic modulus region. Added. As a result, the rigidity of the tire does not increase even when the non-linear elastic modulus cord is provided during straight traveling, so the longitudinal spring coefficient of the tire does not increase. Therefore, the riding comfort when going straight does not deteriorate.
  • the bead portion is bent and deformed and the sidewall portion is bulged and deformed as described with reference to FIG. 3, but the sidewall portion outside the corner is less deformed than when straight ahead,
  • the strain on the nonlinear elastic modulus code is small.
  • the strain applied to the non-linear elastic modulus cord is a cord having a high strain region larger than the inflection point of the curve shown in FIG. 4, so that the cord has a high elastic modulus. Force is applied in the area.
  • the rigidity of the tire can be increased by providing the non-linear elastic modulus code during cornering, the lateral spring coefficient of the tire can be increased, and the ground contact state during cornering can be improved.
  • the pneumatic tire according to the present embodiment can achieve both a high level of riding comfort and steering stability due to the changes in the deformation state of the tire during straight running and during cornering described above.
  • the nonlinear elastic modulus code of the pneumatic tire of this embodiment will be described in more detail.
  • the elastic modulus of the nonlinear elastic modulus cord is measured by cutting the cord out of the tire. That is, the non-linear elastic modulus code is a code that shows a low elastic modulus or a high elastic modulus in a state of being incorporated in an actual tire in accordance with the deformation during straight running or cornering.
  • the concrete method of measuring the elastic modulus is to perform a test in the same manner as the JIS L1017 “tensile strength and elongation” test, measure the tensile strength and elongation, and from this measurement result, the initial length And the tensile strain, which is the ratio of the length to the extension length, and the vertical axis is the stress, and a curve is drawn on the graph.
  • the curve of the graph in which the stress is on the Y axis and the strain is on the X axis, a perpendicular line that passes through the intersection of the tangent drawn to the curve when the strain is 0 and the tangent drawn to the curve at the break point intersects with the curve. Let the point be an inflection point.
  • This inflection point preferably has a tensile strain in the range of 1 to 8%.
  • the elastic modulus in the low strain region is preferably in the range of 10 to 90% with respect to the elastic modulus in the high strain region. It is more preferable that the cord has a nonlinearity such that the elastic modulus in the high strain region is twice or more as large as the elastic modulus in the low strain region.
  • the elastic modulus ratio between the low strain region and the high strain region is expressed by the ratio between the slope of the straight line connecting the strain 0 to the inflection point and the slope of the straight line connecting the inflection point to the break point. To be done.
  • a cord having low rigidity is used on the inside in the tire radial direction and a rigidity is used on the outside. It is conceivable to provide a high code for each.
  • a tire using a plurality of types of cords when the rigidity changes in the tire radial direction, that is, a place where different types of cords switch, strain concentration occurs in the rubber, cracks occur during use, etc. There is a problem in durability.
  • the pneumatic tire of the present embodiment uses a cord having a non-linear elastic modulus characteristic, so that the rigidity in the tire radial direction due to the non-linear elastic modulus cord gradually changes. Therefore, strain concentration on rubber can be avoided, and durability can be improved.
  • the nonlinear elastic modulus code may be composed of two or more kinds of fibers made of different materials, and the fibers may be composed of organic fibers or inorganic fibers.
  • two or more kinds of materials having different elastic moduli such as a low elastic modulus code and a high elastic modulus code are used in one example.
  • the material of the non-linear elastic modulus code can be organic fibers or inorganic fibers used for tires.
  • the organic fiber include nylon, polyethylene terephthalate, polyethylene naphthalate, aramid and the like.
  • examples of the inorganic fiber include glass fiber, carbon fiber, steel and the like. From these materials, those having different elastic moduli are combined. For example, nylon having the lowest elastic modulus can be selected as the material having a low elastic modulus, and the above-mentioned materials other than nylon can be selected and combined as the material having a high elastic modulus.
  • polyethylene terephthalate can be selected as the low elastic modulus material, and any of polyethylene naphthalate, aramid, glass fiber, carbon fiber and steel can be selected and combined as the high elastic modulus material.
  • polyethylene naphthalate can be selected as the low elastic modulus material, and any of aramid, glass fiber, carbon fiber and steel can be selected and combined as the high elastic modulus material.
  • the elastic modulus By using aramid as at least one of the materials of the non-linear elastic modulus cord, it is possible to suppress the external damage that may occur when a foreign matter hits while traveling by taking advantage of the good cut resistance of aramid. it can. Further, by using polyethylene terephthalate as at least one of the materials of the nonlinear elastic modulus code, the elastic modulus can be increased at low cost.
  • the material applied to the nonlinear elastic modulus code may be different from the material applied to the carcass.
  • the material of the non-linear elastic modulus cord is the same as that of the main body ply, strain is concentrated on the rubber sandwiched between the main body ply and the non-linear elastic modulus cord.
  • the cords having different elastic moduli the side having the cord having the low elastic modulus is pushed from the side having the cord having the high elastic modulus and the strain can be dispersed between the cords.
  • the non-linear elastic modulus code has an angle of 0 to 10° with respect to the tire circumferential direction. If the absolute value of the angle with respect to the tire circumferential direction exceeds 10°, the vertical spring coefficient increases when going straight, and the riding comfort deteriorates. Further, it is preferable that the non-linear elastic modulus cords are not substantially corrugated and are arranged in parallel with each other. When the non-linear elastic modulus cord is substantially untyped, it prevents the rubber around the non-linear elastic modulus cord from being subjected to shear deformation by applying a force in a direction different from the tensile direction when subjected to tension. Therefore, durability can be improved.
  • the arrangement of the non-linear elastic modulus cords is not particularly limited, and may be a position where deformation can occur in at least a part from the bead portion to the sidewall portion.
  • the non-linear elastic modulus cord 9 When arranged in a region including at least the bead portion, the non-linear elastic modulus cord 9 can be arranged between the main body portion 7a ply of the carcass 7 and the bead filler 6 as shown in FIG. 5(b), it can be arranged between the bead filler 6 and the ply of the folded-back portion 7b of the carcass 7. Further, as shown in FIG. Can also be arranged radially outside the tire.
  • the non-linear elastic modulus cord By arranging the non-linear elastic modulus cord between the carcass main body ply and the bead filler as shown in FIG. 5A, the non-linear elastic modulus cord is arranged adjacent to the carcass main body ply.
  • the main body ply generates tension by applying internal pressure, and exhibits rigidity. For this reason, the main body ply mainly bears the deformation of the tire, and disposing the non-linear elastic modulus cords on the outer side adjacent to each other is effective in suppressing the outer deformation of this portion.
  • the bead filler receives the rigidity exerted by the non-linear elastic modulus code, and the lateral spring The coefficient can be further increased.
  • the bead filler is arranged to suppress the deformation of the carcass body ply, if the nonlinear elastic modulus cord is arranged outside the bead filler, not only the body ply but also the bead filler is suppressed from being deformed. Therefore, it is possible to further suppress the outward deformation of this portion.
  • the non-linear elastic modulus cord By arranging the non-linear elastic modulus cord on the outer side in the tire radial direction from the folded ply of the carcass as shown in FIG. 5C, the rigidity exhibited by the non-linear elastic modulus cord was sandwiched between the main body ply and the folded ply. The whole bead filler is received, and the lateral spring coefficient can be greatly increased. The main body section ply, the bead filler, and the folded back ply together suppress deformation of the bead section. By disposing the non-linear elastic modulus cord on the outside of the folded ply, it is possible to suppress the deformation of these three-part integrated parts, and thus it is possible to further suppress the outward deformation of these parts.
  • FIG. 6 shows a partial widthwise sectional view of a pneumatic tire 31 according to another embodiment of the present invention.
  • the bead core 5 is composed of a first bead core 5a and a second bead core 5b.
  • the end of the carcass 7 is anchored by being sandwiched between the first bead core 5a and the second bead core 5b, and is not substantially folded back.
  • the nonlinear elastic modulus cord 9 is provided in at least a part from the bead portion to the sidewall portion, in the tire radial direction rather than the carcass 7 in the embodiment specifically shown in FIG. It can be located on the outside.
  • the non-linear elastic modulus code may be prepared so that it has an appropriate elastic modulus in the tire. Further, the non-linear elastic modulus characteristic of the non-linear elastic modulus code may be utilized to control the elastic modulus of the product by deformation in the tire manufacturing process. In the tire manufacturing process, when tensile deformation is applied to the non-linear elastic modulus cord in the cord direction, it can be easily deformed by utilizing the low strain and low elasticity characteristics of the cord, and it is controlled inside the product tire. An appropriate nonlinear elastic modulus characteristic can be obtained.
  • the nonlinear elastic modulus code may have different nonlinear elastic modulus characteristics within the tire depending on the position where the nonlinear elastic modulus code is arranged on the tire.
  • a plurality of types of nonlinear elastic modulus codes having different nonlinear elastic modulus characteristics may be prepared before tire molding, but one kind or two or more kinds of nonlinear elastic modulus codes are prepared.
  • the elastic modulus of the nonlinear elastic modulus code is controlled by the position within the product tire, and the prepared nonlinear elastic modulus is controlled. More types of non-linear elastic modulus cords than cords can also be obtained in a tire.
  • the elastic modulus of the cord can be changed by changing the tension of the nonlinear elastic cord according to the position in the tire during the manufacturing process, the elastic modulus can be changed depending on the position of the tire while using the same material. Therefore, the number of types of materials of the nonlinear elastic modulus code to be prepared can be reduced, and efficient production can be achieved.
  • tires with various characteristics can be obtained.
  • the nonlinear elastic modulus cord of the sidewall portion is greatly stretched in the circumferential direction. Therefore, the sidewall portion uses the high strain region of the non-linear elastic modulus code, resulting in higher rigidity than the non-linear elastic modulus code of the bead portion. By doing so, the rigidity during cornering of the tire can be increased more effectively.
  • the elastic modulus can be changed by the tension at the time of manufacturing, and the elastic modulus of the bead portion can be made higher than that of the sidewall portion. As a result, the rigidity of the tire when cornering can be slightly increased.
  • the elastic modulus of the non-linear elastic modulus cord that spans the bead portion and the sidewall portion can be increased in the tire radial center portion.
  • the rigidity of the tire when cornering can be increased to a medium level.
  • Table 1 shows data when the test is performed by the following test method. Assume the results when a passenger car tire having a tire size of 205/60R16 92V is manufactured by arranging various cords of the following conventional examples, comparative examples and examples in the bead portion. No cord was placed in the conventional example.
  • the main body ply cord is made of polyethylene terephthalate. Assemble the rim with an internal pressure of 210 kPa, a load of 5.73 kN and a rim of 6J ⁇ 16. After filling the internal pressure, a load of up to 6 kN is applied, the relationship between the load and the deflection is plotted, and the inclination when the load is 5.73 kN is taken as the longitudinal spring coefficient.
  • each spring coefficient is expressed as 100 in the conventional example.
  • Comparative Example 1 An aramid cord having a circumferential angle of 45 degrees is arranged.
  • Comparative Example 2 An aramid cord having a linear elastic modulus is arranged with a circumferential angle of substantially 0 degree.
  • Comparative Example 3 An aramid cord having a non-linear elastic modulus is arranged with a circumferential angle of 50 degrees.
  • Example 1 A non-linear elastic modulus cord obtained by twisting nylon and aramid with a circumferential angle of substantially 0 degree is arranged inside the main body ply. The inflection point is at 2% of the tensile strain, and the elastic modulus in the low strain region is 20% of the high strain region.
  • Example 2 A non-linear elastic modulus cord obtained by twisting nylon and aramid with a circumferential angle of substantially 0 degree is arranged between the bead filler and the folded ply. The inflection point is at 2% of the tensile strain, and the elastic modulus in the low strain region is 20% of the high strain region.
  • Example 3 A non-linear elastic modulus cord obtained by twisting nylon and aramid with a circumferential angle of substantially 0 degree is arranged outside the folded ply. The inflection point is at 2% of the tensile strain, and the elastic modulus in the low strain region is 20% of the high strain region.
  • Example 4 A non-linear elastic modulus cord obtained by twisting nylon and polyethylene terephthalate is arranged at the outer side of the folded ply with a circumferential angle of substantially 0 degree. The inflection point is at 2% of the tensile strain, and the elastic modulus in the low strain region is 50% of the high strain region.
  • Example 5 A structure in which the carcass ply is sandwiched between the bead cores and moored, but is not folded back at the bead cores.
  • a non-linear elastic modulus cord obtained by twisting nylon and aramid with a circumferential angle of substantially 0 degrees is arranged between the main body plies. The inflection point is at 2% of the tensile strain, and the elastic modulus in the low strain region is 20% of the high strain region.

Abstract

This pneumatic tyre 1, which combines ride comfort and handling safety to a high level, comprises: a pair of bead sections 2, which each have a bead core 5; a pair of side wall sections 3, which are respectively connected to the pair of bead sections 2 and extend radially outwards; a tread section 4, which connects the outer circumferential ends of the pair of side wall sections 3; a carcass 7, both ends of which are respectively anchored by the bead cores 5 in the pair of bead sections 2 and which forms a toroidal shape from the side wall sections 3 to the tread section 4; and a belt 8, which is provided to the outer circumferential side of a crown portion of the carcass 7. Furthermore, forming an angle of 0-10° in relation to the circumferential direction, cords 9 are provided at least in portions from the bead sections 2 to the side wall sections 3. The cords 9 have an inflection point in a stress/strain curve and have a low modulus of elasticity in a low strain range lower than or equal to said inflection point and a high modulus of elasticity in a high strain range above the inflection point.

Description

空気入りタイヤPneumatic tire
　本発明は、空気入りタイヤ、詳しくは、乗り心地と操縦安定性とを高いレベルで両立させた空気入りタイヤに関する。 The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that achieves both a high level of riding comfort and steering stability.
　空気入りタイヤの構造において、乗り心地を向上させるための工夫と、操縦安定性を向上させるための工夫とは相反することが多く、乗り心地と操縦安定性とを両立させるための研究開発がなされている。空気入りラジアルタイヤに関し、繊維コード又はスチールコードからなる補強層をビード部からサイドウォール部にかけてタイヤ全周にわたって配置し、当該補強層のコード角度をカーカス層のカーカスコードに対しほぼ直角としたものがある（特許文献１）。かかる補強層により、縦剛性を変えることなく周剛性を上げることができるので、乗り心地性能を損なうことなく、操縦安定性や制駆動性能を高めることができると特許文献１では述べられている。 In the structure of pneumatic tires, there are many cases where a device for improving the riding comfort and a device for improving the driving stability conflict with each other, and research and development has been carried out to make the riding comfort and the driving stability compatible. ing. Regarding pneumatic radial tires, a reinforcing layer made of fiber cords or steel cords is arranged over the entire circumference of the tire from the bead portion to the sidewall portion, and the cord angle of the reinforcing layer is made substantially perpendicular to the carcass cord of the carcass layer. There is (Patent Document 1). It is described in Patent Document 1 that the reinforcing layer can increase the circumferential rigidity without changing the vertical rigidity, so that the steering stability and the braking/driving performance can be improved without impairing the riding comfort performance.
特開昭６２－２９４０３号公報JP-A-62-29403
　しかしながら、特許文献１に記載の空気入りラジアルタイヤは、実施例をみると補強層を有していない比較例に比べて乗り心地が悪化しており、よって実際には乗り心地と操縦安定性との両立が実現できていなかった。 However, the pneumatic radial tire described in Patent Document 1 has a poorer riding comfort than the comparative example having no reinforcing layer when viewed from the examples, and thus the riding comfort and the steering stability are actually reduced. It was not possible to achieve both.
　そこで本発明の目的は、乗り心地と操縦安定性とを高いレベルで両立させた空気入りタイヤを提供することにある。 Therefore, an object of the present invention is to provide a pneumatic tire that achieves a high level of both riding comfort and steering stability.
　本発明の空気入りタイヤは、ビードコアをそれぞれ有する一対のビード部と、該一対のビード部のそれぞれに連なり半径方向外方に延びる一対のサイドウォール部と、該一対のサイドウォール部の外周端を接続するトレッド部と、を備えるとともに、
　両端部がそれぞれ前記一対のビード部における前記ビードコアに係留され前記サイドウォール部から前記トレッド部にかけてトロイド状をなすカーカスと、
該カーカスのクラウン部分の外側に設けられたベルトと、
を備える空気入りタイヤにおいて、
　前記ビード部から前記サイドウォール部までの少なくとも一部分に、周方向に対して０～１０°の角度をなしてコードが設けられ、かつ、該コードが、応力－歪曲線において変曲点を有し、該変曲点以下の低歪領域では低弾性率を、変曲点を超えた高歪領域では高弾性率を有するものであることを特徴とする。 The pneumatic tire of the present invention includes a pair of bead portions each having a bead core, a pair of sidewall portions which are continuous with each of the pair of bead portions and extend outward in the radial direction, and outer peripheral ends of the pair of sidewall portions. With a tread portion to be connected,
Both end portions are carcasses that are moored to the bead cores in the pair of bead portions and have a toroidal shape from the sidewall portion to the tread portion,
A belt provided outside the crown portion of the carcass,
In a pneumatic tire comprising
A cord is provided on at least a part from the bead portion to the sidewall portion at an angle of 0 to 10° with respect to a circumferential direction, and the cord has an inflection point in a stress-strain curve. It is characterized in that it has a low elastic modulus in a low strain region below the inflection point and a high elastic modulus in a high strain region above the inflection point.
　かかる空気入りタイヤは、変曲点以下の低歪領域では低弾性率を、変曲点を超えた高歪領域では高弾性率を有するコードにより補強されているから、乗り心地に関与する縦剛性については低弾性率領域における作用で剛性の増加を抑制しつつ、操縦安定性に関与する横剛性については、高弾性率領域における作用で高い剛性を示し、よって、乗り心地と操縦安定性とを高いレベルで両立させることができる。 Since such a pneumatic tire is reinforced by a cord having a low elastic modulus in a low strain region below the inflection point and a high elastic modulus in a high strain region exceeding the inflection point, a vertical rigidity that contributes to riding comfort is obtained. As for the lateral rigidity that is involved in steering stability while suppressing the increase in rigidity due to the action in the low elastic modulus region, it exhibits high rigidity due to the action in the high elastic modulus region. It can be compatible at a high level.
　本発明の空気入りタイヤは、上記コードが、材質の異なる２種以上の繊維からなり、上記繊維は有機繊維又は無機繊維からなる構造とすることができる。
　また、上記コードは、上記カーカスが上記ビードコアで折り返されて本体部と折り返し部とを備え、該本体部と該折り返し部との間にビードフィラーを備える構造を有する空気入りタイヤの場合に、上記カーカスの本体部プライとビードフィラーとの間に配置されているようにしてもよいし、ビードフィラーと上記カーカスの折り返しプライとの間に配置されているようにしてもよいし、上記カーカスの折り返し部プライよりもタイヤ半径方向外側に配置されているようにしてもよい。
　また、上記コードは、上記カーカスの端部が第１のビードコアと第２のビードコアとで挟まれて係留される構造を有する空気入りタイヤの場合に、上記コードが上記カーカスよりもタイヤ半径方向外側に配置されているようにしてもよい。
　さらに、上記コードの材料は、少なくともアラミド又はポリエチレンテレフタレートを含むことが好ましい。
　またさらに、上記コードは、上記変曲点が引張歪１～８％の範囲にあることが好ましく、低歪領域の弾性率が高歪領域の弾性率に対して１０～９０％の範囲にあることが好ましい。 The pneumatic tire of the present invention may have a structure in which the cord is made of two or more kinds of fibers made of different materials, and the fibers are made of organic fibers or inorganic fibers.
Further, the cord, in the case of a pneumatic tire having a structure in which the carcass is folded back at the bead core to include a main body portion and a folded back portion, and a bead filler is provided between the main body portion and the folded back portion. It may be arranged between the main body ply of the carcass and the bead filler, or may be arranged between the bead filler and the folded ply of the carcass, or the folded back of the carcass. It may be arranged outside the partial ply in the tire radial direction.
Further, in the case of a pneumatic tire having the structure in which the end portion of the carcass is sandwiched between the first bead core and the second bead core and moored, the cord is located outside the carcass in the tire radial direction. It may be arranged at.
Further, the material of the cord preferably contains at least aramid or polyethylene terephthalate.
Furthermore, in the above cord, the inflection point is preferably in the range of tensile strain of 1 to 8%, and the elastic modulus of the low strain region is in the range of 10 to 90% with respect to the elastic modulus of the high strain region. It is preferable.
　本発明の空気入りタイヤの製造方法は、上記の空気入りタイヤを製造する方法であって、
　１種又は２種以上の非線形弾性率を有する非線形弾性率コードを用意し、タイヤ成型工程にて、タイヤ内の位置によって上記非線形弾性率コードに異なる張力を付与することで、上記非線形弾性率コードの弾性率を制御して、用意した非線形弾性率コードよりも多い種類の非線形弾性率特性コードをタイヤ内で形成させることを特徴とする。 The method for producing a pneumatic tire of the present invention is a method for producing the above pneumatic tire,
The non-linear elastic modulus code is prepared by preparing one or more non-linear elastic modulus codes having a non-linear elastic modulus and applying different tensions to the non-linear elastic modulus code depending on the position in the tire in the tire molding process. It is characterized in that the elastic modulus is controlled so that more kinds of nonlinear elastic modulus characteristic codes than the prepared nonlinear elastic modulus codes are formed in the tire.
　本発明によれば、乗り心地と操縦安定性とを高いレベルで両立させることができる。 According to the present invention, it is possible to achieve a high level of both riding comfort and steering stability.
本発明の一実施形態の空気入りタイヤの幅方向断面図である。It is a widthwise sectional view of a pneumatic tire of one embodiment of the present invention. 直進時の変形状態を示す空気入りタイヤの幅方向断面図である。FIG. 4 is a cross-sectional view in the width direction of the pneumatic tire showing a deformed state when going straight. コーナリング時の変形状態を示す空気入りタイヤの幅方向断面図である。FIG. 4 is a cross-sectional view in the width direction of the pneumatic tire showing a deformed state during cornering. 非線形弾性率コードの応力－歪曲線を示すグラフである。It is a graph which shows the stress-strain curve of a nonlinear elastic modulus code. 非線形弾性率コードの配置を示す空気入りタイヤの部分的な幅方向断面図であり、図５（ａ）はカーカスの本体部プライとビードフィラーとの間に配置された例、図５（ｂ）はビードフィラーとカーカスの折り返し部プライとの間に配置された例、図５（ｃ）はカーカスの折り返し部プライよりもタイヤ半径方向外側に配置された例である。FIG. 5 is a partial cross-sectional view in the width direction of a pneumatic tire showing a non-linear elastic modulus cord arrangement, FIG. 5( a) being an example arranged between a main body ply of a carcass and a bead filler, FIG. 5( b ). Is an example arranged between the bead filler and the folded back ply of the carcass, and FIG. 5(c) is an example arranged outside the folded back ply of the carcass in the tire radial direction. 本発明の別の実施形態の空気入りタイヤの部分的な幅方向断面図である。It is a partial width direction sectional view of the pneumatic tire of another embodiment of the present invention.
　以下、本発明の空気入りタイヤ（以下、単に「タイヤ」ともいう。）の実施形態を、図面を用いて、より具体的に説明する。 Hereinafter, an embodiment of a pneumatic tire (hereinafter, also simply referred to as “tire”) of the present invention will be described more specifically with reference to the drawings.
　図１に、ホイールのリムＲにリム組みされた状態の、本発明の一実施形態の空気入りタイヤ１の幅方向断面図を示す。図１において、空気入りタイヤ１は、一対のビード部２と、これらのビード部２にそれぞれ連なる一対のサイドウォール部３と、これら一対のサイドウォール部３の外周端を接続するトレッド部４とを備えている。ビード部２は、ビードワイヤが巻回されてなるビードコア５を有している。このビードコアに隣接して、硬質ゴムからなるビードフィラー６が配置されている。ビード部２は空気入りタイヤ１の幅方向に一対を備え、その一方のビード部２のビードコア５に、カーカス７の一方の一端が折り返されるように配置されることで係留され、他方のビード部２のビードコア５に、カーカス７の他方の一端が折り返されるように配置されることで係留されている。 FIG. 1 shows a cross-sectional view in the width direction of a pneumatic tire 1 according to an embodiment of the present invention in a state of being assembled to a wheel rim R. In FIG. 1, a pneumatic tire 1 includes a pair of bead portions 2, a pair of sidewall portions 3 respectively connected to the bead portions 2, and a tread portion 4 connecting outer peripheral ends of the pair of sidewall portions 3. Is equipped with. The bead portion 2 has a bead core 5 formed by winding a bead wire. A bead filler 6 made of hard rubber is arranged adjacent to the bead core. The bead portion 2 includes a pair in the width direction of the pneumatic tire 1, and is anchored to the bead core 5 of one bead portion 2 by arranging one end of the carcass 7 so as to be folded back, and the other bead portion. The carcass 7 is anchored to the second bead core 5 such that the other end of the carcass 7 is folded back.
　カーカス７は、一対のビード部２に連なる一対のサイドウォール部３からトレッド部４にかけて、トロイド状をなしている。カーカス７は、カーカスコードをゴムで被覆したカーカスプライからなり、空気入りタイヤ１のタイヤ形状を保持するための骨格となっている。ラジアルタイヤではカーカス７のカーカスコードはタイヤ半径方向に（ラジアル方向に）延びている。
　カーカス７のクラウン部分の外周側に、一枚以上のベルトプライからなるベルト８が配置されている。 The carcass 7 has a toroidal shape from the pair of sidewall portions 3 connected to the pair of bead portions 2 to the tread portion 4. The carcass 7 is made of a carcass ply in which a carcass cord is covered with rubber, and serves as a skeleton for maintaining the tire shape of the pneumatic tire 1. In the radial tire, the carcass cord of the carcass 7 extends in the tire radial direction (radial direction).
A belt 8 composed of one or more belt plies is arranged on the outer peripheral side of the crown portion of the carcass 7.
　本発明の空気入りタイヤ１は、ビード部２からサイドウォール部３までの少なくとも一部分に、コード９が設けられている。コード９は、タイヤ周方向に対して、０～１０°の角度をなしている。このコード９は、応力－歪曲線において変曲点を有し、引張歪－応力の曲線が、原点から変曲点までを低歪領域とし、変曲点より引張歪が大きい領域を高歪領域とすると、該変曲点以下の低歪領域では低弾性率を、変曲点を超えた高歪領域では高弾性率を有するものである。かかる変曲点以下の低歪領域では低弾性率を、変曲点を超えた高歪領域では高弾性率を有するコードを本明細書では「非線形弾性率コード」という。 In the pneumatic tire 1 of the present invention, the cord 9 is provided on at least a part from the bead portion 2 to the sidewall portion 3. The cord 9 forms an angle of 0 to 10° with respect to the tire circumferential direction. This code 9 has an inflection point in the stress-strain curve, and the tensile strain-stress curve has a low strain region from the origin to the inflection point, and a region having a larger tensile strain than the inflection point is a high strain region. Then, it has a low elastic modulus in a low strain region below the inflection point and a high elastic modulus in a high strain region beyond the inflection point. A cord having a low elastic modulus in a low strain region below the inflection point and a high elastic modulus in a high strain region exceeding the inflection point is referred to as a "non-linear elastic modulus code" in this specification.
　図１に示した本実施形態においては、コード９は、カーカス７を、本体部７ａと、ビードコア５で折り返された部分である折り返し部７ｂとで区分したときの、本体部７ａと、ビードフィラー６との間に配置されている。 In the present embodiment shown in FIG. 1, the cord 9 has a body portion 7a and a bead filler when the carcass 7 is divided into a body portion 7a and a folded portion 7b which is a portion folded back by the bead core 5. It is arranged between 6 and.
　このコード９の作用効果について図２及び図３を用いて説明する。
　タイヤ１に荷重が加えられているときのタイヤ回転軸を含む垂直断面で見た変形状態を、図２にタイヤ幅方向断面図で示す。図２に示した変形状態は、直進して走行中の変形状態と同じである。 The function and effect of the cord 9 will be described with reference to FIGS. 2 and 3.
FIG. 2 is a sectional view in the tire width direction showing a deformed state seen in a vertical section including the tire rotation axis when a load is applied to the tire 1. The deformed state shown in FIG. 2 is the same as the deformed state in which the vehicle is traveling straight ahead.
　図２において、直進時にタイヤ１に荷重が負荷されたとき、一対のサイドウォール部３はそれぞれタイヤの幅方向の外側へ膨出変形する。この時、図２のタイヤ幅方向断面で見ると、ビード部２のうち、ホイールのリム部に組み付けられた部分はほぼ固定され、それ以外の部分が曲げ変形する。かかる変形は、タイヤの半径方向の力による変形である。 In FIG. 2, when a load is applied to the tire 1 when traveling straight, the pair of sidewall portions 3 bulge and deform outward in the width direction of the tire. At this time, as viewed in the tire width direction cross section of FIG. 2, of the bead portion 2, the portion assembled to the rim portion of the wheel is almost fixed, and the other portions are bent and deformed. Such deformation is a deformation due to a radial force of the tire.
　次に、タイヤ１に荷重が加えられてコーナリングしているときのタイヤ回転軸を含む垂直断面で見たタイヤ変形状態を、図３に、タイヤ幅方向断面図で示す。コーナー内側のビード部２は、矢印のように外側へ変形するが、コーナー外側のビード部２は、図１の直進時より変形が小さくなっている。この変形をより詳しく説明すると、コーナリング時には、タイヤ１の接地面へ対してコーナーの外側から内側向きに横方向の力がかかるため、図２に示した直進時のタイヤ変形に比べると、一対のサイドウォール部３のうち、コーナーの外側のサイドウォール部では外側への膨出が減り、コーナーの内側のサイドウォール部３では外側への膨出が増えるような変形をする。この時、図３のタイヤ幅方向断面内で見ると一対のビード部２のうち、コーナーの外側に位置するビード部２では曲げ変形が減少し、コーナーの内側に位置するビード部２では曲げ変形が増加する。 Next, FIG. 3 is a cross-sectional view in the tire width direction showing a tire deformed state as seen in a vertical section including the tire rotation axis when the tire 1 is being subjected to cornering under load. The bead portion 2 inside the corner is deformed outward as indicated by the arrow, but the bead portion 2 outside the corner is less deformed than when traveling straight in FIG. This deformation will be described in more detail. At the time of cornering, a lateral force is applied to the ground contact surface of the tire 1 from the outside to the inside of the corner. Therefore, compared to the tire deformation at the time of straight traveling shown in FIG. In the sidewall portion 3, the sidewall portion outside the corner is deformed so that the outward bulge is reduced, and the sidewall portion 3 inside the corner is deformed such that the outward bulge is increased. At this time, when viewed in the tire width direction cross section of FIG. 3, the bending deformation is reduced in the bead portion 2 located outside the corner of the pair of bead portions 2, and the bending deformation is reduced in the bead portion 2 located inside the corner. Will increase.
　このような図２に示した直進時のタイヤ変形及び図３に示したコーナリング時のタイヤ変形に関して、本実施形態の空気入りタイヤが備える、周方向に対して０～１０°の角度をなす非線形弾性率コード９の効果を、幾つかの比較用タイヤと対比させて説明する。 With respect to the tire deformation during straight running shown in FIG. 2 and the tire deformation during cornering shown in FIG. 3 as described above, the pneumatic tire of the present embodiment has a non-linear angle of 0 to 10° with respect to the circumferential direction. The effect of the elastic modulus code 9 will be described in comparison with some comparative tires.
　まず、ビード部からサイドウォール部までの少なくとも一部分に、周方向に対して１０°を超える大きな角度を付けた補強用コードを設けた比較用タイヤの場合を述べる。
　かかる比較用タイヤのように、ビード部に、周方向に対して大きな角度を有するコードを設けると、タイヤ幅方向断面内でのビード部の曲げ変形の力に対して、ゴムよりも剛性が高いコードに歪がかかる。したがって、当該コードが、タイヤ変形、特にビード部の曲げ変形を抑制するような剛性を発揮する。したがって、かかる比較用タイヤは、縦ばね係数（タイヤ半径方向のばね定数）が大きくなり、換言すれば縦剛性が高くなり、乗り心地は悪化する。また、当該コードがビード部の曲げ変形を抑制することは、縦方向（タイヤ半径方向）の変形を抑制するばかりでなく横方向（タイヤ幅方向）の変形を抑制する。したがって、タイヤの横ばね係数（タイヤ幅方向のばね定数）が大きくなり、換言すれば横剛性が高くなり、操縦安定性は向上する。 First, a case of a comparative tire in which at least a part from the bead portion to the sidewall portion is provided with a reinforcing cord having a large angle of more than 10° with respect to the circumferential direction will be described.
When a cord having a large angle to the circumferential direction is provided in the bead portion as in the comparative tire, the rigidity is higher than that of rubber against the force of bending deformation of the bead portion in the tire width direction cross section. The code is distorted. Therefore, the cord exhibits rigidity that suppresses tire deformation, particularly bending deformation of the bead portion. Therefore, in the comparative tire, the vertical spring coefficient (spring constant in the tire radial direction) becomes large, in other words, the vertical rigidity becomes high, and the riding comfort deteriorates. In addition, suppressing the bending deformation of the bead portion by the cord not only suppresses the deformation in the vertical direction (tire radial direction) but also suppresses the deformation in the lateral direction (tire width direction). Therefore, the lateral spring coefficient of the tire (spring constant in the tire width direction) becomes large, in other words, the lateral rigidity becomes high, and steering stability is improved.
　次に、ビード部からサイドウォール部までの少なくとも一部分に、周方向に対して角度が小さいコード（周方向に対して０～１０°の角度をなすもの）であるけれども、非線形弾性率コードではない、補強用コードを設けた比較用タイヤの場合を考える。
　かかる比較用タイヤのように、ビード部に、周方向に対して角度が小さいコードを設けると、直進時には、タイヤ幅方向断面内でのビード部の曲げ変形の力に対しては、低弾性率であるコード間のゴムが伸びて変形するため、コードの影響がない。また、サイドウォール部の膨出変形の力に対しては高弾性率である周方向に対して近い角度のコードに歪がかかり、このコードが伸びにくいためタイヤの剛性を上げる。したがって、かかる比較用タイヤは、縦ばね係数について、ビード部に設けられたコードの影響はないが、サイドウォール部に設けられたコードの影響のために大きくなる。 Next, a cord having a small angle with respect to the circumferential direction (that makes an angle of 0 to 10° with respect to the circumferential direction) in at least a part from the bead portion to the sidewall portion is not a non-linear elastic modulus cord. Consider the case of a comparative tire provided with a reinforcing cord.
When a cord having a small angle with respect to the circumferential direction is provided in the bead portion as in the comparative tire, the elastic modulus is low against the force of bending deformation of the bead portion in the tire width direction cross section during straight traveling. Since the rubber between the cords is stretched and deformed, there is no influence of the cords. In addition, the bulging deformation force of the sidewall portion distorts the cord having a high elastic modulus at an angle close to the circumferential direction, and the cord is hard to extend, so that the rigidity of the tire is increased. Therefore, in the comparative tire, the longitudinal spring coefficient is not affected by the cord provided in the bead portion, but is increased due to the influence of the cord provided in the sidewall portion.
　この比較用タイヤのコーナリング時を考える。周方向に対して角度が小さいコードをビード部からサイドウォール部までの少なくとも一部分に設けると、タイヤ幅方向断面内でのビード部の曲げ変形の力に対して、低弾性率であるコード間のゴムが伸びて変形するため、影響がない。また、サイドウォール部の膨出変形の力に対しては、一対のサイドウォール部のうち、コーナーの外側のサイドウォール部における膨出変形が減少する部分は、高弾性率である周方向に近い角度のコードが設けてあるものの、膨出変形が減少するためコードには力が加わらずにコードの影響がない。また、コーナーの内側のサイドウォール部の膨出が増大する部分は、高弾性率である周方向に近い角度のコードに歪がかかり、このコードが伸びにくいためタイヤ剛性を上げることができる。このため、タイヤの横ばね係数は、ビード部のコード及びコーナー外側のコードの影響はないが、コーナー内側のコードの影響のため大きくなることが、発明者らの研究により新たに分かった。 Consider when cornering this comparative tire. If cords having a small angle with respect to the circumferential direction are provided in at least a part from the bead portion to the sidewall portion, between cords having a low elastic modulus against the bending deformation force of the bead portion in the tire width direction cross section. There is no effect because the rubber stretches and deforms. Further, with respect to the force of the bulging deformation of the sidewall portion, the portion of the pair of sidewall portions where the bulging deformation is reduced in the sidewall portion outside the corner is close to the circumferential direction, which has a high elastic modulus. Although the cord with the angle is provided, the cord is not affected by the force because the bulging deformation is reduced. Further, in the portion where the bulging of the sidewall portion inside the corner increases, the cord having a high elastic modulus and having an angle close to the circumferential direction is distorted, and the cord is hard to extend, so that the tire rigidity can be increased. Therefore, it has been newly found by the study by the inventors that the lateral spring coefficient of the tire is not affected by the cords on the bead portion and the cords on the outside of the corner, but is increased by the influence of the cord on the inside of the corner.
　直進時のタイヤ縦ばね係数は、乗り心地に影響を及ぼし、コーナー時のタイヤ横ばね係数は、操縦安定性に影響を及ぼす。そこで、直進時のタイヤ縦ばね増加を抑制して乗り心地を向上させ、コーナリング時の横ばね係数の増加を増やして操縦安定性を向上させるためには、ビード部からサイドウォール部までの少なくとも一部分に設けられる、周方向に対して角度が小さいコードについて、直進時の小さな変形時はコード剛性が低く、コーナリング時の大きな変形時はコード剛性を高くすれば良いことが分かった。このようなコード特性は、ビード部からサイドウォール部までの少なくとも一部分に設けられるコードに、非線形弾性率コードを用いることで実現できることを発明者らは研究開発の結果、発見した。 　The tire longitudinal spring coefficient when going straight affects the riding comfort, and the tire lateral spring coefficient when cornering affects the steering stability. Therefore, in order to improve the ride comfort by suppressing the increase of the tire vertical springs when going straight, and to increase the increase of the lateral spring coefficient when cornering to improve the steering stability, at least a part from the bead to the sidewall is required. It was found that the cord with a small angle to the circumferential direction, which has a small angle to the circumferential direction, should have a low cord rigidity at the time of a small deformation during straight running and a high code rigidity at the time of a large deformation during cornering. As a result of research and development, the inventors have found that such a cord characteristic can be realized by using a non-linear elastic modulus cord for the cord provided in at least a part from the bead portion to the sidewall portion.
　図４に、非線形弾性率コードの弾性応力－歪曲線の一例をグラフで示す。図４に示すように、非線形弾性率コードは、同図における曲線の傾きで示される弾性率について、変曲点で区分される低歪領域では低弾性率、高歪領域では高弾性率である非線形弾性率の特性を有している。 FIG. 4 is a graph showing an example of the elastic stress-strain curve of the nonlinear elastic modulus code. As shown in FIG. 4, the nonlinear elastic modulus code has a low elastic modulus in a low strain region divided by an inflection point and a high elastic modulus in a high strain region with respect to the elastic modulus indicated by the slope of the curve in FIG. It has a characteristic of nonlinear elastic modulus.
　図４に示した非線形弾性率コードを周方向に対して低い角度でビード部からサイドウォール部までの少なくとも一部分に設けた本実施形態のタイヤの直進時及びコーナリング時の変形状態を述べる。まず、直進時は、図２を用いて説明したようにビード部が曲げ変形しサイドウォール部が膨出変形し、このサイドウォール部の膨出変形の力に対して非線形弾性率コードに歪がかかる。このときの該非線形弾性率コードにかかる歪が、図４に示した曲線の変曲点よりも小さい低歪領域になるようなコードであることにより、コードには弾性率が低い領域で力が加えられる。その結果、直進時は非線形弾性率コードを設けてもタイヤの剛性が大きくならないため、タイヤの縦ばね係数は増加しない。したがって、直進時の乗り心地が悪化しない。 The deformation state of the tire of the present embodiment in which the non-linear elastic modulus cord shown in FIG. 4 is provided at least at a part from the bead portion to the sidewall portion at a low angle with respect to the circumferential direction during straight running and cornering will be described. First, when traveling straight ahead, the bead portion is bent and deformed, and the sidewall portion is bulged and deformed as described with reference to FIG. 2, and the nonlinear elastic modulus cord is distorted by the force of the bulged deformation of the sidewall portion. It takes. Since the strain applied to the non-linear elastic modulus code at this time is in a low strain region smaller than the inflection point of the curve shown in FIG. 4, the cord has a force in the low elastic modulus region. Added. As a result, the rigidity of the tire does not increase even when the non-linear elastic modulus cord is provided during straight traveling, so the longitudinal spring coefficient of the tire does not increase. Therefore, the riding comfort when going straight does not deteriorate.
　次に、コーナリング時は、図３を用いて説明したようにビード部が曲げ変形しサイドウォール部が膨出変形するものの、コーナーの外側のサイドウォール部では、直進時より変形が小さくなるので、非線形弾性率コードにかかる歪は小さくなる。また、コーナー内側のサイドウォール部では非線形弾性率コードにかかる歪は図４に示した曲線の変曲点よりも大きい高歪領域になるようなコードであることにより、コードには弾性率の高い領域で力が加えられる。その結果、コーナリング時には非線形弾性率コードを設けることでタイヤの剛性を大きくすることができ、タイヤの横ばね係数を増加させることができ、コーナリング時の接地状態を改良できる。例えば、コーナリング内側で発生する接地面浮き上がりを抑制することで、接地面積を増加させたり、コーナリング内側での接地圧減少を抑制させたりすることができる。したがって、コーナリング時の操縦安定性を向上できる。 Next, during cornering, the bead portion is bent and deformed and the sidewall portion is bulged and deformed as described with reference to FIG. 3, but the sidewall portion outside the corner is less deformed than when straight ahead, The strain on the nonlinear elastic modulus code is small. Further, in the sidewall portion inside the corner, the strain applied to the non-linear elastic modulus cord is a cord having a high strain region larger than the inflection point of the curve shown in FIG. 4, so that the cord has a high elastic modulus. Force is applied in the area. As a result, the rigidity of the tire can be increased by providing the non-linear elastic modulus code during cornering, the lateral spring coefficient of the tire can be increased, and the ground contact state during cornering can be improved. For example, it is possible to increase the ground contact area or suppress a decrease in the ground contact pressure inside the cornering by suppressing the lift of the ground contact surface that occurs inside the cornering. Therefore, steering stability during cornering can be improved.
　以上述べた直進時及びコーナリング時のタイヤの変形状態の変化により本実施形態の空気入りタイヤは、乗り心地と操縦安定性とを、高いレベルで両立させることができる。 The pneumatic tire according to the present embodiment can achieve both a high level of riding comfort and steering stability due to the changes in the deformation state of the tire during straight running and during cornering described above.
　次に、本実施形態の空気入りタイヤの非線形弾性率コードについて、より詳しく説明する。
　非線形弾性率コードの弾性率は、タイヤからコードを切り出して計測する。つまり、非線形弾性率コードは、実際のタイヤに組み込まれた状態において、直進時やコーナリング時の変形に応じて低い弾性率や高い弾性率を示すコードである。 Next, the nonlinear elastic modulus code of the pneumatic tire of this embodiment will be described in more detail.
The elastic modulus of the nonlinear elastic modulus cord is measured by cutting the cord out of the tire. That is, the non-linear elastic modulus code is a code that shows a low elastic modulus or a high elastic modulus in a state of being incorporated in an actual tire in accordance with the deformation during straight running or cornering.
　弾性率の計測の具体的な方法は、ＪＩＳ　Ｌ１０１７の「引張強さ及び伸び率」の試験と同様な方法で試験を行い、引張強さ及び伸び率を測定し、この測定結果から、初期長さと伸長長さの比である引張歪、縦軸を応力として曲線をグラフに描く。この応力をＹ軸に、歪をＸ軸にしたグラフの曲線において、歪が０の状態における曲線に引いた接線と、破断点において曲線に引いた接線との交点を通る垂線が当該曲線と交わる点を変曲点とする。 The concrete method of measuring the elastic modulus is to perform a test in the same manner as the JIS L1017 “tensile strength and elongation” test, measure the tensile strength and elongation, and from this measurement result, the initial length And the tensile strain, which is the ratio of the length to the extension length, and the vertical axis is the stress, and a curve is drawn on the graph. In the curve of the graph in which the stress is on the Y axis and the strain is on the X axis, a perpendicular line that passes through the intersection of the tangent drawn to the curve when the strain is 0 and the tangent drawn to the curve at the break point intersects with the curve. Let the point be an inflection point.
　この変曲点は引張歪が１～８％の範囲にあることが好ましい。また、低歪領域の弾性率は高歪領域の弾性率に対して１０～９０％の範囲にあることが好ましい。
　低歪領域の弾性率に対して、高歪領域の弾性率は２倍以上大きいような非線形性を持つコードであることが、より好ましい。なお、低歪領域と高歪領域との弾性率の比率は、歪０から変曲点までを結んだ直線の傾きと、変曲点から破断点までを結んだ直線の傾きとの比率で表される。 This inflection point preferably has a tensile strain in the range of 1 to 8%. Further, the elastic modulus in the low strain region is preferably in the range of 10 to 90% with respect to the elastic modulus in the high strain region.
It is more preferable that the cord has a nonlinearity such that the elastic modulus in the high strain region is twice or more as large as the elastic modulus in the low strain region. The elastic modulus ratio between the low strain region and the high strain region is expressed by the ratio between the slope of the straight line connecting the strain 0 to the inflection point and the slope of the straight line connecting the inflection point to the break point. To be done.
　なお、周方向に対して低い角度をなすコードに関して、本実施形態の空気入りタイヤに設けられる非線形弾性率コードを用いるのではなく、例えばタイヤ径方向の内側に剛性の低いコードを、外側に剛性が高いコードをそれぞれ設けることが考えられる。しかし、このような複数種類のコードを用いたタイヤは、タイヤ径方向で剛性が変化する場所、つまり異なるコードの種類が切り替わる場所で、ゴムに歪集中が発生し、使用時にクラックが発生するなど耐久性に課題がある。これに対して、本実施形態の空気入りタイヤは、非線形な弾性率特性を持つコードを用いることにより、非線形弾性率コードによるタイヤ径方向での剛性は徐々に変化する。よってゴムへの歪集中を避けることができ、耐久性を向上することができる。 Regarding the cord that forms a low angle with respect to the circumferential direction, instead of using the nonlinear elastic modulus cord provided in the pneumatic tire of the present embodiment, for example, a cord having low rigidity is used on the inside in the tire radial direction and a rigidity is used on the outside. It is conceivable to provide a high code for each. However, such a tire using a plurality of types of cords, when the rigidity changes in the tire radial direction, that is, a place where different types of cords switch, strain concentration occurs in the rubber, cracks occur during use, etc. There is a problem in durability. On the other hand, the pneumatic tire of the present embodiment uses a cord having a non-linear elastic modulus characteristic, so that the rigidity in the tire radial direction due to the non-linear elastic modulus cord gradually changes. Therefore, strain concentration on rubber can be avoided, and durability can be improved.
　非線形弾性率コードは、材質の異なる２種以上の繊維からなり、前記繊維は有機繊維又は無機繊維からなるものとすることができる。
　非線形弾性率コードを実現するには、一例では低弾性率のコードと高弾性率のコードという、異なる弾性率の材料の２種以上を用いる。異なる弾性率の２つのコードを撚り合わせて非線形弾性率コードとすることで、低歪時には低弾性率のコード特性を発揮し、高歪時には高弾性のコード特性を発揮することができる。この結果、非線形な弾性率特性が得られる。また、材料の選択により、非線形な弾性率の特性を調整することができる。 The nonlinear elastic modulus code may be composed of two or more kinds of fibers made of different materials, and the fibers may be composed of organic fibers or inorganic fibers.
In order to realize the non-linear elastic modulus code, two or more kinds of materials having different elastic moduli such as a low elastic modulus code and a high elastic modulus code are used in one example. By twisting two cords having different elastic moduli into a non-linear elastic modulus cord, it is possible to exhibit a cord characteristic of a low elastic modulus at a low strain and a cord characteristic of a high elastic modulus at a high strain. As a result, a nonlinear elastic modulus characteristic is obtained. Further, the characteristics of the nonlinear elastic modulus can be adjusted by selecting the material.
　非線形弾性率コードは、材料としては、タイヤ用に使われる有機繊維又は無機繊維を用いることができる。有機繊維として、ナイロン、ポリエチレンテレフタレート、ポリエチレンナフタレート、アラミド等を挙げることができる。また、無機繊維としてガラスファイバー、カーボンファイバー、スチール等を挙げることができる。これらの材料から、弾性率の異なるものを組み合わせる。例えば、低弾性率の材料としてこれらの中で一番弾性率の低いナイロンを選択し、高弾性率の材料として、ナイロン以外の上記材料を選択して組み合わせることができる。また、低弾性率の材料としてポリエチレンテレフタレートを選択し、高弾性率の材料としてポリエチレンナフタレート、アラミド、ガラスファイバー、カーボンファイバー、スチールのいずれかを選択して組み合わせることができる。さらに、低弾性率の材料としてポリエチレンナフタレートを選択し、高弾性率の材料としてアラミド、ガラスファイバー、カーボンファイバー、スチールのいずれかを選択して組み合わせることができる。 The material of the non-linear elastic modulus code can be organic fibers or inorganic fibers used for tires. Examples of the organic fiber include nylon, polyethylene terephthalate, polyethylene naphthalate, aramid and the like. Further, examples of the inorganic fiber include glass fiber, carbon fiber, steel and the like. From these materials, those having different elastic moduli are combined. For example, nylon having the lowest elastic modulus can be selected as the material having a low elastic modulus, and the above-mentioned materials other than nylon can be selected and combined as the material having a high elastic modulus. Further, polyethylene terephthalate can be selected as the low elastic modulus material, and any of polyethylene naphthalate, aramid, glass fiber, carbon fiber and steel can be selected and combined as the high elastic modulus material. Further, polyethylene naphthalate can be selected as the low elastic modulus material, and any of aramid, glass fiber, carbon fiber and steel can be selected and combined as the high elastic modulus material.
　非線形弾性率コードの材料の少なくとも１つにアラミドを使うことで、アラミドが持つ耐カット性が良いことを活かして、走行時に異物が当たった場合に発生する可能性がある外傷を抑制することができる。また、非線形弾性率コードの材料の少なくとも１つにポリエチレンテレフタレートを使うことで、低コストで弾性率を高めることができる。 By using aramid as at least one of the materials of the non-linear elastic modulus cord, it is possible to suppress the external damage that may occur when a foreign matter hits while traveling by taking advantage of the good cut resistance of aramid. it can. Further, by using polyethylene terephthalate as at least one of the materials of the nonlinear elastic modulus code, the elastic modulus can be increased at low cost.
　非線形弾性率コードに適用される材料と前記カーカスに適用される材料が異なるようにしてもよい。非線形弾性率コードの材料を本体部プライと同じ材料にした場合、本体部プライと非線形弾性率コードが交差する部分で、間に挟まれるゴムに歪が集中する。これに対し、異なる弾性率のコードを使うことで、低い弾性率のコードを持つ側が高い弾性率のコードを持つ側から押されてコード相互間にも歪を分散できる。 The material applied to the nonlinear elastic modulus code may be different from the material applied to the carcass. When the material of the non-linear elastic modulus cord is the same as that of the main body ply, strain is concentrated on the rubber sandwiched between the main body ply and the non-linear elastic modulus cord. On the other hand, by using the cords having different elastic moduli, the side having the cord having the low elastic modulus is pushed from the side having the cord having the high elastic modulus and the strain can be dispersed between the cords.
　非線形弾性率コードはタイヤ周方向に対する角度が０～１０°の範囲とする。タイヤ周方向に対する角度の絶対値が１０°を超えると、直進時における縦ばね係数が高くなって乗り心地が悪化する。
　また、非線形弾性率コードは、実質的に波型に型付けされておらず、互いに並行に配置されていることが好ましい。非線形弾性率コードが実質的に型付けされていないと、張力を受けたときに、非線形弾性率コードの周りのゴムに、引張方向とは別方向の力が加わってせん断変形が発生することを防ぐことができるため、耐久性を向上することができる。 The non-linear elastic modulus code has an angle of 0 to 10° with respect to the tire circumferential direction. If the absolute value of the angle with respect to the tire circumferential direction exceeds 10°, the vertical spring coefficient increases when going straight, and the riding comfort deteriorates.
Further, it is preferable that the non-linear elastic modulus cords are not substantially corrugated and are arranged in parallel with each other. When the non-linear elastic modulus cord is substantially untyped, it prevents the rubber around the non-linear elastic modulus cord from being subjected to shear deformation by applying a force in a direction different from the tensile direction when subjected to tension. Therefore, durability can be improved.
　非線形弾性率コードの配置は、特に限定されず、ビード部からサイドウォール部までの少なくとも一部分の、変形が生じ得る位置とすることができる。直進時及びコーナリング時のタイヤの変形状態に応じて、適切な位置に、適切な弾性率の非線形弾性率コードを配置することにより、乗り心地と操縦安定性とを高いレベルで両立させることができる。
　図５に示す空気入りタイヤ１、１１、２１の部分的な幅方向断面図で非線形弾性率コードの配置を説明する。少なくともビード部を含む領域に配置するときには、非線形弾性率コード９は図５（ａ）に示すようにカーカス７の本体部７ａプライとビードフィラー６との間に配置することができ、また、図５（ｂ）に示すようにビードフィラー６とカーカス７の折り返し部７ｂのプライとの間に配置することができ、さらに、図５（ｃ）に示すようにカーカス７の折り返し部７ｂのプライよりもタイヤ半径方向外側に配置することができる。 The arrangement of the non-linear elastic modulus cords is not particularly limited, and may be a position where deformation can occur in at least a part from the bead portion to the sidewall portion. By placing a non-linear elastic modulus code with an appropriate elastic modulus at an appropriate position according to the deformation state of the tire when traveling straight and when cornering, it is possible to achieve a high level of ride comfort and steering stability at the same time. ..
The arrangement of the nonlinear elastic modulus cords will be described with reference to the partial widthwise sectional views of the pneumatic tires 1, 11, and 21 shown in FIG. When arranged in a region including at least the bead portion, the non-linear elastic modulus cord 9 can be arranged between the main body portion 7a ply of the carcass 7 and the bead filler 6 as shown in FIG. 5(b), it can be arranged between the bead filler 6 and the ply of the folded-back portion 7b of the carcass 7. Further, as shown in FIG. Can also be arranged radially outside the tire.
　非線形弾性率コードを図５（ａ）に示すようにカーカスの本体部プライとビードフィラーとの間に配置することにより、非線形弾性率コードは、カーカスの本体部プライに隣接して配置することになり、これにより内圧を負担する本体部プライの変形を効果的に抑制できるので、タイヤの横ばね係数を効果的に上げることができる。本体部プライは内圧を負荷することで張力を発生し、剛性を発揮する。このためタイヤ変形は本体部プライが主として負担しており、隣接した外側に非線形弾性率コードを配置することは、この部分が外側へ変形することを抑制するのに効果的である。 By arranging the non-linear elastic modulus cord between the carcass main body ply and the bead filler as shown in FIG. 5A, the non-linear elastic modulus cord is arranged adjacent to the carcass main body ply. As a result, the deformation of the main body portion ply that bears the internal pressure can be effectively suppressed, so that the lateral spring coefficient of the tire can be effectively increased. The main body ply generates tension by applying internal pressure, and exhibits rigidity. For this reason, the main body ply mainly bears the deformation of the tire, and disposing the non-linear elastic modulus cords on the outer side adjacent to each other is effective in suppressing the outer deformation of this portion.
　非線形弾性率コードを図５（ｂ）に示すようにビードフィラーとカーカスの折り返し部プライとの間に配置することにより、非線形弾性率コードが発揮する剛性をビードフィラーが受け止める形になり、横ばね係数をさらに上げることができる。カーカスの本体部プライの変形を抑制するためにビードフィラーが配置されているところにおいて、ビードフィラーの外側に非線形弾性率コードを配置すれば、本体部プライだけでなく、ビードフィラーの変形も抑制することができるため、この部分が外側へ変形することをさらに抑制できる。 By arranging the non-linear elastic modulus code between the bead filler and the folded portion ply of the carcass as shown in FIG. 5B, the bead filler receives the rigidity exerted by the non-linear elastic modulus code, and the lateral spring The coefficient can be further increased. Where the bead filler is arranged to suppress the deformation of the carcass body ply, if the nonlinear elastic modulus cord is arranged outside the bead filler, not only the body ply but also the bead filler is suppressed from being deformed. Therefore, it is possible to further suppress the outward deformation of this portion.
　非線形弾性率コードを図５（ｃ）に示すようにカーカスの折り返し部プライよりもタイヤ半径方向外側に配置することにより、非線形弾性率コードが発揮する剛性を本体部プライと折り返しプライに挟まれたビードフィラーを合わせた全体が受け止める形になり、横ばね係数を大きく上げることができる。本体部プライ、ビードフィラー、折り返しプライは３者一体となってビード部変形を抑制している。折り返しプライの外側に非線形弾性率コードを配置すれば、これら３者一体部分の変形を抑制できるため、この部分が外側へ変形することをさらに大きく抑制できる。 By arranging the non-linear elastic modulus cord on the outer side in the tire radial direction from the folded ply of the carcass as shown in FIG. 5C, the rigidity exhibited by the non-linear elastic modulus cord was sandwiched between the main body ply and the folded ply. The whole bead filler is received, and the lateral spring coefficient can be greatly increased. The main body section ply, the bead filler, and the folded back ply together suppress deformation of the bead section. By disposing the non-linear elastic modulus cord on the outside of the folded ply, it is possible to suppress the deformation of these three-part integrated parts, and thus it is possible to further suppress the outward deformation of these parts.
　非線形弾性率コードが配置されるタイヤの構造は、図５（ａ）～（ｃ）に示された実施形態のものに限られない。図６に、本発明の別の実施形態の空気入りタイヤ３１の部分的な幅方向断面図を示す。空気入りタイヤ３１は、ビードコア５が第１のビードコア５ａと第２のビードコア５ｂとからなる。カーカス７の端部は、第１のビードコア５ａと第２のビードコア５ｂとに挟まれることで係留されていて、実質的に折り返されてはいない。図６のタイヤ３１の構造であっても、非線形弾性率コード９を、ビード部からサイドウォール部までの少なくとも一部分に、具体的に図６に示した本実施形態ではカーカス７よりもタイヤ半径方向外側に、配置することができる。 The structure of the tire in which the nonlinear elastic modulus code is arranged is not limited to that of the embodiment shown in FIGS. 5(a) to 5(c). FIG. 6 shows a partial widthwise sectional view of a pneumatic tire 31 according to another embodiment of the present invention. In the pneumatic tire 31, the bead core 5 is composed of a first bead core 5a and a second bead core 5b. The end of the carcass 7 is anchored by being sandwiched between the first bead core 5a and the second bead core 5b, and is not substantially folded back. Even in the structure of the tire 31 of FIG. 6, the nonlinear elastic modulus cord 9 is provided in at least a part from the bead portion to the sidewall portion, in the tire radial direction rather than the carcass 7 in the embodiment specifically shown in FIG. It can be located on the outside.
　非線形弾性率コードは、タイヤ内において適切な弾性率となるようなものを準備してもよい。また、非線形弾性率コードの非線形弾性率特性を活用して、タイヤ製造工程での変形により製品での弾性率を制御してもよい。タイヤの製造工程において、非線形弾性率コードに対して当該コード方向に引張変形を付与すると、当該コードの低歪で低弾性の特性を活用して容易に変形でき、そして製品タイヤ内部では制御された適切な非線形弾性率特性が得られる。 The non-linear elastic modulus code may be prepared so that it has an appropriate elastic modulus in the tire. Further, the non-linear elastic modulus characteristic of the non-linear elastic modulus code may be utilized to control the elastic modulus of the product by deformation in the tire manufacturing process. In the tire manufacturing process, when tensile deformation is applied to the non-linear elastic modulus cord in the cord direction, it can be easily deformed by utilizing the low strain and low elasticity characteristics of the cord, and it is controlled inside the product tire. An appropriate nonlinear elastic modulus characteristic can be obtained.
　非線形弾性率コードは、タイヤに配置される位置により、タイヤ内において非線形弾性率特性が異なっていてもよい。タイヤの位置により異なる変形に応じて、適切な非線形弾性率特性の非線形弾性率コードを配置することにより、乗り心地と操縦安定性とを高いバランスで向上させることができる。 The nonlinear elastic modulus code may have different nonlinear elastic modulus characteristics within the tire depending on the position where the nonlinear elastic modulus code is arranged on the tire. By arranging the non-linear elastic modulus cord having an appropriate non-linear elastic modulus characteristic according to the deformation which varies depending on the position of the tire, it is possible to improve the riding comfort and the steering stability with a high balance.
　タイヤに配置される位置に応じて、非線形弾性率特性が異なる複数種類の非線形弾性率コードをタイヤ成型前に用意してもよいが、１種又は２種以上の非線形弾性率コードを用意し、タイヤ製造時におけるタイヤ成型工程にて、タイヤの位置によって非線形弾性率コードに異なる張力を付与することで、製品タイヤ内の位置により非線形弾性率コードの弾性率を制御して、用意した非線形弾性率コードよりも多い種類の非線形弾性率コードをタイヤ内で得ることもできる。製造工程時にタイヤ内の位置に応じて非線形弾性率コードの張力を変化させることで、当該コードの弾性率を変化できるので、同じ材料を用いながらタイヤの位置により弾性率を変化させることができる。よって準備する非線形弾性率コードの材料の種類数を減らし、効率的に生産することができる。 Depending on the position to be arranged on the tire, a plurality of types of nonlinear elastic modulus codes having different nonlinear elastic modulus characteristics may be prepared before tire molding, but one kind or two or more kinds of nonlinear elastic modulus codes are prepared, In the tire molding process during tire manufacturing, by applying different tensions to the nonlinear elastic modulus code depending on the position of the tire, the elastic modulus of the nonlinear elastic modulus code is controlled by the position within the product tire, and the prepared nonlinear elastic modulus is controlled. More types of non-linear elastic modulus cords than cords can also be obtained in a tire. Since the elastic modulus of the cord can be changed by changing the tension of the nonlinear elastic cord according to the position in the tire during the manufacturing process, the elastic modulus can be changed depending on the position of the tire while using the same material. Therefore, the number of types of materials of the nonlinear elastic modulus code to be prepared can be reduced, and efficient production can be achieved.
　かかるタイヤ製造時に加える張力の制御により、種々の特性のタイヤを得ることができる。例えば、タイヤ成型工程では、ドラム上に巻いた部材を生タイヤに拡張して作るので、サイドウォール部の非線形弾性率コードは周方向に大きく伸ばされる。そのためサイドウォール部では、非線形弾性率コードの高歪領域を使用することになり、結果としてビード部の非線形弾性率コードより剛性が高くなる。このようにすることで、より効果的にタイヤのコーナリング時の剛性を高めることができる。 By controlling the tension applied during tire manufacturing, tires with various characteristics can be obtained. For example, in the tire molding process, since a member wound on a drum is expanded to be a raw tire, the nonlinear elastic modulus cord of the sidewall portion is greatly stretched in the circumferential direction. Therefore, the sidewall portion uses the high strain region of the non-linear elastic modulus code, resulting in higher rigidity than the non-linear elastic modulus code of the bead portion. By doing so, the rigidity during cornering of the tire can be increased more effectively.
　また、例えば、製造時の張力により弾性率を変化させ、ビード部の非線形弾性率コードをサイドウォール部に比べて弾性率を高くすることもできる。結果として、タイヤのコーナリング時の剛性を少しだけ高めることができる。 Also, for example, the elastic modulus can be changed by the tension at the time of manufacturing, and the elastic modulus of the bead portion can be made higher than that of the sidewall portion. As a result, the rigidity of the tire when cornering can be slightly increased.
　また、例えばタイヤ成型工程での拡張と張力により、ビード部とサイドウォール部にまたがる非線形弾性率コードを、タイヤ径方向中央部において弾性率を高くすることもできる。結果として、タイヤのコーナリング時の剛性を中くらい高めることができる。 Also, for example, due to expansion and tension in the tire molding process, the elastic modulus of the non-linear elastic modulus cord that spans the bead portion and the sidewall portion can be increased in the tire radial center portion. As a result, the rigidity of the tire when cornering can be increased to a medium level.
　以下の試験方法で試験を行う場合のデータを表１に示す。
　タイヤサイズ　２０５／６０Ｒ１６　９２Ｖの乗用車用タイヤを、以下に示す従来例、比較例及び実施例の種々のコードをビード部に配置して製造した場合の結果を想定する。なお従来例はコードを配置しなかった。本体部プライコードはポリエチレンテレフタレート製とする。内圧２１０ｋＰａ、荷重５．７３ｋＮ、リム６Ｊ×１６で、リム組みする。内圧充填後に荷重６ｋＮまで負荷し、荷重とたわみの関係をプロットし、荷重５．７３ｋＮ時の傾きを縦ばね係数とする。また、荷重５．７３ｋＮを負荷した状態で、横方向に１０ｍｍまで変位させて、変位量と横方向の力の関係をプロットし、横方向変位が５ｍｍの時の傾きを横ばね係数とする。その縦ばね係数及び横ばね係数の推測値を表１に示す。なお、表１において、いずれのばね係数も、従来例を１００として表記する。 Table 1 shows data when the test is performed by the following test method.
Assume the results when a passenger car tire having a tire size of 205/60R16 92V is manufactured by arranging various cords of the following conventional examples, comparative examples and examples in the bead portion. No cord was placed in the conventional example. The main body ply cord is made of polyethylene terephthalate. Assemble the rim with an internal pressure of 210 kPa, a load of 5.73 kN and a rim of 6J×16. After filling the internal pressure, a load of up to 6 kN is applied, the relationship between the load and the deflection is plotted, and the inclination when the load is 5.73 kN is taken as the longitudinal spring coefficient. Further, with a load of 5.73 kN, the lateral displacement is made up to 10 mm, the relationship between the displacement amount and the lateral force is plotted, and the inclination when the lateral displacement is 5 mm is taken as the lateral spring coefficient. Table 1 shows the estimated values of the vertical spring coefficient and the horizontal spring coefficient. In addition, in Table 1, each spring coefficient is expressed as 100 in the conventional example.
　従来例：　　コード配置なし。
　比較例１：　周方向角度４５度のアラミドコードを配置。
　比較例２：　周方向角度が実質０度で、線形弾性率のアラミドコードを配置。
　比較例３：　周方向角度が５０度で、非線形弾性率のアラミドコードを配置。
　実施例１：　周方向角度が実質０度で、ナイロンとアラミドを撚り合わせた非線形弾性率コードを本体部プライ内側に配置する。変曲点は引張歪の２％にあり、低歪領域の弾性率は高歪領域弾性率の２０％。
　実施例２：　周方向角度が実質０度で、ナイロンとアラミドを撚り合わせた非線形弾性率コードをビードフィラーと折り返しプライ間に配置。変曲点は引張歪の２％にあり、低歪領域の弾性率は高歪領域弾性率の２０％。
　実施例３：　周方向角度が実質０度で、ナイロンとアラミドを撚り合わせた非線形弾性率コードを折り返しプライ外側に配置。変曲点は引張歪の２％にあり、低歪領域の弾性率は高歪領域弾性率の２０％。
　実施例４：　周方向角度が実質０度で、ナイロンとポリエチレンテレフタレートを撚り合わせた非線形弾性率コードを折り返しプライ外側に配置。変曲点は引張歪の２％にあり、低歪領域の弾性率は高歪領域弾性率の５０％。
　実施例５：　カーカスプライがビードコアに挟まれて係留されているが、ビードコアで折り返されていない構造。周方向角度が実質０度で、ナイロンとアラミドを撚り合わせた非線形弾性率コードを本体部プライ間に配置に配置する。変曲点は引張歪の２％にあり、低歪領域の弾性率は高歪領域弾性率の２０％。 Conventional example: No code placement.
Comparative Example 1: An aramid cord having a circumferential angle of 45 degrees is arranged.
Comparative Example 2: An aramid cord having a linear elastic modulus is arranged with a circumferential angle of substantially 0 degree.
Comparative Example 3: An aramid cord having a non-linear elastic modulus is arranged with a circumferential angle of 50 degrees.
Example 1: A non-linear elastic modulus cord obtained by twisting nylon and aramid with a circumferential angle of substantially 0 degree is arranged inside the main body ply. The inflection point is at 2% of the tensile strain, and the elastic modulus in the low strain region is 20% of the high strain region.
Example 2: A non-linear elastic modulus cord obtained by twisting nylon and aramid with a circumferential angle of substantially 0 degree is arranged between the bead filler and the folded ply. The inflection point is at 2% of the tensile strain, and the elastic modulus in the low strain region is 20% of the high strain region.
Example 3: A non-linear elastic modulus cord obtained by twisting nylon and aramid with a circumferential angle of substantially 0 degree is arranged outside the folded ply. The inflection point is at 2% of the tensile strain, and the elastic modulus in the low strain region is 20% of the high strain region.
Example 4: A non-linear elastic modulus cord obtained by twisting nylon and polyethylene terephthalate is arranged at the outer side of the folded ply with a circumferential angle of substantially 0 degree. The inflection point is at 2% of the tensile strain, and the elastic modulus in the low strain region is 50% of the high strain region.
Example 5: A structure in which the carcass ply is sandwiched between the bead cores and moored, but is not folded back at the bead cores. A non-linear elastic modulus cord obtained by twisting nylon and aramid with a circumferential angle of substantially 0 degrees is arranged between the main body plies. The inflection point is at 2% of the tensile strain, and the elastic modulus in the low strain region is 20% of the high strain region.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１から、実施例１～５は、従来例に比べて縦ばね係数の増加がなく、乗り心地が良好であり、また、従来例に比べて横ばね係数が増加し、操縦安定性が良好である。これに対して、比較例１～３は、従来例に比べて縦ばね係数が増加していて乗り心地が悪化する。 From Table 1, in Examples 1 to 5, the longitudinal spring coefficient does not increase as compared with the conventional example, and the riding comfort is good, and the lateral spring coefficient increases as compared with the conventional example, and the steering stability is good. Is. On the other hand, in Comparative Examples 1 to 3, the vertical spring coefficient is increased and the riding comfort is deteriorated as compared with the conventional example.
　以上、本発明の空気入りタイヤを、実施形態及び実施例により説明したが、本発明の空気入りタイヤは、本発明の趣旨を逸脱しない範囲で幾多の変形が可能である。 The pneumatic tire of the present invention has been described above with reference to the embodiments and examples, but the pneumatic tire of the present invention can be variously modified without departing from the spirit of the present invention.
１　空気入りタイヤ、２　ビード部、３　サイドウォール部、４　トレッド部、５　ビードコア、６　ビードフィラー、７　カーカス、８　ベルト、９　コード
 
  1 pneumatic tire, 2 bead part, 3 sidewall part, 4 tread part, 5 bead core, 6 bead filler, 7 carcass, 8 belt, 9 cord

Claims (10)

  1. 　ビードコアをそれぞれ有する一対のビード部と、該一対のビード部のそれぞれに連なり半径方向外方に延びる一対のサイドウォール部と、該一対のサイドウォール部の外周端を接続するトレッド部と、を備えるとともに、
    　両端部がそれぞれ前記一対のビード部における前記ビードコアに係留され前記サイドウォール部から前記トレッド部にかけてトロイド状をなすカーカスと、該カーカスのクラウン部分の外側に設けられたベルトと、を備える空気入りタイヤにおいて、
    　前記ビード部から前記サイドウォール部までの少なくとも一部分に、周方向に対して０～１０°の角度をなしてコードが設けられ、かつ、該コードが、応力－歪曲線において変曲点を有し、該変曲点以下の低歪領域では低弾性率を、変曲点を超えた高歪領域では高弾性率を有するものであることを特徴とする空気入りタイヤ。     A pair of bead portions each having a bead core, a pair of sidewall portions that are continuous with each of the pair of bead portions and extend outward in the radial direction, and a tread portion that connects outer peripheral ends of the pair of sidewall portions. With
    A pneumatic tire including both ends of a carcass that is moored to the bead core of the pair of bead parts and has a toroidal shape from the sidewall part to the tread part, and a belt provided outside a crown part of the carcass. At
    A cord is provided on at least a part from the bead portion to the sidewall portion at an angle of 0 to 10° with respect to a circumferential direction, and the cord has an inflection point in a stress-strain curve. A pneumatic tire having a low elastic modulus in a low strain region below the inflection point and a high elastic modulus in a high strain region above the inflection point.
  2. 　前記コードが、材質の異なる２種以上の繊維からなり、前記繊維は有機繊維又は無機繊維からなる請求項１に記載の空気入りタイヤ。 The pneumatic tire according to claim 1, wherein the cord is made of two or more kinds of fibers having different materials, and the fibers are made of organic fibers or inorganic fibers.
  3. 　前記カーカスが前記ビードコアで折り返されて本体部と折り返し部とを備え、該本体部と該折り返し部との間にビードフィラーを備え、前記コードが前記カーカスの本体部プライと前記ビードフィラーとの間に配置されている請求項１又は２に記載の空気入りタイヤ。 The carcass is folded back at the bead core and includes a main body portion and a folded back portion, a bead filler is provided between the main body portion and the folded back portion, and the cord is between the main body portion ply of the carcass and the bead filler. The pneumatic tire according to claim 1, wherein the pneumatic tire is arranged in.
  4. 　前記カーカスが前記ビードコアで折り返されて本体部と折り返し部とを備え、該本体部と該折り返し部との間にビードフィラーを備え、前記コードが前記ビードフィラーと前記カーカスの折り返しプライとの間に配置されている請求項１又は２に記載の空気入りタイヤ。 The carcass is folded back at the bead core and includes a main body portion and a folded back portion, a bead filler is provided between the main body portion and the folded back portion, and the cord is between the bead filler and the folded ply of the carcass. The pneumatic tire according to claim 1 or 2, which is arranged.
  5. 　前記カーカスが前記ビードコアで折り返されて本体部と折り返し部とを備え、該本体部と該折り返し部との間にビードフィラーを備え、前記コードが前記カーカスの折り返し部プライよりもタイヤ半径方向外側に配置されている請求項１又は２に記載の空気入りタイヤ。 The carcass is folded back at the bead core and includes a main body portion and a folded back portion, a bead filler is provided between the main body portion and the folded back portion, and the cord is located outside the folded back portion ply of the carcass in the tire radial direction. The pneumatic tire according to claim 1 or 2, which is arranged.
  6. 　前記カーカスの端部が第１のビードコアと第２のビードコアとで挟まれて係留され、前記コードが前記カーカスよりもタイヤ半径方向外側に配置されている請求項１又は２に記載の空気入りタイヤ。 The pneumatic tire according to claim 1 or 2, wherein an end portion of the carcass is moored by being sandwiched between a first bead core and a second bead core, and the cord is arranged outside the carcass in a tire radial direction. ..
  7. 　前記コードの材料が、少なくともアラミド又はポリエチレンテレフタレートを含む請求項１～６のいずれか一項に記載の空気入りタイヤ。 The pneumatic tire according to any one of claims 1 to 6, wherein the material of the cord contains at least aramid or polyethylene terephthalate.
  8. 　前記コードは、前記変曲点が引張歪１～８％の範囲にある請求項１～７のいずれか一項に記載の空気入りタイヤ。 The pneumatic tire according to any one of claims 1 to 7, wherein the inflection point of the cord is in the range of tensile strain of 1 to 8%.
  9. 　前記コードは、低歪領域の弾性率が高歪領域の弾性率に対して１０～９０％の範囲にある請求項１～８のいずれか一項に記載の空気入りタイヤ。 The pneumatic tire according to any one of claims 1 to 8, wherein the cord has a modulus of elasticity in a low strain region in a range of 10 to 90% with respect to a modulus of elasticity in a high strain region.
  10. 　請求項１～９のいずれか一項に記載の空気入りタイヤを製造する方法であって、
    　１種又は２種以上の非線形弾性率を有する非線形弾性率コードを用意し、タイヤ成型工程にて、タイヤ内の位置によって前記非線形弾性率コードに異なる張力を付与することで、前記非線形弾性率コードの弾性率を制御して、用意した非線形弾性率コードよりも多い種類の非線形弾性率特性コードをタイヤ内で形成させることを特徴とする空気入りタイヤの製造方法。
          A method for manufacturing the pneumatic tire according to any one of claims 1 to 9, comprising:
    By preparing a non-linear elastic modulus code having one or more non-linear elastic modulus and applying different tensions to the non-linear elastic modulus code depending on the position in the tire in the tire molding process, the non-linear elastic modulus code is obtained. A method for manufacturing a pneumatic tire, characterized in that the number of types of non-linear elastic modulus characteristic codes that are larger than the prepared non-linear elastic modulus codes is formed in the tire by controlling the elastic modulus of the non-linear elastic modulus code.
PCT/JP2019/049038 2018-12-13 2019-12-13 Pneumatic tyre WO2020122250A1 (en)

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Application Number Priority Date Filing Date Title
JP2018-233921 2018-12-13
JP2018233921 2018-12-13
JP2019097826A JP7177750B2 (en) 2018-12-13 2019-05-24 pneumatic tire
JP2019-097826 2019-05-24

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WO2020122250A1 true WO2020122250A1 (en) 2020-06-18

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Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003514706A (en) * 1999-11-18 2003-04-22 ソシエテ ド テクノロジー ミシュラン Tires with concentrated cords in the bottom area
JP2003237315A (en) * 2002-02-21 2003-08-27 Fuji Seiko Kk Pneumatic radial tire, and method for manufacturing the same
JP2004058807A (en) * 2002-07-26 2004-02-26 Toyo Tire & Rubber Co Ltd Radial tire
JP2006298162A (en) * 2005-04-20 2006-11-02 Yokohama Rubber Co Ltd:The Pneumatic tire
JP2009286269A (en) * 2008-05-29 2009-12-10 Yokohama Rubber Co Ltd:The Pneumatic tire
JP2011079360A (en) * 2009-10-05 2011-04-21 Bridgestone Corp Run-flat tire
JP2013001206A (en) * 2011-06-15 2013-01-07 Yokohama Rubber Co Ltd:The Pneumatic tire
JP2017141006A (en) * 2016-02-12 2017-08-17 横浜ゴム株式会社 Pneumatic tire and method for manufacturing the same

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003514706A (en) * 1999-11-18 2003-04-22 ソシエテ ド テクノロジー ミシュラン Tires with concentrated cords in the bottom area
JP2003237315A (en) * 2002-02-21 2003-08-27 Fuji Seiko Kk Pneumatic radial tire, and method for manufacturing the same
JP2004058807A (en) * 2002-07-26 2004-02-26 Toyo Tire & Rubber Co Ltd Radial tire
JP2006298162A (en) * 2005-04-20 2006-11-02 Yokohama Rubber Co Ltd:The Pneumatic tire
JP2009286269A (en) * 2008-05-29 2009-12-10 Yokohama Rubber Co Ltd:The Pneumatic tire
JP2011079360A (en) * 2009-10-05 2011-04-21 Bridgestone Corp Run-flat tire
JP2013001206A (en) * 2011-06-15 2013-01-07 Yokohama Rubber Co Ltd:The Pneumatic tire
JP2017141006A (en) * 2016-02-12 2017-08-17 横浜ゴム株式会社 Pneumatic tire and method for manufacturing the same

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