WO2014136523A1 - 空気入りタイヤ - Google Patents
空気入りタイヤ Download PDFInfo
- Publication number
- WO2014136523A1 WO2014136523A1 PCT/JP2014/052742 JP2014052742W WO2014136523A1 WO 2014136523 A1 WO2014136523 A1 WO 2014136523A1 JP 2014052742 W JP2014052742 W JP 2014052742W WO 2014136523 A1 WO2014136523 A1 WO 2014136523A1
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- WO
- WIPO (PCT)
- Prior art keywords
- point
- tread
- tire
- internal pressure
- protruding
- Prior art date
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Classifications
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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
- 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
-
- 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
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/0083—Tyre tread bands; Tread patterns; Anti-skid inserts characterised by the curvature of the tyre tread
-
- 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
- B60C13/00—Tyre sidewalls; Protecting, decorating, marking, or the like, thereof
- B60C13/003—Tyre sidewalls; Protecting, decorating, marking, or the like, thereof characterised by sidewall curvature
-
- 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
- B60C15/0009—Tyre beads, e.g. ply turn-up or overlap features of the carcass terminal portion
- B60C15/0036—Tyre beads, e.g. ply turn-up or overlap features of the carcass terminal portion with high ply turn-up, i.e. folded around the bead core and terminating radially above the point of maximum section width
-
- 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
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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
- B60C9/28—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers characterised by the belt or breaker dimensions or curvature relative to carcass
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M17/00—Testing of vehicles
- G01M17/007—Wheeled or endless-tracked vehicles
- G01M17/02—Tyres
-
- 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
- B60C2009/2038—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel using lateral belt strips at belt edges, e.g. edge bands
Definitions
- the present invention relates to a pneumatic tire.
- Japanese Laid-Open Patent Publication No. 2-106404 proposes a pneumatic tire having improved tread groove crack resistance.
- the radius of curvature of the tread and the amount of protrusion of the tread when filled with air are defined.
- the difference between the amount of protrusion at the center of the tread and the amount of protrusion at the outer side in the axial direction of the tread is within a predetermined range.
- the amount of protrusion of the tread and the amount of change in the radius of curvature of the tread are reduced between the low internal pressure state and the standard internal pressure state.
- Japanese Patent Application Laid-Open No. 58-112804 proposes a pneumatic tire that improves the uneven wear of the tread and the crack resistance of the groove by defining the radius of curvature of the tread and the shape of the shoulder side wall.
- this tire it is proposed that the difference between the shape of the tread and the shoulder in a state where the air is filled and the shape of the tread and the shoulder of the molding die are within a predetermined range. In this tire, the change in shape between the mold shape and the shape when filled with air is reduced.
- the member of the pneumatic tire is an elastic body.
- the shape of the tire is deformed into a shape in which stress is generated and a balanced state is obtained.
- This shape change is unavoidable in a pneumatic tire. Therefore, the inventors have developed a tire whose shape changes so as not to impair the wear resistance and the crack resistance of the grooves when filled with air.
- An object of the present invention is to provide a pneumatic tire excellent in uneven wear and groove crack resistance.
- the pneumatic tire according to the present invention has a tread whose outer surface forms a tread surface, a pair of sidewalls that extend substantially inward in the radial direction from the end of the tread, and the inner side of the tread and sidewalls.
- the passed carcass and a belt laminated on the outer side in the radial direction of the carcass are provided.
- the belt includes an inner layer and an outer layer superimposed on the radially outer side of the inner layer. Grooves are formed on the tread surface.
- the position of the tread surface on the equator plane is a point Pa
- the position on the tread surface 0.8 times the axial width Wb where the inner and outer layers of the belt are overlapped is a point Ph
- the maximum width The position of the outer side surface in the side wall axial direction is a point Pe
- the position on the outer side surface in the side wall axial direction is a point Pd
- the nominal width is W ( mm)
- the amount of protrusion when the internal pressure is increased from the internal pressure state 0.05 times the normal internal pressure P to the internal pressure state of the normal internal pressure P is expressed by the protrusion amount Da (mm) at the point Pa and the protrusion amount Dh and the point Pd.
- Fa ((Dd + De) / W) ⁇ 100 (1) 0.02626 ⁇ A-1.8615 ⁇ Fa (2) Fa ⁇ 0.02626 ⁇ A-0.6615 (3)
- Gs ((Da ⁇ Dh) / W) ⁇ 100 (4) ⁇ 0.010819 ⁇ A ⁇ 0.084658 ⁇ Gs (5) Gs ⁇ 0.010819 ⁇ A + 0.6713 (6)
- the tire includes a band laminated on the outer side in the radial direction of the belt.
- This band includes a full band and a pair of edge bands stacked at the axial end of the full band.
- This full band consists of a cord and a topping rubber.
- the cord extends substantially in the circumferential direction.
- the edge band consists of a cord and a topping rubber. The cord extends substantially circumferentially or axially.
- the flatness ratio A of this tire is 70%.
- the protruding sum Fa is greater than ⁇ 0.02 and smaller than 1.18.
- the protrusion difference Gs is larger than ⁇ 0.84 and smaller than ⁇ 0.09.
- the flatness ratio A of this tire is 40%.
- the protrusion sum Fa is larger than ⁇ 0.81 and smaller than 0.39.
- the protruding difference Gs is larger than ⁇ 0.52 and smaller than 0.24.
- a method for evaluating durability of a pneumatic tire according to the present invention includes a tread whose outer surface forms a tread surface, a pair of sidewalls each extending substantially inward in the radial direction from the end of the tread, and the tread and sidewalls
- a tire durability evaluation method comprising: a carcass stretched along an inner side; and a belt laminated on a radially outer side of the carcass, and the belt is overlapped on a radially outer side of the inner layer and the inner layer. It is.
- the position of the tire tread surface on the equator plane is point Pa
- the position on the tread surface 0.8 times the axial width Wb where the inner layer and the outer layer of the belt are overlapped is point Ph.
- the position of the outer side surface in the sidewall axial direction is a point Pe, the midpoint of the point Pa and the point Pe in the radial direction, and the position on the outer side surface in the sidewall axial direction is the point Pd, and the nominal width is W (mm).
- the amount of protrusion when the internal pressure is increased from the internal pressure state 0.05 times the normal internal pressure P to the internal pressure state of the normal internal pressure P is expressed by the protrusion amount Da (mm) at the point Pa and the protrusion amount Dh and the point Pd.
- the protrusion amount Dd (mm) and the point Pe are the protrusion amount De (mm)
- the protruding sum Fa of the sidewall is obtained by the formula (1)
- the protruding sum Fa satisfies the formulas (2) and (3) as the flatness ratio A
- the protruding difference Gs of the tread is expressed by the formula (4).
- Fa ((Dd + De) / W) ⁇ 100 (1) 0.02626 ⁇ A-1.8615 ⁇ Fa (2) Fa ⁇ 0.02626 ⁇ A-0.6615 (3)
- Gs ((Da ⁇ Dh) / W) ⁇ 100 (4) ⁇ 0.010819 ⁇ A ⁇ 0.084658 ⁇ Gs (5) Gs ⁇ 0.010819 ⁇ A + 0.6713 (6)
- a method for manufacturing a pneumatic tire according to the present invention includes a tread whose outer surface forms a tread surface, a pair of sidewalls each extending substantially inward in the radial direction from an end of the tread, and along the inside of the tread and sidewalls. And a belt laminated on the outer side in the radial direction of the carcass, and the belt is superimposed on the outer side in the radial direction of the inner layer and the inner layer.
- This manufacturing method includes a determination step in which the durability of the prototype tire is evaluated.
- the position of the tread surface on the equator plane is a point Pa
- the position on the tread surface that is 0.8 times the axial width Wb where the inner layer and the outer layer of the belt are overlapped is a point Ph.
- the position of the outer side surface in the sidewall axis direction at the maximum width is a point Pe
- the position on the outer side surface in the sidewall axis direction is a point Pd
- the nominal width is W (mm).
- the amount of protrusion when the internal pressure is increased from the internal pressure state 0.05 times the normal internal pressure P to the internal pressure state of the normal internal pressure P is expressed by the protrusion amount Da (mm) at the point Pa and the protrusion amount Dh and the point Pd.
- the protrusion amount Dd (mm) and the point Pe are the protrusion amount De (mm)
- the protruding sum Fa of the side wall is obtained by the formula (1)
- the protruding sum Fa satisfies the formulas (2) and (3) as the flatness A
- the protruding difference Gs of the tread is expressed by the formula (4).
- the occurrence of cracks at the groove bottom is suppressed.
- the occurrence of uneven wear on the tread is suppressed.
- the durability evaluation method according to the present invention the durability of a pneumatic tire can be easily evaluated.
- a tire having excellent durability can be easily manufactured.
- FIG. 1 is a cross-sectional view showing a part of a pneumatic tire according to an embodiment of the present invention.
- FIG. 2 is an enlarged cross-sectional view showing a part of the tire of FIG.
- FIG. 3 is an enlarged cross-sectional view showing still another part of the tire of FIG.
- FIG. 4 is a cross-sectional view showing a part of a pneumatic tire according to another embodiment of the present invention.
- FIG. 5 is a graph showing a relationship between the flatness ratio and the protruding sum Fa of the sidewalls.
- FIG. 6 is a graph showing the relationship between the flatness ratio and the protruding difference Gs of the tread.
- FIG. 1 shows a pneumatic tire 2.
- the vertical direction is the radial direction of the tire 2
- the left-right direction is the axial direction of the tire 2
- the vertical direction of the paper is the circumferential direction of the tire 2.
- a dashed-dotted line CL in FIG. 1 represents the equator plane of the tire 2.
- the shape of the tire 2 is symmetrical with respect to the equator plane except for the tread pattern.
- a two-dot chain line BL represents a bead base line of the tire 2.
- the tire 2 includes a tread 4, a sidewall 6, a bead 8, a carcass 10, a belt 12, a band 14, an inner liner 16, and a chafer 18.
- the tire 2 is a tubeless type.
- the tire 2 is mounted on a passenger car.
- the tread 4 has a shape protruding outward in the radial direction.
- the tread 4 includes a center region C and a shoulder region S.
- the center region C is located at the center in the axial direction of the tire 2.
- the pair of shoulder regions S are located outside the center region C in the axial direction.
- the tread 4 forms a tread surface 20 that contacts the road surface.
- a groove 22 is carved in the tread surface 20.
- the groove 22 forms a tread pattern.
- the tread 4 has a base layer and a cap layer (not shown).
- the cap layer is located on the radially outer side of the base layer.
- the cap layer is laminated on the base layer.
- the base layer is made of a crosslinked rubber having excellent adhesiveness.
- a typical base rubber for the base layer is natural rubber.
- the cap layer is made of a crosslinked rubber having excellent wear resistance, heat resistance and grip properties.
- the sidewall 6 extends from the end of the tread 4 substantially inward in the radial direction. A radially outer end of the sidewall 6 is joined to the tread 4. This sidewall 6 is made of a crosslinked rubber having excellent cut resistance and weather resistance. The sidewall 6 prevents the carcass 10 from being damaged.
- the bead 8 is located inside the sidewall 6 in the radial direction.
- the bead 8 includes a core 24 and an apex 26 that extends radially outward from the core 24.
- the core 24 has a ring shape and includes a wound non-stretchable wire. A typical material for the wire is steel.
- the apex 26 is tapered outward in the radial direction.
- the apex 26 is made of a highly hard crosslinked rubber.
- the carcass 10 includes a carcass ply 28.
- the carcass ply 28 is spanned between the beads 8 on both sides, and extends along the tread 4 and the sidewall 6.
- the carcass ply 28 is folded around the core 24 from the inner side to the outer side in the axial direction. By this folding, the carcass ply 28 is formed with a main portion 28a and a folded portion 28b.
- the carcass ply 28 is composed of a large number of cords arranged in parallel and a topping rubber.
- the absolute value of the angle formed by each cord with respect to the equator plane is 75 ° to 90 °.
- the carcass 10 has a radial structure.
- the cord is made of organic fiber. Examples of preferable organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.
- the carcass 10 may be formed from two or more plies.
- the belt 12 is located inside the tread 4 in the radial direction.
- the belt 12 is laminated with the carcass 10.
- the belt 12 reinforces the carcass 10.
- the belt 12 includes an inner layer 30 and an outer layer 32 superimposed on the outer side in the radial direction of the inner layer 30.
- the width of the inner layer 30 is slightly larger than the width of the outer layer 32 in the axial direction.
- each of the inner layer 30 and the outer layer 32 includes a large number of cords arranged in parallel and a topping rubber. Each cord is inclined with respect to the equator plane.
- the absolute value of the tilt angle is usually 10 ° to 35 °.
- the direction of inclination of the cord of the inner layer 30 with respect to the equator plane is opposite to the direction of inclination of the cord of the outer layer 32 with respect to the equator plane.
- a preferred material for the cord is steel.
- An organic fiber may be used for the cord.
- the width Wb of the belt 12 is measured as a linear distance in the axial direction of the tire 2.
- the width Wb is measured as the width of the range in which the inner layer 30 and the outer layer 32 are overlapped. In the tire 2, it is measured as the width of the outer layer 32.
- the width Wb is preferably not less than 0.58 times and not more than 0.85 times the maximum width of the tire 2.
- the band 14 is located outside the belt 12 in the radial direction.
- the band 14 includes a full band 34 and a pair of edge bands 36.
- the width of the full band 34 is larger than the width of the belt 12.
- the full band 34 covers the belt 12.
- the full band 34 is composed of a cord and a topping rubber.
- the cord of the full band 34 is spirally wound.
- the full band 34 has a so-called jointless structure.
- the cord of the full band 34 extends substantially in the circumferential direction.
- the angle of the cord with respect to the circumferential direction is 5 ° or less, and further 2 ° or less.
- the pair of edge bands 36 covers the end of the belt 12 in the axial direction.
- the edge band 36 is stacked on the radially outer side of the end portion in the axial direction of the full band 36.
- the edge band 36 is made of a cord and a topping rubber.
- the cord of the edge band 36 is wound spirally.
- the full band 34 has a so-called jointless structure.
- the cord of the full band 34 extends substantially in the circumferential direction.
- the angle of the cord with respect to the circumferential direction is 5 ° or less, and further 2 ° or less.
- the edge band 36 may be stacked on the radially inner side of the full band 36.
- the cord of the edge band 36 may extend substantially in the axial direction.
- cords are made of organic fibers.
- preferable organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.
- the belt 12 and the band 14 constitute a reinforcing layer.
- the reinforcing layer may be formed only from the belt 12.
- the inner liner 16 is located inside the carcass 10.
- the inner liner 16 is made of a crosslinked rubber.
- rubber having excellent air shielding properties is used.
- a typical base rubber of the inner liner 16 is butyl rubber or halogenated butyl rubber.
- the inner liner 16 maintains the internal pressure of the tire.
- the chafer 18 is located in the vicinity of the bead 8. When the tire 2 is incorporated into the rim, the chafer 18 comes into contact with the rim. By this contact, the vicinity of the bead 8 is protected.
- the chafer 18 is made of cloth and rubber impregnated in the cloth.
- a point Ph indicates an intersection between the straight line Lh and the tread surface 20.
- the two-dot chain line Le is a straight line extending in the axial direction through the maximum width of the tire 2.
- This maximum width means the axial width of the tire at a position where the main portion 28a of the carcass 10 passes the outermost side in the axial direction.
- the point Pe is an intersection of the straight line Le and the axially outer side surface 6 a of the sidewall 6.
- the maximum width of the tire 2 is measured as the distance from this point Pe to the other point Pe (not shown).
- a double-headed arrow D indicates the distance from the point Pa to the point Pe in the radial direction.
- a two-dot chain line Ld indicates a straight line extending in the axial direction through the midpoint of the distance D.
- the point Pd is an intersection of the straight line Ld and the axially outer side surface 6a of the sidewall 6. This point Pd is a midpoint between the point Pa and the point Pe in the radial direction.
- FIG. 2 shows an enlarged view of a part of the tire 2.
- the outer side surface 6a in the axial direction of the tire 2 shows a state in which the tire 2 is incorporated in a regular rim and filled with air having a regular internal pressure P.
- An alternate long and two short dashes line 6 a ′ also indicates the outer surface in the axial direction of the tire 2.
- This outer side surface 6a ' shows a state in which the tire 2 is incorporated in a normal rim and is filled with 0.05 times the air pressure 0.05 ⁇ P of the normal internal pressure P.
- the point Pd ' indicates the intersection of the normal line of the axially outer side surface 6a passing through the point Pd and the outer side surface 6a'.
- a double-headed arrow Dd indicates the distance from the point Pd 'to the point Pd.
- This distance Dd is the protruding amount of the tire 2 at the point Pd.
- the amount of protrusion Dd represents the distance from the point Pd 'to the point Pd when the air pressure is increased from 0.05 ⁇ P to the air pressure P.
- the protruding amount Dd is expressed as positive movement amount in the axial direction and negative movement in the axial direction.
- the point Pe ′ indicates the intersection of the straight line Le and the outer surface 6a ′.
- a double-headed arrow De indicates the distance from the point Pe ′ to the point Pe.
- This distance De is the protruding amount of the tire 2 at the point Pe.
- the protruding amount De represents the distance from the point Pe ′ to the point Pe when the air pressure is increased from the state of air pressure 0.05 ⁇ P to the state of air pressure P.
- the protruding amount De represents the amount of movement outward in the axial direction as positive and the amount of movement inward in the axial direction as negative.
- FIG. 3 shows an enlarged view of another part of the tire 2.
- the tread surface 20 of the tire 2 shows a state in which the tire 2 is incorporated in a regular rim and filled with air having a regular internal pressure P.
- a two-dot chain line 20 ′ also indicates the tread surface of the tire 2.
- the tread surface 20 ′ shows a state in which the tire 2 is incorporated in a normal rim and is filled with air having an air pressure of 0.05 ⁇ P that is 0.05 times the normal internal pressure P.
- the point Pa ′ indicates the intersection of the equator plane and the tread surface 20 ′.
- a double-headed arrow Da indicates the distance from the point Pa ′ to the point Pa.
- This distance Da is the protruding amount of the tire 2 at the point Pa.
- the protruding amount Da represents the distance from the point Pa ′ to the point Pa when the air pressure is increased from the state of 0.05 ⁇ P to the state of the air pressure P.
- the protruding amount Da represents the amount of movement outward in the radial direction as positive, and the amount of movement inward in the radial direction as negative.
- the point Ph ′ indicates the intersection of the normal line of the tread surface 20 passing through the point Ph and the tread surface 20 ′.
- a double-headed arrow Dh indicates a distance from the point Ph ′ to the point Ph.
- This distance Dh is the protruding amount of the tire 2 at the point Ph.
- the protruding amount Dh represents the distance from the point Ph ′ to the point Ph when the air pressure is increased from the state of air pressure 0.05 ⁇ P to the state of air pressure P.
- the protruding amount Dh is represented by a positive amount of movement outward in the radial direction and a negative amount of movement inward in the radial direction.
- the tire 2 is assembled into a regular rim, filled with air, and brought into a state of air pressure 0.05 ⁇ P.
- the profile of the tire 2 having an air pressure of 0.05 ⁇ P is measured by a profile measuring machine. Further, the air is filled and the air pressure P is obtained.
- the profile of the tire 2 with the air pressure P is measured by a profile measuring machine.
- a point Pa, a point Ph, a point Pe, and a point Pd are obtained from the profile of the tire 2 with the air pressure P.
- the profile of the tire 2 with the air pressure P and the profile of the tire 2 with the air pressure 0.05 ⁇ P are overlapped with the bead position (rim flange position) matched.
- a point Pa ′, a point Ph ′, a point Pe ′, and a point Pd ′ are obtained from the profile of the tire 2 having an air pressure of 0.5 ⁇ P.
- the protruding amounts Da and Dh of the tread 4 and the protruding amounts Dd and De of the sidewall 6 are obtained.
- the flatness of the tire 2 is 70%.
- the protrusion sum Fa satisfies the following relational expression. ⁇ 0.02 ⁇ Fa ⁇ 1.18
- the shoulder region S of the tread 4 is embedded inward in the radial direction. In this shoulder region S, the ground pressure is lowered. In the shoulder region S where the contact pressure is low, the tread surface 20 is easily worn and easily slipped. In the tire 2, the protrusion sum Fa is set to be smaller than 1.18, so that the large protrusion of the shoulder region S is suppressed. In the tire 2, uneven wear of the shoulder region S is suppressed.
- the protruding difference Gs of the tread 4 is obtained by the following expression from the difference between the protruding amount Da and the protruding amount Dh and the nominal width of the tire 2 as W.
- Gs ((Da ⁇ Dh) / W) ⁇ 100 (4)
- the protruding difference Gs satisfies the following relational expression. ⁇ 0.84 ⁇ Gs ⁇ 0.09
- the opening of the groove 22 is easily expanded.
- the opening of the groove 22 extending in the circumferential direction is easy to expand.
- the opening of the groove 22 located in the shoulder region S is likely to expand.
- a tensile stress acts in the groove width direction on the bottom of the groove 22 extending in the circumferential direction. This tensile stress tends to cause cracks at the bottom of the groove 22.
- the contact pressure of the tread surface 20 in the shoulder region S is increased. Uneven wear of the tread surface 20 in the shoulder region S is promoted.
- the protrusion difference Gs is larger than ⁇ 0.84, the protrusion amount Dh is suppressed from becoming too large with respect to the protrusion amount Da.
- the occurrence of cracks at the bottom of the groove 22 is suppressed. Uneven wear of the tread surface 20 in the shoulder region S is suppressed.
- the center region C of the tread 4 protrudes outward in the radial direction.
- the contact pressure of the tread 4 is increased.
- wear easily proceeds on the tread surface 20 in the center region C where the contact pressure is high.
- the tread surface 20 in the shoulder region S where the ground pressure is low is easy to slip. Thereby, the wear of the tread surface 20 of the shoulder region S easily proceeds.
- the protrusion difference Gs is smaller than ⁇ 0.09 ( ⁇ 0.086), it is suppressed that the protrusion amount Da is too large with respect to the protrusion amount Dh.
- the protrusion of the center region C is suppressed.
- uneven wear of the tread surface 20 is suppressed.
- the protrusion sum Fa and the protrusion difference Gs are shown as a ratio to the nominal width W of the tire 2.
- the protrusion difference Fa and the protrusion difference Gs can be applied to tires having different nominal widths W.
- the protrusion of the shoulder region S of the tread surface 20 is suppressed.
- the protrusion of the shoulder region S is small when the air is filled and the normal internal pressure is set.
- the tire 2 having a high flatness ratio with an aspect ratio A of 65% or more easily protrudes from the shoulder region S, so that the effect of suppressing the protrusion by the edge band 36 is great.
- the dimensions and angles of each member of the tire 2 are measured in a state where the tire 2 is incorporated in a regular rim and filled with air so as to have a regular internal pressure unless otherwise specified.
- the normal rim means a rim defined in a standard on which the tire 2 depends.
- “Standard rim” in the JATMA standard, “Design Rim” in the TRA standard, and “Measuring Rim” in the ETRTO standard are regular rims.
- the normal internal pressure means an internal pressure defined in a standard on which the tire depends.
- FIG. 4 shows another pneumatic tire 42 according to the present invention.
- the tire 42 includes a tread 44, a sidewall 46, a bead 48, a carcass 50, a belt 52, a band 54, an inner liner 56, and a chafer 58.
- the tread 44 forms a tread surface 60 that contacts the road surface.
- a groove 62 is carved on the tread surface 60.
- the bead 48 includes a core 64 and an apex 66 that extends radially outward from the core 64.
- the carcass 50 includes a first ply 68 and a second ply 70.
- the first ply 68 and the second ply 70 are bridged between the beads on both sides, and extend along the tread 44 and the sidewall 46.
- the first ply 68 is folded around the core 64 from the inner side to the outer side in the axial direction. By this folding, the main portion 68a and the folding portion 68b are formed in the first ply 68.
- the second ply 70 is folded around the core 64 from the inner side to the outer side in the axial direction. By this folding, the main portion 70a and the folding portion 70b are formed in the second ply 70.
- the end of the folded portion 68b of the first ply 68 is located outside the end of the folded portion 70b of the second ply 70 in the radial direction.
- the first ply 68 and the second ply 70 are composed of a large number of cords arranged in parallel and a topping rubber.
- the absolute value of the angle formed by each cord with respect to the equator plane is 75 ° to 90 °.
- this carcass has a radial structure.
- the cord is made of organic fiber. Examples of preferable organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.
- the carcass 50 may be formed from a single ply.
- the belt 52 is located inside the tread 44 in the radial direction.
- the belt 52 is laminated with the carcass 50.
- the belt 52 includes an inner layer 72 and an outer layer 74.
- each of the inner layer 72 and the outer layer 74 is composed of a large number of cords arranged in parallel and a topping rubber.
- Each cord is inclined with respect to the equator plane.
- the absolute value of the tilt angle is usually 10 ° to 35 °.
- the inclination direction of the cord of the inner layer 72 with respect to the equator plane is opposite to the inclination direction of the cord of the outer layer 74 with respect to the equator plane.
- the band 54 is located outside the belt 52 in the radial direction.
- the band 54 includes a full band 76 and a pair of edge bands 78.
- the width of the full band 76 is larger than the width of the belt 52.
- the full band 76 and the edge band 78 are made of a cord and a topping rubber. These cords are wound spirally.
- the full band 76 and the edge band 78 have a so-called jointless structure.
- the cords of the full band 76 and the edge band 78 extend substantially in the circumferential direction.
- the cord of the edge band 78 may extend substantially in the axial direction.
- the edge band 78 may be stacked on the radially inner side of the full band 76.
- the belt 52 and the band 54 constitute a reinforcing layer.
- the flatness of the tire 42 is 40%.
- the protrusion sum Fa satisfies the following relational expression. -0.81 ⁇ Fa ⁇ 0.39
- the low flatness means a flatness of 50% or less.
- the radial distance of the sidewall 46 is small. Since the radial distance is small, when both the protruding amount Dd and the protruding amount De become small, the shoulder region S of the tread 44 tends to protrude outward in the radial direction. In the shoulder region S, the contact pressure of the tread 44 is increased. In the shoulder region S, the tread surface 60 is easily worn.
- the protruding difference Gs satisfies the following relational expression. -0.52 ⁇ Gs ⁇ 0.24
- the protrusion difference Gs is larger than ⁇ 0.52, it is suppressed that the protrusion amount Dh becomes too large with respect to the protrusion amount Da.
- the occurrence of cracks at the bottom of the groove 62 is suppressed. Further, uneven wear of the tread surface 60 in the shoulder region S is suppressed.
- the protrusion difference Gs is smaller than 0.24, the protrusion amount Da is suppressed from becoming too large with respect to the protrusion amount Dh.
- the protrusion of the center region C is suppressed.
- uneven wear of the tread surface 60 is suppressed.
- the preferable range of the protrusion sum Fa and the protrusion difference Gs varies depending on the flatness ratio A as described with the tire 2 and the tire 42 as an example.
- the graph of FIG. 5 shows the distribution of prototype tires based on the flatness ratio A and the protrusion sum Fa.
- the circles in this graph indicate the distribution of the prototype tires in which the occurrence of cracks and the occurrence of uneven wear in the shoulder region S were good.
- the X mark in this graph indicates the distribution of prototype tires in which at least one of the occurrence of cracks and the occurrence of uneven wear in the shoulder region S is defective. From this graph, it was confirmed that in the prototype tire having the value Fa smaller than the straight line Lv and larger than the straight line Lw, the occurrence of cracks at the groove bottom and the occurrence of uneven wear were particularly good.
- the graph of FIG. 6 shows the distribution of the prototype tires based on the flatness ratio A and the protrusion difference Gs.
- the circles in this graph indicate the distribution of the prototype tires in which the occurrence of cracks and the occurrence of uneven wear in the shoulder region S were good.
- the X mark in this graph indicates the distribution of the trial tires in which at least one of the crack occurrence state and the uneven wear occurrence state of the shoulder region S is defective. From this graph, it was confirmed that the occurrence of cracks at the bottom of the groove and the occurrence of uneven wear were particularly good in a prototype tire having a protruding difference Gs smaller than the straight line Lt and larger than the straight line Lu.
- the protrusion sum Fa satisfies the above formulas (2) and (3), so that the occurrence of cracks in the groove bottom and the uneven wear of the tread 4 can be suppressed. Furthermore, when the protruding difference Gs of the tread 4 satisfies the above formulas (5) and (6), generation of cracks at the groove bottom and uneven wear of the tread can be suppressed.
- the protrusion sum Fa satisfies the expressions (2) and (3)
- the protrusion difference Gs of the tread 44 satisfies the expressions (5) and (6). Is obtained.
- This manufacturing method includes a determination step in which the durability of the prototype tire is evaluated.
- a prototype tire for obtaining the tire 2 is prepared.
- the quality based on the protrusion sum Fa and the protrusion difference Gs is determined.
- the tire 2 is designed based on the evaluation result of this determination process. For example, when the prototype tire is defective, for example, the carcass line is adjusted so that the protrusion sum Fa and the protrusion difference Gs are within a predetermined range.
- the adjustment of the carcass line is made, for example, by adjusting the vulcanization mold shape.
- the radius of curvature of the carcass line near the point Pd and the radius of curvature of the carcass line near the point Pe are adjusted by the mold shape.
- the tire 2 is manufactured by the molding die of the prototype tire. In this manner, the tire 2 is designed and manufactured based on the prototype tire, so that the tire 2 having excellent durability can be easily manufactured.
- the method of adjusting the carcass line is exemplified as a method of setting the protrusion sum Fa and the protrusion difference Gs within a predetermined range, but is not limited to this method.
- this can be achieved by adjusting the rubber thickness of the sidewall 6 near the point Pd and the rubber thickness of the sidewall 6 near the point Pe.
- the structure of the band 14 of the tire 2 may be changed as a method of setting the protrusion sum Fa and the protrusion difference Gs within a predetermined range.
- This evaluation method includes a step of obtaining a tire assembly, a low internal pressure step, a normal internal pressure step, and a determination step.
- a regular rim is incorporated into the tire 2 to obtain a tire assembly.
- the tire assembly is filled with air at an internal pressure of 0.05 ⁇ P which is 0.05 times the normal internal pressure P.
- the profile of the tire 2 is obtained in a state where the air is filled with the air pressure of 0.05 ⁇ P.
- the positions of point Pa, point Ph, point Pd and point Pe are obtained from the profile of the normal internal pressure step. Further, the positions of the points Pa ′, Ph ′, Pd ′, and Pe ′ are obtained from the profile of the low internal pressure process.
- the protruding amounts Da and Dh of the tread 4 and the protruding amounts De and Dd of the sidewall 6 are calculated.
- the protrusion difference Gs of the tread 4 and the protrusion sum Fa of the sidewall 6 are calculated. It is evaluated whether or not the protrusion sum Fa and the protrusion difference Gs are within a predetermined range. When it is within the predetermined range, a good judgment is made. When it is not within the predetermined range, a failure is determined.
- the durability of the tire 2 can be efficiently determined from the viewpoint of occurrence of cracks at the bottom of the groove 22 and occurrence of uneven wear of the tread 4.
- Example 1 A tire having the basic structure shown in FIG. 1 was prototyped.
- the tire size was “185 / 70R14”. That is, the nominal width W of this tire was 185 (mm), and the flatness ratio A was 70%.
- This tire was incorporated into a regular rim of 14 ⁇ 5.5J.
- the tire was filled with air so that the internal pressure was 12 kPa. Then, it filled with air so that it might become regular internal pressure 240kPa.
- the protruding amount Da (mm), the protruding amount Dh (mm), the protruding amount Dd (mm), the protruding amount De (mm), the protruding difference Gs, and the protruding sum Fa were obtained. The results are shown in Table 1.
- Example 2-3 and Comparative 1-2 A tire was prototyped in the same manner as in Example 1 except that the carcass line was adjusted.
- the protruding amount (Da (mm), Dh (mm), Dd (mm) and De (mm)), the protruding difference Gs, and the protruding sum Fa of these tires were obtained. The results are shown in Table 1.
- Example 4-7 and Comparative Example 3-4 A tire was prototyped in the same manner as in Example 1 except that the band structure was changed and the carcass line was adjusted.
- the protruding amount (Da (mm), Dh (mm), Dd (mm) and De (mm)), the protruding difference Gs, and the protruding sum Fa of these tires were obtained. The results are shown in Table 2.
- Example 8 A tire having the basic structure shown in FIG. 4 was prototyped.
- the tire size was “225 / 40R18”. That is, the nominal width W of this tire was 225 (mm), and the flatness A was 40%.
- This tire was incorporated into a regular rim of 18 ⁇ 8J.
- the tire was filled with air so that the internal pressure was 12 kPa. Then, it filled with air so that it might become regular internal pressure 240kPa.
- the tread protruding amount Da (mm) and the protruding amount Dh (mm), the sidewall protruding amount Dd (mm) and the protruding amount De (mm) were determined, and the protruding difference Gs and the protruding sum Fa were determined. .
- the results are shown in Table 3.
- Examples 9-10 and Comparative 5-6 A tire was manufactured in the same manner as in Example 8 except that the carcass line was adjusted. The protruding amount (Da (mm), Dh (mm), Dd (mm) and De (mm)), the protruding difference Gs, and the protruding sum Fa of these tires were obtained. The results are shown in Table 3.
- Examples 11-14 and Comparative 7-8 A tire was manufactured in the same manner as in Example 8 except that the band structure was changed and the carcass line was adjusted.
- the protruding amount (Da (mm), Dh (mm), Dd (mm) and De (mm)), the protruding difference Gs, and the protruding sum Fa of these tires were obtained. The results are shown in Table 4.
- a tire assembly was obtained by incorporating the prototype tire into a regular rim. This tire assembly was filled with air of normal internal pressure. The bottom of the main groove formed in the circumferential direction in the shoulder region of the tire was cut in the circumferential direction. Using a razor blade having a thickness of 0.25 mm, the bottom of the main groove was cut to a depth of 2 mm and a length of 8 mm. The cut opening was molded and the opening amount of the cut opening was measured. The measurement results are indexed and listed in Tables 1 to 4. The smaller the opening of the cut opening, the larger the index. As the index is larger, the occurrence of cracks is suppressed.
- a tire assembly was obtained by incorporating the prototype tire into a regular rim. This tire assembly was filled with air of normal internal pressure. The tire assembly was attached to a table wear energy measuring device. This tire assembly was set in a rotatable state. The slip angle was set to 1 °. The tire was loaded with 80% of the load index standard MAX load. It was grounded to the grounding stand of the tabletop wear energy measuring device. In this way, the wear energy of each tire in the turning state was measured.
- the tire of the example has a higher evaluation than the tire of the comparative example. From this evaluation result, the superiority of the present invention is clear.
- the tire and the durability test method described above can be applied to various pneumatic tires such as passenger cars, light trucks, light trucks, trucks and buses, and two-wheeled vehicles, and durability tests thereof.
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Abstract
Description
正規内圧Pの0.05倍の内圧状態から正規内圧Pの内圧状態まで内圧が高められたときのせり出し量を、点Paでせり出し量Da(mm)と点Phでせり出し量Dhと点Pdでせり出し量Dd(mm)と点Peでせり出し量De(mm)とすると、
サイドウォールのせり出し和Faが数式(1)で求められたとき、このせり出し和Faが扁平率Aとして数式(2)及び(3)を満たしており、
トレッドのせり出し差Gsが数式(4)で求められたとき、このせり出し差Gsが数式(5)及び(6)を満たしている空気入りタイヤ。
Fa=((Dd+De)/W)×100 (1)
0.02626×A-1.8615 < Fa (2)
Fa < 0.02626×A-0.6615 (3)
Gs=((Da-Dh)/W)×100 (4)
-0.010819×A-0.084658 < Gs (5)
Gs < -0.010819×A+0.6713 (6)
このタイヤのトレッド面の赤道面上の位置を点Paとし、このベルトの内側層と外側層とが重ね合わされた軸方向幅Wbの0.8倍のトレッド面上の位置を点Phとし、最大幅におけるサイドウォール軸方向外側面の位置を点Peとし、この点Paと点Peとの半径方向の中点であり、かつこのサイドウォール軸方向外側面上の位置を点Pdとし、呼び幅をW(mm)とする。
正規内圧Pの0.05倍の内圧状態から正規内圧Pの内圧状態まで内圧が高められたときのせり出し量を、点Paでせり出し量Da(mm)と点Phでせり出し量Dhと点Pdでせり出し量Dd(mm)と点Peでせり出し量De(mm)とすると、
サイドウォールのせり出し和Faが数式(1)で求められ、このせり出し和Faが扁平率Aとして数式(2)及び(3)を満たしていることと、トレッドのせり出し差Gsが数式(4)で求められたときに、このせり出し差Gsが数式(5)及び(6)を満たしていることとでトレッドの耐摩耗性と溝の耐クラック性が良好と判定される。
Fa=((Dd+De)/W)×100 (1)
0.02626×A-1.8615 < Fa (2)
Fa < 0.02626×A-0.6615 (3)
Gs=((Da-Dh)/W)×100 (4)
-0.010819×A-0.084658 < Gs (5)
Gs < -0.010819×A+0.6713 (6)
この判定工程では、このトレッド面の赤道面上の位置を点Paとし、このベルトの内側層と外側層とが重ね合わされた軸方向幅Wbの0.8倍のトレッド面上の位置を点Phとし、最大幅におけるサイドウォール軸方向外側面の位置を点Peとし、この点Paと点Peとの半径方向の中点であり、かつこのサイドウォール軸方向外側面上の位置を点Pdとし、呼び幅をW(mm)とする。正規内圧Pの0.05倍の内圧状態から正規内圧Pの内圧状態まで内圧が高められたときのせり出し量を、点Paでせり出し量Da(mm)と点Phでせり出し量Dhと点Pdでせり出し量Dd(mm)と点Peでせり出し量De(mm)とすると、
サイドウォールのせり出し和Faが数式(1)で求められて、このせり出し和Faが扁平率Aとして数式(2)及び(3)を満たしていることと、トレッドのせり出し差Gsが数式(4)で求められて、このせり出し差Gsが数式(5)及び(6)を満たしていることとが判定され、これらの判定に基づいてトレッドの耐摩耗性と溝の耐クラック性が評価されている。
この判定工程の評価結果に基づいてタイヤが設計されて製造されている。
Fa=((Dd+De)/W)×100 (1)
0.02626×A-1.8615 < Fa (2)
Fa < 0.02626×A-0.6615 (3)
Gs=((Da-Dh)/W)×100 (4)
-0.010819×A-0.084658 < Gs (5)
Gs < -0.010819×A+0.6713 (6)
Fa=((Dd+De)/W)×100 (1)
-0.02 < Fa < 1.18
Gs=((Da-Dh)/W)×100 (4)
-0.84 < Gs < -0.09
-0.81 < Fa < 0.39
-0.52 < Gs < 0.24
Fa = 0.02626×A-0.6615
一方、この直線Lwは、以下の式で表せる。
Fa = 0.02626×A-1.8615
0.02626×A-1.8615 < Fa (2)
Fa < 0.02626×A-0.6615 (3)
Gs = -0.010819×A+0.6713
一方、この直線Luは、以下の式で表せる。
Gs = -0.010819×A-0.084658
-0.010819×A-0.084658 < Gs (5)
Gs < -0.010819×A+0.6713 (6)
「1F+1F’」:コードが周方向の延びるフルバンド1枚とコードが軸方向に延びるフルバンド1枚の2枚からなる構造
「1F」:コードが周方向の延びるフルバンド1枚からなる構造
「1E+1F」:コードが周方向の延びる一対のエッジバンドとコードが周方向に延びるフルバンド1枚とからなる構造
図1に示される基本構造を備えたタイヤが試作された。このタイヤサイズは、「185/70R14」であった。即ち、このタイヤの呼び幅Wは185(mm)であり、扁平率Aは、70%であった。このタイヤを14×5.5Jの正規リムに組み込んだ。このタイヤに内圧が12kPaとなるように空気を充填した。その後、正規内圧240kPaとなるように空気を充填した。このせり出し量Da(mm)、せり出し量Dh(mm)、せり出し量Dd(mm)、せり出し量De(mm)、せり出し差Gs及びせり出し和Faとが求められた。その結果が表1に示されている。
カーカスラインが調整された他は、実施例1と同様にして、タイヤが試作された。これらのタイヤのせり出し量(Da(mm)、Dh(mm)、Dd(mm)及びDe(mm))、せり出し差Gs及びせり出し和Faが求められた。その結果が表1に示されている。
バンド構造が変更されて、カーカスラインが調整された他は、実施例1と同様にして、タイヤが試作された。これらのタイヤのせり出し量(Da(mm)、Dh(mm)、Dd(mm)及びDe(mm))、せり出し差Gs及びせり出し和Faが求められた。その結果が表2に示されている。
図4に示される基本構造を備えたタイヤが試作された。このタイヤサイズは、「225/40R18」であった。即ち、このタイヤの呼び幅Wは225(mm)であり、扁平率Aは、40%であった。このタイヤを18×8Jの正規リムに組み込んだ。このタイヤに内圧が12kPaとなるように空気を充填した。その後、正規内圧240kPaとなるように空気を充填した。このトレッドのせり出し量Da(mm)及びせり出し量Dh(mm)と、サイドウォールのせり出し量Dd(mm)及びせり出し量De(mm)とが求められ、せり出し差Gs及びせり出し和Faが求められた。その結果が表3に示されている。
カーカスラインが調整された他は、実施例8と同様にして、タイヤが試作された。これらのタイヤのせり出し量(Da(mm)、Dh(mm)、Dd(mm)及びDe(mm))、せり出し差Gs及びせり出し和Faが求められた。その結果が表3に示されている。
バンド構造が変更されて、カーカスラインが調整された他は、実施例8と同様にして、タイヤが試作された。これらのタイヤのせり出し量(Da(mm)、Dh(mm)、Dd(mm)及びDe(mm))、せり出し差Gs及びせり出し和Faが求められた。その結果が表4に示されている。
試作されたタイヤを正規リムに組み込んでタイヤ組立体を得た。このタイヤ組立体に正規内圧の空気が充填された。このタイヤのショルダー領域に周方向に形成された主溝の底が周方向にカットされた。厚み0.25mmのカミソリ刃を用いて、主溝の底が、深さ2mm、長さ8mmでカットされた。このカット口が型取りされて、カット口の開き量が測定された。その測定結果が指数化されて、表1から4に記載されている。カット口の開き量が小さいほど、この指数は大きい。指数が大きいほど、クラックの発生が抑制されている。
試作されたタイヤを正規リムに組み込んでタイヤ組立体を得た。このタイヤ組立体に正規内圧の空気が充填された。このタイヤ組立体が台上摩耗エネルギー測定装置に取り付けられた。このタイヤ組立体が回転自在の状態でセットされた。スリップ角は1°にセットされた。このタイヤにロードインデックス規格MAX荷重の80%の荷重が負荷された。台上摩耗エネルギー測定装置の接地台に接地させられた。このようにして、それぞれのタイヤの旋回走行状態の摩耗エネルギーが測定された。
4、44・・・トレッド
6、46・・・サイドウォール
8、48・・・ビード
10、50・・・カーカス
12、52・・・ベルト
14、54・・・バンド
16、56・・・インナーライナー
18、58・・・チェーファー
20、60・・・トレッド面
22、62・・・溝
24、64・・・コア
26、66・・・エイペックス
28・・・カーカスプライ
30、72・・・内側層
32、74・・・外側層
34、76・・・フルバンド
36、78・・・エッジバンド
68・・・第一プライ
70・・・第二プライ
Claims (6)
- その外面がトレッド面をなすトレッドと、それぞれが上記トレッドの端から半径方向略内向きに延びる一対のサイドウォールと、このトレッド及びサイドウォールの内側に沿って架け渡されたカーカスと、このカーカスの半径方向外側に積層されるベルトとを備えており、このベルトが内側層と内側層の半径方向外側に重ね合わされている外側層とを備えており、このトレッド面に溝が形成されており、
このトレッド面の赤道面上の位置を点Paとし、このベルトの内側層と外側層とが重ね合わされた軸方向幅Wbの0.8倍のトレッド面上の位置を点Phとし、最大幅におけるサイドウォール軸方向外側面の位置を点Peとし、この点Paと点Peとの半径方向の中点であり、かつこのサイドウォール軸方向外側面上の位置を点Pdとし、呼び幅をW(mm)とし、
正規内圧Pの0.05倍の内圧状態から正規内圧Pの内圧状態まで内圧が高められたときのせり出し量を、点Paでせり出し量Da(mm)とし、点Phでせり出し量Dhとし、点Pdでせり出し量Dd(mm)とし、点Peでせり出し量De(mm)とすると、
サイドウォールのせり出し和Faが数式(1)で求められたとき、このせり出し和Faが扁平率Aとして数式(2)及び(3)を満たしており、
トレッドのせり出し差Gsが数式(4)で求められたとき、このせり出し差Gsが数式(5)及び(6)を満たしている空気入りタイヤ。
Fa=((Dd+De)/W)×100 (1)
0.02626×A-1.8615 < Fa (2)
Fa < 0.02626×A-0.6615 (3)
Gs=((Da-Dh)/W)×100 (4)
-0.010819×A-0.084658 < Gs (5)
Gs < -0.010819×A+0.6713 (6) - 上記ベルトの半径方向外側に積層されるバンドを備えており、
このバンドがフルバンドとフルバンドの軸方向端部に積層された一対のエッジバンドとを備えており、
このフルバンドがコードとトッピングゴムとからなり、このコードが実質的に周方向の延びており、エッジバンドがコードとトッピングゴムとからなり、このコードが実質的に周方向又は軸方向に延びている請求項1に記載のタイヤ。 - 上記扁平率Aが70%であり、
上記せり出し和Faが-0.02より大きく1.18より小さく、
上記せり出し差Gsが-0.84より大きく-0.09より小さい請求項1又は2に記載のタイヤ。 - 上記扁平率Aが40%であり、
上記せり出し和Faが-0.81より大きく0.39より小さく、
上記せり出し差Gsが-0.52より大きく0.24より小さい請求項1又は2に記載のタイヤ。 - その外面がトレッド面をなすトレッドと、それぞれが上記トレッドの端から半径方向略内向きに延びる一対のサイドウォールと、このトレッド及びサイドウォールの内側に沿って架け渡されたカーカスと、このカーカスの半径方向外側に積層されるベルトとを備えており、このベルトが内側層と内側層の半径方向外側に重ね合わされる外側層とを備えるタイヤの耐久性評価方法であって、
このトレッド面の赤道面上の位置を点Paとし、このベルトの内側層と外側層とが重ね合わされる軸方向幅Wbの0.8倍のトレッド面上の位置を点Phとし、最大幅におけるサイドウォール軸方向外側面の位置を点Peとし、この点Paと点Peとの半径方向の中点であり、かつこのサイドウォール軸方向外側面上の位置を点Pdとし、呼び幅をW(mm)とし、
正規内圧Pの0.05倍の内圧状態から正規内圧Pの内圧状態まで内圧が高められたときのせり出し量を、点Paでせり出し量Da(mm)とし、点Phでせり出し量Dhとし、点Pdでせり出し量Dd(mm)とし、点Peでせり出し量De(mm)とすると、
サイドウォールのせり出し和Faが数式(1)で求められ、このせり出し和Faが扁平率Aとして数式(2)及び(3)を満たしていることと、
トレッドのせり出し差Gsが数式(4)で求められたときに、このせり出し差Gsが数式(5)及び(6)を満たしていることと
でトレッドの耐摩耗性と溝の耐クラック性が良好と判定される耐久性評価方法。
Fa=((Dd+De)/W)×100 (1)
0.02626×A-1.8615 < Fa (2)
Fa < 0.02626×A-0.6615 (3)
Gs=((Da-Dh)/W)×100 (4)
-0.010819×A-0.084658 < Gs (5)
Gs < -0.010819×A+0.6713 (6) - その外面がトレッド面をなすトレッドと、それぞれが上記トレッドの端から半径方向略内向きに延びる一対のサイドウォールと、トレッド及びサイドウォールの内側に沿って架け渡されたカーカスと、このカーカスの半径方向外側に積層されるベルトとを備えており、このベルトが内側層と内側層の半径方向外側に重ね合わされるタイヤの製造方法であって、
試作タイヤの耐久性が評価される判定工程を備えており、
この判定工程では、このトレッド面の赤道面上の位置を点Paとし、このベルトの内側層と外側層とが重ね合わされた軸方向幅Wbの0.8倍のトレッド面上の位置を点Phとし、最大幅におけるサイドウォール軸方向外側面の位置を点Peとし、この点Paと点Peとの半径方向の中点であり、かつこのサイドウォール軸方向外側面上の位置を点Pdとし、呼び幅をW(mm)とし、
正規内圧Pの0.05倍の内圧状態から正規内圧Pの内圧状態まで内圧が高められたときのせり出し量を、点Paでせり出し量Da(mm)とし、点Phでせり出し量Dhとし、点Pdでせり出し量Dd(mm)とし、点Peでせり出し量De(mm)とすると、
サイドウォールのせり出し和Faが数式(1)で求められて、このせり出し和Faが扁平率Aとして数式(2)及び(3)を満たしていることと、
トレッドのせり出し差Gsが数式(4)で求められて、このせり出し差Gsが数式(5)及び(6)を満たしていることとが判定され、これらの判定に基づいてトレッドの耐摩耗性と溝の耐クラック性が評価されており、
この判定工程の評価結果に基づいてタイヤが設計されて製造されているタイヤの製造方法。
Fa=((Dd+De)/W)×100 (1)
0.02626×A-1.8615 < Fa (2)
Fa < 0.02626×A-0.6615 (3)
Gs=((Da-Dh)/W)×100 (4)
-0.010819×A-0.084658 < Gs (5)
Gs < -0.010819×A+0.6713 (6)
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