US20140138002A1 - Pneumatic tire - Google Patents

Pneumatic tire Download PDF

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Publication number
US20140138002A1
US20140138002A1 US14/127,279 US201214127279A US2014138002A1 US 20140138002 A1 US20140138002 A1 US 20140138002A1 US 201214127279 A US201214127279 A US 201214127279A US 2014138002 A1 US2014138002 A1 US 2014138002A1
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United States
Prior art keywords
tire
tread
ratio
carcass
range
Prior art date
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Abandoned
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US14/127,279
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English (en)
Inventor
Shinsaku Katayama
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Bridgestone Corp
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Bridgestone Corp
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Application filed by Bridgestone Corp filed Critical Bridgestone Corp
Assigned to BRIDGESTONE CORPORATION reassignment BRIDGESTONE CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KATAYAMA, SHINSAKU
Publication of US20140138002A1 publication Critical patent/US20140138002A1/en
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Classifications

    • 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
    • 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
    • B60C9/02—Carcasses
    • B60C9/0292—Carcass ply 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
    • 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
    • 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
    • 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
    • B60C2009/283—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers characterised by the belt or breaker dimensions or curvature relative to carcass characterised by belt 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
    • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
    • B60C11/0008—Tyre tread bands; Tread patterns; Anti-skid inserts characterised by the tread rubber
    • B60C2011/0016—Physical properties or dimensions
    • B60C2011/0033—Thickness of the 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
    • 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
    • B60C2015/009—Height of the carcass terminal portion defined in terms of a numerical value or ratio in proportion to section height
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/80—Technologies aiming to reduce greenhouse gasses emissions common to all road transportation technologies
    • Y02T10/86—Optimisation of rolling resistance, e.g. weight reduction 
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T152/00—Resilient tires and wheels
    • Y10T152/10—Tires, resilient
    • Y10T152/10495—Pneumatic tire or inner tube
    • Y10T152/10765—Characterized by belt or breaker structure

Definitions

  • the present invention relates to a pneumatic tire that has low rolling resistance, good partial wear resistance performance, and reduced weight.
  • Patent Literature 1 proposes reducing rolling resistance by regulating a shape of a section of a tire. Although the proposed method indeed makes it possible to reduce rolling resistance, when compatibility with other performance, in particular with good wear resistance performance, is considered, a more meticulous tire design is required.
  • Patent Literature 2 discloses reduction in rolling resistance and improvement of wear resistance performance by the more meticulous design of a tire shape, the tire needs to be designed even more meticulously when the weight of the tire is to be reduced.
  • the present invention is to propose details of a tire shape for achieving a pneumatic tire that has low rolling resistance, good partial wear resistance performance, and reduced weight.
  • the present inventor has found that performance of a tire can be improved as desired by meticulously regulating the tire shape and that it is effective to individually regulate respective shapes of reinforcing members as a skeleton of the tire because the shapes of the reinforcing members have significant influence on tire performance.
  • the inventor of the present invention has found that, by suppressing shear deformation of a tire in a section in a tire width direction, particularly shear deformation in a tread on an outer side in the widthwise direction thereof, improvement is achieved simultaneously in reduction in rolling resistance resulting from energy loss caused by the deformation and in reduction of wear often generated by shearing force and slip also caused by the deformation.
  • the present inventor has regulated the shapes of the reinforcing members and then studied the shape of an optimal tire outer surface when the tire is combined with the shapes of the reinforcing members. Then, the present inventor has found that wear resistance performance is ensured even when the tread thickness is reduced, although conventionally it was not possible to reduce the tread thickness. Thus, the present inventor has found that three types of performance, i.e., reduction in rolling resistance, improvement of partial wear resistance performance, and reduction in weight, are simultaneously satisfied, thereby completing the present invention.
  • a pneumatic tire having at least one carcass layer as a skeleton extending in a toroidal shape over a pair of bead portions, at least one belt layer and a tread that are disposed on an outer side in a tire radial direction of a crown portion of the carcass layer, wherein
  • a ratio BD/BW of radius difference BD between radius at a center portion and radius at an end portion in the tire widthwise direction of an innermost layer of the belt layer, to a width BW of the innermost layer is in the range of 0.01 to 0.04, and
  • a ratio TD/TW of radius difference TD between radius at a center portion and radius at an end portion of the tread in the tire widthwise direction of a tread ground surface, to a tread ground-contact width TW, satisfies the relation BD/BW ⁇ TD/TW.
  • a ratio TGh/TGc of a tread gauge TGh measured in a tread end portion, to a tread gauge TGc measured in a tread center portion is in the range of 0.5 to 0.9, and
  • a ratio TGe/TGc of a tread gauge TGe measured in the end portion in the tire widthwise direction of the innermost layer to a tread gauge TGc measured in the tread center portion is in the range of 0.2 to 0.6.
  • a ratio SWh/SH of a shortest distance SWh between a line drawn in parallel with the rotation axis of the tire at a maximum width position of the tire and a line drawn in parallel with the rotation axis of the tire at the bead toe, to a sectional height SH of the tire is in the range of 0.5 to 0.8.
  • a ratio BW/CSW of the width BW of the innermost layer, to a maximum width CSW of the carcass is in the range of 0.8 to 0.94.
  • a ratio CSL/CSP of a path length CSL from a position corresponding to the end portion in the tire widthwise direction of the innermost layer to a position corresponding to the maximum width position of the carcass, to a path length CSP from a position corresponding to the center portion in the tire widthwise direction of the innermost layer to a position right below a bead core is in the range of 0.1 to 0.25.
  • a shortest distance CSEh between a terminal end of a turn-up portion of at least one carcass ply layer and a line drawn in parallel with the rotation axis of the tire at the bead toe is greater than the shortest distance SWh.
  • FIG. 1 is a view illustrating a section in a widthwise direction of a pneumatic tire according to the present invention
  • FIG. 2A is a view illustrating behaviors before and after application of load to a conventional pneumatic tire
  • FIG. 2B is a view illustrating behaviors before and after application of load to a pneumatic tire according to the present invention
  • FIG. 3 is a view illustrating how a tread gauge is measured
  • FIGS. 4A and 4B are views illustrating tensile strain when a neutral axis of bending is changed
  • FIGS. 5A-5E are views illustrating examples of different belt structures of a pneumatic tire according to the present invention.
  • FIG. 6 is a graph illustrating rolling resistance performance and wear performance with respect to a ratio BD/BW
  • FIG. 7 is a graph illustrating rolling resistance performance and wear performance with respect to a ratio TGh/TGc
  • FIG. 8 is a graph illustrating rolling resistance performance and wear performance with respect to a ratio TGe/TGc
  • FIG. 9 is a graph illustrating rolling resistance performance and wear performance with respect to a ratio CSWh/CSH
  • FIG. 10 is a graph illustrating rolling resistance performance and wear performance with respect to a ratio SWh/SH
  • FIG. 11 is a graph illustrating rolling resistance performance and wear performance with respect to a ratio BW/CSW.
  • FIG. 12 is a graph illustrating rolling resistance performance and wear performance with respect to a ratio CSL/CSP.
  • FIG. 1 illustrates a section of a pneumatic tire (which may be referred to below as a tire) according to the present invention in a widthwise direction thereof.
  • a tire 10 according to the present invention includes: a carcass 2 as a skeleton, having at least one carcass ply layer (one carcass ply layer in the illustrated example) that extends toroidally between bead portions each embedded with one of a pair of bead cores 1 and that is turned up along each of the bead cores 1 from an inner side to an outer side in the tire widthwise direction; a belt disposed on the outer side in a radial direction of a crown portion of the carcass 2 , the belt having at least one slant belt layer (two slant layers 3 a and 3 b in the illustrated example) formed by coating a number of cords extending in a direction inclined with respect to an equatorial plane CL of the tire with rubber and one circumferential belt layer 4 formed by coating a number of cords extending along the
  • a ratio BD/BW of a radius difference BD between radius at a center portion (the tire equatorial plane CL) and radius at an end portion 3 a E in the widthwise direction of the innermost layer 3 a among the slant belt layers 3 a and 3 b and the circumferential belt layer 4 , to a width BW of the innermost layer 3 a is in the range of 0.01 to 0.04, in a section in the tire widthwise direction in a state where the tire 10 is assembled to the application rim 7 .
  • the radius difference of the innermost layer 3 a in the tire radial direction gradually decreases from the center portion (the tire equatorial plane CL) to the end portion 3 a E in the widthwise direction.
  • the radius difference of a tread surface in the tire radial direction gradually decreases from the center portion in the widthwise direction (the tire equatorial plane CL) to the tread end portion TE of the tread ground surface.
  • the state where the tire 10 is assembled to the application rim 7 refers to a state where the tire 10 is assembled to a standard rim specified by JATMA and the tire is not filled with an internal pressure or filled with an extremely low internal pressure of up to approximately 30 kPa.
  • the tread ground-contact width TW refers to a width of the ground contact surface of the tread that comes into contact with a road surface when the tire 10 is pressed against the road surface (e.g. a smooth road surface such as a steel road surface) at the specified internal pressure and at load of 80% in the state where the tire 10 is assembled to the standard rim specified by the JATMA.
  • a road surface e.g. a smooth road surface such as a steel road surface
  • the radius differences BD and TD are measured in a direction parallel to the tire equatorial plane CL.
  • the innermost layer refers to a layer positioned radially innermost among belt layers having a width greater than or equal to 90% of the tread ground-contact width TW. That is to say, even when a belt layer having a width less than 90% of the tread ground-contact width TW is positioned radially innermost, this belt layer is not regarded as the innermost layer defined in the present invention. From the viewpoint of usability and specification of the tread gauge described below, it is preferable that the relation TW ⁇ BW is satisfied, and it is more preferable that the relation 1.1 BW/TW 1.6 is satisfied.
  • the restriction that the BD/BW is in the range of 0.01 to 0.04 means that the radius difference of the slant belt layer 3 a in the width direction thereof is small. In other words, the restriction means that the belt is nearly flat.
  • rolling resistance is primarily due to energy loss occurring in rubber of the tread portion, and it is effective to suppress shear deformation, the shear deformation being one example of relevant deformation, in the section in the width direction in order to reduce rolling resistance.
  • Shear deformation described above occurs due to deformation before and after application of load by which the belt which was curved in the ground-contact area is extended flat, as indicated in FIG.
  • a normal radial tire has a radius difference due to a smaller radius in a shoulder portion relative to that in a tread center portion, a portion of the belt that is located near the shoulder portion is stretched in the tire circumferential direction.
  • the slant belt layer in which cords are disposed crisscross are deformed like a pantograph to be extended in the circumferential direction, and accordingly, shrink in the width direction. Consequently, the aforementioned shear deformation is promoted, resulting in an increase in hysteresis loss of the tread rubber.
  • the ratio BD/BW By setting the ratio BD/BW to be 0.04 or less, as shown in FIG. 2B (refer to arrows), the deformation before and after application of load is limited to an extremely low level. Accordingly, by setting the ratio BD/BW to be 0.04 or less, hysteresis loss of the tread rubber is reduced, and the tire with low rolling resistance is achieved.
  • the restriction that the ratio BD/BW and the ratio TD/TW satisfy the relation BD/BW ⁇ TD/TW indicates that the belt has the flat shape, while the shape of the crown portion on the tire outer surface has a greater falling ratio than the belt and is curved.
  • the shape of the tire outer surface in order to obtain an appropriate ground-contact configuration and an appropriate distribution of ground-contact pressure, it is essential to define the shape of the tire outer surface to have an appropriate relation with the belt shape without making the shape of the tire outer surface completely flat.
  • the tire outer surface has a shape more flat than the belt shape, the tire center portion is off the road surface, and the ground-contact length is greater in the tread end portion TE than in the tire center portion.
  • rolling resistance is deteriorated, and moreover, the ground-contact pressure in the shoulder portion, which includes the tread end portion TE, is increased, and partial wear resistance performance is badly deteriorated. From the above, by setting the relation BD/BW ⁇ TD/TW, rolling resistance performance and partial wear resistance performance are improved.
  • the ratio restriction BD/BW ⁇ TD/TW also means that a tread gauge TGh measured in the tread end portion TE is less than a tread gauge TGc measured in the tread center portion.
  • the shoulder portion with the smaller tread gauge prevents the aforementioned increase in the ground-contact length and in the ground-contact pressure in the shoulder portion. As a result, good wear-resistance is achieved. Furthermore, with the small tread gauge in the shoulder portion, the amount of rubber deformed is reduced. As a result, rolling resistance is further lowered, and moreover, an advantageous effect that the weight of the tire is reduced is achieved.
  • a ratio TGh/TGc of the tread gauge TGh measured in the tread end TE, to the tread gauge TGc measured in the tread center portion is preferably in the range of 0.5 to 0.9
  • a ratio TGe/TGc of the tread gauge TGe measured in the end portion 3 a E of the innermost layer 3 a in the width direction, to the tread gauge TGc measured in the tread center portion is preferably in the range of 0.2 to 0.6.
  • the ratio TD/TW is preferably greater than or equal to 0.05, more preferably in the range of 0.05 to 0.15.
  • the ratio TD/TW is greater than 0.15, this means, in a case of a normal size tire, that the tread gauge measured in the shoulder portion does not exist.
  • the tread gauge gradually decreases from the tread center portion to the shoulder portion.
  • the tread gauge refers to a thickness of the tread rubber from an outer side of the reinforcing member of the outermost circumferential belt layer 4 among the belts to the tread ground surface as measured on a normal line of the carcass 2 in the section in the tire widthwise direction in the state where the tire 10 is assembled to the application rim 7 .
  • the tread gauge is measured on the normal line of the innermost layer 3 a.
  • the tread gauge TGc in the tread center portion is measured on the tire equatorial plane CL and is identified as the thickness of the tread rubber measured from an outer side of a cord C included in the circumferential belt layer 4 to the tread ground surface.
  • the tread gauge TGh at the tread end portion TE is measured on the normal line L 1 of the carcass 2 passing through the tread end portion TE and is identified as the thickness of the tread rubber measured from the outer side of a cord C included in the circumferential belt layer 4 to the tread ground surface.
  • the tread gauge TGe at the end portion 3 a E of the innermost layer 3 a in the widthwise direction is measured on the normal line L 2 of the carcass 2 passing through the end portion 3 a E in the widthwise direction and is identified as the thickness of the tread rubber measured from the outer side of a cord C included in the circumferential belt layer 4 to the tread ground surface.
  • the tread gauges TGc and TGh each refer to the thickness of the tread rubber measured from the outer side of the corresponding cord included in the slant belt layer 3 b to the tread ground surface
  • the tread gauge TGe refers to the thickness of the tread rubber measured from the outer side of the corresponding cord included in the slant belt layer 3 a to the tread ground surface. That is to say, the tread gauges each refer to a distance from the outer side of the corresponding outermost belt layer to the tread ground surface.
  • the tread gauge measured at a point of the tread portion that is closest to the tire equatorial plane CL and not provided with any groove is defined as the tread gauge TGc.
  • the tread gauge refers to the thickness of the tread rubber including cap rubber plus base rubber.
  • the shoulder portion is provided with lug grooves extending in the tire widthwise direction
  • a ratio CSWh/CSH of the shortest distance CSWh between a line drawn in parallel with the rotation axis of the tire at a maximum width position Wcmax of the carcass 2 and a line drawn in parallel with the rotation axis of the tire at a bead toe 8 , to a distance CSH in the tire radial direction between the radially outermost side of the carcass 2 and the bead toe 8 is preferably in the range of 0.6 to 0.9, and more preferably in the range of 0.65 to 0.8.
  • a carcass line of a tire side portion in the vicinity of the road surface has a locally bent region, and bending rigidity is relatively small in this region.
  • portions around the bent region located on the outer side of the belt end in the widthwise direction deforms to a significant degree when load is applied thereto, whereby a magnitude of deformation in the tread portion decreases.
  • a magnitude of shear deformation within the aforementioned section is reduced in the tread.
  • a ratio SWh/SH of the shortest distance SWh (which may be referred to below as the maximum width height) between a line drawn in parallel with the rotation axis of the tire at the maximum width position Wmax of the tire and a line drawn in parallel with the rotation axis of the tire at a bead toe 8 , to a sectional height SH of the tire, is preferably in the range of 0.5 to 0.8, and more preferably in the range of 0.6 to 0.75.
  • the side portion is no exception to the phenomenon that energy loss occurs inside rubber and contributes to rolling resistance. That is to say, by providing the side portion with a shape also different from that of a conventional tire in conformity to the carcass line, efficient improvement would be achieved.
  • Providing such a shape means to make side rubber relatively thin, for example.
  • the dimension of the side portion would coincide with the maximum width of the carcass line. In actual practice, however, it is necessary to give a predetermined thickness to side rubber because the side rubber serves for example to protect the carcass upon contact with curbstones.
  • a ratio BW/CSW of a width BW of the innermost layer 3 a , to the maximum width CSW of the carcass 2 is preferably in the range of 0.8 to 0.94, and more preferably in the range of 0.84 to 0.93.
  • the tire according to the present invention has the belt of the flat shape. Therefore, as a matter of fact, a ground-contact shape of the tire is likely to expand in the widthwise direction, and the reinforcing layer needs to be structured in accordance with the expansion.
  • a ground-contact width over which the tire is in contact with the road surface is preferably less than a width along which a plurality of reinforcing layers are present.
  • a ratio CSL/CSP of a path length CSL from a position corresponding to the end portion in 3 a E in the widthwise direction of the innermost layer 3 a to the maximum width position Wcmax of the carcass 2 , to a path length CSP from a position corresponding to the center portion in the widthwise direction of the innermost layer 3 a to a position right below the bead core 1 is preferably in the range of 0.1 to 0.25, and more preferably in the range of 0.12 to 0.18.
  • the above range is for restricting the length of a portion of the carcass 2 where the carcass 2 is locally bent as described above.
  • a desired localized deformation may be caused by optimizing, when designing a smooth curve linking the maximum width position Wcmax of the carcass line and the position below the belt, a carcass length in the corresponding curved region.
  • the carcass length is short in the above region, this means that the carcass direction changes from the radial direction to substantially the widthwise direction over the short length. Accordingly, the shape characteristics that the carcass is locally bent is reinforced.
  • the pass length CSP to the position right below the bead core 1 refers to the substantial pass length of the carcass 2 , and in case of an interposed-type bead core, the path length does not include a turning portion around the bead core 1 as illustrated in FIG. 1 , and the path length is a length of the interposed portion.
  • the shortest distance CSEh (which may be referred to below as a turned-up height) between a terminal end 2 E of a turn-up portion of at least one carcass ply layer and a line drawn in parallel with the rotation axis of the tire at the bead toe 8 is preferably greater than the maximum width height SWh.
  • one possible way is to increase bending rigidity of the side portion so as to restrain flexture of the side portion.
  • bending due to flexture is concentrated on the side portion to reduce the degree of deformation of the tread portion and to reduce energy loss of the tread portion as described above, it is required to reduce outer surface strain in the side portion while flexture in the side portion is maintained to be large.
  • the inventor has tried various ways to reduce strain on the outer surface in the side portion while maintaining flexture in the side portion to be large and found it possible to restrain strain on the outer surface in the side portion by setting the turn-up height CSEh from the bead portion of the carcass ply higher than the maximum width height SWh.
  • the turn-up portion of the carcass ply is laid on a body portion of the carcass ply to form double layers so that a neutral axis of bending in this portion is displaced to the outer surface side.
  • strain of the outer surface is restrained.
  • an inner side of the neutral axis of is subject to compression stress while the outer side thereof is subject to tensile stress.
  • Rubber has high rigidity with respect to compression stress but low rigidity with respect to tensile stress. Accordingly, as illustrated in FIG. 4A , when a distance d from the neutral axis of bending to the surface of the side portion is large, tensile strain acting on the outer side of the neutral axis of bending becomes small, and cracks tend to occur in this portion.
  • FIG. 4B by setting the distance d from the neutral axis of bending to the surface of the side portion small, tensile strain acting on the outer side of the neutral axis of bending becomes small, whereby cracks are prevented from occurring in this position.
  • the present invention by setting the turn-up height CSEh from the bead portion of the carcass ply higher than the maximum width height SWh, two carcass plies are disposed at the maximum width position Wmax of the tire on which bending of the side portion is concentrated, and the neutral axis of bending is displaced to the outer surface side. As a result, strain of the outer surface in the side portion is restrained. It is noted that, since only the turn-up height CSEh of the carcass ply is changed, flexture of the tire as a whole is not largely influenced.
  • a ratio CSEh/SWh is preferably greater than 1.0, more preferably in the range of 1.02 to 2.0, even more preferably in the range of 1.02 to 1.24.
  • the ratio CSEh/SWh is 1.0, i.e., when the end of the turn-up portion of the carcass ply is positioned at the maximum width position Wmax, the position of the end coincides with the center of bending, and therefore, it is likely that cracks may occur, starting from the end of the turn-up portion. Therefore, it is preferable that the ratio CSEh/SWh is greater than 1.
  • the lower limit of the preferable range of the ratio CSEh/SWh is set to be 1.02 because of the fact that the turn-up height CSEh slightly varies due to manufacturing tolerance and because of the need for the turn-up height CSEh to be greater than the maximum width height SWh.
  • the upper limit of the preferable range of the ratio CSEh/SWh is set to 2.0 because the effect to restrain surface strain is not improved even when the turn-up height CSEh is increased to a height much above the maximum width height SWh.
  • the ratio exceeds 2.0, the positional relation (envelope structure) that the end of the turn-up portion of the carcass ply exceeds a belt edge is established.
  • the turn-up portion is excessively large, flexture might be affected, and ride comfort might be degraded due to an increase in longitudinal spring. According to examples described below, it has been confirmed that advantageous effects of the present invention are sufficiently achieved when the CSEh/SWh is 1.24.
  • the carcass 2 may be constituted by using two carcass ply layers.
  • the carcass 2 may also be configured to be interposed between the bead cores without being turned around the bead core 1 .
  • the carcass 2 may also have the envelop structure.
  • the tire having an asymmetrical crown shape, asymmetrical belt shape/structure is included in the present invention. In the case of the asymmetrical tire, average values of left and right BD and TD are used as BD and TD.
  • one circumferential belt layer 4 with a width of 90% or more of the tread ground-contact width TW may be provided.
  • a so-called delta configuration which includes one circumferential belt layer 4 having the width of 90% or more of the tread ground-contact width TW, and one slant belt layer 3 a disposed on a radially outer side of the circumferential belt layer 4 , may be adopted.
  • one circumferential belt layer 4 may be disposed on a radially outer side of one slant layer 3 a having the width of 90% or more of the tread ground-contact width TW.
  • the circumferential belt layer 4 may be constituted by a circumferential belt layer 4 a formed by coating a steel cord with rubber in the tread shoulder portion and a circumferential belt layer 4 b formed by coating an organic fiber cord such as a nylon cord with rubber.
  • the circumferential belt layer 4 may be constituted by a left circumferential belt layer 41 and a right circumferential belt layer 4 r , and the circumferential belt layer 4 may be interrupted near the tire equatorial plane CL.
  • the circumferential belt layer 4 corresponds to the “innermost layer” defined in the present invention.
  • the radius difference BD is defined as an average value of falling heights of the layers 4 l and 4 r from an end on a tire center side to an end in the widthwise direction.
  • Example tire, Comparative Example tires, and Example tires having the size of 195/65R15 with the specifications shown in Tables 1 and 2 are experimentally produced, and each test tire is subjected to examination of rolling resistance performance, examination of wear resistance performance, and weight measurement as Example 1 (Table 1) and also subjected to examination of rolling resistance performance, examination of wear resistance performance, weight measurement, examination of longitudinal spring performance, and durability examination of cracks in the side portion.
  • Each test tire has the same tire structure including one carcass ply layer, two slant belt layers in which cords in one layer cross cords in the other layer, the cords being disposed at an inclination angle of 24° with respect to the tire equatorial plane CL, and a circumferential nylon belt disposed thereabove.
  • the thickness from the tire inner surface to the tire outer surface at the tire maximum width position Wmax is approximately the same.
  • Rolling resistance was examined in such a manner that each test tire was assembled to a standard rim and filled with an internal pressure of 210 kPa, and then, rolling resistance of the vehicle axis was measured using a drum examination machine (of a speed of 80 km/h) having an iron plate whose diameter was 1.7 m.
  • the measurement of rolling resistance was performed in smooth drum and forth way according to ISO18164.
  • Measurement results shown in Tables 1 and 2 are indexed with rolling resistance of Conventional Example tire being defined as 100, and a smaller value indicates better rolling resistance. In evaluation, tolerance is ignored, and a difference of more than or equal to 4% is regarded as a significant difference from the viewpoint of market superiority. In particular, when rolling resistance of greater than or equal to 10% is observed, this indicates a significant effect.
  • Wear resistance examination was conducted in such a manner that each test tire was assembled to the standard rim and filled with an internal pressure of 210 kPa, using an indoor drum examination machine (of the speed of 80 km/h) having a surface with a safety walk whose diameter was 1.7 m under the same load condition as the rolling resistance examination.
  • the input of fee rolling for 10 minutes and the input of 0.1 G in a braking direction are alternately repeated.
  • the abrasion weight (the amount of abraded rubber) after 1,200 km run under the above condition was measured.
  • Measurement results shown in Tables 1 and 2 are indexed with the abrasion weight of Conventional Example tire being defined as 100, and a smaller value indicates better wear performance. Difference of more than or equal to 1.5% is regarded as a significant difference, and difference of more than or equal to 10% is regarded as a remarkable difference.
  • the amount of deflection was measured during the rolling resistance examination, and spring calculated by a “load/bending amount” was indexed.
  • a larger value indicates a small flexture amount. In other words, a smaller value indicates a larger flexture amount and better ride comfort.
  • the flexture amount is calculated by subtracting the tire axis height under load from the tire axis height under no load.
  • FIG. 6 is a graph representing the results shown in Table 1, with the horizontal axis representing the ratio BD/BW and the vertical axis representing rolling resistance performance and wear performance.
  • FIG. 7 is a graph representing the results shown in Table 1, with the horizontal axis representing the ratio TGh/TGc and the vertical axis representing rolling resistance performance and wear performance.
  • FIG. 8 is a graph representing the results shown in Table 1, with the horizontal axis representing the ratio TGe/TGc and the vertical axis representing rolling resistance performance and wear performance.
  • Comparative Example tire 2 also satisfies the relation TD/TW ⁇ BD/BW, which deviates from the restriction of the present invention. Accordingly, although both rolling resistance performance and wear performance are improved compared with Conventional Example tire, the tire weight is increased to 102.
  • the tire weight is reduced compared with Conventional Example tire, and rolling resistance performance and wear performance are improved to be greater than or equal to Comparative Example tire 2 .
  • FIG. 9 is a graph representing the results shown in Table 1, with the horizontal axis representing the ratio CSWh/CSH and the vertical axis representing rolling resistance performance and wear performance.
  • FIG. 10 is a graph representing the results shown in Table 1, with the horizontal axis representing the ratio SWh/SH and the vertical axis representing rolling resistance performance and wear performance.
  • FIG. 11 is a graph representing the results shown in Table 1, with the horizontal axis representing the ratio BW/CSW and the vertical axis representing rolling resistance performance and wear performance.
  • FIG. 12 is a graph representing the results shown in Table 1, with the horizontal axis representing the ratio CSL/CSP and the vertical axis representing rolling resistance performance and wear performance.
  • CSEh/SWh is less than or equal to 1.0, it is ensured that durability performance against cracks in the side portion tends to be decreased.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
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PCT/JP2012/003236 WO2012176372A1 (ja) 2011-06-20 2012-05-17 空気入りタイヤ

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US20170197470A1 (en) * 2016-01-13 2017-07-13 Sumitomo Rubber Industries, Ltd. Pneumatic tire
US20210237519A1 (en) * 2018-04-23 2021-08-05 Bridgestone Corporation Tire
US11400761B2 (en) * 2018-03-02 2022-08-02 Sumitomo Rubber Industries, Ltd. Tire
US11453250B2 (en) 2013-08-12 2022-09-27 The Yokohama Rubber Co., Ltd. Pneumatic tire for passenger vehicle

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JP6236978B2 (ja) * 2013-08-12 2017-11-29 横浜ゴム株式会社 乗用車用空気入りタイヤ
JP6241125B2 (ja) * 2013-08-12 2017-12-06 横浜ゴム株式会社 乗用車用空気入りタイヤ
JP6152741B2 (ja) * 2013-08-12 2017-06-28 横浜ゴム株式会社 乗用車用空気入りタイヤ
JP6052227B2 (ja) * 2014-05-12 2016-12-27 横浜ゴム株式会社 更生タイヤ
JP5928525B2 (ja) * 2014-05-20 2016-06-01 横浜ゴム株式会社 空気入りタイヤ
FR3026989B1 (fr) * 2014-10-08 2016-11-04 Michelin & Cie Sommet de pneumatique pour avion
JP6489917B2 (ja) * 2015-04-21 2019-03-27 株式会社ブリヂストン 空気入りタイヤ
JP6785104B2 (ja) * 2015-10-02 2020-11-18 株式会社ブリヂストン 建設車両用タイヤ
WO2017057705A1 (ja) * 2015-10-02 2017-04-06 株式会社ブリヂストン 建設車両用タイヤ
CN105437870A (zh) * 2015-12-22 2016-03-30 三角轮胎股份有限公司 充气工业子午线轮胎
JP7077556B2 (ja) * 2017-09-25 2022-05-31 横浜ゴム株式会社 乗用車用空気入りタイヤ
JP6988540B2 (ja) * 2018-02-14 2022-01-05 横浜ゴム株式会社 空気入りタイヤ
JP6835110B2 (ja) * 2019-01-31 2021-02-24 横浜ゴム株式会社 空気入りタイヤ
JP7238599B2 (ja) * 2019-05-24 2023-03-14 横浜ゴム株式会社 空気入りタイヤ
JP7463712B2 (ja) * 2019-12-18 2024-04-09 住友ゴム工業株式会社 重荷重用チューブレスタイヤ及び製造方法

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US11453250B2 (en) 2013-08-12 2022-09-27 The Yokohama Rubber Co., Ltd. Pneumatic tire for passenger vehicle
US20170197470A1 (en) * 2016-01-13 2017-07-13 Sumitomo Rubber Industries, Ltd. Pneumatic tire
US10589572B2 (en) * 2016-01-13 2020-03-17 Sumitomo Rubber Industries, Ltd. Pneumatic tire
US11400761B2 (en) * 2018-03-02 2022-08-02 Sumitomo Rubber Industries, Ltd. Tire
US20210237519A1 (en) * 2018-04-23 2021-08-05 Bridgestone Corporation Tire

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JP6050568B2 (ja) 2016-12-21
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EP2722198A1 (en) 2014-04-23
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CN103619612A (zh) 2014-03-05
WO2012176372A1 (ja) 2012-12-27

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