Tire for vehicle wheels

Abstract

At least one carcass ply ( 3 ) is formed by depositing a strip-like element ( 13 ) comprising longitudinal thread-like elements ( 13 a ) incorporated into a layer of elastomer material ( 13 b ), onto a toroidal support ( 11 ). Deposition of the strip-like element ( 13 ) takes place in alternated deposition sections ( 23, 24 ) each comprising two radially-extending side portions ( 23 a , 24 a , 23 c , 24 c ) and a crown portion ( 23 b , 24 b ) extending at a radially external position. The side portions of each deposition section ( 23, 24 ) are at least partly overlapped with side portions belonging to an adjacent deposition section. Associated with the carcass ply ( 3 ) are annular structures ( 4 ) comprising a circumferentially inextensible annular insert ( 32 ) axially external to an anchoring element ( 31 ). A belt structure ( 5 ), a tread band ( 8 ) and sidewalls ( 9 ) are combined with the thus formed carcass structure ( 2 ) to define a tire ( 1 ) to be submitted to a vulcanization step.

What is claimed is:  
     
         1 . A tire for vehicle wheels, comprising: 
 a carcass structure ( 2 ) having at least one carcass ply ( 3 ) formed of at least one thread-like element ( 13   a ) disposed along deposition paths each extending in a substantially U-shaped conformation about the profile in transverse section of the tire ( 1 ), and a pair of circumferentially inextensible annular structures each engaged close to a respective circumferential inner edge of the carcass ply ( 3 );    a belt structure ( 5 ) applied to the carcass structure ( 2 ) at a circumferentially external position thereof;    a tread band ( 8 ) applied to the belt structure ( 5 ) at a circumferential external position thereof;    at least one pair of sidewalls ( 9 ) applied to the carcass structure ( 2 ) at laterally opposite positions;    wherein said at least one carcass ply ( 3 ) comprises:    at least one continuous strip-like element ( 13 ) comprising a plurality of longitudinal and parallel thread-like elements ( 13   a ) at least partly coated with at least one layer of raw elastomer material ( 13   b );    said strip-like element ( 13 ) having distinct deposition sections ( 23 ,  24 ), each of which extends in a substantially U-shaped conformation about the profile in transverse section of the tire ( 1 ), to define two side portions ( 23   a ,  23   c ,  24   a ,  24   c ) substantially extending in planes orthogonal to a geometric axis of rotation of the tire ( 1 ) at mutually spaced apart positions in an axial direction, and a crown portion ( 23   b ,  24   b ) extending in a radially external position between the side portions ( 23   a ,  23   c ,  24   a ,  24   c );    the crown portions ( 23   b ,  24   b ) of each deposition section ( 23 ,  24 ) being disposed in side by side relationship along the circumferential extension of the tire ( 1 ), whereas the side portions ( 23   a ,  23   c ,  24   a ,  24   c ) of each deposition section ( 23 ,  24 ) are each partly overlapped with a side portion of at least one adjacent deposition section.    
     
     
         2 . The tire as claimed in  claim 1 , wherein the side portions ( 23   a ,  23   c ,  24   a ,  24   c ) in mutual-overlapping relationship mutually converge at the geometric axis of rotation of the tire ( 1 ).  
     
     
         3 . The tire as claimed in  claim 1 , wherein mutual overlapping of the side portions ( 23   a ,  23   c ,  24   a ,  24   c ) of the deposition sections ( 23 ,  24 ) progressively decreases starting from a maximum value at the radially inner ends of the side portions until a zero value at transition regions between said side portions and crown portions ( 23   b ,  24   b ).  
     
     
         4 . The tire as claimed in  claim 1 , wherein the side portions ( 23   a ,  23   c ,  24   a ,  24   c ) in mutual-overlapping relationship are joined to each other at a bending end region ( 25 ) where the strip-like element ( 13 ) is folded upon itself.  
     
     
         5 . The tire as claimed in  claim 1 , wherein the individual deposition sections ( 23 ,  24 ) are laid down onto the tire ( 1 ) according to a circumferential distribution pitch corresponding to the width of the strip-like element ( 13 ).  
     
     
         6 . The tire as claimed in  claim 1 , wherein the individual deposition sections ( 23 ,  24 ) are disposed on the tire ( 1 ) according to a circumferential distribution pitch corresponding to a multiple of the width of the strip-like element ( 13 ).  
     
     
         7 . The tire as claimed in  claim 1 , wherein the strip-like element ( 13 ) has a width corresponding to a submultiple of the circumferential extension of the tire ( 11 ), as measured at its equatorial plane.  
     
     
         8 . The tire as claimed in  claim 1 , wherein the side portions ( 23   a ,  23   c ,  24   a ,  24   c ) of the deposition sections ( 23 ,  24 ) have regions of greater width close to the inner circumferential edges of the carcass structure ( 2 ).  
     
     
         9 . The tire as claimed in  claim 8 , wherein the thread-like elements ( 13   a ) comprised within the strip-like element ( 13 ) are mutually moved apart at said regions of enlarged width.  
     
     
         10 . The tire as claimed in  claim 1 , wherein said strip-like element ( 13 ) has a width included between 3 mm and 15 mm  
     
     
         11 . The tire as claimed in  claim 1 , wherein said strip-like element comprises three to ten thread-like elements ( 13   a ).  
     
     
         12 . The tire as claimed in  claim 1 , wherein each of said thread-like elements ( 13   a ) is made up of a textile cord of a diameter included between 0.6 mm and 1.2 mm.  
     
     
         13 . The tire as claimed in  claim 1 , wherein each of said thread-like elements ( 13   a ) is made up of a metallic cord of a diameter included between 0.3 mm and 2.1 mm.  
     
     
         14 . The tire as claimed in  claim 1 , wherein said thread-like elements ( 13   a ) are disposed within the strip-like element ( 13 ) according to a density greater than six thread-like elements per centimeter, circumferentially measured on the carcass ply ( 3 ) close to the median equatorial plane (X-X) of the tire ( 1 ).  
     
     
         15 . The tire as claimed in  claim 14 , wherein said thread-like elements ( 13   a ) are disposed within the strip-like element ( 13 ) according to a mutual distance between centers not lower than 1.5 times the diameter of the thread-like elements themselves.  
     
     
         16 . The tire as claimed in  claim 1 , wherein said side portions ( 23   a ,  23   c ,  24   a ,  24   c ) have end flaps turned back about the respective inextensible annular structures ( 4 ).  
     
     
         17 . A tire for vehicle wheels, comprising: 
 a carcass structure ( 2 ) having at least one carcass ply ( 3 ) formed of at least one thread-like element ( 13   a ) disposed along deposition paths each extending in a substantially U-shaped conformation about the profile in transverse section of the tire ( 1 ), and a pair of circumferentially inextensible annular structures each engaged close to a respective circumferential inner edge of the carcass ply ( 3 );    a belt structure ( 5 ) applied to the carcass structure ( 2 ) at a circumferentially external position thereof;    a tread band ( 8 ) applied to the belt structure ( 5 ) at a circumferential external position thereof;    at least one pair of sidewalls ( 9 ) applied to the carcass structure ( 2 ) at laterally opposite positions;    wherein each of said inextensible annular structures ( 4 ) comprises:    an annular anchoring element ( 31 ) disposed coaxially with said tire ( 1 );    a circumferentially inextensible annular insert ( 32 ) disposed axially in side by side relationship with the annular anchoring element and substantially extending parallelly to adjacent surfaces of the carcass ply ( 3 ), said annular insert being formed of at least one thread-like element extending in concentric coils ( 32   a );    a filling body ( 33 ) of elastomer material intimately joined to the annular anchoring element ( 31 ) and the circumferentially inextensible annular insert ( 32 ).    
     
     
         18 . The tire as claimed in  claim 17 , wherein said circumferentially inextensible annular insert ( 32 ) is disposed axially in side by side relationship with the annular anchoring element ( 31 ) at a position axially external to the latter.  
     
     
         19 . The tire as claimed in  claim 17 , wherein said circumferentially inextensible annular insert ( 32 ) is disposed axially in side by side relationship with the annular anchoring element ( 31 ) at a position axially internal to the latter.  
     
     
         20 . The tire as claimed in  claim 17 , wherein said circumferentially inextensible annular insert ( 32 ) has a radial extension greater than the radial extension of the bead core ( 31 ).  
     
     
         21 . The tire as claimed in  claim 20 , wherein the radial extension of said circumferentially inextensible annular insert ( 32 ) substantially corresponds to at least twice the radial extension of the bead core ( 31 ).  
     
     
         22 . The tire as claimed in  claim 1 , wherein the carcass structure ( 2 ) further comprises at least one second carcass ply similar in structure to the first carcass ply ( 3 ).  
     
     
         23 . A tire for vehicle wheels, comprising: 
 a carcass structure ( 2 ) having at least one carcass ply ( 3 ) formed of at least one thread-like element ( 13   a ) disposed along deposition paths each extending in a substantially U-shaped conformation about the profile in transverse section of the tire ( 1 ), and a pair of circumferentially inextensible annular structures each engaged close to a respective circumferential inner edge of the carcass ply ( 3 );    a belt structure ( 5 ) applied to the carcass structure ( 2 ) at a circumferentially external position thereof;    a tread band ( 8 ) applied to the belt structure ( 5 ) at a circumferential external position thereof;    at least one pair of sidewalls ( 9 ) applied to the carcass structure ( 2 ) at laterally opposite positions;    wherein said belt structure ( 5 ) comprises at least one first continuous belt strip ( 6 ) formed of a plurality of belt lengths ( 42 ) each comprising at least one layer of raw elastomer material ( 36   b ) at least partly incorporating a plurality of parallel cords ( 36   a ) disposed transversely, said belt lengths ( 42 ) being disposed consecutively in circumferential alignment on the tire ( 1 ) and in mutual side by side relationship along respective junction edges parallel to said cords ( 36   a ).    
     
     
         24 . The tire as claimed in  claim 23 , wherein each of said belt lengths ( 42 ) has a circumferential size corresponding to a submultiple of the circumferential extension of the first belt strip ( 6 ).  
     
     
         25 . The tire as claimed in  claim 23 , wherein the belt structure ( 5 ) further comprises at least one second belt strip ( 7 ) formed of at least one continuous elongated element ( 44 ) wound in coils disposed axially in side by side relationship and extending circumferentially about the first belt strip ( 6 ).  
     
     
         26 . The tire as claimed in  claim 25 , wherein the winding coils of the continuous elongated element ( 44 ) are disposed mutually in side by side relationship according to a varying axial-distribution pitch.  
     
     
         27 . The tire as claimed in  claim 26 , wherein said axial-distribution pitch is greater close to the median equatorial plane (X-X) of the tire than at the opposite side edges of the belt structure ( 5 ).  
     
     
         28 . The tire as claimed in  claim 1 , wherein said tread band ( 8 ) comprises at least one continuous sheet of raw elastomer material ( 49 ) circumferentially wound about the belt structure ( 5 ) in a plurality of radially superposed coils (S).  
     
     
         29 . The tire as claimed in  claim 28 , wherein said continuous sheet of elastomer material ( 49 ) has a progressively decreasing width away from the rotation axis of the tire ( 1 ).  
     
     
         30 . The tire as claimed in  claim 1 , wherein each of said sidewalls ( 9 ) comprises a radially outer portion (a) and a radially inner portion (b) made of a first and a second elastomer material respectively and intimately joined to each other by an overmolding process.  
     
     
         31 . The tire as claimed in  claim 1 , wherein the carcass structure ( 2 ) is further comprised of at least one sealing layer ( 10 ) made of elastomer material impervious to air, coating said carcass ply internally of the tire ( 1 ).  
     
     
         32 . The tire as claimed in  claim 31 , wherein said sealing layer or “liner” is essentially made up of at least one ribbon-like band ( 12 ) of an air-proof elastomer material extending in coils disposed side by side along the profile in transverse section of the tire ( 1 ).