Anchorage system for the rotors of a rotating fluid machine

Abstract

An anchorage system is described for a rotor ( 18 ) of a rotating fluid machine ( 10 ). The rotor ( 18 ) has a profile which comprises a first front surface ( 24 ) substantially concave and a second rear surface ( 26 ) substantially convex, opposite to the first front surface ( 24 ). The rotor ( 18 ) also has a central portion ( 28 ), configured for being constrained with interference on a rotating shaft ( 14 ) of the machine ( 10 ) and equipped with a shank ( 30 ) connected with the second rear surface ( 26 ). The system comprises at least one check ring ( 32 ) assembled by interference on the shank ( 30 ) of the rotor ( 18 ). The check ring ( 32 ) has a first internal circumferential surface ( 34 ), coupled by interference with the shank ( 30 ), and a second internal circumferential surface ( 36 ), coupled by interference with the shaft ( 14 ), to increase the torque which can be transmitted from the shaft ( 14 ) to the rotor ( 18 ).

1 . An anchorage system for a rotor ( 18 ) of a rotating fluid machine ( 10 ), said rotor ( 18 ) having a profile which comprises a first front surface ( 24 ) substantially concave and a second rear surface ( 26 ) substantially convex, opposite to the first front surface ( 24 ), a central portion ( 28 ) of said rotor ( 18 ), configured for being constrained with interference on a rotating shaft ( 14 ) of said machine ( 10 ) and being equipped with a shank ( 30 ) connected with said second rear surface ( 26 ) of said rotor ( 18 ), wherein it comprises at least one check ring ( 32 ) assembled by interference on said shank ( 30 ) of said rotor ( 18 ), said check ring ( 32 ) having a first internal circumferential surface ( 34 ), coupled with interference with said shank ( 30 ), and a second internal circumferential surface ( 36 ), coupled with interference with said shaft ( 14 ), to increase the torque which can be transmitted from said shaft ( 14 ) to said rotor ( 18 ). 
   
   
       2 . The system according to  claim 1 , wherein said first internal circumferential surface ( 34 ) has a larger diameter with respect to said second internal circumferential surface ( 36 ). 
   
   
       3 . The system according to  claim 2 , wherein between the outer surface of said shaft ( 14 ) and said second internal circumferential surface ( 36 ) of said check ring ( 32 ), one or more keys ( 38 ) are inserted to increase the interference between the parts and boost the transmissibility of the torque from said shaft ( 14 ) to said rotor ( 18 ). 
   
   
       4 . The system according to  claims 1  or  2 , wherein the ratio between the external diameter (D e ) of said shank ( 30 ) and the diameter (D) of said shaft ( 14 ) is within the range of 1.10 and 1.25. 
   
   
       5 . The system according to  claims 1  or  2 , wherein the ratio between the external diameter (D a ) of said check ring ( 32 ) and the diameter (D) of said shaft ( 14 ) is within the range of 1.40 and 1.60. 
   
   
       6 . The system according to  claims 1  or  2 , wherein the ratio between the length (L c ) of said shank ( 30 ), measured along the axial direction of said shaft ( 14 ), and the diameter (D) of said shaft ( 14 ) is within the range of 0.25 and 0.35. 
   
   
       7 . The system according to  claims 1  or  2 , wherein the ratio between the length (L a ) of said second internal circumferential surface ( 36 ), measured along the axial direction of said shaft ( 14 ), and the diameter (D) of said shaft ( 14 ) is within the range of 0.40 and 0.70. 
   
   
       8 . A rotating fluid machine ( 10 ) comprising an anchorage system for a rotor ( 18 ) according to any of the previous claims.