Turbocharger and system for compressor wheel-burst containment

Abstract

A turbocharger includes a turbine disc, a compressor wheel mechanically coupled to the turbine disc, and a single-walled air inlet. Made of ductile iron, the air inlet is configured to admit air to the compressor wheel and to provide clearance for rotation of the compressor wheel.

1 . A turbocharger comprising:
 a turbine disc;   a compressor wheel mechanically coupled to the turbine disc; and   a single-walled air inlet configured to admit air to the compressor wheel and to provide clearance for rotation of the compressor wheel, the air inlet comprising ductile iron.   
     
     
         2 . The turbocharger of  claim 1 , wherein the ductile iron has an ultimate tensile strength of greater than about 410 megapascals (MPa) and a yield strength of greater than about 280 MPa. 
     
     
         3 . The turbocharger of  claim 1 , wherein the ductile iron has a percent elongation of greater than about 10 percent, wherein the ductile iron has a modulus of elasticity, measured in tension, of greater than about 162 GPa, and wherein the ductile iron has a Poisson's ratio of about 0.275. 
     
     
         4 . The turbocharger of  claim 1 , wherein a coefficient of thermal expansion of the ductile iron is within ten percent of a coefficient of thermal expansion of grey cast iron. 
     
     
         5 . The turbocharger of  claim 1 , further comprising a turbine casing surrounding the turbine disc and a blower casing configured to receive compressed air from the compressor wheel, wherein the air inlet, the turbine casing, and the blower casing are sufficient in gauge and material strength to contain one or more fragments of the compressor wheel with a total kinetic energy of 110 kilojoules, following a compressor wheel burst. 
     
     
         6 . The turbocharger of  claim 5 , wherein the turbine casing is single-walled and comprises the ductile iron. 
     
     
         7 . The turbocharger of  claim 5 , wherein the blower casing is single-walled and comprises the ductile iron. 
     
     
         8 . The turbocharger of  claim 5 , wherein the air inlet is coupled to the blower casing with seven or more bolts in a radially symmetric arrangement. 
     
     
         9 . The turbocharger of  claim 5 , wherein the blower casing is coupled to the turbine casing with seven or more bolts in a radially symmetric arrangement. 
     
     
         10 . The turbocharger of  claim 1 , wherein the compressor wheel has a mass of at least 8 kilograms and is driven in at least one mode of operation at 27,000 or more revolutions per minute. 
     
     
         11 . An engine system comprising:
 an engine configured to draw compressed air from a compressor, the compressor including a compressor wheel mechanically coupled to an exhaust-driven turbine disc;   a single-walled air inlet configured to admit air to the compressor wheel and provide clearance for rotation of the compressor wheel, the inlet comprising ductile iron; and   a blower casing coupled to the air inlet with exactly twelve bolts in a radially symmetric arrangement, the blower casing configured to receive compressed air from the compressor wheel.   
     
     
         12 . The system of  claim 11 , wherein in at least one mode of operation of the engine, the turbine disc is configured to drive the compressor wheel at more than twenty thousand revolutions per minute. 
     
     
         13 . The system of  claim 11 , wherein the compressor wheel is sized and shaped to deliver intake air compressed to from 275 to 450 kilopascals at a mass flow rate of at least 4.5 kilograms per second when the compressor wheel is driven at about 27,000 revolutions per minute. 
     
     
         14 . The system of  claim 11 , wherein the compressor wheel carries more than 110 kilojoules of kinetic energy when rotating at 27,000 revolutions per minute. 
     
     
         15 . A turbocharger comprising:
 a turbine disc;   a compressor wheel mechanically coupled to the turbine disc;   a single-walled air inlet configured to admit air to the compressor wheel and to provide clearance for rotation of the compressor wheel, the air inlet comprising a ferrous material, the ferrous material having an ultimate tensile strength of greater than about 410 megapascals (MPa) and a yield strength of greater than about 280 MPa;   a single-walled turbine casing comprising the ferrous material and surrounding the turbine disc; and   a single-walled blower casing comprising the ferrous material and configured to receive compressed air from the compressor wheel, the air inlet coupled to the blower casing with seven or more bolts in a radially symmetric arrangement.   
     
     
         16 . The turbocharger of  claim 15 , wherein the air inlet, the turbine casing, and the blower casing are sufficient in gauge and material strength to contain one or more fragments of the compressor wheel with a total kinetic energy of 110 kilojoules, following a compressor wheel burst. 
     
     
         17 . The turbocharger of  claim 15 , wherein the ferrous material has a percent elongation of greater than about 15 percent and a coefficient of thermal expansion within ten percent of a coefficient of thermal expansion of grey cast iron. 
     
     
         18 . The turbocharger of  claim 15 , wherein the ferrous material has a modulus of elasticity, measured in tension, of greater than about 162 gigapascals and a Poisson's ratio of about 0.275. 
     
     
         19 . The turbocharger of  claim 15 , wherein the ferrous material has a dynamic elastic modulus in a range from about 162 to 186 gigapascals, as measured by a resonant frequency test. 
     
     
         20 . The turbocharger of  claim 15 , wherein the ferrous material has a hardness in a range from about 150 to 250 Brinell hardness number.