Turbocharger having pneumatic actuator with pilot valve
AssigneeAlliedSignal Inc.
InventorsDavid G. Elpern, James E. T. Blake
Life of this patent
Estimating the term…
Abstract
A pneumatic actuator for controlling the wastegate valve of an exhaust gas driven turbocharger includes a pilot piston which is responsive to boost pressure to open only when a desired boost pressure is attained. Accordingly, premature opening of the wastegate valve is avoided because the main actuator piston is maintained at atmospheric pressure until the desired actuating pressure is attained.
Claims20
Exhaust gas driven turbocharger comprising a compressor housing, a turbine housing, and a center housing supporting the turbine housing on one end thereof and the compressor housing on the other end thereof, a shaft supported for rotation within said center housing, one end of the shaft extending into said compressor housing and supporting a compressor wheel for rotation relative to the compressor housing, the other end of said shaft extending into said turbine housing and supporting a turbine wheel for rotation relative to said turbine housing, said turbine housing including means for directing engine exhaust gases through the turbine wheel to effect rotation of the shaft, said compressor housing including means for directing air through a compressor inlet and then to said compressor wheel for compression thereby to generate boost air and for directing boost air out of said compressor housing through an outlet, said turbine housing including a mechanically actuated device operable to limit the pressure of the boost air, and a pressure operated actuator responsive to the pressure level of the boost air for operating said mechanically actuated device, said actuator including a housing having an axis, a circumferentially extending wall circumscribing the axis, and an actuator inlet communicated with said boost air, an actuator piston responsive to the pressure level communicated into said housing through the actuator inlet, linkage means connecting the actuator piston with said mechanically actuated device, and a pilot piston slidably mounted within said housing for closing said actuator inlet until the pressure level of the boost air attains a predetermined level wherein each of said pistons includes a fluid pressure responsive surface, and a diaphragm having a peripheral portion secured to said circumferentially extending wall of the actuator housing and extending across the fluid pressure responsive surfaces of both pistons, and means securing the diaphragm to said pilot position.
Pressure operated actuator responsive to the pressure level of the boost air delivered by an exhaust gas driven turbocharger for operating a mechanically actuated device operable to limit the pressure of the boost air said actuator consisting of a single housing having an actuator inlet communicated with said boost air, an actuator piston responsive to the pressure level communicated into said housing throughout the actuator inlet, linkage means connecting the actuator piston with said mechanically actuated device, a pilot piston slidably mounted in said housing concentric with said actuator piston, and a single diaphragm interposed between the pistons and the actuator inlet, said pilot piston being controlled by a pilot control spring yieldably urging said pilot piston into sealing engagement with a valve seat to control communication of the boost air into said housing.
Pressure operated actuator responsive to the pressure level of the boost air delivered by an exhaust gas driven turbocharger for operating a mechanically actuated device operable to limit the pressure of the boost air, said actuator consisting of a single housing having an actuator inlet communicated with said boost air and terminating in a pilot piston valve seat, an actuator piston responsive to the pressure level communicated into said housing through the actuator inlet, linkage means connecting the actuator piston with said mechanically actuated device, a pilot piston slidably mounted in said housing concentric with said actuator piston, and a single diaphragm interposed between the pistons and the actuator inlet, said pilot piston being controlled by a pilot control spring yieldably urging said pilot piston into sealing engagement with a valve seat to control communication of the boost air into said housing until the pressure level of the boost air attains a predetermined level, said pilot piston when in contact with said valve seat exhibiting an effective area of A1 and said pilot piston when not in contact with said valve seat exhibiting an effective area of A2 wherein A2 is greater than A1 whereby a higher pressure is required to open the pilot valve than is required to close the pilot valve.
Dependencies are inferred from the claim text.