Control system for a variable inlet area turbocharger turbine

Claim 1

A control system for a variable effective inlet area means of a turbocharger turbine having a compressor driven by the turbine to pressurize air for delivery through the compressor outlet to an internal combustion engine, the exhaust of which drives the turbine, said control system comprising: pressure responsive actuating means for the variable effective inlet area means of the turbine, said actuating means being responsive to a control signal to increase the effective inlet area as a direct function of the control signal, said actuating means comprising a variable volume chamber formed in part by a movable wall means and connected to said pressure signals, a shaft connected to said movable wall means and to the variable effective inlet area means so that expansion of said variable volume chamber increases such effective inlet area, and means for yieldably urging said movable wall toward a position of minumum volume whereby said movable wall is displaced in response to said pressure signals, and means for selectively applying to said actuating means the higher of a signal proportional to compressor outlet pressure and a signal proportional to turbine inlet pressure, said selective application means comprising: means for connecting the compressor outlet pressure and turbine inlet pressure signals in parallel to said variable volume chamber, said connecting means comprising a conduit, and a passageway means comprising means forming a sleeve through which said shaft extends with a clearance therebetween, one end of said sleeve means open to said variable volume chamber and the other end of said sleeve being open to the turbine inlet pressure, whereby the sleeve means and shaft form an annular passage, and valve means comprising a non return valve in said conduit, for applying the higher of the two pressure signals to said actuating means, whereby turbine inlet throttling losses are minimized during certain engine operating conditions.