Patent ID: 7775043

Claim:
A control system for controlling turbocharger boost pressure of an internal combustion engine at various different altitudes, said engine having an intake manifold and an exhaust manifold respectively connected to a compressor section and a turbine section of a turbocharger, comprising: a wastegate valve connected between said exhaust manifold and said turbine section, said wastegate valve being movable between an open position at which fluid flow exhausted by the engine is free to bypass the turbine and a closed position at which fluid flow exhausted by the engine is restricted from bypassing the turbine; a first sensor configured to sense a speed of the engine and deliver a responsive speed signal; a second sensor configured to sense a boost pressure of the engine and deliver a responsive boost signal; a third sensor configured to sense a rack position of the engine and deliver a responsive rack position signal; a fourth sensor configured to sense a speed of the turbocharger and deliver a responsive turbocharger speed signal; a controller connected to said first, second, third, and fourth sensors, the controller being configured to receive the speed, boost, rack position, and turbocharger speed signals, determine a boost error based on actual and target boost values and deliver a responsive control signal; the controller including a processor, said processor determining the target boost value based on the speed, rack position, and sensed turbocharger speed signals, said processor selecting a boost value from a boost map and a boost offset value from a boost offset map, and combining said selected boost and offset boost values to determine said target boost value, said boost map value being a function of engine speed and rack position and said boost offset value being a function of engine speed and turbocharger speed; and an actuator for receiving said control signal, responsively moving said wastegate valve toward one of the open and closed positions, and to a position between the open and closed positions; and the controller is configured to determine whether said wastegate valve is operating properly; and the controller delivers a signal to derate said engine if the controller determines that said wastegate valve is operating improperly.