Patent ID: 7493762
Filing Date: 2009-02-24
Classification: F02B,F02D,F02M,Y02T

Abstract:
1. A method for controlling a diesel engine having an intake system and an exhaust system, the engine further having a turbocharger coupled between the intake and exhaust systems of the engine, a low pressure exhaust gas recirculation system with a first end coupled to the exhaust system downstream of the turbocharger and a second end coupled to the intake system upstream of the turbocharger, said low pressure exhaust gas recirculation system having a first valve coupled thereto for regulating flow, a high pressure exhaust gas recirculation system with a first end coupled to the exhaust system upstream of the turbocharger and a second end coupled to the intake system downstream of the turbocharger said high pressure exhaust gas recirculation system having a second valve coupled thereto for regulating flow, a first throttle coupled in the intake system between said second end of said high pressure exhaust gas recirculation system and said second end of said low pressure exhaust gas recirculation system, and a second throttle coupled upstream of said second end of said low pressure exhaust gas recirculation system, the method comprising; coordinating adjustment of the first and second valves and first and second throttles, said coordinating including: during a first condition: adjusting low pressure exhaust gas recirculation flow by adjusting the first valve with the first throttle fully opened and adjusting high pressure exhaust gas recirculation flow by adjusting both the second valve and the second throttle, where said first condition includes insufficient pressure in the high pressure exhaust gas recirculation system and sufficient pressure in the low pressure exhaust gas recirculation system, where sufficient pressure in the low pressure exhaust gas recirculation system includes at least when pressure across the low pressure exhaust gas recirculation system is greater than a first threshold, and where insufficient pressure in the high pressure exhaust gas recirculation system includes at least when pressure across the high pressure exhaust gas recirculation system is less than a second threshold; during a second condition: adjusting low pressure exhaust gas recirculation flow by adjusting the first valve and the first throttle and adjusting high pressure exhaust gas recirculation flow by adjusting the second valve with the second throttle fully opened, where said second condition includes sufficient pressure in the high pressure exhaust gas recirculation system and insufficient pressure in the low pressure exhaust gas recirculation system, where sufficient pressure in the high pressure exhaust gas recirculation system includes at least when pressure across the high pressure exhaust gas recirculation system is greater than a first threshold, and where insufficient pressure in the low pressure exhaust gas recirculation system includes at least when pressure across the low pressure exhaust gas recirculation system is less than a second threshold; and during a third condition: adjusting low pressure exhaust gas recirculation flow by adjusting both the first valve and the first throttle and adjusting high pressure exhaust gas recirculation flow by adjusting both the second valve and the second throttle, where said third condition includes insufficient pressure in both the high and low pressure exhaust gas recirculation systems, where insufficient pressure in the high pressure exhaust gas recirculation system includes at least when pressure across the high pressure exhaust gas recirculation system is less than a first threshold, and where insufficient pressure in the low pressure exhaust gas recirculation system includes at least when pressure across the low pressure exhaust gas recirculation system is less than a second threshold.