Method and system for improved dilution purging
First Claim
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1. A method for a hybrid vehicle, comprising:
- in response to decreasing engine torque demand while operating an engine with EGR,disabling EGR; and
until EGR in an engine intake is less than a threshold,operating the engine, fueled, with EGR disabled and propelling the vehicle with engine output torque higher than demanded torque for vehicle propulsion; and
charging a system battery.
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Abstract
Methods and systems are provided for expediting EGR purging in a hybrid vehicle during transient operations, such as tip-out to lower load conditions. In response to decreasing engine torque demand, engine fueling is disabled and a motor is used to spin the engine unfueled until a desired LP-EGR rate is achieved. Alternatively, engine operation is maintained with EGR disabled until the desired LP-EGR rate is achieved, and the excess engine torque generated is stored in a system battery.
33 Citations
20 Claims
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1. A method for a hybrid vehicle, comprising:
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in response to decreasing engine torque demand while operating an engine with EGR, disabling EGR; and until EGR in an engine intake is less than a threshold, operating the engine, fueled, with EGR disabled and propelling the vehicle with engine output torque higher than demanded torque for vehicle propulsion; and charging a system battery. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for a hybrid vehicle system, comprising:
during a tip-out from operating an engine with EGR flowing, while a battery state of charge is lower than a threshold charge, charging a battery while propelling a vehicle by operating the engine with EGR disabled until an engine intake EGR level is lower than an EGR threshold, the engine operated to generate more torque than demanded for vehicle propulsion. - View Dependent Claims (14, 15, 16)
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17. A hybrid vehicle system, comprising:
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an engine including an intake and an exhaust; an intake throttle; an electric motor/generator coupled to a battery; vehicle wheels propelled using torque from one or more of the engine and the motor; a direct fuel injector coupled to an engine cylinder; a turbocharger including an intake compressor driven by an exhaust turbine; an EGR passage for flowing EGR from the exhaust, downstream of the turbine, to the intake, upstream of the compressor, via an EGR valve; and a controller with computer readable instructions for; in response to an operator pedal tip-out while operating the engine with EGR flowing, estimating a battery state of charge; and if the estimated battery state of charge is lower than a threshold charge, closing the EGR valve; operating the engine with the EGR valve closed for a duration until EGR in the engine is lower than a threshold, the engine operated to propel the vehicle and to generate more torque than demanded; and charging the battery with excess engine torque generated while operating the engine with the EGR valve closed. - View Dependent Claims (18, 19, 20)
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Specification