METHOD AND SYSTEM FOR IMPROVED DILUTION PURGING
First Claim
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1. A method for a hybrid vehicle system, 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 an engine with EGR disabled and with engine output torque higher than demanded torque; 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.
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Citations
20 Claims
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1. A method for a hybrid vehicle system, 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 an engine with EGR disabled and with engine output torque higher than demanded torque; 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 the battery by operating the engine with EGR disabled until an engine intake EGR level is lower than a threshold, the engine operated to generate more torque than demanded. - 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 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