Internal Combustion Engine Having Dedicated EGR Cylinder(s) With Intake Separate From Intake Of Main Cylinders

摘要

A method and system for using an internal combustion engine with dedicated EGR cylinders to provide an adjustable EGR rate to the main (non dedicated) cylinders. The dedicated EGR cylinder(s) are configured to receive fresh air via a fresh air intake or to receive a portion of the mixture of fresh air and EGR gas via the same mixed intake line that delivers intake to the main cylinders. If the dedicated EGR cylinder(s) receive only fresh air, the main cylinder(s) receive EGR at higher EGR rate. If the dedicated EGR cylinder(s) receive only the portion of fresh air and EGR gas, the main cylinder(s) receive EGR at a lower EGR rate. The EGR rate to the main cylinder(s) may be adjusted between these rates in response to operating conditions of the engine.

主权项

1. A method of using exhaust gas recirculation (EGR) to improve combustion efficiency of an internal combustion engine having a number of cylinders, comprising:
operating one or more of the cylinders as dedicated EGR cylinder(s), such that all of its exhaust, during all or some engine cycles, may be recirculated via an EGR loop as EGR gas; operating all non dedicated EGR cylinder(s) as main cylinders that receive a mixture of fresh air and EGR gas via a mixed intake line; wherein the dedicated EGR cylinder(s) are configured to receive only fresh air via a separate fresh air intake to the EGR cylinder or to receive a portion of the EGR gas and fresh air; wherein if the dedicated EGR cylinder(s) receive only fresh air, the main cylinder(s) receive EGR at a first EGR rate; wherein if the dedicated EGR cylinder(s) receive only the portion of EGR gas and fresh air, the main cylinder(s) receive EGR at a second EGR rate; and adjusting the rate of EGR gas received by the main cylinder(s) to the first EGR rate or to the second EGR rate in response to operating conditions of the engine.