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Systems, methods and techniques for exhaust gas recirculation are provided. The system includes controlling the mixing of exhaust flow from at least one cylinder of an engine with air in an air intake system prior to combustion in response to an EGR fraction deviation condition. The exhaust flow fro

Systems, methods and techniques for exhaust gas recirculation are provided. The system includes controlling the mixing of exhaust flow from at least one cylinder of an engine with air in an air intake system prior to combustion in response to an EGR fraction deviation condition. The exhaust flow from the at least one cylinder is accumulated prior to mixing and distributed into the intake air system in a controlled manner to mitigate or prevent the EGR flow from deviating from an expected EGR fraction.

대표청구항 ▼

1. A method, comprising: operating an engine having a plurality of cylinders;directing a charge flow into the plurality of cylinders from an air intake system;combusting a mixture of the charge flow and fuel within the plurality of cylinders to generate a power output and a flow of exhaust;directing

1. A method, comprising: operating an engine having a plurality of cylinders;directing a charge flow into the plurality of cylinders from an air intake system;combusting a mixture of the charge flow and fuel within the plurality of cylinders to generate a power output and a flow of exhaust;directing a first portion of the flow of the exhaust from a first portion of the plurality of cylinders to an aftertreatment system;directing a second portion of the flow of the exhaust from a second portion of the plurality of cylinders to an accumulator in an exhaust gas recirculation (EGR) system connected to the air intake system, the accumulator extending between an inlet to the accumulator and a plurality of outlets connected to the air intake system, wherein the accumulator stores a supply of recirculated exhaust gas for release into the air intake system through the plurality of outlets; andselectively increasing or decreasing the supply of stored recirculated exhaust gas in the accumulator in response to a deviation of an EGR Plow from an expected EGR fraction by controlling an opening size of one or more of the plurality of outlets into the air intake system, wherein the expected EGR fraction is ratio of a number of cylinders in the second group to a number of cylinders in the first group. 2. The method of claim 1, wherein the second portion of the flow of the exhaust from the second portion of the plurality of cylinders is directed only to the accumulator. 3. The method of claim 1, wherein the deviation of the EGR flow from the expected EGR fraction is determined in response to an EGR flow determination. 4. The method of claim 1, wherein the deviation of the EGR flow from the expected EGR fraction is determined by interpreting an engine operating condition corresponding to at least one of an accelerator tip-in condition, an accelerator tip-out condition, and a steady state low load condition. 5. The method of claim 1, further comprising increasing the supply of stored recirculated exhaust gas in response to the EGR flow exceeding the expected EGR fraction. 6. The method of claim 5, further comprising decreasing the supply of stored recirculated exhaust gas in response to the EGR flow being less than the expected EGU fraction. 7. The method of claim 1, wherein the plurality of outlets includes at least three outlets and each outlet includes a flow control member operable to control the opening size of the respective outlet. 8. The method of claim 7, wherein selectively increasing or decreasing the supply of stored recirculated exhaust gas in the accumulator in response to the deviation of the EGR flow from the expected EGR fraction includes opening first portion of the at least three outlets and closing a second portion of the at least three outlets. 9. A method, comprising: operating an engine having a plurality of cylinders;directing a charge flow into the plurality of cylinders from an air intake system;combusting a mixture of the charge flow and fuel within the plurality of cylinders to generate a power output and a flow of exhaust;directing a first portion of the flow of the exhaust from a first portion of the plurality of cylinders to an aftertreatment system;directing a second portion of the flow of the exhaust from a second portion of the plurality of cylinders to an accumulator in an exhaust gas recirculation (EGR)system connected to the air intake system, the accumulator extending between an inlet to the accumulator and a plurality of outlets connected to the air intake system, wherein the accumulator stores a supply of recirculated exhaust gas for release into the air intake system through the plurality of outlets, wherein the accumulator includes a storage volume between the inlet and the plurality of outlets, and the storage volume is sized as a function of a total number of the plurality of cylinders contributing to the second portion of the flow of exhaust to mix with air in the air intake system; andselectively increasing or decreasing the supply of stored recirculated exhaust gas in the accumulator in response to a deviation of an EGR flow from an expected EGR fraction by controlling an opening size of one or more of the plurality of outlets into the air intake system. 10. A system, comprising: an engine including a plurality of cylinders;an intake passage configured to direct a charge flow to the plurality of cylinders;an exhaust passage configured to receive exhaust from a first portion of the plurality of cylinders and direct the exhaust from the first portion of the plurality of cylinders to an aftertreatment system; andan exhaust gas recirculation (EGR) system configured to receive exhaust from a second portion of the plurality of cylinders and direct the exhaust from the second portion to the intake passage, wherein the EGR system includes an accumulator having an inlet for receiving the exhaust from the second portion of the plurality of cylinders, a plurality of outlets along the intake passage that directly connects the accumulator to the intake passage, and a storage volume between the inlet and the plurality of outlets, wherein each of the plurality of outlets includes a flow control member operable to selectively open and close the respective outlet to permit passage of the exhaust therethrough into the intake passage, wherein the storage volume is sized as a function of a total number of the plurality of cylinders contributing to the second portion of the flow of exhaust to mix with air in the air intake system. 11. The system of claim 10, wherein each of the plurality of outlets is fluidly connected with a mixing chamber of the intake passage. 12. The system of claim 10, further including: a cooler located within the EGR system; anda valve located upstream of the cooler to regulate exhaust flow from the second portion of the plurality of cylinders through the EGR system. 13. The system of claim 10, wherein the plurality of outlets includes at least three outlets and the flow control member in each outlet is operable to control the opening size of the respective outlet. 14. The system of claim 10, wherein the second portion of the plurality of cylinders provides exhaust only to the EGR system. 15. The system of claim 14, wherein the first portion of the plurality of cylinders provides exhaust only to the aftertreatment system. 16. A system, comprising: a combustion engine having a first group of cylinders and a second group of cylinders, wherein the first group of cylinders and the second group of cylinders each includes at least one cylinder;an exhaust manifold configured to receive exhaust from the first group of cylinders;an aftertreatment system configured to receive exhaust from the exhaust manifold;an intake system configured to receive a fresh air flow and direct a charge flow to the first and second groups of cylinders;an exhaust gas recirculation (EGR) system configured to receive exhaust from the second group of cylinders and provide an EGR flow to the fresh air flow in the intake system and form the charge flow;an accumulator connecting the exhaust gas recirculation system to the intake system, the accumulator including an inlet and a plurality of separate exhaust outlets in flow communication with the intake system, wherein each of the plurality of exhaust outlets includes a flow control member that is movable between an open position and a closed position to control an amount of EGR flow that is supplied to the intake system; anda controller configured to interpret an EGR fraction deviation condition in response to an EGR flow produced by the second group of cylinders deviating from an expected EGR fraction from the second group of cylinders, wherein the expected EGR fraction is a ratio of a number of cylinders in the second group to a number of cylinders in the first group, and further wherein the controller is further configured to move at least one of the flow control members between the open and closed positions in response to the EGR fraction deviation condition to control the amount of EGR flow to the intake system. 17. The system of claim 16, wherein the second group of cylinders includes at least two cylinders, at least one of the cylinders in the second group is deactivated, and the number of the cylinders in the second group does not include the at least one deactivated cylinder. 18. The system of claim 16, wherein the controller is configured to close at least one of the flow control members in response to the EGR fraction deviation condition indicating the EGR flow exceeds the expected EGR fraction. 19. The system of claim 16, wherein the controller is configured to open at least one of the flow control members in response to the EGR fraction deviation condition indicating the EGR flow is less than the expected EGR fraction. 20. The system of claim 16, wherein the flow control members are valves that are actuated to open or close in response to an EGR flow control command from the controller. 21. The system of claim 16, wherein the EGR flow control command closes at least one of the plurality of flow control members while a remaining portion of the plurality of flow control members are open.