Control method and apparatus for turbocharged diesel engines having exhaust gas recirculation

Claim 3

The method as set forth in claim 1 wherein the step of determining a desired intake manifold pressure (p 1d ) and desired EGR flow fraction (r d ) includes the step of retrieving p 1d and r d from a table of values indexed by the requested fueling rate (W f ,req) and current engine speed (N).

Claim 4

The method as set forth in claim 1 wherein the step of estimating the EGR flow fraction (r) further comprises the steps of estimating the EGR mass flow rate (W 21 ) and compressor mass flow rate (W c1 ) based on p 1 and p 2 , and calculating the EGR flow fraction according to the following equation: r=W.sub.21 /(W.sub.21 +W.sub.c1)

Claim 5

The method as set forth in claim 1 wherein the step of estimating the EGR flow fraction (r) further comprises the steps of measuring the compressor flow rate (W c1 ), estimating the EGR mass flow rate (W 21 ) as a function of p 1 and p 2 , and calculating the EGR flow fraction according to the following equation: r=W.sub.21 /(W.sub.21 +W.sub.c1)

Claim 6

The method as set forth in claim 1 wherein the step of generating proportional and integral feedback gains for the EGR valve (K p ,egr, K i ,egr) and turbocharger turbine (K p ,vgt, K i ,vgt) includes the step of retrieving K p ,egr, K i ,egr, K p ,vgt, and K i ,vgt from a table of values indexed by the current fueling rate (W f ) and engine speed (N).

Claim 7

The method as set forth in claim 1 wherein the steps of generating said EGR valve control signal (U egr ) and said turbocharger signal (U vgt ) includes the step of calculating U egr according to the following equation: U.sub.egr =V.sub.egr +K.sub.p,egr e.sub.r +K.sub.i,egr Z.sub.r wherein Z r represents the accumulated error and calculating U vgt according to the following equation: U.sub.vgt =V.sub.vgt +K.sub.p,vgt e.sub.p1 +K.sub.i,vgt Z.sub.p1 wherein Z p1 represents the integrator state.

Claim 8

A compression ignition engine system comprising: an exhaust gas recirculation (EGR) passage including a EGR valve connecting an intake manifold and exhaust manifold of the engine, said EGR valve responsive to an EGR valve control signal for regulating the fraction of exhaust gas flowing into said intake manifold; a variable geometry turbocharger (VGT) including a compressor connected to a turbine, the compressor in communication with the intake manifold and the turbine in communication with the exhaust manifold, said turbine responsive to a turbocharger signal for regulating the intake manifold pressure; an exhaust manifold pressure sensor located in said exhaust manifold for providing an exhaust manifold pressure signal; an intake manifold pressure sensor located in said intake manifold for providing an intake manifold pressure signal; an engine control unit including memory and a microprocessor, said engine control adapted to receive as inputs said intake and exhaust manifold pressure signals and transmit as outputs the EGR valve control signal for regulating the EGR flow fraction and the turbocharger signal for regulating the intake manifold pressure.

Claim 9

A compression ignition engine system comprising: an exhaust gas recirculation (EGR) passage including a EGR valve connecting an intake manifold and exhaust manifold of the engine, said EGR valve responsive to an EGR valve control signal for regulating the fraction of exhaust gas flowing into said intake manifold; a variable geometry turbocharger (VGT) including a compressor connected to a turbine, the compressor in communication with the intake manifold and the turbine in communication with the exhaust manifold, said turbine responsive to a turbocharger signal for regulating the intake manifold pressure; an exhaust manifold pressure sensor located in said exhaust manifold for providing an exhaust manifold pressure signal; an intake manifold pressure sensor located in said intake manifold for providing an intake manifold pressure signal; an engine control unit including memory and a microprocessor, said engine control adapted to receive as inputs said intake and exhaust manifold pressure signals and transmit as outputs the EGR valve control signal for regulating the EGR flow fraction and the turbocharger signal for regulating the intake manifold pressure.

Claim 10

In a compression ignition engine system having an exhaust gas recirculation (EGR) passage including an EGR valve connecting an intake manifold and exhaust manifold of the engine, said EGR valve responsive to an EGR valve control signal for regulating the flow of exhaust gas into said intake manifold, and a variable geometry turbocharger (VGT) including a compressor connected to a turbine, the compressor in communication with the intake manifold and the turbine in communication with the exhaust manifold, said turbine responsive to a turbocharger signal for regulating the intake manifold pressure, an engine control unit for regulating the airflow into said engine, said engine control unit comprising: memory for storing feedback gains and desired engine operating values; and a microprocessor for generating said EGR valve control signal and said turbocharger signal, said microprocessor programmed to: retrieve from said memory a desired intake manifold pressure value (p 1d ) and a desired EGR flow fraction value(r d ); receive a first pressure signal (p 1 ) indicative of the actual intake manifold pressure; generate a first deviation value (e p1 ) between the desired and actual intake manifold pressure; receive a second pressure signal (p 2 ) indicative of the actual exhaust manifold pressure; estimate the EGR flow fraction (r) based on p 1 and p 2 ; generate a second deviation value (e r ) between the desired and estimated EGR flow fraction; retrieve from said memory an open loop EGR valve value (V egr ) and an open loop turbocharger value (V vgt ) from a table of values indexed as a function of engine speed and fueling rate; calculate proportional and integral feedback gains for the EGR valve (K p ,egr /K i ,egr) and turbocharger turbine (K p ,vgt, K i ,vgt); generate said EGR valve control signal (U egr ) as a function of V egr , K p ,egr, K i ,egr and e r ; generate said turbocharger signal (U vgt ) as a function of V vgt , K p ,vgt, K i ,vgt and e p1 ; transmit U egr to said EGR valve to regulate r; and transmit U vgt to said turbocharger turbine to regulate p 1 .

Claim 11

In a compression ignition engine system having an exhaust gas recirculation (EGR) passage including an EGR valve connecting an intake manifold and exhaust manifold of the engine, said EGR valve responsive to an EGR valve control signal for regulating the flow of exhaust gas into said intake manifold, and a variable geometry turbocharger (VGT) including a compressor connected to a turbine, the compressor in communication with the intake manifold and the turbine in communication with the exhaust manifold, said turbine responsive to a turbocharger signal for regulating the intake manifold pressure, an engine control unit for regulating the airflow into said engine, said engine control unit comprising: memory for storing feedback gains and desired engine operating values; and a microprocessor for generating said EGR valve control signal and said turbocharger signal, said microprocessor programmed to: retrieve from said memory a desired intake manifold pressure value (p 1d ) and a desired EGR flow fraction value(r d ); receive a first pressure signal (p 1 ) indicative of the actual intake manifold pressure; generate a first deviation value (e p1 ) between the desired and actual intake manifold pressure; receive a second pressure signal (p 2 ) indicative of the actual exhaust manifold pressure; estimate the EGR flow fraction (r) based on p 1 and p 2 ; generate a second deviation value (e r ) between the desired and estimated EGR flow fraction; retrieve from said memory an open loop EGR valve value (V egr ) and an open loop turbocharger value (V vgt ) from a table of values indexed as a function of engine speed and fueling rate; calculate proportional and integral feedback gains for the EGR valve (K p ,egr /K i ,egr) and turbocharger turbine (K p ,vgt, K i ,vgt); generate said EGR valve control signal (U egr ) as a function of V egr , K p ,egr, K i ,egr and e r ; generate said turbocharger signal (U vgt ) as a function of V vgt , K p ,vgt, K i ,vgt and e p1 ; transmit U egr to said EGR valve to regulate r; and transmit U vgt to said turbocharger turbine to regulate p 1 .

Claim 12

The engine control unit of claim 8 wherein said microprocessor is programmed to generate said EGR valve control signal (U egr ) and said turbocharger signal (U vgt ) according to the following equations: U.sub.egr =V.sub.egr +K.sub.p,egr e.sub.r +K.sub.i,egr Z.sub.r U.sub.vgt =V.sub.vgt +K.sub.p,vgt e.sub.p1 +K.sub.i,vgt Z.sub.p1 wherein Z r represents the integrator state of r, and Z p1 represents the integrator state of p 1 .