EGR Rate Control For Internal Combustion Engine With Dual Exhaust-Ported Cylinders

An improved dual exhaust-ported internal combustion engine, the engine having multiple cylinders, an EGR loop and a main exhaust line, comprising:

• at least two dual exhaust-ported cylinders having two exhaust ports;
• wherein, for the at least two dual exhaust-ported cylinders, one of the exhaust ports is connected, via an EGR exhaust valve, to the EGR loop and the other of the exhaust ports is connected, via a main exhaust valve, to the main exhaust line;
• memory for storing EGR rate data that provides desired EGR rates in response to input data representing engine operating conditions;
• a control unit programmed to control each dual exhaust-ported cylinder such that one exhaust port is open and the other exhaust port is closed during each engine cycle;
• to control each dual exhaust-ported cylinder on a cycle-by-cycle basis, such that for any engine cycle, one exhaust valve may be opened and the other exhaust valve may be closed;
• and to generate control signals for operating, for selected engine cycles, any or none of the dual exhaust-ported cylinders as an EGR cylinder whose entire exhaust is delivered to the EGR loop;
• wherein the number of cylinders operating as EGR cylinders per engine cycle is in response to a current desired EGR rate.