A method of using exhaust gas recirculation (EGR) in an internal combustion engine. At least two of the cylinders are "dual exhaust-ported cylinders" having two exhaust ports. For each of these cylinders, one of the exhaust ports is connected to the EGR loop and the other of the exhaust ports is connected to the main exhaust line. These cylinders are controlled such that one exhaust port is open and the other exhaust port is closed during each engine cycle, and are operated, on a cycle-by-cycle basis so that all of the exhaust produced by a cylinder may be delivered to the EGR loop at any cycle. The number of cylinders operating as EGR cylinders per engine cycle is in response to a desired EGR rate.
Jess W. Gingrich; Raphael F. Gukelberger