US Patent 7246609 Internal combustion engine having cylinder disablement

A multi-cylinder internal combustion engine having an exhaust system with an exhaust emission after-treatment device for exhaust gases from the cylinders, an air supply system for supplying fresh air to the cylinders, a fuel supply system for supplying fuel to each cylinder, and a controller to cut off the fuel supply and disable at least one cylinder, and preferably two cylinders in opposing pairs. A valve assembly is located between the cylinders to be disabled and the emission after-treatment device and is operable to divert gases from said the disabled cylinders via a recirculation conduit back to the air supply system.