US Patent 9212600 Variable cylinder engine

A variable cylinder engine is provided. The engine includes an engine body having a plurality of cylinders, a cooling mechanism for cooling the engine body, and a controller for controlling the cooling mechanism and changing a number of active cylinders according to an operating state of the engine. The controller reduces the number of active cylinders in a reduced-cylinder operating range set within a partial engine load range, and in a first reduced-cylinder range set within a high load part of the reduced-cylinder operating range, the controller improves a cooling performance of the cooling mechanism compared with that in a second reduced-cylinder range set within a low load part of the reduced-cylinder operating range.