Controlling an engine with a multi-link type piston crank mechanism
The invention provides an engine having a piston (3) which is slidably received within an associated cylinder and a crankshaft (15) connected to the piston (3) for reciprocably moving the piston (3) with respect to the cylinder, a multi-link piston crank mechanism (30) connected to the crankshaft (15) for controlling movement of the piston (3) such that an acceleration of the piston (3) at top dead centre is less than an acceleration of the piston (3) at bottom dead centre. The engine further includes determining means to determine an operating condition of the engine and combustion mode control means to control a combustion mode of the engine to operate at an air-fuel ratio leaner than a stoichiometric air-fuel ratio when the determining means determines that the operating condition of the engine resides in a predetermined first operating region. The invention also provides a control system and a method for operating such an engine.
