Internal-combustion engine with cylinders that can be deactivated, in which the deactivated cylinders are used as pumps for recirculating the exhaust gases into the active cylinders, and method for controlling said engine

摘要

In an internal-combustion engine provided with a system for variable actuation of the intake valves of the cylinders, some of said cylinders are deactivated in given conditions of operation of the engine by interrupting the supply of fuel. During de-activation, the cycle of opening and closing of the intake valves and exhaust valves of the deactivated cylinders is maintained. The intake valves of each deactivated cylinder are opened when the exhaust valves of the same cylinders are also open. The inactive cylinders are used as reciprocating volumetric pumps for recirculation of exhaust gases from the exhaust manifold of the engine up to the intake manifold. The recirculated gases are cooled in the intake manifold by the air introduced into the latter and can consequently be fed in a larger mass to the active cylinders, which enables a better global efficiency of the engine to be obtained.

主权项

1. An internal-combustion engine comprising:
a plurality of cylinders; an intake manifold and an exhaust manifold each with a chamber in common and respective intake ducts or runners and exhaust ducts or runners, which connect said common chamber to said cylinders; at least one intake valve and at least one exhaust valve for each cylinder, associated to respective intake and exhaust runners; a first system for variable actuation of the intake valves; a second system for supply of fuel to each cylinder; and electronic control means for controlling said first system and said second system, wherein said electronic control means are programmed for interrupting supply of fuel to one or more cylinders of the engine in given conditions of operation of the engine so as to deactivate said cylinders, maintaining supply of fuel to one or more further cylinders, which thus remain active, wherein said electronic control means are moreover programmed for maintaining an operating cycle of opening and closing of the intake valves and exhaust valves of the deactivated cylinders, wherein said electronic control means are moreover programmed for keeping open said at least one intake valve of each deactivated cylinder when said at least one exhaust valve of the same deactivated cylinder is also open, wherein an opening lift and an opening duration of said at least one intake valve of each deactivated cylinder in a stage of operation of the engine with deactivated cylinders are chosen in such a way that said deactivated cylinders are able to pump exhaust gases from the common chamber of the exhaust manifold up to the common chamber of the intake manifold of the engine, whereby said recirculated exhaust gases enter the active cylinders after being cooled by the air present in the intake manifold, as to enable a larger mass thereof to enter into the active cylinders, and wherein the aforesaid electronic control means are programmed for keeping open said at least one intake valve of each deactivated cylinder only when said at least one exhaust valve of the same deactivated cylinder is also open.