C.r.f. Societa Consortile Per Azioni

Andrea Stroppiana

Fabio Borean

Sabino Luisi

Francesco Vattaneo

A spark-ignition supercharged internal-combustion gasoline engine is equipped with a system for variable actuation of the intake valves including a pressurized fluid chamber set between intake valve and a respective control cam, and an electrically actuated valve, the opening of which vents the pressure chamber so as to cause rapid closing of the valve, as a result of the respective elastic return means, even when the respective cam would tend to keep the valve open. The variable-valve-actuation system is used in combination with control cams of the intake valves shaped in such a way as to generate an intake valve lift profile including a boot portion with substantially constant lift. The boot portion is provided in the final part of the opening cycle of the intake valve, after bottom dead center.

Spark ignition internal combustion engine having intake valves with variable actuation and delayed closure

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.

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

An electronic control means of an engine controls a system for the variable actuation of intake valves and for controlling gasoline injection into the combustion chamber. To the electronic control means there are associated memory means. The electronic means are programmed for detecting a value of a crank angle at which the intake valve is closed, controlling the end of the injection with an anticipation with respect to the closing of the intake valve controlling the start of the injection substantially according to said crank angle limit value, and regulating the injection pressure to a value which is defined as a function of the injection time to guarantee the injection of a predefined amount of gasoline.

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Orbassano, Italy

Andrea Stroppiana