Multi-cylinder diesel engine with variably actuated valves

Abstract

In a Diesel engine with variably actuated valves, the cam controlling each inlet valve is shaped to provoke the opening of the respective inlet valve during the engine's normal exhaust phase and thus realize exhaust gas recirculation within the engine, due to the fact that during the normal exhaust phase, part of the exhaust gas passes from the cylinder into the inlet port, from where it returns to the cylinder during the next induction phase, while part of the exhaust gas that had previously passed into the exhaust port returns to the cylinder during the induction phase due to the additional opening of the exhaust valve, in consequence of which the exhaust gas charges that return to the cylinder are subjected to further combustion in the next engine cycle.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates to multi-cylinder Diesel engines of the type employing variably actuated valves.[0002]In American patent U.S. Pat. No. 6,237,551, the Applicant has already proposed an engine of this type including:[0003]two inlet valves and two exhaust valves for each cylinder, each equipped with respective elastic means of return that push the valve towards its closed position, for controlling the respective inlet and exhaust ports,[0004]at least one camshaft for operating the inlet and exhaust valves of the engine's cylinders via respective valve lifters, each inlet valve and the two exhaust valves being controlled by a respective cam of the said camshaft,[0005]in which each of the said valve lifters commands the respective inlet or exhaust valve against the action of the said elastic means of return via the interposition of hydraulic means including a pressurized fluid chamber.[0006]the pressurized fluid chamber associated with each ...

AI Technical Summary

Benefits of technology

[0011]The object of the present invention is that of further perfecting the previously proposed engine for the purposes of achieving a series of advantages with regards to reducing harmful exhaust emissions and / or overcoming problems of cold starting or creating the so-called “blue smoke” in the “warm-up” phase after a cold start, and / or achieving improved performance and / or consumption reductions.

Problems solved by technology

In traditional engines, internal EGR can only be realized in a limited measure, as there would otherwise be an excessive reduction in the “swirl” of the air charge introduced into the cylinder due to the introduction of a mass of burnt gases with an angular motion that is null, or low or in the opposite direction.

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