Multicylinder petrol engine with variable actuation of the valves
AssigneeC.R.F. Societa Consortile per Azioni
InventorsVittorio Doria, Marco Lucatello
Life of this patent
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Abstract
A multicylinder petrol engine is provided with a hydraulic system for variable actuation of the valves, which enables easy control of operation of the engine according to different strategies. The engine according to the invention is, in particular, able to operate with a variable engine displacement in a modular way via the exclusion of selected cylinders, to control combustion by means of adjustment of the effective compression ratio, and to control recirculation of the exhaust gases at intake, in order to achieve low levels of consumption and reduced harmful exhaust emissions.
Claims6
A multicylinder petrol engine, comprising:
- at least one intake valve and at least one exhaust valve for each cylinder, each valve being provided with respective elastic return means, which push the valve towards a closed position for controlling respective intake and exhaust pipes;
- and
- at least one camshaft, for actuating the intake valves and exhaust valves of the engine cylinders by means of respective tappets;
- in which each intake valve is controlled by the respective tappet against the action of the aforesaid elastic return means by interposition of hydraulic means that include a pressurized fluid chamber;
- said pressurized fluid chamber being designed to be connected by means of a solenoid valve to an exhaust channel in order to uncouple the valve from the respective tappet and bring about fast closing of the valve as a result of the respective elastic return means;
- electronic control means for controlling each solenoid valve so as to vary the time and the stroke of opening of the respective intake valve according to one or more operating parameters of the engine;
- wherein said engine comprises second electronic control means for keeping the exhaust valves of pre-set engine cylinders closed, and in that said electronic control means are pre-arranged for keeping the intake valves of selected cylinders of the engine closed, simultaneously with the activation of the aforesaid means for keeping the exhaust valves closed, so as to inhibit operation of said selected cylinders.
The engine according to any one of the preceding claims, wherein it comprises two intake valves for each cylinder, and in that said electronic control means are pre-arranged for carrying out one or more of the following strategies of control of the intake valves of each cylinder:
- anticipated closing of both intake valves with the same valve lifts;
- anticipated closing of the intake valves with different valve lifts;
- alternate anticipated closing of the intake valves, opening just one valve per engine cycle alternately;
- retarded opening of both intake valves with the same valve lifts;
- retarded opening of the intake valves with different valve lifts;
- alternate retarded opening of the intake valves, opening just one valve per engine cycle alternately;
- retarded opening of one valve and anticipated closing of the other valve;
- retarded opening and anticipated closing on each of the two valves with the same valve lifts;
- retarded opening and anticipated closing on each of the two valves with different valve lifts;
- and retarded opening/anticipated closing on each valve, opening, however, just one valve per engine cycle alternately.
Dependencies are inferred from the claim text.