Multi-cylinder internal combustion engine with variable actuation of the engine valves

Abstract

In a multi-cylinder internal combustion engine, valves of the engine, in particular the exhaust valves ( 3 ), are actuated by rocker arms ( 18 ) each of which is rotatably mounted on the structure of the engine with the interposition of an eccentric bushing ( 39 ), whose rotation allows varying the position of the rotational axis of the respective rocker arm, so as to activate and deactivate an extra-lift of the engine valve. The eccentric bushings ( 38 ) associated to the rocker arms ( 18 ) of the various cylinders of the engine are all connected in rotation with a common shaft ( 100 ) which is rotatably supported on the structure of the engine and which can be rotated through actuator means ( 105 ) preferably arranged outside the engine.

1 . Multi-cylinder internal combustion engine, comprising, for each cylinder, a combustion chamber with at least one intake conduit and at least one exhaust conduit intake valves and exhaust valves associated to said conduits and biassed by spring means towards a closed condition of the respective conduit, at least one camshaft for controlling the abovementioned valves, each valve being movable towards an opened condition of the respective conduit, against the action of the respective spring means, by a cam of the abovementioned camshaft by means of a mechanical transmission including a rocker arm rotatably mounted on the structure of the engine,
 wherein each of the rocker arms associated to the exhaust or intake valves of the engine is rotatably mounted on the structure of the engine with the interposition of an eccentric bushing, and   wherein actuator means are provided for rotating the abovementioned eccentric bushings associated to the rocker arms controlling the valves of the various cylinders, to vary the position of the rotation axis of the rocker arms,   characterised in that the abovementioned eccentric bushings associated to the rocker arms of the various cylinders of the engine are all connected in rotation with a common support shaft which is rotatably supported on the structure of the engine, and   in that said actuator means are arranged to control a rotation of the abovementioned common support shaft.   
     
     
         2 . Engine according to  claim 1 , characterised in that said actuator means are positioned outside the structure of the engine. 
     
     
         3 . Engine according to  claim 1 , characterised in that said actuator means are chosen among actuator means of the pneumatic type, actuator means of the electric type and actuator means of the hydraulic type. 
     
     
         4 . Engine according to  claim 1 , characterised in that interposed between the actuator means and the abovementioned common support shaft is a mechanical transmission, such as a linkage or a gearing. 
     
     
         5 . Engine according to  claim 1 , characterised in that the abovementioned common support shaft is rotatably supported within seats partly defined by supports forming part of the cylinder head of the engine and partly by caps fixed onto said supports. 
     
     
         6 . Engine according to  claim 1 , characterised in that said actuator means are hydraulically controlled actuator means, including a rotor connected in rotation with said common support shaft and rotatable within a stator fixed onto the structure of the engine, said stator and rotor defining hydraulic chambers therebetween which can be selectively connected by means of a control valve to a hydraulic supply and a reservoir. 
     
     
         7 . Vehicle, in particular an industrial vehicle, characterised in that it has an engine according to  claim 1 .