C.r.f. Societa Consortile Per Azioni

Stefano Chiappini

Francesco Vattaneo

Andrea Pecori

Gianluca Canino

Dante Rodolfo Malatto

Macor Lorentino

In an internal combustion engine with variable actuation valves, each variable actuation valve is actuated by an actuator assembly including an actuating piston slidably mounted in a guide bushing. Between the actuating piston and the stem of the respective valve is interposed an auxiliary hydraulic tappet comprising a first bushing and a second bushing positioned inside the first bushing in such a way as to define a first chamber between the second bushing and the actuating piston, and a second chamber between the two bushings of the hydraulic tappet. The first chamber is fed a pressurized chamber of the engine lubrication loop. A check valve controls a communication between the two chambers of the tappet, to allow the passage of fluid in the direction of the second chamber. The first bushing of the auxiliary hydraulic tappet is positioned outside the guide bushing of the actuating piston, so that said bushing can be dimensioned with a relatively small diameter, regardless of the outer diameter of the auxiliary hydraulic tappet.

Internal combustion engine having valves with variable actuation each provided with a hydraulic tappet at the outside of the associated actuating unit

Described herein is a multicylinder internal-combustion engine provided with an electronically controlled hydraulic device for controlling variable actuation of the valves of the engine. The final phase of the movement of closing the intake valves is slowed down by a hydraulic braking device of an improved type.

Multicylinder engine with valve variable actuation, and an improved valve braking device therefor

In an internal-combustion engine with a hydraulic system for variable operation of the valves, the tappet actuated by each cam of the camshaft is slidably mounted in a tubular body which is made of a single piece with a bushing for guiding the valve-actuating piston.

Internal-combustion engine with hydraulic system for variable operation of the engine valves

In an internal-combustion engine with a hydraulic system for variable operation of the valves, the piston for operating each valve includes an auxiliary hydraulic tappet.

Internal-combustion engine with variable-operation valves and auxiliary hydraulic tappet

In an internal-combustion engine with a hydraulic system for variable operation of the engine valves, there is envisaged at least one supplementary reservoir bled off to the atmosphere, communicating with the low-pressure circuit for compensating for the variations in volume of the hydraulic fluid that derive from the variations in temperature and for thus preventing air bubbles from forming in the circuit.

Internal-combustion engine with hydraulic system for variable operation of the valves and means for compensating variations in volume of the hydraulic fluid

In an internal combustion engine comprising an hydraulic system for the variable driving of valves, one tappet comprises two separate piston sections that are connected to two distinct pressure chambers, which control the driving pistons of two separate valves of the same engine cylinder.

Internal combustion engine with an hydraulic system for the variable driving of valves and a double-piston tappet

In an internal-combustion engine with a hydraulic system for variable operation of the valves, associated to the tappet controlled by each cam of the cam shaft is a passage for bleeding the hydraulic system.

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Orbassano, Italy

Stefano Chiappini