Patent ID: 7086358

Claim:
A method of controlling the speed of impact (V I ) of the valves into their respective seats in an electro-hydraulic actuation unit for the valves of an internal combustion engine (M), the electro-hydraulic unit comprising a hydraulic actuator in order to open a respective valve with a pressurized fluid, a spring opposing the hydraulic actuator in order to close the valve and discharge the fluid from the hydraulic actuator to a collection tank, wherein the pressure of the fluid is controlled, during the final phase of closure of the valve, in the hydraulic actuator by the slide distributor valve, which is a four-way valve of the nonproportional type adapted substantially to assume a first operating stable end position (P 1 ); a second and third transit positions (P 2 , P 3 ) and a fourth stable end position (P 4 ); the second and third positions (P 2 , P 3 ) are between the opposing first and fourth positions (P 1 , P 4 ); in the first operating position (P 1 ) the hydraulic actuator is connected to the collection tank so as to allow the fluid to be discharged from hydraulic actuator and the valve to be closed; in the second operating position (P 2 ) all four ways are disconnected; in the third operating position (P 3 ) the hydraulic actuator is fed with pressurized fluid; and in the fourth operating position (P 4 ) all four ways are disconnected; the slide distributor valve comprising a bushing and a slide reciprocated inside the bushing between the first and the fourth operating positions (P 1 , P 4 ); the method providing for oscillating said slide in order to transit through at least one of the second, the third, and the fourth operating positions (P 2 , P 3 , P 4 ) in order to slow down the discharge of the fluid from the hydraulic actuator.