Patent ID: 8453619

Claim:
A hydraulic valve actuation assembly comprising: a housing defining a first fluid chamber, a second fluid chamber, and a third fluid chamber; a piston axially secured to an engine valve and located within the housing and including a first piston surface exposed to the first fluid chamber, a second piston surface exposed to the second fluid chamber and a third piston surface exposed to the third fluid chamber; a supply control valve in communication with a first hydraulic fluid supply operating at a first pressure and a second hydraulic fluid supply operating at a second pressure less than the first pressure; a closing control valve located between the supply control valve and the second fluid chamber, the closing control valve being in communication with the first fluid chamber, the second fluid chamber and the supply control valve and controlling fluid flow from the second fluid chamber to the supply control valve; and an opening control valve located between the supply control valve and the second fluid chamber, the opening control valve being in communication with the second fluid chamber, the third fluid chamber and the supply control valve and controlling fluid flow from the supply control valve to the second fluid chamber.