Lost motion variable valve actuation systems and method

An engine valve actuation assembly for controlling motion of at least one engine valve in an engine comprising:

• a motion source;
• an engine valve train for conveying motion from the motion source to the at least one engine valve, the engine valve train including a housing;
• a master piston bore defined in the housing;
• a master piston cooperating with the master piston bore to define a master piston chamber;
• the master piston having a motion receiving interface for receiving motion from the motion source;
• a slave piston bore defined in the housing;
• a slave piston cooperating with the slave piston bore to define a slave piston chamber;
• the slave piston having a motion transferring interface for transferring motion to a motion receiving component in the engine valve train and to the at least one engine valve, the slave piston chamber being in hydraulic communication with the master piston chamber;
• a control piston bore defined in the slave piston;
• a control piston cooperating with the control piston bore to define an auto-lashing chamber;
• a control pin operatively connected to the control piston, the control pin having multiple control pin ports arranged to permit flow from the slave piston chamber to the master piston chamber;
• a check disk cooperating with the control pin such that the check disk progressively occludes flow through at least one of the multiple control pin ports in response to motion of the slave piston during engine valve closing;
• and
• a valve catch seat having a common seating surface for the control pin and check disk, wherein the common seating surface facilitates precise positioning of the check disk relative to the control pin,
• wherein at least one of the multiple control pin ports in the control pin is not occluded by the check disk when the at least one engine valve is in a seated position.