US Patent 7162982 Hydraulic valve actuator for reciprocating engine

A hydraulic valve actuator for reciprocating engine includes at least a hydraulic cylinder (3) for opening at least one valve (2) via at least one valve opening selector (11) with at least one hydraulic positive displacement pump (4) whereof the hydraulic fluid supplied at the output can be forced into a high pressure circuit (10) by at least one pump outlet closure (8), the valve (2) capable of being maintained opened by an opening non-return valve (24), then of being reseated by a valve closing selector (25) which directs the hydraulic fluid contained in the hydraulic cylinder (3) in the hydraulic positive displacement pump (4) input by co-operating with a pump input non-return valve (26).