Abstract: A cylinder-piston drive, e.g., an hydraulically controlled actuator for actuating a gas-exchange valve of an internal combustion engine, has an operating piston that is displaceable inside a cylinder and delimits pressure chambers by piston sides facing away from one another. The operating piston has a multipart design and is made up of at least two partial pistons that are placed inside one another, are displaceable relative to each other and strike against one another at stop faces. One pressure chamber is delimited by all, and the other pressure chamber is delimited by only a part, of the partial pistons and the sliding paths of the partial pistons not delimiting the other pressure chamber may be reduced compared to the overall sliding path of the operating piston. At least one stop face, arranged on the cylinder, may be provided against which a stop face of one of the partial pistons strikes after traveling the reduced sliding path.

Abstract: A device for controlling gas-exchange valves of an internal combustion engine is provided, which device has hydraulic valve actuators each allocated to one gas-exchange valve. Each valve actuator has an actuating piston acting on the gas-exchange valve, and two hydraulic working chambers delimited by the actuating piston, of which the first working chamber acting upon the gas-exchange valve in the closing direction is constantly filled with fluid under pressure, and the second working chamber acting upon the gas-exchange valve in the opening direction is able to be alternately filled with fluid under pressure and relieved via two electric control valves. For the purpose of cost reduction, provided for each valve-actuator pair is a single first electric control valve that is acted upon with the fluid pressure on the intake side, and is connected on the outlet side to the second working chamber of one valve actuator.

Abstract: The present invention is directed to a cylinder-piston drive, in particular an hydraulically controlled actuator (1) for actuating a gas-exchange valve (2) of an internal combustion engine, which has an operating piston (8) that is displaceable inside a cylinder (6) and delimits pressure chambers (10, 12) by piston sides (14, 16) facing away from one another, the operating piston (8) having a multipart design and being made up of at least two partial pistons (18, 20) that are placed inside one another, are displaceable relative to each other and strike against one another at stop faces (36, 38).

Abstract: A device is indicated for controlling at least one gas exchange valve (10) for an combustion cylinder of an internal combustion engine, having an hydraulic actuator (12) for valve actuation and having a high-pressure pump that supplies the actuator (12) with a pressure medium. In order to reduce the production costs, the high-pressure pump is formed as a control-sleeve pump (13) having a stroke-driven pump plunger (22) that limits a pump chamber (24), and having a spool valve (13) surrounding this plunger. In the pump plunger (22) and spool valve (13), on the one hand a control groove (27) that runs obliquely to the stroke direction is provided, and on the other hand a spill opening (30) that cooperates therewith is provided, which together bring about a relief of pressure of the pump chamber (24) when they overlap.

Abstract: An apparatus for controlling gas exchange valves of an internal combustion engine is disclosed, which have hydraulic valve actuators (11) each assigned to one gas exchange valve, with one adjusting piston (13) acting on the gas exchange valve and two hydraulic work chambers (121, 122) defined by the adjusting piston (13), of which chambers the first work chamber (121), acting on the gas exchange valve (10) in the closing direction, is constantly filled with fluid that is under pressure, and the second work chamber (122), acting on the gas exchange valve (10) in the opening direction, can be filled with and relieved of fluid that is under pressure in alternation via a first and second electrical control valve (24, 25; 26, 27).