A system for variable actuation of an engine valve of an internal-combustion engine includes a master piston and a slave piston, driven by the master piston. A control valve controls a communication of a volume of a pressurized fluid with a lower pressure environment, which is connected to a fluid accumulator, and an electronic control unit controls the electrically operated control valve. A device for dampening pressure oscillations is connected to the volume of pressurized fluid and includes an additional volume adapted for receiving fluid from the volume of pressurized fluid only when, following upon oscillations of the pressure in the volume of pressurized fluid, the pressure exceeds a maximum threshold value, which is higher than a mean pressure value that is set up in the volume of pressurized fluid when the master piston drives the slave piston in normal operating conditions.

A system for variable actuation of an engine valve of an internal-combustion engine includes a master piston and a slave piston, driven by the master piston. A control valve controls a communication of a volume of a pressurized fluid with a lower pressure environment, which is connected to a fluid accumulator, and an electronic control unit controls the electrically operated control valve. A device for dampening pressure oscillations is connected to the volume of pressurized fluid and includes an additional volume adapted for receiving fluid from the volume of pressurized fluid only when, following upon oscillations of the pressure in the volume of pressurized fluid, the pressure exceeds a maximum threshold value, which is higher than a mean pressure value that is set up in the volume of pressurized fluid when the master piston drives the slave piston in normal operating conditions.

An engine roller lifter for use in a valve train of an internal combustion engine and constructed in accordance to another example of the present disclosure includes a body having an outer peripheral surface configured for sliding movement in a bore provided in the engine. The bore is supplied by an oil passage communicating therewith. The body can define a transverse passage. A groove can be formed around the body and inset from the outer peripheral surface. A connecting channel can be formed in the body and inset from the outer peripheral surface, the connecting channel fluidly connects the groove and the transverse passage. A roller bearing can be rotatably mounted to the body and configured for rolling contact with an engine camshaft. Oil received at the groove from the bore flows along the connecting channel, into the transverse passage and onto the roller bearing.

An engine roller lifter for use in a valve train of an internal combustion engine and constructed in accordance to another example of the present disclosure includes a body having an outer peripheral surface configured for sliding movement in a bore provided in the engine. The bore is supplied by an oil passage communicating therewith. The body can define a transverse passage. A groove can be formed around the body and inset from the outer peripheral surface. A connecting channel can be formed in the body and inset from the outer peripheral surface, the connecting channel fluidly connects the groove and the transverse passage. A roller bearing can be rotatably mounted to the body and configured for rolling contact with an engine camshaft. Oil received at the groove from the bore flows along the connecting channel, into the transverse passage and onto the roller bearing.

The variable valve actuating device (20) comprises a switch pin (53) slidably received in the valve lifter (24) so as to selectively abut the end surface of the valve stem as the valve lifter is actuated by the cam. The device further comprises a first spring retainer (36) attached to an intermediate part of the valve stem (32) to engage a first valve spring (35), and a second spring retainer (44) slidably engaged by an end part of the valve stem to engage a second valve spring (43). The valve stem is provided with a stem end (39) which is enlarged with respect to a part of the valve stem slidably engaging the second spring retainer so as to define a shoulder surface (40a) that engages the second spring retainer against a spring force of the second valve spring.

The variable valve actuating device (20) comprises a switch pin (53) slidably received in the valve lifter (24) so as to selectively abut the end surface of the valve stem as the valve lifter is actuated by the cam. The device further comprises a first spring retainer (36) attached to an intermediate part of the valve stem (32) to engage a first valve spring (35), and a second spring retainer (44) slidably engaged by an end part of the valve stem to engage a second valve spring (43). The valve stem is provided with a stem end (39) which is enlarged with respect to a part of the valve stem slidably engaging the second spring retainer so as to define a shoulder surface (40a) that engages the second spring retainer against a spring force of the second valve spring.

An actuator for an electrohydraulic gas exchange valve train of a combustion engine is provided. The actuator has an actuator housing which can be mounted on the combustion engine with a borehole, a hydraulic piston, which is mounted therein such that it can carry out a reciprocating movement, for actuating the gas exchange valve and an axial stop which, when the actuator housing is in the unmounted state relative to the combustion engine, limits the piston stroke out of the borehole to a mounting stroke (T). This mounting stroke is smaller than a maximum operating stroke (L) with which the hydraulic piston actuates the gas exchange valve, the piston stroke being only temporarily limited to the mounting stroke by the axial stop and no longer being limited to the mounting stroke once the actuator is in operation.

An actuator for an electrohydraulic gas exchange valve train of a combustion engine is provided. The actuator has an actuator housing which can be mounted on the combustion engine with a borehole, a hydraulic piston, which is mounted therein such that it can carry out a reciprocating movement, for actuating the gas exchange valve and an axial stop which, when the actuator housing is in the unmounted state relative to the combustion engine, limits the piston stroke out of the borehole to a mounting stroke (T). This mounting stroke is smaller than a maximum operating stroke (L) with which the hydraulic piston actuates the gas exchange valve, the piston stroke being only temporarily limited to the mounting stroke by the axial stop and no longer being limited to the mounting stroke once the actuator is in operation.

An internal-combustion engine has a plurality of cylinders each with two intake valves driven by respective pumping pistons operatively associated to cams of a camshaft, by respective hydraulic circuits. The hydraulic has its pressure chamber communicating with hydraulic actuators of the two intake valves, so that the two intake valves of each cylinder are controlled, via two different hydraulic circuits, by cams associated to two different cylinders. Each cam is configured to give rise to a cycle of opening and closing of each of the intake valves in an angular range of rotation of the crankshaft less than 180 such that, in each operating cycle of a cylinder, only the first intake valve initially opens and closes while the second intake valve remains closed, and then the second intake valve opens and closes while the first intake valve remains closed.

A method for adding fluid to an hydraulic lash adjuster (HLA) comprises the steps of placing the HLA in to a centrifuge, the centrifuge having a fluid container, placing a sufficient amount of a first fluid in the fluid container to fluidly communicate with at least one fluid port of the HLA, and spinning the HLA at a first speed sufficient to move the first fluid in to at least the second of two fluid chambers in the HLA.