A valve stem seal includes an elastomeric annular seal body including a first seal body section and a second seal body section. The first seal body section includes a first seal lip configured to sealingly abut against the valve stem to delimit an oil space and a second seal lip axially spaced from the first seal lip and configured to sealingly abut against the valve stem to delimit an air space. The first seal body section includes an annular channel in a radially inner wall between the first seal lip and the second seal lip that is spaced from the valve stem when the valve stem seal is mounted on the valve stem, and the surface of the channel includes an undercut configured to facilitate a deformation of the second seal lip toward the first seal lip.

A valve system that includes a housing defining an intake port, a cylinder port and a valve bore; wherein the intake port defining a valve seat portion at an interface between the intake port and the cylinder port. The valve system also includes a valve to control fluid communication between the intake port and the cylinder port. The valve includes a valve stem disposed within the valve bore and extending into the cylinder port and extending out of the housing, the valve stem having an open face exposed to atmospheric pressure and a valve head coupled to the valve stem comprising a first face and an opposing second face. A diameter of the valve stem is selected to control a closing force on the first face of the valve head.

Systems and methods for operating exhaust valves of an internal combustion engine with poppet exhaust valves are described. The systems and methods provide for locking exhaust valves in a closed state when the exhaust valves are in mechanical communication with a base circle of a camshaft lobe. Locking the exhaust valves in a closed state may reduce the possibility of exhaust pressures opening the exhaust valves at times they may not be desired to be open.

A method for introducing combustion air into a cylinder (25) of an internal combustion engine, a high-pressure inlet valve (1) provided therefor and an internal combustion engine that operates using the method and the high-pressure inlet valve are described. All the combustion air for the respective cylinders (25) is introduced into the cylinder (25) of the internal combustion engine, by means of a high-pressure inlet valve (1) arranged in the relevant cylinder head (26) and on the basis of a controlled mass flow, such that mixture formation and charge exchange are intensified. In addition, the temperature and/or pressure of the combustion air is measured and the quantity of combustion air is introduced into the cylinder (25), in a controlled manner and on the basis of the measurement results, by means of the high-pressure inlet valve (1) by opening or closing a sliding piston (3) of the high-pressure inlet valve (1) by displacement. As a result of an axial displacement of the sliding piston (3) between guide sections (5) in the housing (2) of the high-pressure inlet valve (1), passage areas (6) for combustion air are blocked in a closed position (7) and opened in an open position (8). In the passage area (6), the sliding piston (3) has two pressurization areas (10, 11) facing each other, the surfaces of which are of equal size or differ from each other when projected in one plane. The first pressurization area (10) can be designed as a poppet valve (12) and the second pressurization area (11) can be designed as an annular surface (13). The internal combustion engine has a high-pressure line (27) for the combustion air, which line is connected to the high-pressure inlet valve (1). With respect to the longitudinal axis of the cylinder (25), the high-pressure inlet valve (1) is arranged in the cylinder head (26) in an upright or horizontal position.

A hydraulic support element for a variable valve train of an internal combustion engine, which has a cylindrical pot-shaped housing and a hollow cylindrical piston guided for movement in this housing and whose inner end is supported by a compression spring on the base wall of the housing. The outer end extends past the housing and is formed as a hemispherical bearing head. The interior is divided into an inner supply pressure space and an outer switching pressure space that are connected by inlet openings in the cylindrical side walls of the housing and the piston with a cylinder head side supply pressure line and by a non-return valve to a high-pressure space enclosed between the inner end of the piston and the base wall of the housing, or to a cylinder head side switching pressure line and also by a central hole formed in the bearing head to a rocker arm side switching pressure channel. To prevent the entry of harmful particles into the supply pressure space and/or the switching pressure space of the piston, the piston has a ring-shaped recess in its cylindrical side wall in the area of the inlet openings on the outside in the radial direction, and a filter element constructed as a ring filter is inserted into the ring-shaped recess of the piston with an axial positive-fit connection.

A hydraulic support element for a variable valve train of an internal combustion engine, which has a cylindrical pot-shaped housing and a hollow cylindrical piston guided for movement in this housing and whose inner end is supported by a compression spring on the base wall of the housing. The outer end extends past the housing and is formed as a hemispherical bearing head. The interior is divided into an inner supply pressure space and an outer switching pressure space that are connected by inlet openings in the cylindrical side walls of the housing and the piston with a cylinder head side supply pressure line and by a non-return valve to a high-pressure space enclosed between the inner end of the piston and the base wall of the housing, or to a cylinder head side switching pressure line and also by a central hole formed in the bearing head to a rocker arm side switching pressure channel. To prevent the entry of harmful particles into the supply pressure space and/or the switching pressure space of the piston, the piston has a ring-shaped recess in its cylindrical side wall in the area of the inlet openings on the outside in the radial direction, and a filter element constructed as a ring filter is inserted into the ring-shaped recess of the piston with an axial positive-fit connection.

Systems and methods for operating exhaust valves of an internal combustion engine with poppet exhaust valves are described. The systems and methods provide for locking exhaust valves in a closed state when the exhaust valves are in mechanical communication with a base circle of a camshaft lobe. Locking the exhaust valves in a closed state may reduce the possibility of exhaust pressures opening the exhaust valves at times they may not be desired to be open.