Abstract: The invention relates to an air-compressing internal combustion engine, comprising at least one piston (1) having a combustion chamber trough (3) substantially rotationally symmetrical to a piston axis (2), which has a trough bottom (4) with a substantially cone-like elevation (5) and a circumferential trough wall (6), wherein the trough wall (6) forms a substantially torus-like first section (6a) having a maximum inner first trough diameter (d1), a second section (6b) having a minimum inner second trough diameter (d2) smaller than the inner first trough diameter (d1), and a third section (6c), wherein—as seen in a meridian section of the piston (1)—the first section (6a) has a concave first radius of curvature (R1) and the second section (6b) has a convex second radius of curvature (R2), and wherein the third section (6c) forms a first annular surface (8) adjoining the second section (6b) and a second annular surface (9) terminating in the piston end surface (7), which second annular surface (9) defines an a

Abstract: A variable valve drive for a cam-actuated lift valve of an internal combustion engine which is loaded by a closing pressure against the direction of opening, includes a hydraulic power generating device acting on the lift valve against the closing force with a control piston arranged longitudinally displaceable in a cylinder and adjacent to a hydraulic control chamber, a stroke of the lift valve produced by an actuating cam being at least reducible by removing hydraulic liquid from the control chamber by means of a control valve. In order to arrange the valve stroke and valve opening as free as possible in the simplest possible way the control chamber is connectable with a high pressure level preferably by means of the control valve.

Abstract: The invention relates to a variable valve drive for a cam-actuated lift valve of an internal combustion engine which is loaded by a closing pressure against the direction of opening, with a hydraulic power generating device acting on the lift valve against the closing force with a control piston arranged longitudinally displaceable in a cylinder and adjacent to a hydraulic control chamber, with a stroke of the lift valve produced by an actuating cam being at least reducible by removing hydraulic liquid from the control chamber by means of a control valve. In order to arrange the valve stroke and valve opening as free as possible in the simplest possible way it is provided that the control chamber is connectable with a high pressure level preferably by means of the control valve.