Abstract: The invention relates to a roller tappet comprising an axle which supports the roller. The aim of the invention is to secure said roller in a simple manner in the roller bearings. To this end, the base body of the tappet is provided with a surrounding groove at pin level. A locking ring similar to a piston ring is arranged in the groove.

Abstract: A camshaft provided with three-dimensional cams is connected at its one end to a valve lift-varying actuator. By the valve lift-varying actuator or displacing the camshaft in the directions of an axis of the camshaft, the lift characteristic of intake valves set by the three-dimensional cams is variably controlled to a target amount of valve lift. The valve lift characteristic related to this control is detected as a detected amount of valve lift by a reference-purposed detected portion and a cam angle sensor. An apparatus and a method diagnoses abnormalities in the valve lift-varying actuator by, for example, evaluating whether the amount of change in the detected amount of valve lift is at most a predetermined value and the absolute value of a difference between the detected amount of valve lift and the target amount of valve lift is greater than a predetermined value.

Abstract: An internal combustion engine includes two intake side solenoid driving valve mechanisms for opening and closing intake valves by cooperation of an electromagnetic coil and a spring, and/or two exhaust side solenoid driving valve mechanisms for opening and closing exhaust valves provided on each cylinder. A controller commands a driving circuit to cause the valve-opening timing of the exhaust valves or the intake valves to be different.

Abstract: Method for protection against overheating of electromagnetic actuators for actuation of intake and exhaust valves in internal-combustion engines, in which an actuator of an engine is connected to a respective intake or exhaust valve, and includes a mobile unit which is actuated magnetically, in order to control the movement of the said valve, and a first and a second electromagnet, which are disposed on opposite sides of the mobile unit; the actuator also being connected to a control unit, via a piloting circuit, which supplies at least one current to a current-measuring circuit, which supplies to the control unit measured values of the current.