Device for varying valve timing of gas exchange valves of internal combustion engines, particularly a hydraulic camshaft adjusting device of a rotary piston type

Abstract

The invention concerns a device for varying valve timing of gas exchange valves of an internal combustion engine, particularly a hydraulic camshaft adjusting device of a rotary piston type, said device comprising a drive pinion ( ) connected in driving relationship to a crankshaft of the internal combustion engine and a winged wheel ( ) connected rotationally fast to a camshaft of the internal combustion engine. The drive pinion ( ) comprises a hollow space formed by a circumferential wall ( ) and two side walls ( ), at least one hydraulic working chamber ( ) being formed in the hollow space by at least two limiting walls ( ). The winged wheel ( ) comprises at least one radial wing ( ), and with each wing ( ) it divides one hydraulic working chamber ( ) into two hydraulic pressure chambers ( ) which, when pressurized by a hydraulic pressure medium effect a pivoting or a fixing of the winged wheel ( ) relative to the drive pinion ( ). When the internal combustion engine is switched off, the camshaft is rotated into a preferred basic position for starting the internal combustion engine, and in this position, the winged wheel ( ) can be mechanically coupled to the drive pinion ( ) by a lock. The novel lock is configured as a cage-guided free-wheel ( ) arranged between the winged wheel ( ) and the drive pinion ( ) and comprises at least one clamping body ( ) that blocks the direction of rotation of the winged wheel ( ) opposed to the basic position of the camshaft. The cage ( ) of the free-wheel ( ) is configured at least partly as a pressure application surface ( ) for the hydraulic pressure medium for unlocking the free-wheel ( ).