Device for changing the control timing of gas exchange valves of an internal combustion engine, particularly a rotary piston adjustment device for rotation angle adjustment of a camshaft relative to crankshaft

Abstract

A device for changing the control times of gas exchange valves of an internal combustion engine, particularly a rotary piston adjusting device for rotation angle adjustment of a camshaft relative to a crankshaft, which device is fastened by a central fastening screw to a camshaft mounted in the cylinder head of the internal combustion engine. The device includes a stator, in driving connection with the crankshaft and having two side covers, and of a rotor connected to rotate with the camshaft, with at least two hydraulic working spaces being formed in the stator by at least two radial boundary walls. The chambers are divided by at least two radial vanes on the rotor, respectively, into two hydraulic pressure chambers which work in opposition to one another. The stator and the one side cover of the device are formed as an integral stator unit, and the rotor and the other side cover are formed as an integral rotor unit. These are fixed together axially and radially and to the camshaft by the central fastening screw and by additional positive locking elements on the drive-side end of the camshaft or on the head of the fastening screw.

1 . Device for changing the control times of gas exchange valves of an internal combustion engine of a rotary piston adjustment type for rotation angle adjustment of a camshaft relative to a crankshaft, comprising: 
 a central fastening screw to fasten the device to a drive-side end of a camshaft mounted in a cylinder head of the internal combustion engine,    a stator in driving connection with the crankshaft of the internal combustion engine, having two axial side covers and of a rotor connected to rotate with the camshaft of the internal combustion engine,    the stator including a hollow cylindrical circumferential wall and at least two boundary walls directed radially toward a longitudinal central axis of the device, at least two working spaces being formed between the at least two hydraulic boundary walls,    the rotor including a hub with at least two radial vanes which extend into the working spaces of the stator and divide the working spaces, respectively, into at least two hydraulic pressure chambers acting in opposition to one another,    upon selectively or simultaneously acting on the pressure chambers with a hydraulic pressure medium, a relative rotation or fixing of the rotor takes place relative to the stator and thereby of the camshaft relative to the crankshaft,    the stator and the one axial side cover of the device are formed as an integral stator unit, and the rotor and the other axial side cover of the device are formed as an integral rotor unit which are axially and radially fixed together and to the camshaft solely by the central fastening screw and positive locking elements on a drive-side end of the camshaft or on a head of the fastening screw ( 2 ).    
     
     
         2 . The device according to  claim 1 , wherein 
 the stator unit and the rotor unit are produced as one of sintered steel compression molded parts, aluminum or magnesium diecast parts or as plastic injection molded parts.    
     
     
         3 . Apparatus according to  claim 1 , wherein 
 the positive locking elements are arranged on the drive-side end of the camshaft and comprise a reduced-diameter stub and a stepped shoulder machined in a front side of the camshaft.    
     
     
         4 . Device according to  claim 3 , wherein 
 the rotor unit is positively fixed radially to the stub of the camshaft, by a camshaft-side axial bore in the hub having a widened portion which fits on the stub on the camshaft, and    the rotor is axially fixed to the camshaft by a screwing-on moment of the central fastening screw, with a camshaft-side side face of the hub abutting on a front of the camshaft.    
     
     
         5 . Device according to  claim 3 , wherein the stator unit is rotatably mounted on the rotor unit with radial front sides of the boundary walls abutting on an outside surface of the hub of the rotor unit, and is also thereby positively fixed radially to the camshaft ( 5 ), and 
 wherein the side cover of the stator unit is arranged with an axial opening enclosing a stepped shoulder on the camshaft between a vertical annular surface and the camshaft-side side surface of the hub of the rotor unit, and the stator unit is thus also positively fixed axially with respect to the camshaft.    
     
     
         6 . Device according to  claim 1 , wherein 
 the circumferential wall of the stator unit has, on a side remote from the camshaft, an edge portion, axially lengthened in comparison with a width of the radial boundary walls, which encloses with an inner surface thereof a circumferential surface of the side cover of the rotor unit and is situated with an end face of the edge portion opposite to an annular land arranged on the circumferential surface of the side cover of the rotor unit.    
     
     
         7 . Device according to  claim 6 , wherein 
 an additional sealing element is inserted between the circumferential surface of the side cover of the rotor unit and the inner surface of the edge portion of the circumferential wall of the stator unit.    
     
     
         8 . The device of  claim 7 , wherein 
 the sealing element is one of a steel sealing ring or an  0 -ring seal inserted into an annular groove in the circumferential surface of the side cover of the rotor unit.