Appliance for modifying the timing of gas-exchange valves of an internal combustion engine, in particular hydraulic camshaft adjustment device of rotary piston type

Appliance for modifying the timing of gas-exchange valves of an internal combustion engine, including a hydraulic camshaft adjustment device comprising

• a driving wheel (2) which is configured as an external rotor, which is in drive connection with a crankshaft of the internal combustion engine and has a hollow space (6) formed by a hollow-cylindrical peripheral wall (3) and two side walls (4, 5),
• at least one hydraulic working space (8) is formed in the hollow space (6) of the driving wheel (2) by at least two boundary walls (7) extending from the inside of the peripheral wall (3) and directed toward the longitudinal center line of the driving wheel (2),
• an impeller (10) which is configured as an internal rotor, is torsionally connected to a camshaft (9) of the internal combustion engine and is inserted in the hollow space (6) of the driving wheel (2),
• on the periphery of an impeller hub (11), the impeller (10) has at least one vane (13) which is arranged in an axial retention groove (12) and which extends radially in a working space (8) of the driving wheel (2) and subdivides each working space (8) into two oppositely acting hydraulic pressure chambers (14, 15),
• the outer end surface (18) of each vane (13 of the impeller (10) is in sealing contact with the inside of the peripheral wall (3) of the driving wheel (2) due to the force of a spring element (17) arranged on the inner end surface (16) of the vane in the axial retention groove (12),
• during pressurization by means of a hydraulic fluid, the pressure chambers (14, 15) cause a pivoting motion or fixed location of the impeller (10) relative to the driving wheel (2) and, therefore, of the camshaft (9) relative to the crankshaft, characterized in that
• the vanes (13) of the impeller (10) are additionally configured with pressure balance means with which, during pressurization of one or both pressure chambers (14, 15) of each hydraulic working space (8) of the appliance (1), the hydraulic fluid pressure, in the pressurized pressure chambers (14, 15), which acts on the outer end surface (18) of the vanes (13), can also be transmitted to the inner end-surface (16) of the vanes (13).