The invention relates to a hydraulic actuator for actuating a gas exchange valve
(1) of an internal combustion engine, which valve is especially closed by
the effect of a spring. The actuator is configured by a feed pump (6) with
intermittent and thus variable delivery. The feed pump (6) has a high frequency
and can be equipped for this purpose with piezoelectric, magnetorestrictive and/or
electrochemical actuators as the feed elements. Optionally, the feed pump (6)
can be operated with a stop valve (7) that is disposed downstream of the
gas exchange valve (1) and that is controlled or regulated depending on
the feed pump.
