A displacer unit with a valve plate body is disclosed. The displacer unit having at least one displacer space which is arranged in a cylindrical drum rotating about an axis of rotation and which can be connected to an inlet connection and an outlet connection by a control surface. The control surface is formed on a valve plate body which is provided with a first control opening, which is connected to the inlet connection, and with a second control opening, which is connected to the outlet connection. The first control opening and the second control opening are spaced apart radially, where the displacer space can be connected to the first control opening by a first connecting passage and to the second control opening by a second connecting passage. The connecting passages are provided with a respective mechanical face seal for sealing relative to the control openings.