Displacer unit with a valve plate body

A displacer unit having a displacer space which is arranged in a cylindrical drum rotating about an axis of rotation and which is connectable to an inlet connection and an outlet connection by a control surface, wherein the control surface is formed on a valve plate body which is provided with a first control opening, which is connectable to the inlet connection, and with a second control opening, which is connectable to the outlet connection, wherein the first control opening and the second control opening are spaced apart radially, wherein the displacer space is connectable to the first control opening by a first connecting passage and to the second control opening by a second connecting passage, wherein the first control opening and the first connecting passage are arranged at a first radial distance from an axis of rotation of the valve plate body, wherein the second control opening and the second connecting passage are arranged at a second radial distance from the axis of rotation of the valve plate body, wherein the first radial distance is greater than the second radial distance, and wherein the connecting passages are provided with respective mechanical face seals for sealing relative to the control openings.