Vacuum fillers are known that are used for conveying sausage meat and comprise a vane-type conveying mechanism as a metering or proportioning unit. Such a vacuum filler is e.g. described in European patent specification EP 0 432 388 B2. A further embodiment of a vane-type conveying mechanism for use in a vacuum filler is e.g. disclosed in German patent application DE 42 27 621 A1.
In such vacuum fillers, the filling material to be conveyed in the vane-type conveying mechanism can only be evacuated through gaps at places at which the vanes of the conveying mechanism, the rotor and the housing of the conveying mechanism are in contact. Such gaps should only be so large that filling material cannot be passed therethrough, in particular when the conveying mechanism is at a standstill in the activated state of the vacuum pump as, otherwise, said filling material would be sucked into the vacuum channel and would then clog said channel. However, the width of the gap which is to be kept small renders the evacuating process difficult because the suction effect is thereby restricted or limited.