US Patent 7837430 Rotary blower and aspirator having a modifiable conformation

The machine comprises an impeller, provided with blades connected to a central body of the impeller; the impeller is closed in a casing which defines an annular conduit, in which the blades rotate, which annular conduit exhibits an intake mouth and a delivery mouth and further exhibits a first tract which goes from the intake mouth to the delivery mouth, a free space is provided in the first tract between the rotating blades and the internal walls of the annular conduit. The conformation of the radial section of the annular conduit can be modified by application of interchangeable elements to parts of the machine which define the free space.