Variable volume rotary piston pump - has cylindrical piston rotating on eccentric of shaft itself capable of limited eccentric rotation in drive shaft

摘要

The pump has a cylindrical pump chamber containing a cylindrical piston (10) which is rotatable about its own axis on an eccentric extension (8) of a drive shaft (6). The extension (8) is an eccentric shaft end of a shaft (7) which is itself eccentrically carried in the drive shaft (6). The arrangement permits limited relative rotation between the shafts (7, 6). The eccentricity of the extension (8) relative to the inner shaft (7) may be equal to that of the inner shaft relative to the drive shaft (6). Relative rotation of the inner shaft (7) relative to the drive shaft may be limited by stops whilst a spring tends to move the shaft (7) towards one of the stops.