Abstract: A rotary positive displacement pump (1) that includes an impeller (3) that defines, within a pumping chamber (20), a plurality of successive chambers (21) with variable volume through which a fluid is mechanically conveyed from an inlet (7) to an outlet (8). The chambers (21) with variable volume are defined, at axially opposite ends, by a pair of rotational surfaces (40, 50) that close the pumping chamber (20) and are arranged to rotate about mutually inclined axes. Also described is a method of manufacturing the pump.

Abstract: A rotor (1-3) molded of plastic material, intended for rotary installation in a cavity of a pump body and for reception of one or more vanes forming the pumping members, characterized in that at least a part of the surfaces thereof, intended to undergo sliding displacements against other pump members, is covered by at least one metallic foil (4) caused to adhere to the subjacent surface of plastic material. The metallic foil can consist of a steel sheet or an aluminum alloy sheet, intended for reducing the resistances to the sliding as well as for mechanically reinforcing the rotor. The metallic foil can be fastened to the plastic material body (1) of the rotor by a co-molding operation, or it can be mechanically fixed to the body (1) of the rotor molded of plastic material.

Abstract: A rotary positive displacement pump (1) includes an impeller (3) that defines, within a pumping chamber (20), a plurality of successive chambers (21) with variable volume through which a fluid is mechanically conveyed from an inlet (7) to an outlet (8). The chambers (21) with variable volume are defined, at axially opposite ends, by a pair of rotational surfaces (40, 50) that close the pumping chamber (20) and are arranged to rotate about mutually inclined axes. The invention also concerns the method of manufacturing the pump.

Abstract: A rotor (1-3) moulded of plastic material, intended for rotary installation in a cavity of a pump body and for reception of one or more vanes forming the pumping members, characterized in that at least a part of the surfaces thereof, intended to undergo sliding displacements against other pump members, is covered by at least one metallic foil (4) caused to adhere to the subjacent surface of plastic material. The metallic foil can consist of a steel sheet or an aluminum alloy sheet, intended for reducing the resistances to the sliding as well as for mechanically reinforcing the rotor. The metallic foil can be fastened to the plastic material body (1) of the rotor by a co-moulding operation, or it can be mechanically fixed to the body (1) of the rotor moulded of plastic material.