Variable displacement vane pump, component parts and method

A durable, single action, variable displacement vane pump capable of undervane pumping comprising:

• (a) a cylindrical rotor member having journal ends and a central vane section comprising a plurality of radial vane slots uniformly spaced around the central circumference thereof, said vane slots being elongate in the axial direction and each having a central vane-supporting portion surrounded at each end by slot extension portions;
• (b) a plurality of vane elements, each slidably-engaged within the central vane-supporting portion of a said vane slot for radial movement therewithin;
• (c) a unitary cam member having opposed faces and a circular bore therethrough forming a cam chamber having a continuous interior cam surface, the central vane section of said rotor member being supported axially and non-concentrically within said cam chamber so that the outer tip surfaces of all of the vane elements make continuous contact with said continuous interior cam surface during rotation of said rotor member, and said vane slot extensions project axially-outwardly beyond the faces of said cam member;
• (d) an opposed pair of manifold bearings rotatably supporting the journal ends of said rotor member and overlying said vane slot extensions, each said bearing having a bearing face surface which contacts a face surface of said cam member and encloses the central vane-supporting portion of said rotor member within said cam chamber, each manifold bearing comprising an inlet arc segment containing means for admitting fluid to expanding vane bucket areas of the rotating vaned rotor, and means for admitting fluid into said vane slot extensions and undervane areas, and a discharge arc segment containing means for discharging pressurized fluid from contracting vane bucket areas of the rotating vaned rotor and from undervane areas as the vanes are depressed into the vane slots during rotation through the discharge arc,
• said cam member being adjustable relative to said vaned rotor to vary the extent of eccentricity therebetween for varying the displacement capacity of said vane pump.