Balanced variable displacement vane pump with floating face seals and biased vane seals

A variable displacement vane pump assembly comprising:

• a) a rotary cam ring having an outer circumferential surface and an elliptical inner bore defining a pumping chamber, the pumping chamber having a continuous interior camming surface, the rotary cam ring also defining at least one port for admitting fluid into the pumping chamber;
• b) a rotor having a front and rear face and mounted for axial rotation within the elliptical inner bore of the rotary cam ring, the rotor defines a plurality of circumferentially spaced apart radially extending vane slots, an axial cavity, an annular groove centrally located about the axial cavity, and a plurality of radial bores in fluid communication with the annular groove and the vane slots, and a plurality of flowpaths extending from the annular groove to the front and rear face of the rotor;
• c) a vane assembly supported in each radially extending vane slot to define a plurality of circumferentially spaced vane buckets, wherein each vane assembly is elongated and has a front end and a rear end, and further comprising a dynamic vane seal on each end of each vane assembly for reducing circumferential leakage between the vane buckets, each vane assembly defining a radial flow bore in fluid communication with a radial bore of the rotor and an outer vane channel in fluid communication with the radial flow bore;
• d) an annular spacer surrounding the rotary cam ring and defining an interior bearing surface to accommodate selective rotation of the cam ring for varying the effective displacement of the pumping chamber, the annular spacer also defining at least one passage in fluid communication with the at least one port for admitting low pressure fluid into the pumping chamber;
• and
• e) front and rear side plates separated by the annular spacer and enclosing the pumping chamber, the front side plate defining at least one discharge port for discharging fluid from the pumping chamber and at least one discharge pressure pocket in fluid communication with the at least one discharge port,
• wherein the discharge pressure flows from the at least one discharge pressure pocket to the flowpaths and the annular groove to the radial bores of the rotor to the radial flow bore and an outer vane channel of the vane assemblies.

A hydrostatically balanced double-acting variable displacement vane pump assembly comprising:

• a) a rotary cam ring having an outer circumferential surface and an elliptical inner bore defining a hydraulic pumping chamber, the pumping chamber having a continuous interior camming surface, the rotary cam ring also defining opposing ports for admitting low pressure fluid into the pumping chamber;
• b) a rotor mounted for axial rotation within the inner bore of the rotary cam ring, the rotor having a front and rear face and defining:
• an axial cavity;
• an annular groove centrally located about the axial cavity;
• a plurality of circumferentially spaced apart radial bores in fluid communication with the annular groove;
• a plurality of angled bores extending from the annular groove to the front and rear face of the rotor;
• and a plurality of circumferentially spaced apart radially extending vane slots in fluid communication with the radial bores;
• c) a vane assembly supported in each radially extending vane slot to define a plurality of circumferentially spaced vane buckets;
• d) an undervane pin disposed within each radial bore;
• e) an annular spacer surrounding the rotary cam ring and defining an interior bearing surface to accommodate selective rotation of the cam ring for varying the effective displacement of the pumping chamber, the annular spacer also defining opposing passages in fluid communication with the opposing ports for admitting low pressure fluid into the pumping chamber;
• and
• f) a front side plate having an inner and outer face, and defining:
• a central axial passage for a drive shaft;
• two diametrically opposed inlet ports for admitting low pressure fluid into the pumping chamber;
• two diametrically opposed discharge ports for discharging high pressure fluid from the pumping chamber;
• a flowpath adjacent each discharge port for providing discharge pressure to the angled bores;
• and opposing pockets to create inlet pressure zones in fluid communication with the vane slots;
• and
• g) a rear side plate having an inner and outer face, and defining:
• a central axial passage for a drive shaft;
• two diametrically opposed inlet ports for admitting low pressure fluid into the pumping chamber;
• two diametrically opposed discharge ports for discharging high pressure fluid from the pumping chamber;
• a flowpath adjacent each discharge port for providing discharge pressure to the angled bores;
• and opposing pockets to create inlet pressure zones in fluid communication with the vane slots,
• wherein:
• the front and rear side plates are separated by the annular spacer to enclose the pumping chamber;
• discharge pressure fills the flowpaths adjacent each discharge port, passes through the angled bores to the annular groove and into the radial bores of the rotor to act on the undervane pins to push the respective undervane pin and, in turn, the respective vane assembly radially outwardly against the camming surface of the cam ring;
• the discharge pressure also passes through the vane slots.

A variable displacement vane pump assembly comprising:

• a) a rotary cam ring having an outer circumferential surface and an inner bore defining a pumping chamber, the pumping chamber having a continuous interior camming surface, the rotary cam ring also defining at least one port for admitting fluid into the pumping chamber and at least one cam ring slot;
• b) a rotor mounted for axial rotation within the inner bore of the rotary cam ring, the rotor defines a plurality of circumferentially spaced apart radially extending vane slots;
• c) a vane assembly supported in each radially extending vane slot to define a plurality of circumferentially spaced vane buckets;
• d) an annular spacer surrounding the rotary cam ring and defining an interior bearing surface to accommodate selective rotation of the cam ring for varying the effective displacement of the pumping chamber, the annular spacer also defining at least one passage in fluid communication with the at least one port for admitting low pressure fluid into the pumping chamber;
• e) front and rear side plates separated by the annular spacer and enclosing the pumping chamber, the front side plate defining at least one discharge port for discharging fluid from the pumping chamber;
• and
• f) at least one screw to fix the annular spacer, the front side plate and the rear side plate with respect to the rotary cam ring, wherein the at least one screw passes through the at least one cam ring slot to act as a mechanical stop for movement of the rotary cam ring.