Vane pump with pressure ramp tracking assist

Claim 3

The method of claim 1 wherein the said limiting of pressure is timed to occur while the respective vane is traversing the central portion of the pressure ramp.

Claim 4

The method of claim 1 wherein said higher pressure is applied to the inner end of the respective vane.

Claim 5

In a vane type hydraulic pump having rotor and stator members, vanes mounted in vane slots in one member for engaging a cam surface presented by the other member, the cam surface including a pressure ramp in a pressure zone of the pump which ramp cams the vanes into their respective slots as they move relatively thereover, the improvement comprising, flow restricting means for each said vane through which fluid in the inner end of the slot is displaced when the vane is moved into its slot, such displacement establishing a pressure differential force on an inwardly facing surface of the vane opposing the inward vane movement, and a relief port communicating with said inwardly facing surface for controlling the pressure thereon during movement of the vane along the pressure ramp, said relief port positioned to communicate with the inner end of a vane slot only when the respective vane is traversing a central portion of the pressure ramp.

Claim 6

In a vane type hydraulic pump having rotor and stator members, vanes mounted in vane slots in one member for engaging a cam surface presented by the other member, the cam surface including a pressure ramp in a pressure zone of the pump which ramp cams the vanes into their respective slots as they move relatively thereover, the improvement comprising, flow restricting means for each said vane through which fluid in the inner end of the slot is displaced when the vane is moved into its slot, such displacement establishing a pressure differential force on an inwardly facing surface of the vane opposing the inward vane movement, and a relief port communicating with said inwardly facing surface for controlling the pressure thereon during movement of the vane along the pressure ramp, said relief port positioned to communicate with the inner end of a vane slot only when the respective vane is traversing a central portion of the pressure ramp.

Claim 7

The improvement of claim 1 wherein said relief port communicates with a pressure port of the pump.

Claim 8

The improvement of claim 5 wherein said relief port is in the form of an aperture in a cheek plate and has a diameter smaller than that of the inner end of a vane slot.

Claim 9

The improvement of claim 1 wherein said flow restricting means comprises a passage extending through the vane between the inner and outer ends thereof.

Claim 10

The improvement of claim 7 wherein said passage includes a sharp orifice which is defined by a bore that meets an end surface of the vane at substantially a right angle.

Claim 11

In a hydraulic vane pump having a rotor carrying vanes that are slidable in vane slots therein, a stator presenting a cam surface engaged by the outer ends of the vanes as the rotor rotates, the cam surface including a pressure ramp in a pressure zone of the pump which ramp cams the vanes inwardly in their respective slots as they traverse it, and a cheek plate presenting a pressure port opening to the space between the rotor and cam surface in the pressure zone, the improvement comprising, flow restricting means in each vane providing a path for restricted flow of fluid in an outward direction to the outer end of the vane from an inwardly facing surface thereof, said flow restricting means being sized so that flow therethrough resulting from inward vane movement on the pressure ramp will establish a pessure differential force on said inwardly facing surface, and a relief port in said cheek plate, said relief port connected to said pressure port and positioned to communicate with the said inwardly facing surface where the inward velocity of the vane is at its highest value, but not when the vane is at the inner end of the pressure ramp.

Claim 12

In a hydraulic vane pump having a rotor carrying vanes that are slidable in vane slots therein, a stator presenting a cam surface engaged by the outer ends of the vanes as the rotor rotates, the cam surface including a pressure ramp in a pressure zone of the pump which ramp cams the vanes inwardly in their respective slots as they traverse it, and a cheek plate presenting a pressure port opening to the space between the rotor and cam surface in the pressure zone, the improvement comprising, flow restricting means in each vane providing a path for restricted flow of fluid in an outward direction to the outer end of the vane from an inwardly facing surface thereof, said flow restricting means being sized so that flow therethrough resulting from inward vane movement on the pressure ramp will establish a pessure differential force on said inwardly facing surface, and a relief port in said cheek plate, said relief port connected to said pressure port and positioned to communicate with the said inwardly facing surface where the inward velocity of the vane is at its highest value, but not when the vane is at the inner end of the pressure ramp.

Claim 13

The improvement of claim 9 where said relief port communicates with said inwardly facing surfae where the respective vane is moving on the central part of the pressure ramp.

Claim 14

The improvement of claim 9 wherein said inwardly facing surface is the inner end of the vane.

Claim 15

The improvement of claim 11 wherein said relief port is positioned to communicate with the inner end of a vane slot.

Claim 16

The improvement of claim 9 wherein the flow restricting means is at least one restricted passage extending radially through the vane, between the inner and outer ends thereof.

Claim 17

The improvement of claim 13 wherein the passage includes a sharp, short orifice.

Claim 18

A vane for use in a hydraulic pump of the type having a rotor carrying vanes that are slidable in vane slots therein, a stator presenting a cam surface engaged by the outer ends of the vanes as the rotor turns, the cam surface including a ramp in a pressure zone of the pump which ramp cams each vane inwardly in its respective slot as it traverses the ramp, and a cheek plate presenting a pressure port opening to the space between the rotor and cam surface in the pressure zone. said vane having flow restricting means associated with it providing a path for restricted flow of fluid between the inner and outer ends of the vane, said flow restricting means being sized so that flow therethrough resulting from inward vane movement on the said ramp will establish a pressure differential force beneath the vane of magnitude sufficient to prevent skip at the inner end of the pressure ramp, said flow restricting means being provided in the form of a passage including a sharp, short orifice, flow across which establishes the pressure drop, and a larger diameter passage portion connecting said sharp orifice to an opposite edge of the vane.

Claim 19

A vane for use in a hydraulic pump of the type having a rotor carrying vanes that are slidable in vane slots therein, a stator presenting a cam surface engaged by the outer ends of the vanes as the rotor turns, the cam surface including a ramp in a pressure zone of the pump which ramp cams each vane inwardly in its respective slot as it traverses the ramp, and a cheek plate presenting a pressure port opening to the space between the rotor and cam surface in the pressure zone. said vane having flow restricting means associated with it providing a path for restricted flow of fluid between the inner and outer ends of the vane, said flow restricting means being sized so that flow therethrough resulting from inward vane movement on the said ramp will establish a pressure differential force beneath the vane of magnitude sufficient to prevent skip at the inner end of the pressure ramp, said flow restricting means being provided in the form of a passage including a sharp, short orifice, flow across which establishes the pressure drop, and a larger diameter passage portion connecting said sharp orifice to an opposite edge of the vane.

Claim 20

The vane of claim 15 wherein said passage is a radial passage in the vane, and said orifice is adjacent the inner edge of the vane, and meets said inner edge at a right angle.