Variable displacement vane pump

Claim 1

In a double acting, variable displacement vane pump, the combination comprising: a rotor; a plurality of radially movable, spaced vanes mounted on the periphery of the rotor; two rigid, similarly shaped track elements mounted for movement toward and away from the rotor between maximum and minimum displacement positions, the track elements being closest to the rotor in their respective maximum displacement positions and furthest from the rotor in their respective minimum displacement positions, the inner peripheries of the track elements defining a contoured vane track which contacts the tips of the vanes during rotation of the rotor, each track element having a first lip and a second lip, the first lip of each track element having a tongue with a flat inner surface extending therefrom and tangential to the vane track in all displacement positions, the second lip of each track element having a groove receding therefrom, the tongue of each track element slidingly engaging the groove of the other track element such that when the track elements occupy their respective maximum displacement positions, the tips of the vanes move directly from the second lip of one track element to the first lip of the other track element to thereby minimize vane dynamics at high pressure loadings and prevent binding of the vanes on the vane track, the inner periphery of each track element defining: a first curvilinear transfer arc with a length of at least one vane spacing extending from the first lip, a second curvilinear transfer arc with a length of at least one vane spacing spaced from the first transfer arc and the second lip, a curvilinear discharge arc extending between the first and second transfer arcs, and a curvilinear inlet arc encompassing the groove extending from the second transfer arc to the second lip; the radial spacing of each track element''s inner periphery from the rotor progressively decreasing in the discharge arc thereof and progressively increasing in the inlet arc thereof in the peripheral direction from the first lip thereof to the second lip thereof, each track element having a radial discharge passage communicating with the discharge arc thereof and a radial inlet passage communicating with the inlet arc thereof, the discharge passages of the track elements being diametrically opposed and the inlet passages being diametrically opposed so as to pressure balance the rotor.