Vane-type oil pump for automotive vehicle

In combination with an automotive-vehicle engine having a lubricating system through which a liquid lubricant needs to be circulated and an output, a lubricating pump comprising:

• a stator having an outer part forming intake and output ports and an inner part pivotal about a pivot axis on the outer part and having an inner surface defining a chamber centered on a stator axis extending between the ports, the ports opening axially into the chamber at locations diametrally opposite each other relative to the pivot axis and the chamber being closed radially outwardly relative to the axes by the inner part;
• an adjustment tab projecting radially outwardly from the inner stator part generally diametrally opposite the pivot axis;
• a rotor rotatable in the chamber about a rotor axis normally parallel to and offset from the stator axis and having an outer surface centered on the rotor axis, the rotor being formed with a plurality of angularly equispaced and radially extending guides open at the outer surface;
• respective vanes of substantially the same radial length received in the guides and having radially outer ends riding on the inner stator surface and radially opposite inner ends;
• at least one circular inner ring in the chamber and having an outer ring surface radially outwardly engaging the inner vane ends, the vanes angularly defining compartments axially closed by the stator outer part, radially outwardly closed by the stator inner part, and radially inwardly closed by the inner ring, whereby, when the stator axis is offset outward from the rotor axis and the rotor is rotated in a predetermined sense, the compartments move from the intake to the output port and decrease in volume at the output port and when the stator and rotor axes are coaxial there is no pumping action even when the rotor turns in the stator;
• biasing means including a spring and pusher element braced between the tab and the outer stator part for urging the inner stator part pivotally outward about the pivot axis with a fixed force for separating the pivot and stator axes and thereby increasing the pump flow volume;
• hydraulic biasing means pressurized from the output port and including a piston-and-cylinder assembly pressurizable to bear against the tab in one angular direction relative to the stator axis for urging the inner stator part pivotally inwardly for bringing the axes together and thereby decreasing the pump flow volume;
• and
• abutment means connected to the inner stator part for permitting relative free movement of the inner stator part in the outer stator part between an intermediate position with the stator and rotor axes relatively close and an outer position with the stator and rotor axes relatively widely spaced, and for limiting movement between the intermediate position and an inner position with the stator and rotor axes coaxial, the abutment means including another spring engageable with the pusher element only when the inner stator part moves toward the inner position from the intermediate position.