Rotary gear pump with vanes

A rotary gear pump which comprises a housing, and at least a pair of rotatable, meshing gears positioned within said housing, said meshing gears defining spaced teeth which extend helically in the general direction of the axis of each gear rotation;

• a flow inlet and flow outlet, each positioned in the housing to permit flow of fluid substantially longitudinally between said meshing gears as said gears rotate said teeth through a tooth-meshing area;
• a plurality of spaced first vanes covering said teeth of said gears at a rotational position upstream of said tooth-meshing area to shield the covered teeth from an energy consuming backflow of fluid from said tooth-meshing area as said gears rotate, and at least one second vane covering said teeth of each gear at a rotational position downstream of said tooth-meshing position to direct depressurizing, expanding fluid from between said gear teeth into a flow direction substantially opposite to the direction of gear rotation.