Slipper-type pumping element for a pump or motor

Claim 1

A pump comprising a housing having a cam bore wall forming a pumping chamber for a pump of the expanding chamber type and specifically including a crossover arc disposed between respective inlet and outlet portions of the pumping chamber, a rotor in said pumping chamber having a plurality of circumferentially spaced apart peripheral notches for carrying a corresponding plurality of slipper vanes and such notches and vanes being sufficient in number to position at least one such vane in the crossover arc at all times, and each such slipper vane being constructed to exhibit the following proportions relating to the slipper cam bore relationship; 1. a slipper width in specified dimension, i.e., a slipper width measured from the maximum protuberance of each slipper flank to contact depth aspect ratio of W/D congruent 2.6 to 2.8, 2. a circumferential contact arc on the outer surface of said slipper of specified dimension, i.e., a circumferential contact arc to contact depth ratio CA/D 1.4 to 1.9, and 3. an underslipper surface curvature formed on said slipper to allow unencumbered spring rock without attrition to the spring in its shrouding guide hole, i.e., a curvature on any curve whose curvature departs within a range of 2 1/2 to 5 percent of the spring Radius measured from the slipper center and wherein the spring ratio (SL/SD) is 1.55/1 or less in the installed position.