High pressure helium pump for liquid or supercritical gas

Claim 1

In a pump for compressing and transferring a cryogenic liquid from a storage receptacle of the type comprising a piston mounted for reciprocal movement inside a tubular housing communicating with said liquid, means to move said piston, means to permit movement of liquid from said receptacle to a variable pumping chamber in said tubular member during a portion of the stroke of said piston of said pump and means to discharge liquid from said pumping chamber through an outlet valve during the reverse portion of the stroke of said piston the improvement comprising: a base plate mounted on a support frame for positioning said tubular housig containing a piston rod one end of which projects from said housing said projecting end positioned relative to a motor driven fly wheel containing thereon an eccentric; and a four bar linkage disposed between said eccentric and the projecting end of said piston rod, said four bar linkage includes as its prime element a beam having at least three mounting points having centers disposed relative to each other at the apecies of a right triangle, said beam positioned by fixing the mounting point at the 90° apex to said frame by means of a rocker arm, and the mounting point at the other apecies to said eccentric and said piston rod respectively, said connection to said piston rod including a yoke; and a piston of a hollow elongated structure extending substantially the length of said piston rod and mounted for reciprocation through a suitable aperture in said base plate said piston being sealed to said rod by means of a rigid boot; whereby rotation of said fly wheel causes said linkage to translate rotating motion of said fly wheel to nearly true straight line reciprocating motion of said piston rod so that said piston assembly travels through both the warm zone and cold zone packing with deviations from straight line motion being accommodated by elastic deformation of the piston rod.