Patent ID: 7219594

Claim:
A reciprocating pump assembly, comprising: a housing having a piston chamber with a working fluid inlet and a working fluid outlet; a crankshaft rotatably driven in the housing; a connector rod having a first end mounted to the crankshaft for rotation therewith and a second end; a movable piston rod pivotally mounted to the second end of the connector rod, the piston rod having a piston portion at an end that stokes linearly within the piston chamber, the piston portion having a working fluid side for pumping out the outlet working fluid entering the inlet; a stationary piston rod sleeve that houses the piston rod and defines an annulus; a cooling fluid line leading into the annulus; and a cooling fluid flow passage having an inlet in fluid communication with the annulus and an outlet in fluid communication with the piston chamber on a side of the piston portion opposite the working fluid side for cooling the piston portion.