Closed circuit hydraulic compression device with stroke-consistent pump intake

Abstract

An improved, compact and efficient arrangement of axial piston hydraulic pump and hydraulic cylinder into a single self-contained compression or actuating device. A combination of back-flow volume-acting pump pistons and a hollow main piston rod that serves as both a working fluid container and a head-creating organ is introduced.

1 . A closed circuit hydraulic compression device comprising: 
 a housing;    a main hydraulic cylinder within the housing and comprising a hollow rod, a main piston, a bore, a piston seal, means for returning the main piston to a predetermined position within the bore after commencing a stroke to any distance, and means for preventing a loss of a working fluid,    wherein the hollow rod includes means for containing the working fluid under a predetermined pressure,    wherein the main piston allows a free passage of the working fluid in both directions between a space within the hollow rod and a space within the bore in front of the main piston,    wherein the bore in front of the main piston permits an unobstructed outward flow of the working fluid from the space within the bore in front of the main piston while preventing a reverse flow;    a group of pump cylinders located within the housing and oriented approximately parallel to a longitudinal axis of the main cylinder, wherein a front portion of each pump cylinder is openly connected to the means of preventing the reverse flow of the working fluid into the space within the bore of the main cylinder in front of the main piston and a rear portion of each cylinder has means to allow unobstructed flow of working fluid into a space within the bore behind the main piston while preventing the reverse flow,    wherein the means to allow for unobstructed unidirectional flow of working fluid from the bore in front of the main piston via the pump cylinders into the bore behind the main piston remain functional throughout a full predetermined stroke of the main piston,    each pump cylinder further incorporating a pump piston and a fluid-tight seal between a rear portion of the pump piston and a rear portion of the pump cylinder, wherein the rear portion of each pump piston extends beyond the fluid-tight seal so that a predetermined reciprocal movement of the pump piston is allowed,    each pump cylinder further incorporating means to return pump piston to a predetermined position after commencing a stroke to any distance,    each pump piston further comprising means to allow for unobstructed flow of the working fluid in a direction approximately parallel to a longitudinal axis of the pump piston,    means to allow for a return of the working fluid from the bore behind the main piston into the bore in front of the main piston throughout a duty cycle of the closed circuit hydraulic compression device;    means to impart reciprocal movement to the pump pistons; and    means to allow for charging the closed circuit compression device with the working fluid and for subsequent elimination of gas bubbles from the working fluid.    
   
   
       2 . The closed circuit hydraulic compression device of  claim 1 , further comprising manual means to control means to allow for the return of the working fluid.  
   
   
       3 . The closed circuit hydraulic compression device of  claim 1 , further comprising automatic means to control means to allow for the return of the working fluid.  
   
   
       4 . The closed circuit hydraulic compression device of  claim 1 , further comprising means to prevent an increase in pressure of the working fluid above a predetermined value.