Pumping apparatus having a varying phase relationship between reciprocating piston motions

Abstract

A pumping apparatus for delivering liquid at high pressure at which compressibility of the liquid becomes noticeable. The pumping apparatus comprises a first actuator for actuating a first reciprocation piston for pumping at least a part of the fluid, a second actuator for actuating a second reciprocation piston for pumping at least a part of the fluid, and a main drive coupled to the first actuator and to the second actuator. A phase shifter is provided for varying a phase relationship between reciprocating motions of the first piston and the second piston.

1 . A pumping apparatus, comprising: 
 a first actuator for actuating a first reciprocation piston for delivering liquid at a high pressure at which compressibility of the liquid becomes noticeable,    a second actuator for actuating a second reciprocation piston for delivering liquid at a high pressure at which compressibility of the liquid becomes noticeable,    a main drive coupled to the first actuator and to the second actuator, and    a phase shifter for varying a phase relationship between reciprocating motions of the first piston and the second piston.    
   
   
       2 . The apparatus of  claim 1 , wherein 
 the phase shifter is adapted for varying the phase relationship between the reciprocating motions of the pistons by timely shifting a top dead center of one of the pistons to late or by timely shifting a bottom dead center of one of the pistons to early.    
   
   
       3 . The apparatus of  claim 2 , wherein 
 the phase shifter is adapted for and/or controlled for timely shifting the top dead center of one of the pistons to late such that the other piston has enough time to build up the high pressure in a chamber in which the respective piston moves.    
   
   
       4 . The apparatus of  claim 2 , wherein 
 the phase shifter is adapted for and/or controlled for timely shifting the bottom dead center of one of the pistons to early such that the respective piston is enabled to build up the high pressure in a chamber, in which the respective piston moves, until the other piston reaches its top dead center.    
   
   
       5 . The apparatus of  claim 1 , wherein 
 the actuators are drive coupled to each other such that the pistons move in opposite directions when the phase shifter is deactivated.    
   
   
       6 . The apparatus of  claim 1 , wherein 
 each actuator comprises a spindle drive comprising a spindle having an external thread and being drive coupled to the main drive, and a nut having an internal thread and being drive coupled to the respective piston,    one of the nuts is torque proof guided parallel to the longitudinal extension of the respective spindle by a guiding,    the phase shifter comprises an auxiliary drive coupled to the other of the nuts such that the respective nut is movable parallel to the longitudinal extension of the respective spindle.    
   
   
       7 . The apparatus of  claim 6 , wherein 
 the auxiliary drive is adapted for and/or controlled for inducing enough torque into the respective nut such that the respective nut is torque proof movable parallel to the longitudinal extension of the respective spindle when the phase shifter is deactivated.    
   
   
       8 . The apparatus of  claim 6 , wherein 
 the auxiliary drive is adapted for and/or controlled for inducing a rotary motion into the respective nut such that a top dead center of the respective piston is timely shifted to late in order to vary the phase relationship between the reciprocating motions of the pistons or such that a bottom dead center of the respective piston is timely shifted to early in order to vary the phase relationship between the reciprocating motions of the pistons.    
   
   
       9 . The apparatus of  claim 6 , wherein 
 the coupling between the main drive and the actuators is adapted for driving the actuators with different velocities such that the pistons have different stroke lengths between the respective top dead center and the respective bottom dead center,    the nut drive coupled to the auxiliary drive is assigned to the piston having the shorter stroke length,    a controller is coupled to the main drive for adjusting the stroke length of each of the pistons,    the phase shifter is adapted for and/or controlled for displacing the respective nut along the respective spindle in order to reduce a dead volume between the top dead center of the respective piston and a front wall of the respective chamber in which the respective piston moves.    
   
   
       10 . The apparatus of  claim 1 , wherein 
 a controller is coupled to the main drive for adjusting a driving power of the main drive at a predetermined and/or selectable value as long as the pistons move between their top and bottom dead centers in order to maintain the high pressure and for adjusting the driving power at a predetermined and/or selectable higher value and for a predetermined and/or selectable time when a certain one of the pistons reaches its bottom dead center in order to reduce the time necessary for building up the high pressure in a chamber, in which the respective piston moves,    the phase shifter is adapted for timely shifting the bottom dead center of the certain piston to early or for timely shifting a top dead center of the other piston to late.    
   
   
       11 . The apparatus of  claim 1 , comprising at least one of the following features: 
 the pumping apparatus is adapted for delivering the liquid at a predetermined and/or selectable high pressure;    the pumping apparatus is adapted for delivering the liquid at a predetermined and/or selectable flow rate;    the respective actuator is adapted for bidirectionally actuating the respective piston;    the pumping apparatus comprises a first pump comprising a first chamber in which the first piston moves;    the pumping apparatus comprises a second pump comprising a second chamber in which the second piston moves;    the main drive is coupled to the actuators by a gear.    
   
   
       12 . A separation device or system adapted for separating compounds of a mobile phase and comprising a pumping apparatus of  claim 1  and being adapted for driving the mobile phase, further comprising at least one of: 
 A column device for separating compounds of the mobile phase;    A sampling unit adapted for introducing a sample fluid to the mobile phase;    A detector adapted for detecting separated compounds of the mobile phase;    A fractionating unit adapted for outputting separated compounds of the mobile phase.    
   
   
       13 . A pumping method comprising: 
 actuating a first reciprocation piston for delivering liquid at a high pressure at which compressibility of the liquid becomes noticeable,    actuating a second reciprocation piston for delivering liquid at a high pressure at which compressibility of the liquid becomes noticeable, wherein the first reciprocation piston and the second reciprocation piston are coupled by a main drive,    varying a phase relationship between reciprocating motions of the first piston and the second piston.