High pressure pumping apparatus with coupled volumes in a pump working chamber

Abstract

A pumping apparatus ( 10 ), for delivering liquid at a high pressure at which compressibility of the liquid becomes noticeable, comprises a piston ( 20 ) adapted for reciprocation in a pump working chamber ( 30 ), wherein a movement of the piston ( 20 ) into a first direction ( 40 ) decreases a first volume (V 1 ) in the pump working chamber ( 30 ) and increases a second volume (V 2 ) in the pump working chamber ( 30 ), and a movement of the piston ( 20 ) into a second direction ( 50 ) opposite to the first direction ( 40 ) increases the first volume (V 1 ) and decreases the second volume (V 2 ). A coupling ( 70, 80, 90, 100 ) is provided for coupling the first volume (V 1 ) with the second volume (V 2 ) as long as a pressure (Psup) in the first volume (V 1 ) exceeds a pressure in the second volume (V 2 ). An outlet valve ( 120 ) is provided for coupling the second volume (V 2 ) with an outlet ( 110 ) of the pumping apparatus ( 10 ) as long as a pressure in the second volume (V 2 ) exceeds a pressure (Psys) at the outlet ( 110 ).

1 . A pumping apparatus for delivering liquid at a high pressure at which compressibility of the liquid becomes noticeable, comprising
 a piston adapted for reciprocation in a pump working chamber, wherein a movement of the piston into a first direction decreases a first volumes in the pump working chamber and increases a second volume in the pump working chamber, and a movement of the piston into a second direction opposite to the first direction increases the first volume and decreases the second volume,   a coupling for coupling the first volume with the second volume as long as a pressure in the first volume exceeds a pressure in the second volume,   an outlet valve for coupling the second volume with an outlet of the pumping apparatus as long as a pressure in the second volume exceeds a pressure at the outlet, and   a control unit adapted to control the inlet pressure to be in a given pressure proportion to the pressure at the outlet.   
   
   
       2 . The pumping apparatus of  claim 1 , wherein:
 a first effective area of the piston facing the first volume is in a given area proportion to a second effective area of the piston facing the second volume, wherein the first effective area is opposing the second effective area, and the first effective area is greater than the second effective area of the piston, so that a force required to move the piston into the first directions is partly compensated.   
   
   
       3 . The pumping apparatus of  claim 1 , wherein the first volume receives liquid at an inlet pressure, comprising at least one of:
 the pressure proportion of the inlet pressure to the outlet pressure is selected essentially in accordance to the area proportion of second are to the first effective area;   an inlet coupled to the first volume for receiving liquid at the inlet pressure;   a first pressure sensor adapted for sensing a value indicative of the inlet pressure;   a second pressure sensor adapted for sensing a value indicative of the pressure at the outlet;   an inlet pump coupled to at least one of the first volume and the second volume and is adapted to provide liquid thereto at the inlet pressure;   the inlet pump comprises at least one of a piston pump, a gear pump, a hydraulic pump, a pneumatic pump.   
   
   
       4 . The pumping apparatus of  claim 1 , comprising at least one of:
 one side of the piston provides a first effective area facing the first volume, and an opposing side of the piston provides a second effective area facing the second volume;   the side of the piston facing the second volume is coupled via a piston rod to a drive,   a drive coupled to the piston adapted for reciprocating the piston;   a return mechanism, coupled to the piston, being adapted for counteracting against the movement of the piston into a first direction and to apply a force onto the piston in order to move the piston into a second direction opposite to the first direction.   a drive seal adapted for sealing the pump working chamber against the drive;   a seal adapted for sealing the first volume against the second volume;   the drive comprises at least one of a spindle drive mechanism, a linear motor, a stepper motor, a DC-Motor, a VR-Motor; a driving rod coupled to the piston;   the return mechanism comprises at least one of a spring, a hydraulic cylinder, a drive mechanism, a deflection mechanism, a return rod coupled to the piston;   the coupling comprises a coupling valve for coupling the first volume with the second volume as long as a pressure in the first volume exceeds a pressure in the second volume.   
   
   
       5 . The pumping apparatus of  claim 1 , comprising at least one of:
 the inlet pressure is in the range of 100 to 1000 bar, preferably between 300 and 700 bar, and more preferably about 600 bar;   the achievable outlet pressure is in the range of 500 to 2000 bar, preferably between 800 and 1500 bar, and more preferably about 1200 bar;   a flow rate of the liquid at the outlet is in the range of nanoliter per minute to milliliter per minute, and more preferably in the range of microliter per minute to milliliter per minute.   
   
   
       6 . The pumping apparatus of  claim 1 , further comprising
 a second pumping apparatus of  claim 1 ,   wherein the first and the second pumping apparatus are coupled in a parallel manner, with an inlet of the first pumping apparatus being coupled to an inlet of the second pumping apparatus, and an outlet of the first pumping apparatus being coupled to an outlet of the second pumping apparatus, thus providing an outlet of the pump.   
   
   
       7 . The pumping apparatus of  claim 6 , comprising at least one of:
 a liquid outlet of the first pumping apparatus is phase shifted, preferably essentially 180 degrees, with respect to a liquid outlet of the second pumping apparatus;   the first and the second pumping apparatus have a common first volume in a common pump working chamber.   
   
   
       8 . A fluid separation system, comprising
 a separating device comprising a stationary phase for separating compounds of a sample fluid comprised in a mobile phase, and   a pumping apparatus of  claim 1 , adapted for driving a mobile phase through the separating device.   
   
   
       9 . The separation system of  claim 8 , comprising at least one of:
 a sampling unit adapted for introducing the sample fluid to the mobile phase,   a detector adapted for detecting separated compounds of the sample fluid,   a fractionating unit adapted for outputting separated compounds of the sample fluid.   
   
   
       10 . A method of delivering liquid at a high pressure at which compressibility of the liquid becomes noticeable, comprising
 reciprocating a piston in a pump working chamber, wherein a movement of the piston into a first direction decreases a first volume in the pump working chamber and increases a second volume in the pump working chamber, and a movement of the piston into a second direction opposite to the first directions increases the first volume and decreases the second volume,   coupling the first volume with the second volume as long as a pressure in the first volume exceeds a pressure in the second volume,   coupling the second volume with an outlet of the pumping apparatus as long as a pressure in the second volume exceeds a pressure at the outlet, and   controlling the inlet pressure to be in a given pressure proportion to the pressure at the outlet.   
   
   
       11 . A software product, embodied on a computer readable medium, for executing the control of the piston movement and for controlling the inlet pressure to be in a given pressure proportion to the pressure at the outlet in the method of  claim 10 , when run on a data processing system.