Linear liquid dispensing pump for dispensing liquid in nanoliter volumes

Linear liquid dispensing pumping apparatus for dispensing liquid in a nanoliter volumes comprising:

• a rotary/reciprocating liquid dispensing pump, said pump comprising:
• a relatively stationary pump housing having means defining a smooth elongated cylindrical bore sealable closed at one end of said housing, a cylindrical piston having an outside diameter slightly less than that of said bore and sealably, slidably and rotatably mounted in said cylindrical bore and defining with said housing at said sealed end, a sealed pumping chamber,
• at least two circumferentially spaced, ports within said housing opening to said bore at longitudinally aligned, circumferentially spaced positions, means for supplying a liquid to be dispensed to one of said ports, said other of said at least two ports acting to discharge liquid from said pumping chamber, said cylindrical piston including in an axial end face proximate to the pumping chamber a narrow radial slot extending longitudinally away from the pumping chamber and opening to the outer periphery of the piston and selectively alignable with said two ports, said apparatus further comprising:
• a frame coupled to said pump, axially aligned therewith and projecting to one side of said pump, a stepping motor, carried by said frame, said stepping motor including a relatively fixed stator and a hollow tubular rotor coaxial with said pump piston including an integral hollow tubular rotor shaft, and axially aligned therewith, a lead screw positioned coaxially within said stepping motor hollow tubular rotor shaft, threadably engaged therewith, and axially aligned with said pump piston, an electromagnetic clutch/braking mechanism carried by said frame to one side of said stepping motor, concentrically surrounding said lead screw for selectively operatably coupling said lead screw to said stepping motor tubular rotor shaft, a flexible coupling connecting an end of said lead screw proximate to said pump to said slidably and rotatably mounted piston, an anti-backlash assembly operatively coupling said stepping motor rotor to said lead screw, means for driving said stepping motor tubular rotor shaft incrementally, and means for energizing said electromagnetic clutch/braking mechanism to effect selective, incremental rotation of said cylindrical piston and axial reciprocation thereof bidirectionally for delivery of a liquid to be dispensed in nanoliter amounts to said other of said at least two ports.

Linear liquid dispensing pumping apparatus for dispensing liquid in a nanoliter volumes comprising:

• a rotary/reciprocating liquid dispensing pump, said pump comprising:
• a relatively stationary pump housing having means defining a smooth elongated cylindrical bore sealable closed at one end of said housing, a cylindrical piston having an outside diameter slightly less than that of said bore and sealably, slidably and rotatably mounted in said cylindrical bore and defining with said housing at said sealed end, a sealed pumping chamber,
• at least two circumferentially spaced, ports within said housing opening to said bore at longitudinally aligned, circumferentially spaced positions, means for supplying a liquid to be dispensed to one of said ports, said other of said at least two ports acting to discharge liquid from said pumping chamber, said cylindrical piston including in an axial end face proximate to the pumping chamber a narrow radial slot extending longitudinally away from the pumping chamber and opening to the outer periphery of the piston and selectively alignable with said two ports, said apparatus further comprising:
• a frame coupled to said pump, axially aligned therewith and projecting to one side of said pump, a motor, carried by said frame, said motor including a relatively fixed stator and a hollow tubular rotor coaxial with said pump piston including an integral hollow tubular rotor shaft, and axially aligned therewith, a lead screw positioned coaxially within said motor hollow tubular rotor shaft, threadably engaged therewith, and axially aligned with said pump piston, an electromagnetic clutch/braking mechanism carried by said frame to one side of said motor, concentrically surrounding said lead screw for selectively operatably coupling said lead screw to said motor tubular rotor shaft, a flexible coupling connecting an end of said lead screw proximate to said pump to said slidably and rotatably mounted piston, an anti-backlash assembly operatively coupling said motor rotor to said lead screw, means for driving said motor tubular rotor shaft, and means for energizing said electromagnetic clutch/braking mechanism to effect selective, controlled rotation of said cylindrical piston and axial reciprocation thereof bidirectionally for delivery of a liquid to be dispensed in nanoliter amounts to said other of said at least two ports.