US 4,089,624 AGranted

Controlled pumping system

AssigneeBecton, Dickinson and Company

InventorsPhilip Thorbus Nichols, Paul Jene Watts

Life of this patent

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Abstract

A pumping system for dispensing controlled and variable amounts of fluids in predetermined quantities includes a pump piston which moves axially in a pump chamber. The piston is reciprocated by a drive lead nut cooperating with a non-rotatable lead screw attached to the piston. The piston is sealed to the pump chamber by a seal element whose distance from the lead nut is fixed regardless of the position of the piston, thus protecting the seal. The rotatably driven lead nut includes a hollow driven shaft, containing lubricant, so that the lead screw is lubricated as it travels into the shaft of the lead nut. The motor for the system is a pulse operated reversible stepping motor enabling accurate output from the pump, for example, between .01 ml/min to 9.99 ml/min as controlled by the stepping motor. One motor may drive two pumps for a continuous controlled pumping system. If desired a flush mechanism may be used to rinse the piston of any pumped material which adheres to the surface.

Claims10

Dependent claims

A pumping system for dispensing controlled variable amounts of pumpable material comprising:

means forming a support housing,
a pump cylinder assembly mounted on said housing and including pump cylinder means forming a pump chamber, said pump cylinder assembly including inlet and outlet means for the material being pumped,
a pump piston and lead screw assembly mounted on said support housing for generally axial movement of the pump piston into and out of said pump chamber,
driven nut means rotatably mounted in said support housing and receiving said lead screw,
stationary seal means positioned at one end of said pump cylinder assembly and forming a fluid tight seal between said piston and pump cylinder means preventing leakage between said piston and pump chamber,
said seal means being a distance from said drive nut which remains fixed during movement of said pump piston whereby the geometry between the seal means and said pump piston is maintained the same during movement of said pump piston relative to said seal means,
said pump piston including an outer peripheral surface spaced from the opposing surface of said pump chamber and movable in sealing contact relative to said stationary seal means,
means mounted on said pump piston and lead screw assembly to prevent rotation thereof, and
motor means connected to effect rotation of said driven nut means whereby said pump piston is reciprocated relative to said pump cylinder assembly for pumping and filling said pump chamber.

6 more elements

A pump for dispensing controlled variable amounts of a pumpable material comprising:

a generally cylindrical pump housing having a pump base affixed at one end thereof and a cylinder assembly at the other end thereof,
said cylinder assembly including a pump chamber and means forming an inlet and an outlet for said chamber,
rotatable and axially fixed drive shaft means positioned within said pump base and including one end extending out of said pump base,
bearing means mounted in said pump base to support said drive shaft in rotating relation relative to said housing,
axially fixed drive nut means mounted on said drive shaft for rotation therewith,
lead screw means mounted for axial movement by said drive nut,
cylindrical pump piston means mounted for axial movement with said lead screw and movable axially into and out of said chamber to fill and discharge fluid therein,
stationary seal means mounted in said cylinder assembly and in sealing relation with said piston to prevent leakage between said piston and said pump chamber,
said piston being cylindrical and having an outer peripheral surface spaced from the opposing surface of said chamber and movable in sealing relation to said stationary seal means,
said seal means being a distance from said drive nut which remains fixed during movement of said piston whereby the geometry between said seal means and said piston is maintained the same during movement of said piston relative to said seal means, and
means to prevent rotation of said lead screw and said piston.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 05/692,897Filed 4 Jun 1976
Granted: 16 May 1978
Term ends: Not estimatedThe source records don’t support an estimate.

Classification10 codes

F04B 9/02
Piston machines or pumps characterised by the driving or driven means to or from their working members: the means being mechanical
B01L 3/0206
Burettes, i.e. for withdrawing and redistributing liquids through different conduits: of the plunger pump type
F04B 7/0007
The distribution member forming both the inlet and discharge distributor for one single pumping chamber: and having a rotating movement
F04B 17/03
Pumps characterised by combination with, or adaptation to, specific driving engines or motors: driven by electric motors