Pumps – Motor driven – Electric or magnetic motor
Reexamination Certificate
1999-05-28
2001-05-22
Thorpe, Timothy S. (Department: 3746)
Pumps
Motor driven
Electric or magnetic motor
C417S360000
Reexamination Certificate
active
06234771
ABSTRACT:
STATEMENT OF FEDERALLY SPONSORED RESEARCH
Not Applicable
BACKGROUND OF THE INVENTION
Pumps are used to dispense and aspirate fluids. When it is desirable to repeatedly dispense and/or aspirate small quantities of fluid, the pump must be made to provide precise dispensing and aspirating operations. Pumps typically comprise many pieces, which make the pump difficult to manufacture and assemble. Additionally, the multiple pieces have varying tolerances that affect the accuracy and precision of the pump.
Sanwa Tsusho Co., LTD. Tokyo, Japan produces a micro pump. The pump of Sanwa Tsusho Co., LTD. has a piston seal that includes a washing port, does not include an anti-backlash follower and does not include a manual adjustment for changing the position of the piston within the pump.
It would be desirable to have a precision pump which includes a minimal amount of parts, which is simple to manufacture and assemble, and which provides a high degree of accuracy for a large number of aspirating and/or dispensing operations.
SUMMARY OF THE INVENTION
A precision pumping device for aspirating and dispensing different volumes of fluid is presented. The precision pumping device comprises a housing with integral anti-rotation guides, a stepper motor which drives a fine pitch lead screw, a coupling for linking the piston to the leadscrew, an anti-backlash leadscrew follower, a split hub clamp nut, and a nut for securing the chamber to the housing. A seal is provided which seals around the piston and against the chamber, as is an o-ring that is set into a groove in the chamber and seals against a flange of the seal. A piston is driven into and out of a cooperating chamber to provide aspirating and dispensing of fluids. By way of the anti-rotation guides, the fine pitch leadscrew, the anti-backlash leadscrew follower, and other parts of the pump, precise volumes of fluid are aspirated and dispensed. The precision pumping device may further include sets of cooperating pistons and chambers of different sizes for aspirating and dispensing different volumes of fluid. The chamber can include a single port or multiple ports. Due to the self-aligning features and the reduced number of parts, the pump can be easily changed from precisely aspirating and dispensing a first volume of fluid to precisely aspirating and dispensing a second volume of fluid.
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Sanwa Tsusho Co., Ltd., Tokyo, Japan, Micro Pumps OEM Models, Jun. 16, 1998.
Carey Glen A.
Downing William R.
Lapeus David J.
Richey Randi L.
Whitesel Mary Beth
Bayer Corporation
Solak Timothy P
Thorpe Timothy S.
Weingarten, Schurgin Gagnebin & Hayes LLP
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