Fluid dispensers

• US 6,540,486 B2
• Filed: 08/02/2001
• Issued: 04/01/2003
• Est. Priority Date: 09/20/2000
• Status: Expired due to Term

• Current Assignee: Fluid Management Incorporated, Micropump, Inc. (RELX PLC)
• Original Assignee: Fluid Management Incorporated, Micropump, Inc. (RELX PLC)
• Inventors: Martin, James, Lowan, Margaret M., Carr, Charles F., Hogan, Tim, McDermott, Susan G., Barton, Jeffrey G., Miller, William A., Amsler, Thomas J.
• Primary Examiner(s): FREAY, CHARLES GRANT
• Application Number:
  US09/920,976
• Publication Number:
  US 20020057970A1
• Time in Patent Office: 607 Days
• Field of Search: 417/53, 417/490, 417/500, 417/326, 141/168
• US Class Current: 417/53
• CPC Class Codes: G01F 11/021 of the piston type G01F11/04 takes precedence
• CPC Class Codes: G01F 11/029 provided with electric controlling means G01F11/022 and G01F11/024 take precedence
• CPC Class Codes: G01F 11/20 wherein the measuring chamber rotates or oscillates
• CPC Class Codes: G01F 11/22 for liquid or semiliquid

Abstract

A fluid dispense system having a computer control system that operatively controls a stepper motor driving a nutating pump. The stepper motor actuates the nutating pump piston through partial revolutions. The computer control system determines the number of stepper motor steps required to pump a desired amount of fluid by the nutating pump by rotating the piston through segments which are less than a full revolution.

Claims

1. A method of pumping fluid comprising the steps of:

flowing fluid to a pump having a volume output for one complete pump cycle, the pump being engaged to a stepper motor;

sensing a home position of the stepper motor;

operating the fluid pump through a segment which is less than one complete pump cycle by running the stepper motor through a predetermined number of steps; and

flowing fluid out of the fluid pump in an amount which is less than the volume output for one complete pump cycle.

2. A method of controlling a nutating pump, comprising the steps of:

dividing a dispense curve of the nutating pump into a number of segments in which each segment represents a dispense amount less than an entire dispense amount of the dispense curve;

determining a number of segments required to dispense a desired amount of fluid which is less than the entire amount of the dispense curve; and

operating the nutating pump through the determined number of segments.

3. The method of controlling a nutating pump of claim 2, further comprising the step of determining a number of steps of a stepper motor engaged with the nutating pump that corresponds to each of the segments.

4. The method of controlling a nutating pump of claim 2, wherein the dividing step further comprises dividing the dispense curve of the nutating pump into a number of substantially equal volume segments.