The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 26, 1999
Filed:
Dec. 29, 1998
Howard L North, Jr, Los Gatos, CA (US);
Other;
Abstract
A liquid supply system including a diaphragm pump, a novel liquid accumulator providing exceptionally high volume compliance, and a control of accumulator volume within narrow limits by continuous control of the pump motor. The accumulator achieves high volume compliance by arranging the kinematics of a main spring loading the accumulator to have a negative spring rate equal to the sum of all other positive spring rates produced by a second spring used to adjust the accumulator pressure, by the diaphragm, and by a pivot for a sensor lever. This lever moves with the diaphragm to actuate an optical sensor producing an signal indicative of small changes in liquid volume in the accumulator. This signal continuously modulates the power to the motor driving the pump so as to maintain the accumulator volume lose to a datum valve. This close control of liquid volume in a high compliance accumulator provides substantially pulse-free constant pressure liquid delivery from a pulsatile pump. The second spring may be adjusted to modify this constant pressure without disturbing the balance between positive and negative spring rates. Adjustment may be automatic in response to a variable such as liquid temperature whereby liquid pressure is automatically increased with lower liquid temperature to maintain liquid flow substantially constant through a flow cytometry apparatus used for particle analysis.