Low pressure low volume liquid pump

• US 5,547,351 A
• Filed: 03/01/1994
• Issued: 08/20/1996
• Est. Priority Date: 03/01/1994
• Status: Expired due to Term

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: United States Department Of Health And Human Services
• Inventors: Hanus, James P.
• Primary Examiner(s): Gluck, Richard E.
• Application Number:
  US08/203,781
• Time in Patent Office: 903 Days
• Field of Search: 417/386, 417/387, 417/395, 417/DIG. 1
• US Class Current: 417/386
• CPC Class Codes: F04B 43/067 the fluid being actuated directly by a piston
• CPC Class Codes: G01N 13/00 Investigating surface or boundary effects, e.g. wetting power; Investigating diffusion effects; Analysing materials by determining surface, boundary, or diffusion effects scanning-probe techniques or apparatus G01Q
• CPC Class Codes: G01N 35/1095 for supplying the samples to flow-through analysers for a specific analyser see relevant groups, e.g. under G01N15/00, G01N21/00, G01N27/00, G01N30/00, H01J49/00
• CPC Class Codes: Y10S 417/01 Materials digest

Abstract

A diaphragm pump which provides a low internal volume and minimizes volume contributions for applications which require the transfer of fluid volumes on the order of one to several microliters. The pump includes a plunger which reciprocates within a bore and applies fluid pressure to a diaphragm of a head cavity that is connected to the cylinder bore. Hydraulic feed and vent passages connect to the cylinder bore at a point where the end of the plunger passes during reciprocal movement to ensure that the amount of hydraulic fluid within the cylinder bore is consistent during each stroke of the plunger. The pump is particularly useful for supplying receptor media to a Franz cell.

Claims

1. A diaphragm pump which comprises:

a cylinder block having a cylinder bore formed therein;

a plunger provided in said cylinder bore for reciprocal movement therein, said plunger having an end which remains within said cylinder bore during the reciprocal movement;

a diaphragm which defines a deformable wall of a head cavity, said diaphragm being in fluid communication with said cylinder bore whereby fluid pressures within said cylinder bore act on said diaphragm to cause movement thereof;

two hydraulic fluid passages which connect to said cylinder bore at a common point at which said end of said plunger passes during the reciprocal movement thereof, whereby said plunger closes said two hydraulic fluid passages periodically during reciprocal movement of said plunger;

inlet and outlet fluid passages connected to said head cavity; and

check valves provided in said inlet and outlet fluid passages.

2. A diaphragm pump which comprises:

a cylinder block having a cylinder bore formed therein;

a plunger provided in said cylinder bore for reciprocal movement therein, said plunger having an end which remains within said cylinder bore during the reciprocal movement;

a diaphragm which defines a deformable wall of a head cavity, said diaphragm being in fluid communication with said cylinder bore whereby fluid pressures within said cylinder bore act on said diaphragm to cause movement thereof;

at least one hydraulic fluid passage connected to said cylinder bore for supplying hydraulic fluid therein, said at least on hydraulic fluid passage being connected to said cylinder bore at a location at which said end of said plunger passes during the reciprocal movement thereof, whereby said plunger closes said at least one hydraulic fluid passage periodically during reciprocal movement of said plunger;

a hydraulic fluid reservoir for storing a hydraulic fluid, said at least one hydraulic fluid passage being in fluid communication with said hydraulic fluid reservoir;

a coaxial well provided at an upper portion of said cylinder bore, said well being connected by a fluid passage to an upper portion of said hydraulic fluid reservoir;

inlet and outlet fluid passages connected to said head cavity; and

check valves provided in said inlet and outlet fluid passages.