Michael S Shepard

US Patent:

47386657, Apr 19, 1988

Filed:

Sep 27, 1985

Appl. No.:

6/781010

Inventors:

Michael H. Shepard - Cockeysville MD

Assignee:

Hall Hill Co. - Houston TX

International Classification:

A61M 500

US Classification:

604248

Abstract:

A method and an apparatus for controlling the flow rate of a fluid are disclosed. Fluid is flowed through an elongated passage having a small cross-sectional area to control the flow rate thereof. The length of the elongated passage through which the fluid is flowed is changed in a predetermined manner to change the flow rate of fluid. The apparatus comprises a first member having a spiral shaped elongated groove with a small cross-sectional area formed in a surface thereof and a second member having a surface overlying the groove to form the elongated passage for controlling the flow rate of the fluid. A second groove having a substantially larger cross-sectional area than the elongated passage is formed in the surface of the second member and configured such that it can be selectively placed in communication with spaced locations of said first groove thereby effectively bypassing a portion of the elongated passage and changing the length of the elongated passage through which the fluid is flowed whereby the flow rate of fluid flowed through the elongated passage is changed. The relative position of the first and second members is changed to adjust the length of the elongated passage which is bypassed.