Variable area obstruction gas flow meter

• US 5,038,621 A
• Filed: 08/20/1990
• Issued: 08/13/1991
• Est. Priority Date: 11/06/1989
• Status: Expired due to Term

• Current Assignee: Bird Products Corporation (Becton, Dickinson & Co)
• Original Assignee: Bicore Monitoring Systems, Inc. (Allied Healthcare Products Incorporated)
• Inventors: Stupecky, Josef
• Primary Examiner(s): Goldstein, Herbert
• Application Number:
  US07/569,950
• Time in Patent Office: 358 Days
• Field of Search: 73/861.53, 73/861.54, 73/861.71, 73/861.74, 73/861.73, 130/45, 130/46, 128/725
• US Class Current: 73/861.53
• CPC Class Codes: A61B 5/0876 using means deflected by the fluid stream, e.g. flaps
• CPC Class Codes: G01F 1/40 Details of construction of the flow constriction devices
• CPC Class Codes: G01F 1/42 Orifices or nozzles

Abstract

A flow meter including a variable area obstruction which is mounted in a conduit. Inputs to a differential pressure transducer are positioned in the conduit on opposite sides of the obstruction to measure fluid pressure differential across the obstruction. In one embodiment, a sleeve is secured within the conduit thereof substantially separated from the conduit so as to prevent fluid condensation on the sleeve, and to create a dead end pocket between the conduit and the sleeve for collecting liquids from the conduit end preventing them from contacting the obstruction. The variable area obstruction comprises an elastic membrane that includes first, second and third leaves which extend into the flow stream and are compliant to fluid flow so that an increase in flow rate increases the deflection of the leaves and increases the through flow area through the obstruction. The first leaf is secured at a fixed end adjacent a first portion of the interior surface of the conduit and extends in a first direction to a free end preferably positioned adjacent a second portion of the interior surface of the conduit opposite the first portion. The second and third leaves are located adjacent opposite sides of the first leaf and extend from their fixed ends toward their free ends in directions which are generally opposite to the first direction.

Claims

1. A flow meter comprising:

a conduit for communicating fluids therethrough and having a first port positioned at a first location in said conduit and a second port positioned at a second location in said conduit, wherein said first and second ports are adapted for connection to a transducer;

an inner conduit surface located within the conduit and substantially insulated from influence of ambient temperature present outside the conduit, wherein said inner conduit surface prevents exposure of the second port form upstream flow and the first port from downstream flow when flow is in one direction and wherein said inner conduit surface prevents exposure of the first port from upstream flow and the second port from downstream flow when flow is in an opposite direction;

an obstruction secured within the conduit so that a variable area portion thereof lies within boundaries defined by the inner conduit surface, wherein fluid flow area through said variable area portion increases and decreases in response to corresponding increases and decreases in flow rates of fluid passing therethrough, and

a sleeve secured within said conduit so that fluids within said conduit flow through said sleeve, with a portion of said sleeve being separated from contact with the conduit and wherein said inner conduit surface comprises an inner surface of said sleeve.

2. A flow meter as defined in claim 1, wherein the sleeve is positioned with respect to the conduit so as to form a dead end pocket between the sleeve and the conduit, so that liquids on interior surfaces of the conduit will collect therein without contacting the obstruction.

3. A flow meter as defined in claim 2, wherein one of the first and second ports is located within a dad end pocket, so as to be substantially protected from fluid turbulences localized around and downstream of the obstruction.

4. A flow meter as defined in claim 2, wherein a first and second end of the sleeve extend away from the obstruction and beyond the first and second port, respectively.

5. A flow meter as defined in claim 1, further comprising:

transducer connected to the firs and second ports so as to thereby be in fluid communication with fluid flowing through the conduit, for sensing a pressure differential between said first and second ports.

6. A flow meter comprising:

a conduit for communicating fluids therethrough and having a first port positioned at a first location in said conduit and a second port positioned at a second location in said conduit, wherein said first and second ports are adapted for connection to a transducer;

an obstruction secured within the conduit having a variable area portion thereof and restricting fluid flow through said conduit such that a first fluid pressure is realized proximal to the first fluid pressure is realized proximal to the first port and a second fluid pressure is realized proximal to the second port;

an inner conduit surface located within the conduit so as to prevent substantial exposure of the first fluid pressure to the second port and to prevent substantial exposure of the second fluid pressure to the first port, said obstruction housed within boundaries defined by said inner conduit surface, and

a sleeve secured within said conduit so that fluids within said conduit flow through said sleeve, with a portion of said sleeve being separated from contact with the conduit and wherein said inner conduit surface comprises an inner surface of said sleeve.

7. A flow meter as defined in claim 6, wherein a first and second end of the sleeve extend away from the obstruction and beyond the first and second port, respectively.