Gas flow metering

• US 4,484,479 A
• Filed: 04/05/1978
• Issued: 11/27/1984
• Est. Priority Date: 04/05/1978
• Status: Expired due to Term

• Current Assignee: Eckhardt, Richard
• Original Assignee: Eckhardt, Richard
• Inventors: Eckhardt, Richard
• Primary Examiner(s): Yasich, Daniel M.
• Application Number:
  US05/893,679
• Time in Patent Office: 2,428 Days
• Field of Search: 73/205 R, 73/211, 73/715, 73/730, 73/724, 73/213, 73/861.63, 73/861.61, 73/861.71, 73/861.47, 73/861.53, 361/285, 361/283
• US Class Current: 73/861.47
• CPC Class Codes: G01F 1/383 with electrical or electro-mechanical indication
• CPC Class Codes: G01F 1/56 by using electric or magnetic effects G01F1/66 takes precedence
• CPC Class Codes: G01L 9/0005 using variations in capacitance G01L9/0072 takes precedence

Abstract

Gas flow metering using a capacitance measurement and comprising a taut elastomeric membrane, preferably tubular in form, which expands or contracts as a function of flow rate past it to an extent determined by Bernouilli'"'"'s principle. The thus changing distance between this membrane and one or more external electrodes measured by capacitance change or other means is correlatable with the instantaneous flow rate and such measurement can be made essentially without regard to entrained solids or liquids in the gas flow, phase and temperature changes (moderate) within the gas flow or mixture or changing composition therein and with rapid response and low back pressure.

Claims

1. Flow metering instrument comprising a casing, a a tubular flow through passage in said casing, a membrane stretched taut in said flow passage and arranged to deflect in accordance with flow back pressure changes to an extent in accordance with Bernouilli'"'"'s principle,

means on the interior of said casing providing a signal directly responsive to the deflection of the membrane by measuring capacitance change,

means defining a conductive surface on said stretched membrane,

said signal providing means comprising means defining a capacitive gap between said means on the interior of said casing and the said conductive surface,

whereby the said deflection of the membrane will vary the size of the capacitive gap and thereby vary an electrical signal obtainable through use of said gap.

4. Flow metering instrument in accordance with claim 1, wherein two fixed electrodes are provided in opposing relation to said conductive membrane surface.

5. Flow metering instrument in accordance with claim 4 wherein the membrane is pretensioned so that in the absence of flow induced back pressure drop the membrane would touch said electrodes and is deflected to be spaced therefrom by such drop.

6. Flow metering instrument in accordance with any of claims 1 and 3 wherein the membrane comprises longitudinal folds to establish its expansion and contraction capability.

7. Flow metering instrument in accordance with claim 6 wherein the membrane has transverse (to membrane tensioning direction) end folds to relieve lengthwise tension as the membrane expands and contracts.

2. Flow metering instrument comprising a casing, a flow through passage in said casing, a tubular membrane stretched taut therein and arranged to deflect inwardly to an extent in accordance with flow back pressure changes within the tube in accordance with Bernouilli'"'"'s principle,

means mounted on the interior of said casing,

means for establishing a capacitive gap between said means on the interior said casing and a portion of said tubular membrane therein,

said portion of the tubular membrane being electrically conductive,

whereby the said deflection of the membrane will vary the size of the capacitive gap and thereby vary an electrical signal obtainable through use of said gap.

3. Flow metering instrument in accordance with claim 2 wherein a central core is provided within the tubular membrane defining a flow passage therebetween.