Pressure-based fluid flow sensor

• US 7,647,842 B1
• Filed: 07/25/2008
• Issued: 01/19/2010
• Est. Priority Date: 07/25/2008
• Status: Expired due to Fees

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Kilian, Wayne, Morales, Gilberto, Beck, Scott Edward
• Primary Examiner(s): THOMPSON, JEWEL VERGIE
• Application Number:
  US12/180,070
• Publication Number:
  US 20100018324A1
• Time in Patent Office: 543 Days
• Field of Search: 7386142-86147
• US Class Current: 73/861.47
• CPC Class Codes: G01F 1/28 by drag-force, e.g. vane type or impact flowmeter
• CPC Class Codes: G01F 1/38 the pressure or differential pressure being measured by means of a movable element, e.g. diaphragm, piston, Bourdon tube or flexible capsule

Abstract

A volumetric fluid flow sensor (100) includes a flow channel (120) for flowing a fluid therein; and a diaphragm (110) having an outer surface within the flow channel (120). The diaphragm (110) includes at least one flow disrupting feature mechanically coupled to or emerging from the outer surface of the diaphragm (110). A sensing structure (126) is coupled to the diaphragm (110) for generating a sensing signal responsive to a pressure signal on the diaphragm (110).

Claims

1. A volumetric fluid flow sensor, comprising:

a flow channel for flowing a fluid therein;

a diaphragm having an outer surface within said flow channel, said diaphragm comprising at least one flow disrupting feature mechanically coupled to or emerging from said outer surface; and

a sensing structure coupled to said diaphragm for generating a sensing signal responsive to a pressure signal on said diaphragm.

2. The flow sensor of claim 1, wherein said sensing structure comprises a plurality of piezoresistive elements.

3. The flow sensor of claim 1, wherein said sensing structure comprises a capacitive element.

4. The flow sensor of claim 1, further comprising a substrate for supporting said flow sensor, wherein said diaphragm is formed from said substrate and said flow sensor is a monolithic device.

5. The flow sensor of claim 4, wherein said substrate comprises silicon or glass.

6. The flow sensor of claim 1, wherein said flow disrupting feature comprises a wedge.

7. The flow sensor of claim 1, wherein said flow disrupting feature comprises a moment generating geometry.

8. The flow sensor of claim 1, wherein said diaphragm and said flow disrupting feature are formed from different materials.

9. The flow sensor of claim 1, further comprising signal detection circuitry coupled to receive said sensing signal operable for determining a flow rate of said fluid from said sensing signal.

10. The flow sensor of claim 1, wherein said sensing structure comprises a plurality of piezoresistive elements, further comprising a plurality of bond pads coupled to each of said plurality of piezoresistive elements, wherein said plurality of bond pads are outside said flow channel.

11. A method for sensing a volumetric flow of a fluid, comprising:

flowing a fluid over a diaphragm having an outer surface within a flow channel, wherein said diaphragm comprises at least one flow disrupting feature mechanically coupled to or emerging from said outer surface;

generating a sensing signal responsive to a pressure signal from a portion of said diaphragm, and

determining a flow rate of said fluid from said sensing signal.

12. The method of claim 11, wherein said sensing signal is an electrical signal provided by a piezoresistive sensing structure.

13. The method of claim 11, wherein said flow disrupting feature partially obstructs a flow of said fluid to create a pressure differential between opposite sides of said diaphragm, along a direction of said flow.

14. The method of claim 11, wherein said flow disrupting feature deflects said flow of said fluid to produce a force on said diaphragm.