AIRFLOW SENSOR WITH PITOT TUBE FOR PRESSURE DROP REDUCTION

• US 20090139348A1
• Filed: 11/30/2007
• Published: 06/04/2009
• Est. Priority Date: 11/30/2007
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Speldrich, Jamie W.
• Granted Patent: US 7,654,157 B2
• Time in Patent Office: Days
• US Class Current: 73/861.660
• CPC Class Codes: G01F 1/46 Pitot tubes
• CPC Class Codes: G01F 1/6842 with means for influencing the fluid flow
• CPC Class Codes: G01F 5/00 Measuring a proportion of the volume flow

Abstract

An airflow sensor apparatus for measuring flow rate includes a pitot tube with a bypass channel wherein the pitot tube extends halfway into a flow channel in order to reduce a pressure drop. One or more upstream taps can be spaced along the pitot tube facing into a direction of a flow stream which directs the flow to the bypass channel. At least one or more downstream taps can be located to face perpendicular to the direction of flow, such that the fluid after passing over a flow sensor passes through the downstream tap(s). The upstream tap senses stagnation pressure and the down stream tap senses static pressure which is exerted in all directions in the flow channel in order to determine a velocity pressure based on a difference between pressures.

Claims

1. A flow sensor apparatus, comprising:

a pitot tube having a bypass channel, said pitot tube extending parallel and halfway into a flow channel with respect to the direction of flow of a fluid within said flow channel;

at least one upstream tap spaced apart along said pitot tube oriented into the direction of a fluid flowing through said flow channel thereby creating an upstream port for said bypass channel and adapted to direct said fluid to a sensor adapted to sense the flow of said fluid; and

at least one downstream tap spaced apart along said pitot tube and facing perpendicular to said direction of said fluid in order to determine a pressure difference between the pressure identified by said at least one upstream tap and the pressure identified by said at least one downstream tap.

2. The apparatus of claim 1 further comprising;

a housing including a wall that defines said pitot tube with said bypass channel through which said fluid flows.

3. The apparatus of claim 2, wherein said housing further comprises an inlet end and an outlet end and are adapted for coupling the apparatus to a flow system.

4. The apparatus of claim 1, wherein said sensor comprises a MEMS flow sensor with an upstream sensing element, a downstream sensing element and a heating element.

5. The apparatus of claim 1 wherein said pitot tube extends parallel and halfway into said flow channel minimizes obstruction to said fluid flow.

6. The apparatus of claim 1 wherein said Pitot tube has a sharp leading edge for substantially reducing turbulence.

7. A flow sensor apparatus, comprising:

a housing including a wall defining a pitot tube including a bypass channel through which fluid is enabled to flow, said pitot tube defined by said housing extending parallel and halfway into a flow channel with respect to the direction of flow of a fluid within said flow channel;

at least one upstream tap spaced apart along said pitot tube facing into the direction of a fluid flowing through said flow channel thereby creating an upstream port for said bypass channel and adapted to direct said fluid to a sensor adapted to sense the flow of said fluid; and

at least one downstream tap spaced apart along said pitot tube and facing perpendicular to said direction of said fluid in order to determine a pressure difference between a pressure identified by said at least one upstream tap and a pressure identified by said at least one downstream tap.

8. The apparatus of claim 7, wherein said housing comprises an inlet end and an outlet end and are adapted for coupling the apparatus to a flow system.

9. The apparatus of claim 7 wherein said sensor comprises a MEMS flow sensor with an upstream sensing element, a downstream sensing element and a heating element.

10. The apparatus of claim 7 wherein said pitot tube extends transversely halfway into said flow channel minimizes obstruction to said fluid flow.

11. The apparatus of claim 7 wherein said Pitot tube has a relatively sharp leading edge for substantially reducing turbulence.

12. A flow sensor apparatus, comprising:

a pitot tube having a bypass channel, said pitot tube extending transversely halfway into a flow channel with respect to the direction of flow of a fluid within said flow channel;

at least one upstream tap spaced apart along said pitot tube facing into a direction of a fluid flowing through said flow channel thereby creating an upstream port for said bypass channel and adapted to direct said fluid to a flow sensor;

a flow sensor adapted to sense the flow of said fluid from said upstream port; and

at least one downstream tap spaced apart along said pitot tube and facing perpendicular to said direction of said fluid in order to determine a velocity pressure based on a difference between a pressure identified by said at least one upstream tap and a pressure identified by said at least one downstream tap.

13. The apparatus of claim 12 further comprising;

a housing including a wall that defines said pitot tube with said bypass channel through which said fluid flows.

14. The apparatus of claim 13, wherein said housing further comprises an inlet end and an outlet end and are adapted for coupling the apparatus to a flow system.

15. The apparatus of claim 12, wherein said sensor comprises a MEMS flow sensor with an upstream sensing element, a downstream sensing element and a heating element.

16. The apparatus of claim 12 wherein said pitot tube extend parallel and halfway into said flow channel minimizes obstruction to said fluid flow.

17. The apparatus of claim 12 wherein said Pitot tube has a sharp leading edge for substantially reducing turbulence and pressure drop.

18. The apparatus of claim 14, wherein said sensor comprises a MEMS flow sensor with an upstream sensing element, a downstream sensing element and a heating element.

19. The apparatus of claim 13 wherein said pitot tube extend parallel and halfway into said flow channel minimizes obstruction to said fluid flow.

20. The apparatus of claim 19 wherein said Pitot tube has a sharp leading edge for substantially reducing turbulence and pressure drop.