Airflow sensor for filter blockage detection

• US 7,726,186 B2
• Filed: 07/19/2006
• Issued: 06/01/2010
• Est. Priority Date: 07/19/2006
• Status: Expired due to Fees

• Current Assignee: Degree Controls, Inc. (Nova Holdings LLC)
• Original Assignee: Degree Controls, Inc. (Nova Holdings LLC)
• Inventors: Nair, Rajesh M.
• Primary Examiner(s): PATEL, HARSHAD R
• Application Number:
  US11/458,630
• Publication Number:
  US 20080198896A1
• Time in Patent Office: 1,413 Days
• Field of Search: None
• US Class Current: 73/204.25
• CPC Class Codes: G01F 1/684 Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
• CPC Class Codes: H01L 23/34 Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements thermal treatment apparatus H01L21/00
• CPC Class Codes: H01L 23/467 by flowing gases, e.g. air H01L23/473 takes precedence
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H05K 7/207 Thermal management, e.g. cabinet temperature control
• CPC Class Codes: H05K 7/20736 within cabinets for removing heat from server blades

Abstract

A thermal management system includes an airflow sensor that measures airflow in an air path inside an enclosure to be cooled, wherein the air path includes a filter and a fan. A controller is responsive to the airflow sensor for monitoring the rate of airflow inside the enclosure and determining the condition of the filter. In one embodiment, the airflow sensor is an active type sensor, such as a thermistor, disposed on circuit boards. In further embodiments, the airflow sensor is disposed proximate a tube through the filter.

Claims

1. A thermal management system comprising:

an active airflow sensor that measures airflow in an air path inside an enclosure to be cooled, wherein the air path includes a filter and a fan, and wherein the active airflow sensor is intergrated with the filter, a separate sensor to measure airflow through the filter;

a separate sensor to measure airflow through the filter; and

a controller responsive to the airflow sensor for monitoring the measured airflow inside the enclosure and determining the condition of the filter, wherein the active airflow sensor provides airflow information to the controller that determines when the filter should be replaced, and wherein the controller initiates a graceful shut down of electronics within the enclosure as a function of measured airflow.

2. The thermal management system of claim 1 wherein the active airflow sensor measures airflow through a tube through the filter.

3. The thermal management system of claim 2 wherein the tube is integrated with the filter.

4. The thermal management system of claim 3 wherein the tube is approximately 1 mm in diameter.

5. The thermal management system of claim 3 wherein airflow through the tube does not significantly adversely affect the air quality within the enclosure.

6. The thermal management system of claim 2 wherein the active airflow sensor comprises a heated thermistor.

7. The thermal management system of claim 1 wherein the active airflow sensor is mounted on a circuit board within the enclosure.

8. The thermal management system of claim 1 wherein the airflow sensor communicates with the controller via wired or wireless connection.

9. A thermal management system comprising:

an airflow path inside an enclosure to be cooled, wherein the air path includes a filter and a fan;

an airflow sensor disposed within the filter to measure airflow inside the enclosure;

a second sensor supported within the enclosure to measure airflow through the filter; and

a controller responsive to the airflow sensor and second sensor for monitoring the measured airflow inside the enclosure and determining the condition of the filter.

10. The thermal management system of claim 9 and further comprising a tube through the filter, wherein the airflow sensor is disposed to measure airflow through the tube.

11. The thermal management system of claim 10 wherein the tube is integrated with the filter.

12. The thermal management system of claim 11 wherein the tube is approximately 1 mm in diameter.

13. The thermal management system of claim 11 wherein airflow through the tube does not significantly adversely affect the air quality within the enclosure.

14. The thermal management system of claim 9 wherein the airflow sensor comprises a temperature dependent resistive device.

15. The thermal management system of claim 9 wherein the airflow sensor provides airflow information to the controller that determines when the filter should be replaced.

16. The thermal management system of claim 15 wherein the controller initiates a graceful shut down of electronics within the enclosure as a function of measured airflow.

17. A filter for an air path of an enclosure to be cooled by moving air, the filter comprising:

a tube disposed through the filter for providing a laminar air path through the filter;

an active airflow sensor coupled to the tube that provides a signal representative of airflow through the filter;

a second sensor supported within the enclosure to measure airflow through the filter; and

a controller responsive to the airflow sensor and second sensor for determining the condition of the filter.

18. A filter for a laminar flow air path of an enclosure to be cooled by moving air, the filter comprising:

a filter assembly formed to fit in the laminar flow air path of the enclosure;

a first sensor supported by the filter assembly that detects a difference in pressure across the filter;

a second active sensor supported by the filter assembly that detects airflow through the filter; and

a controller supported by the filter assembly responsive to the first and second sensors for monitoring the rate of airflow inside the enclosure and determining the condition of the filter.

19. The filter of claim 18 wherein the condition of the filter is a function of the ratio of the difference in pressure to the airflow.