DETECTION OF AIR FILTER CLOGGING AND PROVISION OF EMERGENCY VENTILATION IN AN OUTDOOR ELECTRONICS CABINET COOLED BY AMBIENT FORCED AIR

• US 20080316038A1
• Filed: 06/22/2007
• Published: 12/25/2008
• Est. Priority Date: 06/22/2007
• Status: Active Grant

• Current Assignee: CommScope Technologies, LLC (CommScope Holding Company, Inc.)
• Original Assignee: Andrew LLC (CommScope Holding Company, Inc.)
• Inventors: Palaszewski, Stephen
• Granted Patent: US 7,714,731 B2
• Time in Patent Office: Days
• US Class Current: 340/584
• CPC Class Codes: H05K 7/20181 Filters; Louvers
• CPC Class Codes: H05K 7/207 Thermal management, e.g. cabinet temperature control

Abstract

A detection mechanism for monitoring airflow in an electronics enclosure that has an interior space cooled with forced ambient air, includes a first thermal sensor positioned proximate the enclosure for measuring an ambient air temperature. A second thermal sensor is positioned proximate an exit air stream of the enclosure for measuring the temperature of air that is heated by the electronics in the enclosure. A control circuit is coupled with the first and second thermal sensors and is configured for receiving output signals from the thermal sensors and determining a temperature differential between the measured temperatures. The control circuit initiates an alarm when the temperature differential exceeds a setpoint thereby indicating restricted airflow in the enclosure. Other remedial steps might also be taken prior to initiating the alarm. The cabinet ventilation system prevents equipment thermal shutdown, even in the event of restricted airflow by allowing cool ambient air to be drawn into the lower screens, located in the rear of the cabinet by natural convection. This air absorbs heat from the electronics and exits the cabinet through the upper screens, thus providing sufficient cabinet ventilation to prevent the electronics from overheating.

Claims

1. A detection mechanism for monitoring airflow in an enclosure that has an interior space housing electronics cooled with forced ambient air, the detection mechanism comprising:

a first thermal sensor positioned proximate the enclosure for measuring an ambient air temperature;

a second thermal sensor positioned proximate an exit air stream of the enclosure for measuring the temperature of air that is heated in the enclosure;

a control circuit coupled with the first and second thermal sensors and configured for receiving output signals from the thermal sensors and determining a temperature differential between the measured temperatures;

the control circuit operable to initiating an alarm when the temperature differential exceeds a setpoint thereby indicating restricted airflow in the enclosure.

2. The detection mechanism of claim 1 further comprising an alarm device, wherein the alarm device is configured for providing an alarm that includes at least one of an aural and a visual indication to alert an observer of restricted airflow.

3. The detection mechanism of claim 1 further comprising an alarm device, wherein the alarm device is configured for providing an alarm that is visible at a monitor screen to alert an observer of restricted airflow.

4. The detection mechanism of claim 1 wherein the exit air stream is positioned in the interior space proximate to the electronics therein.

5. The detection mechanism of claim 1 wherein the exit air stream is positioned proximate to an outlet opening of the enclosure for measuring the temperature of air that is exiting the enclosure.

6. The detection mechanism of claim 1 wherein the enclosure includes at least one air intake unit for forcing air through the enclosure interior space, the control circuit coupled with the air intake unit and operable to selectively deactivate or reverse the direction of the air intake unit when the temperature differential exceeds the setpoint.

7. The detection mechanism of claim 6 wherein the control circuit selectively deactivates or reverses the direction of the air intake unit prior to initiating an alarm.

8. The detection mechanism of claim 6 wherein the control circuit includes a timer and selectively deactivates or reverses the direction of the air intake unit for a selected time and then activates or restores the forward direction of flow of the air intake unit.

9. The detection mechanism of claim 8 wherein the control circuit selectively deactivates/activates or reverses/restores the forward direction of the flow of the air intake unit multiple times prior to initiating an alarm.

10. The detection mechanism of claim 1 wherein the set point is in the range of 15°

to 40°

C.

11. The detection mechanism of claim 1 wherein the second thermal sensor is positioned proximate an exit air stream of the enclosure that produces the warmest air temperature.

12. A ventilation system for cooling the interior space of an enclosure having an inlet opening and an outlet opening, the ventilation system comprising:

at least one air intake unit positioned proximate the inlet opening in the enclosure for forcing ambient air through the enclosure and out the outlet opening;

a first thermal sensor positioned proximate the enclosure opening for measuring the ambient air temperature;

a second thermal sensor positioned proximate an exit air stream of the enclosure for measuring the temperature of air that is heated in the enclosure;

a control circuit coupled with the first and second thermal sensors and configured for receiving output signals from the thermal sensors and determining a temperature differential between the measured temperatures;

the control circuit operable for initiating an alarm from the alarm device when the temperature differential exceeds a setpoint thereby indicating restricted airflow in the enclosure.

13. The ventilation system of claim 12 further comprising an alarm device, wherein the alarm device is configured for providing an alarm that includes at least one of an aural and a visual indication to alert an observer of restricted airflow.

14. The ventilation system of claim 12 further comprising an alarm device, wherein the alarm device is configured for providing an alarm that is visible at a monitor screen to alert an observer of restricted airflow.

15. The ventilation system of claim 12 wherein the exit air stream is positioned in the interior space proximate to the electronics therein.

16. The ventilation system of claim 12 wherein the exit air stream is positioned proximate to the outlet opening of the enclosure for measuring the temperature of air that is exiting the enclosure.

17. The ventilation system of claim 12 wherein the control circuit is coupled with the air intake unit and is operable to selectively deactivate or reverse the direction of the air intake unit when the temperature differential exceeds the setpoint.

18. The ventilation system of claim 12 wherein the control circuit selectively deactivates or reverses the direction of the air intake unit prior to initiating an alarm.

19. The ventilation system of claim 18 wherein the control circuit includes a timer and selectively deactivates or reverses the direction of the air intake unit for a selected time and then activates or restores the forward direction of flow of the air intake unit.

20. The ventilation system of claim 19 wherein the control circuit selectively deactivates/activates or reverses/restores the forward direction of the flow of the air intake unit multiple times prior to initiating an alarm.

21. The ventilation system of claim 12 wherein the set point is in the range of 15°

to 40°

C.

22. An enclosure for housing electronics comprising;

a cabinet having an interior space and inlet openings into the space and outlet openings from the space;

at least one air intake unit positioned proximate the inlet openings in the cabinet for forcing ambient air through the interior space and out the outlet openings for cooling electronics in the cabinet;

a first thermal sensor positioned proximate the inlet openings for measuring the air ambient temperature;

a second thermal sensor positioned proximate an exit air stream of the cabinet for measuring the temperature of air that is heated in the cabinet;

a control circuit coupled with the first and second thermal sensors and configured for receiving output signals from the thermal sensors and determining a temperature differential between the measured temperatures;

the control circuit operable for initiating an alarm when the temperature differential exceeds a setpoint thereby indicating restricted airflow through the cabinet.

23. The enclosure of claim 22 further comprising a screen over at least an inlet opening or an outlet opening of the cabinet.

24. The enclosure of claim 22 wherein the inlet openings are located on one side of the cabinet and the outlet openings are located on an opposite side of the cabinet.

25. The enclosure of claim 22 wherein the inlet openings include multiple inlet openings that are positioned in spaced apart relation on the one side of the cabinet, and further comprising multiple air intake units positioned proximate to respective inlet openings to force air through the interior space.

26. The enclosure of claim 22 wherein the outlet openings include multiple outlet openings that are positioned in spaced apart relation on the opposite side of the cabinet, a first outlet opening positioned proximate a top of the cabinet and a second outlet opening positioned proximate a bottom of the cabinet for convectively passing air through the interior space to cool electronics in the cabinet.

27. The enclosure of claim 22 wherein the exit air stream is positioned in the interior space proximate to the electronics therein.

29. The enclosure of claim 22 further comprising an alarm device, wherein the alarm device is configured for providing an alarm that includes at least one of an aural and a visual indication to alert an observer of restricted airflow.

30. The enclosure of claim 22 further comprising an alarm device, wherein the alarm device is configured for providing an alarm that is visible at a monitor screen to alert an observer of restricted airflow.

31. The enclosure of claim 22 wherein the control circuit is coupled with the air intake unit and is operable to selectively deactivate or reverse the direction of the air intake unit when the temperature differential exceeds the setpoint.

32. The enclosure of claim 22 wherein the control circuit selectively deactivates or reverses the direction of the air intake unit prior to initiating an alarm.

33. The enclosure of claim 32 wherein the control circuit includes a timer and selectively deactivates or reverses the direction of the air intake unit for a selected time and then activates or restores the forward direction of flow of the air intake unit.

34. The enclosure of claim 33 wherein the control circuit selectively deactivates/activates or reverses/restores the forward direction of the flow of the air intake unit multiple times prior to initiating an alarm.

35. The enclosure of claim 22 wherein the set point is in the range of 15°

to 40°

C.

28. The enclosure of 22 wherein the exit air stream is positioned proximate to an outlet opening of the cabinet for measuring the temperature of air that is exiting the cabinet.