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Robust, Low-Cost, and Highly Sensitive Means to Detect Presence of Air Flow and Direction

IP.com Disclosure Number: IPCOM000117152D
Original Publication Date: 1996-Jan-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Kang, SS: AUTHOR [+2]

Abstract

In air cooling of electronic systems, it sometimes becomes important to know if air flow is present at some location, and the direction in which the air is flowing. The concept disclosed is a low-cost and very sensitive detector that can be placed in a critical air flow path to detect if the air flow has stopped or reversed direction so as to alert the system/user of a potential overheating hazard.

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Robust, Low-Cost, and Highly Sensitive Means to Detect Presence of
Air Flow and Direction

      In air cooling of electronic systems, it sometimes becomes
important to know if air flow is present at some location, and the
direction in which the air is flowing.  The concept disclosed is a
low-cost and very sensitive detector that can be placed in a critical
air flow path to detect if the air flow has stopped or reversed
direction so as to alert the system/user of a potential overheating
hazard.

      The Figure shows the sensor which consists of a detector part
and a signal conditioning part.  The detector part contains three
elements:  a heat source 1 (e.g., an electrically heated resistor)
and two sensitive temperature sensors 2,3 such as thermistors.  The
temperature sensors are located symmetrically about the heater and
aligned along the direction of air flow.  When air flow is present
and in the forward direction, temperature sensor 3, washed by heated
air, is at a higher temperature than sensor 2.  When the air flow is
reduced to zero, both sensors 2 and 3 are at the same temperature.
If air flow direction is reversed, temperature sensor 2 is at a
higher temperature than sensor 3.  The temperature difference between
sensors 2 and 3 provides a very sensitive means to determine the
presence of and the direction of the air flow.  This low-cost and
rugged sensor is able to respond to very low air speeds that would
challenge the measurement capabilities of...