Browse Prior Art Database

Solid State Air Flow Switch

IP.com Disclosure Number: IPCOM000079151D
Original Publication Date: 1973-May-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

O'Toole, JF: AUTHOR

Abstract

Fluid flow responsive switches are useful in monitoring the operation of systems, wherein the presence or absence of fluid flow may be critical. For example, in air-cooled machines, loss of flow of cooling air may require immediate action. In monitoring devices of this kind, a device which is simple and sturdy and yet sensitive is desirable.

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Solid State Air Flow Switch

Fluid flow responsive switches are useful in monitoring the operation of systems, wherein the presence or absence of fluid flow may be critical. For example, in air-cooled machines, loss of flow of cooling air may require immediate action. In monitoring devices of this kind, a device which is simple and sturdy and yet sensitive is desirable.

As seen in side view Fig. 1 and end view Fig. 2, this fluid flow responsive switch has a body 10 adapted to project into the air stream 12-12 to be monitored. Body 10 has an inlet port 14 and a pair of outlets ports 16-16. Port 14 communicates via la and ports 16 communicate via 20 to opposite sides of tape 22 in pressure chamber 24. Tape 22 is of low friction, elastically yieldably sheet material which is readily deformed to the position shown in cavity 24, when the pressure differential at 14, 16 resulting from air flow 12 past 10 is communicated via 18, 20 to chamber 24.

One end of tape 22 is anchored by block 26 in 10. The other end is free to move in slot 28 as 22 moves from the position shown in Fig. 1 to its normal set, parallel to surface 30, when air flow 12 decreases below a critical velocity. Tape 22 is opaque except for a transparent window 32. Body 10 mounts a light- emitting diode 34 and a phototransistor 36 in alignment with the position of window 32 when 22 is deformed as in Fig. 1. When 22 returns to its normal set position in the absence of air flow, the end of 22 moves to the lef...