| 摘要 |
<p>820,591. Detecting icing conditions. NATIONAL RESEARCH COUNCIL. May 15, 1957 [May 24, 1956], No. 15419/57. Class 97(3) [Also in Group XXXIII] A device for detecting icing conditions at a surface comprises two orifice type probes extending outwardly from the surface one being continuously heated to prevent ice formation, each probe being connected to a vacuum source through a pneumatic resistance, and a pressure operated switch connected between the probes for operation if the pressure in the unheated probe falls a predetermined amount. The form shown has identical probes 1 and 2, the former being heated by a coil 16 energized from the source 20. The probes may be as described in Specification 739,527 and have orifices 18 and baffles 3. They are connected through water traps 4, 5 to pipes 8, 9, containing adjustable orifices 10, 11, to a source of vacuum. The pipes 8, 9 are connected to spaces 21, 22 on either side of a diaphragm 28. If the probe 2 is blocked by ice the pressure in the space 22 falls and the diaphragm is deflected to close contacts 24, 25 and give a warning indication on a lamp 13 and energize a heating coil 17 for the probe 2. The circuit of the lamp 13 may also include a relay for operating the main de-icing equipment, e.g. of a helicopter.</p> |
