GB621489A - Ice detector means and de-icing means - Google Patents

Abstract

621,489. Preventing and signalling formation of ice on aircraft. BENDIX AVIATION CORPORATION. Sept. 13, 1944, No. 17533. Convention date, Aug. 11, 1943. [Class 4] [Also in Group XL (b)] Means for removing ice from aircraft or for detecting ice formation are set in action only when a predetermined thickness of ice has accumulated on an aerofoil surface. In the construction shown, embodying expansible iceremoving means comprising a boot 11 and inflatable tubes 13, 14, 15 as in Specification 621,490, the actuating means is electrically controlled by a photo-electric device including two glass rods 20, 21 between the free ends 23, 24 of which ice may accumulate and interrupt light normally passing from an electric lamp 27 along the rods to a photo-electric cell 31 connected to the grid of an electronic valve 41 through which a current normally flows to excite an electromagnet 55 controlling the deicing means 67 by holding spring contacts 65, 65A apart; on interruption of the light, the negative bias of the valve grid is increased and the valve current is diminished so that the attraction of the electromagnet is insufficient to hold open the control contacts of the deicing means which is thus brought into operation. As shown in Fig. 6, a metal sleeve 100 is secured by a flange 102 and nut 109 in an aperture of the wing so as to expose the end of an insulation member 103 mounted in the sleeve. Leads 108 and 107 of an electric control circuit for the de-icer are connected respectively to nut 109 and a metal cap 105 on the outer end of member 103, which insulates the cap from the flange 102 of the sleeve 100 ; the leads 108 and 107 will be electrically connected when ice accumulates on the insulator and allows a grid leak to be produced in the electronic valve 114 of the control circuit for the de-icer. A warning light 67A may also be shown when either of the devices shown actuates the de-icer ; or a whistle or alarm may be sounded. Reference is made to Specification 621,464 as showing a timing device for the de-icer operation.