Aeronautics and astronautics – Aircraft structure – Ice prevention
Patent
1985-02-21
1986-12-16
Barefoot, Galen
Aeronautics and astronautics
Aircraft structure
Ice prevention
B64D 1516, B64D 1500
Patent
active
046291490
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to de-icing and more particularly, but not exclusively, concerns de-icing of surface components of aircraft.
As used herein, the term "ice" and cognate expressions should be taken to refer primarily, but not exclusively, to water in its solid state. The present invention may have application to, for example, certain industrial processes, the operation of which is hindered by build-up of a layer of a crystalline substance on a wall surface of process plant, such build-up being analogous to the build-up of ice on the surface components of aircraft.
BACKGROUND ART
British Patent Application No. 2105520A discloses an electro-mechanical aircraft de-icer in which an electrical coil induces electro-magnetic impulses within a metal plate secured through a compliant spacing layer to the surface to be de-iced. The de-icer requires the use of high voltages and high energy special purpose capacitors and components such as thyristors and diodes which operate at the necessary high voltage and handle large currents for short periods. The high voltage brings difficulties with electrical insulation, weight and space requirements. None of this is desirable in aircraft, and one object of the present invention is to employ, for de-icing, voltages which are lower than those previously proposed.
British Patent Specifications Nos. 1222151 and 1369350 are earlier publications which, in common with 2105520A, proposed to induce electro-magnetic impulses within the sheath or skin of an aircraft. They therefore suffer from the same disadvantages.
DISCLOSURE OF INVENTION
According to a first aspect of the present invention there is provided a method of de-icing an exposed surface of a resilient sheet member, which method comprises the steps of:
i. applying a force to the sheet member to displace it relatively slowly from a relaxed disposition to an elastically loaded disposition;
ii. abruptly removing the said force to allow the sheet member to return to the relaxed disposition at a relatively fast rate of displacement for de-icing the sheet member; and
iii. repeating steps (i) and (ii) for as long as de-icing is required.
According to a second aspect of the present invention there is provided apparatus for de-icing an exposed surface of a resilient sheet member comprising means for applying a force to the sheet member to displace it relatively slowly from a relaxed disposition to an elastically loaded disposition, means to remove abruptly the said force to allow the sheet member to return to the relaxed disposition at a relatively fast rate of displacement for de-icing the sheet member; and means for effecting the said force application and removal repeatedly for as long as de-icing is required.
The actuator is conveniently an iron-cored solenoid. The sophistication of control of the movement of the core will vary with embodiments of the invention, as is illustrated hereinbelow.
It will be appreciated that ice is dislodged from the exposed surface of the sheet member more by the sudden relaxing movement of the sheet which follows removal of the force than by the flexing of the sheet, away from its relaxed disposition, under the action of the applied mechanical force. It will also be appreciated that it is the application of the flexing force in a gradual manner and over a relatively lengthy period of time which allows low voltages to be used instead of the high voltages needed to generate a sudden, impulsive flexing of the sheet member.
Normally, in use of the invention, an aircraft will be fitted with a plurality of the actuators. When more than one actuator operates on a single sheet member, means would be provided to cause the operation of the actuators to complement, rather than conflict with, one another.
Feedback elements can be provided, as thought desirable, to monitor and complement de-icing performance and to detect faults. Useful as feedback elements are pressure sensors on the actuator, sensors of electrical current in the actuator and strain sensors to measure sheet displacem
REFERENCES:
patent: 2297951 (1942-10-01), Frank
patent: 2675456 (1954-04-01), Cleminson et al.
patent: 4399967 (1983-08-01), Sandorff
Carrington James E.
Carson Oliver S.
McMurtry George
Barefoot Galen
Fiorito Lynn M.
Short Brothers Limited
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