Thermal and shock resistant data recorder assembly

• US 5,708,565 A
• Filed: 06/28/1996
• Issued: 01/13/1998
• Est. Priority Date: 07/01/1995
• Status: Expired due to Fees

• Current Assignee: Meggitt UK Ltd (Parker-Hannifin Corporation)
• Original Assignee: British Aerospace, Inc. (BAE Systems Plc)
• Inventors: Fairbanks, Terence M.
• Primary Examiner(s): Thompson, Gregory D.
• Application Number:
  US08/673,340
• Time in Patent Office: 564 Days
• Field of Search: 174/52.2, 206/305, 206/521, 206/811, 220/88.1, 220/429, 220/452, 220/468, 244/1 R, 361/600, 361/689, 361/704, 361/715, 361/728, 361/730, 361/736, 361/752, 455/96, 455/98
• US Class Current: 361/704
• CPC Class Codes: H05K 3/285 Permanent coating compositions
• CPC Class Codes: H05K 5/021 specially adapted for data recorders, e.g. for flight recorders
• CPC Class Codes: H05K 5/0213 Venting apertures; Constructional details thereof
• CPC Class Codes: Y10S 206/811 Waterproof

Abstract

A thermal and shock resistant data recorder assembly as an outer container (1) containing an inner container (2) which in turn houses one or more data recorder elements (3). The elements (3) which have a thin conformal coating thereon are encapsulated in an innermost cavity (4) of the inner container (2) in an Ester wax material which absorbs heat when changing from a solid to a liquid. An outermost cavity (8) surrounds the innermost cavity (4) in the container (2) and in turn contains a first insulating material which gives off water vapor when heated to absorb heat. Surrounding the inner container (2) in the outer container (1) is a second insulating material. The Ester wax material is enabled to leak when liquid into the outer container and from thence, if necessary, to the exterior of the outer container. This permits pressure equalization. The first insulating material is provided with a fusible material plug which melts under heat and allows the vapor to escape to the exterior of the assembly.

Claims

1. A thermal and shock resistant data recorder assembly including an inner container defining an innermost cavity containing at least one data recorder element encapsulated in an Ester wax material operative to absorb heat by liquifaction when the temperature of the assembly exceeds a specific value and an outermost cavity surrounding, but not in communication with, the innermost cavity, which outermost cavity contains a first insulating material operative to absorb heat by release of water vapour when the temperature of the assembly exceeds a specific value, and an outer container housing in the interior thereof, the inner container and a surrounding layer of a second insulating material which remains solid when heat is applied to the assembly, and which outer container interior is in fluid flow communication with the exterior thereof, with the innermost cavity being in fluid flow communication with the outer container interior to permit escape thereto of a limited amount of the Ester wax material when liquid to minimise shear damage to the at least one data recorder element, with the innermost cavity being in fluid flow communication with the outer container exterior via the outer container interior and second insulating material for pressure equalisation purposes and with at least one fusible material plug being provided between the outermost cavity and the outer container interior operative to allow fluid flow communication, when the temperature of the assembly exceeds a specific value, to allow released water vapour to escape from the outermost cavity and outer container interior to the exterior of the outer container.

2. An assembly according to claim 1, in which the Ester wax material comprises glyceryl tribehenate and calcium behenate which changes phase from solid to liquid at a temperature in the range from 105 to 130 degrees Centigrade.

3. An assembly according to claim 1, in which the first insulating material is magnesium sulphate.

4. An assembly according to claim 1, in which the second insulating material is a combination of fibrous material and particulate matter having a low thermal conductivity.

5. An assembly according to claim 4, in which the second insulating material is a combination of fibrous material and particluate matter having a low thermal conductivity.

6. An assembly according to claim 1, in which the inner container is in the form of an aluminium box with a removable access cover plate through which is a vent to provide said fluid flow communication.

7. An assembly according to claim 6, in which the inner container box is compartmented to provide said innermost and outermost cavities, with the outer wall bounding the outermost cavity having at least one aperture therethrough provide with said fusible material plug.

8. An assembly according to claim 1, in which the fusible material plug is made of an alloy having a melting point of substantially 104 degrees C.

9. An assembly according to claim 1, in which the outer container is in the form of a titanium box with a removable access cover plate provided with an outlet therethrough for a cable which extends from said at least one data recorder element, through an outlet from the inner container, which outer container outlet provides the fluid flow communication between the interior and exterior of the outer container.

10. An assembly according to claim 9, in which the second insulating material is in the form of a hollow block with one wall removable to permit insertion and removal of the inner container which is spring loaded against said removable wall which in turn bears on the outer container access cover plate.