US2948126A

US2948126A - Protective container for electronic assemblies

Info

Publication number: US2948126A
Application number: US838004A
Authority: US
Inventors: Kenneth E Woodward
Original assignee: Individual
Current assignee: Individual
Priority date: 1959-09-03
Filing date: 1959-09-03
Publication date: 1960-08-09
Anticipated expiration: 1977-08-09

Description

Aug. 9, 1950 K. E. WOODWARD 2,948,126

PROTECTIVE CONTAINER FOR ELECTRONIC ASSEMBLIES Filed Sept. 3, 1959- IN, p

INVENTOR AENNETH Wooomeo PROTECTIVE CONTAINER FOR ELECTRONIC ASSEMBLIES Kenneth E. Woodward, McLean, Va, assignor to the United States of America as represented by the Secretary of the Army Filed Sept. 3, 1959, Ser. No. 838,004

2 Claims. (Cl. 62-316) (Granted under Title 35, US. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental pur-- poses without the payment to me of any royalty thereon.

This invention relates to a novel protective container for theprotection of electronic components or assemblies used in guided missiles from harmful environmental effects such as shock, vibration, noise, and high temperatures. The invention provides superior protection of guided missile electronic equipment during storage and handling, as well as under the very severe conditions en countered during missile flight.

While known prior art packaging units or containers may protect the electronic component against any one of these conditions, these systems do not package the electronic components so that they simultaneously control and minimize the effect of all these environmental conditions.

It is the object of this invention, therefore, to provide a container which will ensure that electronic components are properly isolated from vibration and noise; that shocks impinging on the package are filtered of damaging highfrequency components, shaped into simple waveforms and prevented from being excessively amplified; and that high internally or externally generated temperatures will be reduced and positively controlled.

The specific nature of the invention, as well as other objects, uses and advantages thereof, will clearly appear from the following description and from the accompanying drawing, in which:

Fig. 1 is a side view of the packaging unit of this invention, one quarter of the unit being shown in section.

Fig. 2 a perspective view of the packaging unit of Fig. 1 taken through lines 22.

As shown in Figs. 1 and 2, container consists of outer and

inner casings

12 and 13, respectively. Outer casing 12 is designed to be fixed by brackets 11 (Fig. 1) or by any other suitable means to the inside of the body of any missile (not shown).

Outer casing 12 comprises a pair of flat circular end plates 14 and a hollow cylindrical shell 15. Shell 15 is provided with outwardly extending flanges 18 at both ends. Flanges 18 are cut with annular slots 22 of rectangular cross-section into which O-rings 24 are tightly pressed. Flat plates 14 are fixed by machine screws 20 to flanges 18, as shown.

Inner casing 13, like outer casing 12, consists of a hollow cylindrical shell 17 and a pair of flat circular end plates 16 which are fastened by screws 21 to inwardly extending flanges 19. Flanges 19, like flanges 18, are provided with annular slots 23 into which O-n'ngs 25 can be tightly pressed. Electronic components which are required in the missile are mounted to the inside of inner cylinder 13.

Outer casing 12 is separated from inner casing 13 by circular angle-shaped resilient rings 28. Rings 28 act as a spring and cause inner casing 13 to resonate at a frenited States Patent quency determined by the stiffness of the spring. A spring material found to be satisfactory is silicone rubber. Also positioned between outer casing 12 and inner casing 13 is a cylindrical sleeve 27 composed of a compressible cellular material possessing good damping characteristics. The purpose of this material is to control the amplitudes of inner casing 13 when casing 13 is vibrated at resonance by shock, vibration or noise. A material which has been found satisfactory for this purpose consists of polyurethane foam. Circular flat plates 26 are shaped sub stantially as

plates

14 and 16 and are also composed of polyurethane foam. Any other materials possessing characteristics similar to silicone rubber and polyurethane foam could be substituted for these.

Cylindrical sleeve 27 and end plates 26 are partially saturated with. an evaporative coolant. The degree of saturation depends on the amount of heat input anticipated in service; A preferred evaporative coolant consists of a 40% to 60% methanol alcohol-water mixture. Any coolant having large specific heats and suitable freezing and boiling points could also be used.

When the outer casing 12 experiences a high temperature as a result of missile flight, the methanol alcoholwater mixture will evaporate and in evaporating will keep inner casing 13 at a controlled and substantially constant temperature during the flight of the missile.

Escape vents 36 formed in shell 15 allow the evaporating cooling fluid to escape from between casing 12 and casing 13. Circular angleshaped damping ports 34 formed between angle-shaped rings 28, end plates 16 and shell 17, allow the evaporating coolant to escape to vents 36 from plates 26 and sleeve 27. Damping ports 34 trap air between plates 26 and sleeve 27. This trapped air dampens the amplitudes of inner casing 13 when casing 13 is vibrating at resonance as a result of missile vibration.

O-

rings

24 and 25 is

slots

22 and 23, respectively, ensure that the mixture of methanol alcohol and water will not leak out from between the

end plates

14 and 16 and

shells

15 and 17.

A feed-through connection 30 prov-ides a means for hermetically sealing the electronic components (not shown) which are housed in inner casing 13 from the environment surrounding outer casing 12. Connection 30 consists of two substantially cylindrical elements 31 which are internally threaded so that inserts 32 can be screwed into elements 31. Inserts 32 are designed to press the flared ends of hollow sleeve 33 against the tapered sides of elements 31 as shown in Figs. 1 and 2. Sleeve 33 is composed of a flexible material such as synthetic rubber. Electrical wiring (not shown) which connects the electrical components housed in inner casing 13 to other circuits in the missile will pass through bore 32a formed in insert 32 and in sleeve 33. The wiring when positioned in bore 32 can be sealed in bore 32a by any suitable resin or rubber seal. Thus, all the electronic components housed in inner casing 1-3 are hermetically sealed therein. I

As described above, high temperatures received by outer casing 12 will cause evaporation of the alcohol coolant mixture absorbed in plates 26 and sleeve 27. This will ensure that the outermost surface of inner casing 13 remains at a substantially constant temperature regardless of the temperature reached by outer casing 12.

Plates 26 and sleeve 27 also dampen out the detrimental eifects of noise, which is ordinarily produced by missile flight. If great noise attenuation is required, plates 26 and sleeve 27 should contain little or no coolant. The coolant mixture of methanol alcohol and water can be applied to the package 10 by placing a cylindrical sleeve of absorbent material containing the coolant mixture around the periphery of shell 15 in the same manner as sleeve 27 is wrapped around shell '17. Or, thecooling fluid could be placed in a hollow cylindrical shell or jacket encasing container 10 so that outer casing 12 is immersed completely in the fluid. In most instances, the system shown in Figs. land 2 will dampen out noise ordinarily encountered during missile operation.

Whencontainer 10 is positioned properly inside the missile gbody -inneneasing 1-3 will cooperate-With 'the spring and damping materials, 26 and 27, respectively, so that detrimental vibration and noise are isolated from the electronic components mounted in inner casing 13 and shockimpinging on outer casing '12 are filtered of damaging high-frequency components, shaped in-tosimple waveforms and prevented from being amplified. The resilience of rings 28 isolates vibration and noise and filters,- shapes and controls shock. The damping material of polyurethane foam in plates 26; and sleeve 2-7 prevents inner casing13 from vibrating with uncontrolled amplitudes at resonance.

While casings 12 and 1-3 have been described as cylindrical, they may also have other shapes. For example, casings -12 andp13 may be in the shape of hollow cubes in Which case the polyurethane damping material therebetween would consist of a hollow square sleeve and two square ends.

It will be apparent that the embodiment shown is only exemplary and that various modifications can be made in construction and arrangement the scope of the invention as defined in the appended claims.

I claim as my invention:

1. A container for housing electronic components comprising: first and second hollow cylinders, said first cylinder being encased in :saidseeond cylinder, the longitudinal axis of said first cylinder being substantially coaxial to the longitudinal axis ofsaid-second cylinder, a substantially cylindrical'member positioned between aid fir n se on cylinder s d m m r onsistin of a spongy cellular-.rnaterial and apair of resilient rings, said rings forming the corners of said member, said material being partially ,impregnated, with, an evaporative coolant liquid, and vents in said first cylinder for permitting the escape of .coolant gas therethrough.

2, The container as recited in claim 1 in which said rings are composed of silicone rubber.

Saltzman Sept. 1, 1959