Isolation chamber for electronic devices

• US 4,259,843 A
• Filed: 10/09/1979
• Issued: 04/07/1981
• Est. Priority Date: 10/09/1979
• Status: Expired due to Term

• Current Assignee: Cromemco, Inc.
• Original Assignee: Cromemco, Inc.
• Inventors: Kausch, Marvin L.
• Primary Examiner(s): King, Lloyd L.
• Application Number:
  US06/082,965
• Time in Patent Office: 546 Days
• Field of Search: 62/3
• US Class Current: 62/3.1
• CPC Class Codes: F25B 21/02 using Peltier effect; using Nernst-Ettinghausen effect
• CPC Class Codes: H05K 7/202 Air circulating in closed loop within enclosure wherein heat is removed through heat-exchangers

Abstract

The isolation chamber has an aluminum outer housing with heat transfer fins extending therefrom on the outside vertical surfaces, and insulation material mounted along each inside surface thereof forming a thermally insulative shell. Large aluminum studs extend inwardly from the side surfaces of the housing through the insulative shell for supporting a solid state heat pump. Each pump has a set of inwardly directed heat exchange fins. Each stud and associated pump and inwardly directed set of fins forms a heat conductive path between the surrounding ambient air and the interior of the isolation chamber for controlling the heat flow therebetween. The combined configuration of the inner heat exchange fins defines a central cavity which is temperature controlled to within a desired operating temperature range. A card cage containing the electronic devices is installed in the temperature regulated central region. The atmosphere within the central region is isolated from the surrounding ambient air, and supports internal convective heat transfer between the electronic devices and the inner fins by recirculating throughout the card cage and between the inner heat transfer fins. The operating level of the heat pumps are adjustable to provide the most efficient pumping as the external temperature varies. The outer housing and card cage form a double wall electrically conductive structure which twice encloses the electronic devices for providing double shielding from electrical interference. The card cage is cushioned from external vibration by the absorption affect of the insulative shell material.

Claims

1. An isolation chamber for providing a controlled environment for an electronic device, comprising:

a rigid outer support shell formed of thermally conductive material with outer heat exchange means exposed to the external environment;

a plurality of inner heat exchange means positioned inside the isolation chamber defining a temperature controlled central region for receiving the electronic device;

thermal insulation means positioned inside the isolation chamber between the outer support shell and the inner heat exchange means;

a plurality of thermally conductive standoff means extending from the outer shell through the insulation means to the plurality of inner heat exchange means forming a plurality of heat conductive paths therebetween;

a plurality of heat pump means, one positioned in each of the plurality of heat paths for controlling the temperature of the central region by supporting heat flow along the conductive paths when energized and inhibiting heat flow along the conductive paths when not energized;

an internal atmosphere within the central region for supporting convection heat currents which transfer heat between the electronic device and the inner heat exchange means;

circulation means within the central region for moving the internal atmosphere therein; and

power means for providing electric power to the electronic device and to the heat pumps.

2. The isolation chamber of claim 1, wherein the heat pumps are solid state devices.

3. The isolation chamber of claim 2, further comprising a thermal controller responsive to the temperature within the isolation chamber for controlling the operation of the solid state heat pumps.

4. The isolation chamber of claim 3, wherein the thermal controller controls the duty cycle of the solid state heat pumps to regulate the temperature within the central region.

5. The isolation chamber of claim 3, wherein the pumping level of the solid state heat pumps is variable as a function of the power applied thereto.

6. The isolation chamber of claim 5, wherein the thermal controller controls the power applied to the solid state heat pumps to determine the pumping level thereof and regulate the temperature within the central region.

7. The isolation chamber of claim 6, wherein the thermal controller minimizes the power applied to the heat pumps in response to the temperature within the isolation chamber to operate the solid state heat pumps at the lowest pumping level and longest on time permitted by the thermal requirements of the isolation chamber.

8. The isolation chamber of claim 1, wherein the heat pumps are connected to the power means in banks of at least one.

9. The isolation chamber of claim 8, wherein each bank of pumps is separately fused to the power means.

10. The isolation chamber of claim 1, further comprising an inner housing shell enclosing the central region for housing the electronic device.

11. The isolation chamber of claim 10, wherein the inner housing shell is removable from the central region for housing the electronic device when the electronic device is removed from the isolation chamber.

12. The isolation chamber of claim 10, further comprising a layer of resilient material positioned between the inner heat exchange means and the inner housing shell.

13. The isolation chamber of claim 12, wherein the resilient material is compressed outwardly by the insertion of the inner housing shell into the central region for securely retaining the inner housing shell and the electronic device therein.

14. The isolation chamber of claim 10, wherein the outer support shell is made of an electrically conductive material and is connected to a reference potential means for shielding the interior of the isolation chamber from external electro-magnetic radiations.

15. The isolation chamber of claim 14, wherein the inner housing shell is made of an electrically conductive material and is connected to a reference potential means for shielding the interior of the central region from electro-magnetic radiations.

16. the isolation chamber of claim 15, wherein the outer support shell and the inner housing shell are connected to a common reference potential.

17. The isolation chamber of claim 16, wherein the common reference potential is the ground potential of the surrounding environment.

18. The isolation chamber of claim 1, wherein:

the circulation means is the expansion and upwards motion of the internal atmosphere as it absorbs heat from that portion of the surrounding structure which is warmer than the internal atmosphere, and the contraction and downwards motion of the internal atmosphere as it releases heat to that portion of the surrounding structure which is cooler than the internal atmosphere; and

The circulation means causes the internal atmosphere to move vertically through the electronic device in one direction and then vertically through the inner heat exchange means in the other direction and then return to the electronic device.

19. The isolation chamber of claim 18, wherein the the circulation means additionally comprises a fan means for supporting the motion of the internal atmosphere vertically through the electronic device in the one direction and vertically through the inner heat exchange means in the other direction.

20. The isolation chamber of claim 1, wherein the circulation means is a rotary fan means for causing the internal atmosphere to circulate between the electronic device and the inner heat exchange means.

21. the isolation chamber of claim 20, wherein the fan means is a first and second fan having staggered duty cycles for alternately causing the internal atmosphere to circulate.