Heat exchange – Heat transmitter
Reexamination Certificate
1999-11-08
2001-09-11
Flanigan, Allen (Department: 3743)
Heat exchange
Heat transmitter
C361S704000
Reexamination Certificate
active
06286591
ABSTRACT:
BACKGROUND
The present invention relates generally to heat conducting apparatus, and more particularly, to a thermal harness employing carbon based fiber and polymer matrix material that may be used in spacecraft applications.
Conventional thermal straps or harnesses for use as thermal interfaces in spacecraft applications use aluminum rope encased at the ends in an aluminum block and secured by bonding. These thermal straps or harnesses are relatively heavy and are limited thermally by the adhesive bond. These thermal straps also provide only point-to-point solutions, and can add significant weight.
Conventional thermal interface materials use a highly loaded (organic) carrier with many conductive particles. With such conventional interface materials, the bond line thickness is minimized in order to maximize thermal performance. Unfortunately, a thermal bottleneck exists because of the poor conductance through the matrix and at (many) particle-to-particle contact points. The conventional gasket interface materials work relatively well for thin bond lines and flat surfaces. Additionally, the gasket interface materials require significant pressure to achieve higher conductance values.
Accordingly, it is an objective of the present invention to provide for an improved thermal harness that may be used in spacecraft applications that overcome the limitation of available heat conducting apparatus, and especially those used in spacecraft applications.
SUMMARY OF THE INVENTION
To accomplish the above and other objectives, the present invention comprises a thermal harness that provides the ability to branch to multiple components and requires no metallic end fittings. The thermal harness comprises one or more groups of tows of braided or bundled thermally conductive (carbon) fiber respectively extending from one or more heat generating devices to one or more heat dissipating devices. The harness may include an encapsulating membrane to contain the multiple tows. The heat generating devices are typically disposed on printed circuit boards, are part of feedhorns, or provide signal amplification, for example. In a spacecraft application, the heat dissipating device is typically a radiator panel of a spacecraft, or components that are pointed to radiate energy.
At each node or endpoint of the tows of thermally conductive fiber, the tows are fanned out and splayed onto a patch of polymer matrix material, such as silicone, urethane, or Gelvet™ material, for example. A second piece of polymer matrix material, such as silicone, urethane, or Gelvet material, for example, may be used to encompass or encapsulate the splayed tows of thermally conductive fiber at each node. The node may be attached to the heat generating and heat dissipating devices using fasteners, or a layer of adhesive disposed between the polymer matrix material and the respective the heat generating and heat dissipating devices. Alternatively, a plastic connector, or a backing plate may be secured to the heat generating and heat dissipating devices. Furthermore, pyrolytic graphic flakes may be used to thermally connect the carbon fibers of the harness with fibers of the polymer matrix (Gelvet) material.
The polymer matrix material comprises high thermal conductivity, small diameter fibers that are disposed normal to surfaces to which they are attached, and hence are normal to surfaces of the polymer matrix material. The high thermal conductivity fibers protrude from at least one surface of the polymer matrix material so that they contact the tows of thermally conductive fiber. The high conductivity fibers adjust to and penetrate surfaces to which they are attached and conform to macroscopic non-planarity of the surfaces.
The fibers of the polymer matrix material thermally contact the heat generating devices, the heat dissipating devices, and the tows of thermally conductive fiber, thus providing a thermal path between the multiple components. The fibers act as continuous conductors of heat from surfaces of the heat generating devices to the tows of thermally conductive fiber. A gel encapsulant may be used to keep the fibers in place and reduce possible contamination.
The thermal harness, because it is designed to pass outgassing requirements for space applications, may be used to interface to electrical boxes, amplifiers, and heat pipes, and the like, employed in spacecraft.
REFERENCES:
patent: 4916038 (1990-04-01), Lau et al.
patent: 5077637 (1991-12-01), Martorana
patent: 5542471 (1996-08-01), Dickinson
patent: 5769158 (1998-06-01), Yao
patent: 5858537 (1999-01-01), Brown et al.
patent: 6052280 (2000-04-01), Dilley et al.
Flanigan Allen
Float Kenneth W.
Space Systems Loral, Inc.
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