Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2003-07-28
2004-10-12
Chervinsky, Boris (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S699000, C361S719000, C361S721000, C257S715000, C174S015200, C165S080400, C165S104260, C165S104330
Reexamination Certificate
active
06804117
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to heat management systems for high power electronics equipment, and more particularly to a thermal bus system for a cabinet housing high power, high thermal profile electronic components and systems.
BACKGROUND OF THE INVENTION
In many electronic systems, the efficient cooling of electronic components has become a significant problem. With the advent of large-scale integrated circuit (IC) modules containing many thousands of circuit elements, it has become possible to pack great numbers of electronic components together within a very small volume. As is well known, these integrated circuit modules generate significant amounts of heat during the course of their normal operation. Since most solid state devices are sensitive to excessive temperatures, a solution to the problem of the generation of heat by large scale IC's in close proximity to one another has become of increasing concern to industry.
A typical prior art approach to cooling electronic components is to direct a stream of cooling air across the modules and/or circuit cards carrying such devices. However, the increasing power density of electronic systems is reaching the point where it is no longer possible to adequately cool heat generating electronic components by forcing air over them. Power densities are anticipated to reach the point where it is physically impossible to force sufficient ambient temperature air through a cabinet to adequately cool the electronics inside. Several other disadvantages to this approach have also been identified, including: high pressure drop; uniformity of component form factors; placing the components containing the integrated circuits further apart on the circuit cards; increasing the distance between circuit cards; and increasing the volume and velocity of cooling air directed over the components. This required increase in volume and velocity of cooling air requires special considerations in the design of the housings containing the circuit cards and in the mechanical systems for delivering the cooling air. Also, the air quality (moisture content, contamination, etc.) must be tightly controlled to inhibit corrosion, loss of cooling effectiveness, etc. Thus, cooling of components by this means necessitates a number of compromises to the overall system that prevent its use in many systems.
The foregoing thermal management problems have brought about the evolution of other techniques for cooling card-mounted electronic components. For example, one technique includes the use of solid metal thermal mounting cards or plates which conduct the heat dissipated by electronic components to a heat sink (cold plate) disposed at the edge of each circuit card. Such an approach, however, results in a large thermal resistance from the component mounting surface to the heat sink, which causes high component temperatures.
Other known techniques for cooling electronic systems include loop thermosyphons and heat pipes. Loop thermosyphons are devices that use gravity to maintain two-phase fluid circulation during operation. Each loop thermosyphon has an evaporator, where vaporization occurs when it is heated, a vapor tube through which the vapor flows to a condenser where it is cooled and condenses, and a liquid return tube to return the liquid to the evaporator. Sometimes a capillary structure is used in the evaporator to reduce its thermal resistance.
A heat pipe includes a sealed envelope that defines an internal chamber containing a capillary wick and a working fluid capable of having both a liquid phase and a vapor phase within a desired range of operating temperatures. When one portion of the chamber is exposed to relatively high temperature it functions as an evaporator section. The working fluid is vaporized in the evaporator section causing a slight pressure increase forcing the vapor to a relatively lower temperature section of the chamber (a condenser section). The vapor is condensed in the condenser section and returns through the capillary wick to the evaporator section by capillary pumping action. Because a heat pipe operates on the principle of phase changes rather than on the principles of conduction or convection, a heat pipe is theoretically capable of transferring heat at a much higher rate than conventional heat transfer systems. Consequently, heat pipes have been utilized to cool various types of high heat-producing apparatus, such as electronic equipment (See, e.g., U.S. Pat. Nos. 5,884,693, 5,890,371, and 6,076,595).
U.S. Pat. No. 4,366,526, issued to Lijol et al., discloses a circuit card for high-density packaging of electronic components for use in high power-density card racks in computer and other electronic and avionic systems. The card has an all metal construction with an elongate planar body for the mounting of electronic components on opposite sides, and has a heat pipe located along the edges of one elongate side and two ends. Edge tabs on the ends of the card permit the card to be installed into a card rack in electronic equipment. The elongate portion of the heat pipe serves as the evaporator section and the two end portions act as the condensing sections.
U.S. Pat. No. 4,931,905, issued to Cirrito et al., discloses two metal plates that have U-shaped grooves so that the plates may form congruent halves wherein matching grooves complete independent heat pipes. A bight section of each heat pipe serves as an evaporator section while the parallel arms of each heat pipe form condenser sections. A wick is positioned within each heat pipe to improve liquid transport when a module is in a non-upright position. The condenser sections are located coincident with the normally upright edges of each module so that, when the module is upright, the vertically disposed condenser sections of the heat pipe provide gravity-assisted liquid transport to the evaporator section.
U.S. Pat. No. 5,283,715, issued to Carlsten et al., discloses a heat pipe structure that is incorporated directly into the metal base plate of a circuit card thereby eliminating thermal contact resistance between the base plate and the heat pipe assembly. Components are mounted on a copper circuit layer bonded to a dielectric layer in a first portion of the base plate with a second portion of the base plate/heat pipe assembly extending into a heat sink/cold plate condensing area for removal of heat generated in the component portion.
U.S. Pat. No. 6,055,157, issued to Bartilson, discloses a computer module that includes a first heat pipe assembly having an evaporator plate with an evaporator surface. The first heat pipe also has a condenser in fluid communication with the evaporator plate. The evaporator plate is positioned adjacent a printed circuit board populated with at least one electronic component. When a printed circuit board having components on two sides is used, a second heat pipe having the same construction is positioned adjacent the other side of the printed circuit board so that the electronic components on the other side are positioned adjacent the evaporator surface of the second heat pipe. The evaporator plate of each heat pipe is connected to the condenser by a plurality of necked-down regions. This forms at least one window between the condenser and the evaporator plate of each heat pipe. When more than one heat pipe is used in the computing module, the windows of the various heat pipes align.
U.S. Pat. No. 6,388,882, issued to Hoover, et al., discloses a thermal energy management architecture for a functioning system of electronic components and subsystems comprising a hierarchical scheme. Here the thermal management components are operatively engaged with individual portions of the system of electronic components and subsystems, in multiple defined levels, and are substantially only thermally driven, i.e., heat transfer devices that have no moving parts and require no external power for their operations.
U.S. Pat. No. 6,536,510, issued to Khrustalev, et al., discloses a thermal bus for cabinets housing high power electronic
Broadbent John
Khrustalev Dmitry K.
Phillips Alfred L.
Wattelet Jonathan P.
Wert Kevin L.
Chervinsky Boris
Morris LLP Duane
Thermal Corp.
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