Power plants – Fluid within expansible chamber heated or cooled – Having means within the working chamber to effect the...
Reexamination Certificate
2000-04-28
2001-12-25
Nguyen, Hoang (Department: 3748)
Power plants
Fluid within expansible chamber heated or cooled
Having means within the working chamber to effect the...
C060S515000
Reexamination Certificate
active
06332318
ABSTRACT:
FIELD OF THE INVENTION
The invention is generally directed toward a thermal management system for electronics, especially in outdoor settings, and more particularly to such a thermal management system adapted for a wide range of temperatures (e.g., −40° C. to 46° C.), and more particularly to such a system employing a solidification engine.
BACKGROUND OF THE INVENTION
The electronic circuitry (electronics) used to provide telephony, cable television and data communication, including wireless communication, etc., inevitably generates excess heat. Because such electronics can only function properly within a specified temperature range, e.g., −20° C. to 70° C., dissipation of the excess heat must be managed. A typical solution is to provide a thermal path from inside an electronics enclosure to large heat sinks located outside the enclosure. The heat sinks are sized to dissipate enough excess heat to maintain the electronics at a temperature at or below their maximum rated operating temperature when the external ambient temperature reaches an expected maximum, e.g., 46° C.
The Background Art thermal management system of heat sinks is effective at keeping the operating temperature of the electronics at or below their maximum operating temperature. Unfortunately, the heat sink-based system becomes a liability at low temperatures. When the external ambient temperature falls below the required minimum for the electronics, they still must be maintained at or above the required minimum temperature. The heat sinks work contrary to this by dissipating the now-potentially useful heat generated by the electronics to outside the cabinet.
A Background Art solution to this problem has been to provide heaters that can be activated at lower temperatures to provide additional heat so that the resulting operating temperature stays at or above the specified minimum operating temperature of the electronics. But this has some disadvantages.
The power supply must be adequate to run the electronics as well as the heater circuitry, i.e., much larger than needed to merely run the electronics. Also, such heating circuitry is needed infrequently, for example on the order of 8-10 times per year. This type of solution is very costly in terms of the frequency of its use. A typical battery backup system for the electronics does not have the capacity to provide the tremendous power required by the heating circuitry. It is noted that power outages due to extreme temperatures can occur at very low temperatures as well as very high temperatures. The infrequency of the need for the heater circuitry, compounded by the likelihood of its unavailability due to power outages, makes this low temperature compensation scheme even less useful.
SUMMARY OF THE INVENTION
The invention, in part, is a recognition that (especially for outdoor settings) it is more efficient to disable the Background Art thermal management system at low operating temperatures than it is to generate additional heat as described above.
The invention, in part, is recognition that the Background Art thermal management system can be disabled by selectively breaking the thermal connection between the heat sinks and the electronics being cooled. This has the advantage that the excess heat generated by the electronics is preserved rather than dissipated, which can maintain the electronics at or above the minimum specified operating temperature.
The invention, also in part, is a recognition that the thermal connection can be broken several ways, including a thermostatically controlled electrical device such as an solenoid or via a device (e.g., a bimetallic or other thermally-reactive spring) that harnesses a phenomenon of the same low temperatures that is the ultimate source of the problem to be solved. A preferred example of such a device is a solidification engine, which is a type of phase transition engine.
The invention, also in part, provides a solidification engine that produces reversible motion based upon the tendency of certain substances to expand with a significant force upon freezing and to contract upon melting.
The invention, also in part, provides a solidification engine comprising: an enclosure having an opening; a substance in said enclosure, that expands (with a significant force) upon transition from a liquid to a solid; and a movable plug assembly fitted to said opening in said enclosure to seal said substance. Reversible motion of said movable plug assembly relative to said confinement chamber is imparted when said substance freezes from a liquid to a solid or melts from a solid to a liquid.
A solidification engine using water will operate as follows. As water turns to ice it expands. That expansion creates a force. The expansion force of ice is greater than approximately 30,000 lbs. per square foot and the volume of ice is approximately 1.0855 that of water. That expansion and force can be used to de-couple a heatsink from a heat source as the temperature drops, and re-couple them together when the temperature rises.
The invention also, in part, provides a thermal management system comprising: a structure to be cooled; a heat sink thermally connected to the structure-to-be-cooled; an engine or engines arranged to break the thermal connection between said heat sink and said structure-to-be-cooled depending upon a temperature to which said solidification engine is exposed.
The invention also, in part, provides a solidification engine comprising: a male part and a corresponding female part that together define an enclosure; and a substance, in said enclosure, that expands upon transition from a liquid to a solid; wherein reversible motion of said male part relative to said female part is imparted when said substance freezes from a liquid to a solid or melts from a solid to a liquid.
Advantages of the present invention will become more apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
REFERENCES:
patent: 2115501 (1938-04-01), Vernet
patent: 2395984 (1946-03-01), Bartholomew
patent: 3027729 (1962-04-01), Chace
patent: 4075845 (1978-02-01), Allen
patent: 5927094 (1999-07-01), Nickum
Lucent Technologies - Inc.
Nguyen Hoang
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