Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2002-07-17
2004-03-23
Tolin, G. (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C062S259200, C165S104330, C257S714000
Reexamination Certificate
active
06711017
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a cooling apparatus for electronic systems, and in particular to a cooling apparatus which utilizes liquid coolant so as to cool, one by one, electronic parts such as semiconductor devices, a CPU, an FET and a power amplifier, which are used in an electronic circuit within an electronic system.
RELATED ART
Several circuit boards are densely installed in a housing rack of an electronic system such as an electronic computer or a broad casting system, and they are mounted thereon with electronic parts including semiconductor devices, a CPU, a FET and a power amplifier, which generate high heat power Accordingly, a cooling apparatus is required for cooling the electronic system. Electronic parts generating high temperature heat, such as electronic devices, a CPU and a power amplifier, are effectively operated in a narrow temperature range, and accordingly, they have to be individually cooled, instead of cooling the electronic system in its entirety. Accordingly, in a cooling apparatus for an electronic system, these years, electronic parts are located, adjacent to a cooling pipe through which liquid coolant flows in order to cool them.
For example, JP-U-2-28965, JP-A-63-131469 and JP-A-6-304739, propose such a configuration that a flattened cooling pipe which meanders is attached to a water-cooled cooling plate on which electronic parts are mounted so as to increase the thermal contact area between the cooling plate and the cooling pipe in order to enhance the cooling efficiency. With this configuration, in order to efficiently transfer heat generated from the electronic part to the flattened cooling pipe, the oblateness of the flattened cooling pipe is increased so as to increase the thermal transfer cross-sectional area between the electronic part and the flatted cooling pipe. For example, the width of the flattened cooling pipe is widened up to a value which is equal to or greater than the width of the electronic part. However, if several electronic parts are arrayed, the flattened cooling pipe should successively be bent so as to meander along the electronic parts which are densely mounted on a circuit board, and accordingly, the radii of curvature with which the flattened cooling pipe is bent must be smaller. In general, bending a flattened pipe having a high oblateness to a small radius of curvature is extremely difficult in comparison with bending a flattened pipe having a small oblateness in view of the manufacture thereof. Further, if has been found, the higher the oblateness, the larger the pressure loss of the flattened cooling pipe.
Meanwhile, if the oblateness of the flattened cooling pipe is restrained to be small, the radius of curvature of the flattened cooling pipe would be decreased. However, the heat transfer cross-sectional area (thermal contact area) between the electronic part and the flattened cooling pipe becomes smaller, thereby enhancement of the cooling capacity for the electronic part is restricted.
Thus, successively bending the flattened cooling pipe having a high oblateness so as to cope with an array of electronic parts which are densely mounted causes restriction to any of enhancement of cooling efficiency, enhancement of the productivity of the flattened cooling pipe and reduction of pressure loss in the flattened cooling pipe.
Further, the cooling apparatus for an electronic system, dewing is likely to occur around a cooling pipe through which liquid coolant flows, and an electronic part to be cooled in view of a relationship between a temperature and a humidity of an environment surrounding them. This dewing would cause inferior insulation, deterioration of the electronic part, inferior contact of a connector and the like. Further, in a cold season, when the temperature of the environment around the electronic system, such as, the atmospheric temperature is lowered, liquid coolant which carries out heat-exchange with the environment through the intermediary of a heat-exchanger is frozen, causing fracturing of the cooling pipe, or lowering of the performance of the electronic part. That is, it is required to control the temperature of the electronic part with the use of a cooling apparatus in order to efficiently operate the electronic part within a relatively narrow effective operating temperature range.
JP-A-6-164178 proposes a cooling apparatus that detects a humidity of the environment surrounding electronic parts in an electronic system and computes a supply temperature of liquid coolant which can prevent dewing so as to control this supply temperature.
JP-A-5-75284 proposes a cooling apparatus which carries out heat-exchange between coolant and an atmosphere in an electronic system when the difference between a temperature of the coolant and a temperature of the atmosphere in the electronic system becomes equal to a predetermined value during deenergization of the electronic parts, in order to prevent dewing during a start of operation of the electronic system.
JP-B2-2656581 discloses a cooling apparatus that measures an atmospheric temperature in an electronic system and a temperature of liquid coolant, and detects dewing around a cooling pipe in the cooling apparatus by means of a dew sensor in order to surely prevent dewing around the cooling pipe.
Further, JP-B2-2508640 discloses a cooling apparatus which controls turn-on and -off operation of a plurality of heat-exchanger units having different cooling capacities in accordance with a difference between a supply side temperature and a return side temperature of liquid coolant, and a difference between an atmospheric temperature in an electronic system and the supply side temperature of the liquid coolant in order to carry out efficient cooling.
As stated above, in the cooling apparatus using liquid coolant, the capacity of the heat-exchanger unit is set so as to obtain a temperature range in which electronic parts including semiconductor devices, an FET, a CPU and a power amplifier efficiently function. Since the heat-exchanger unit introduces the atmospheric air and carries out heat-exchange between the atmospheric air and liquid coolant so as to cool the liquid coolant, the liquid coolant is excessively cooled as the temperature of the atmospheric air lowers, causing problems of excessive consumption of power, freezing and dewing.
Further, in an unmanned broadcasting system, a plurality of parallel electronic systems are in general provided in order to enhance the reliability, one of which is used as a living system for usual operation while the other of which is used as a stand-by system that is adapted to operate if the living system malfunctions. Further, in an electronic apparatus, a plurality of electronic systems are operated, independent from one other, and accordingly, there may be such a case that one of the electronic system is operated but the other rests. In this apparatus, the electronic systems are incorporated with cooling apparatuses, respectively, and if one of the electronic system rests, the corresponding cooling apparatus also rests. Accordingly, in the electronic system on resting, since liquid coolant stagnates, it is required to prevent the liquid coolant from being frozen when the temperature of ambient air lowers. Thus, anti-freezing fluid is in general used as liquid coolant. This anti-freezing fluid causes possible corrosion of a part of the cooling pipe or that of a tank with which the anti-freezing fluid makes contact. Further, handling of the anti-freezing fluid requires consideration fully to the environment. Further, should the liquid coolant having a low temperature pass through the electronic system which has a high temperature, and which is started from a rest condition, there would be caused a problem of dewing as mentioned above. Thus, it is required to maintain the temperature of the liquid coolant at a temperature higher than the dewing temperature. Thus, it is desirable to always heat liquid coolant in the system on resting by means of a heater or the like or to operate all electronic
Daikoku Takahiro
Fukukawa Toshio
Harada Mikio
Kurokawa Tateki
Saito Akira
Antonelli Terry Stout & Kraus LLP
Hitachi Kokusai Electric Inc.
Tolin G.
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