Closed loop feedback control variable conductance heat pipe

#The present invention relates to temperature control of electronic components and more particularly to an electronic mounting plate which includes a variable conductance heat pipe.

#In many applications, temperature control of electronic components is critical. For example, as a resistor heats up, the resistance itself increases and this can seriously alter the operation of the circuit in which the resistor is connected. In sensitive applications, a simple mechanical heat sink is insufficient to maintain a constant temperature.

#Frequently, heat pipes are employed for cooling the environment of electronic circuits. However, they normally operate with a range of temperature variations which may be unacceptable for sensitive applications. More complicated refrigeration techniques, having feedback temperature control, may be employed. Unfortunately, they are quite expensive, require substantial power, and demonstrate limited reliability due to their complicated electromechanical nature.

#The above-mentioned objects and advantages of the present invention will be more clearly understood when considered in conjunction with the accompanying drawings, in which:

#FIG. 1 is a diagrammatic illustration of a VCHP in accordance with the present invention.

#FIG. 1A is a diagrammatic illustration of an alternate VCHP construction in accordance with the present invention.

#Referring to the figures and more particularly FIG. 1 thereof, the mechanical connection of the various components constituting the present invention is diagrammatically illustrated. Reference numeral 10 collectively indicates a heat pipe including the evaporator 12 which includes a metallic heat sink body 16 and internal passages 14 through which working vapor/liquid flows. The heat sink 16 may mount various electronic components thereon thus serving as a mounting plate. The purpose of the present invention is the maintenance of a constant and uniform temperature distribution in the heat sink body which results in a uniform temperature of the electronic components mounted thereon. The heat sink 16 is enclosed within an insulator jacket 17 to further maintain the desired constant and uniform temperature distribution by assuring that almost all the heat dissipated within the insulation is rejected through the heat pipe condenser.

#Heat from the electronic components is absorbed by the working fluid of the heat pipe (preferably liquid ammonia) and after vaporization in the evaporator 12 the working vapor flows through the passage 18 of a condenser 15. An assembly of fins 20 are mounted to the passage 18 so that air cooling of the condenser is effected.

#In order to automatically adjust for the amount of heat convected by condenser 15, the degree of liquid vapor penetration through the passage 18 is controlled by introducing an inert gas such as nitrogen from an interconnected reservoir 22. This reservoir is maintained in a relatively cool state by the attachment of fins 24 thereto. The interface region between the inert gas and the working vapor is indicated by reference numeral 28.