Electronic unit
First Claim
1. An electronic unit comprising a housing including a heat sink, an electronic circuitry member within the housing, biasing means normally operable to urge the heat sink and the circuitry member away from relative positions in which the circuitry member is in heat conductive relationship with the heat sink, and means heat conductively connected to the circuitry member and operable as temperature increases through specific temperature conditions to urge the circuitry member towards the heat sink to bring the circuitry member into heat conductive relationship with the heat sink and remove heat from the circuitry member, the means heat conductively connected to the circuitry member then being operable as the temperature decreases through the specific temperature conditions to allow the biasing means to urge the circuitry member away from the heat sink and out of heat conductive relationship with the heat sink, the electronic unit also including a heat conduction means disposed intermediate the heat sink and the circuitry member, the heat conduction means being compressible and increasing in heat conductive efficiency as compression increases, the heat conduction means being compressed between the heat sink and the circuitry member as the circuitry member moves towards the heat sink.
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0 Petitions
Accused Products
Abstract
Electronic unit in which a printed circuit board is located within a housing which includes a heat sink. The board is normally urged out of heat conductive relationship with the heat sink. As temperature increases the circuit board and heat sink are caused to move relatively so as to bring the board into heat conductive relationship with the heat sink so as to remove heat from the board. As temperature decreases the board and heat sink are again moved out of heat conductive relationship. Preferably a heat conduction element is provided to conduct heat from the board. This comprises at least one compressible member, e.g. compressible cellular material, which is progressively compressed as temperature increases. Preferably the heat conductive efficiency of the compressible member increases as compression increases.
45 Citations
20 Claims
- 1. An electronic unit comprising a housing including a heat sink, an electronic circuitry member within the housing, biasing means normally operable to urge the heat sink and the circuitry member away from relative positions in which the circuitry member is in heat conductive relationship with the heat sink, and means heat conductively connected to the circuitry member and operable as temperature increases through specific temperature conditions to urge the circuitry member towards the heat sink to bring the circuitry member into heat conductive relationship with the heat sink and remove heat from the circuitry member, the means heat conductively connected to the circuitry member then being operable as the temperature decreases through the specific temperature conditions to allow the biasing means to urge the circuitry member away from the heat sink and out of heat conductive relationship with the heat sink, the electronic unit also including a heat conduction means disposed intermediate the heat sink and the circuitry member, the heat conduction means being compressible and increasing in heat conductive efficiency as compression increases, the heat conduction means being compressed between the heat sink and the circuitry member as the circuitry member moves towards the heat sink.
- 3. An electronic unit comprising a housing including a heat sink, an electronic circuitry member within the housing, biasing means normally operable to urge the heat sink and the circuitry member away from relative positions in which the circuitry member is in heat conductive relationship with the heat sink, and means heat conductively connected to the circuitry member and operable as temperature increases through specific temperature conditions to urge the circuitry member towards the heat sink to bring the circuitry member into heat conductive relationship with the heat sink and remove heat from the circuitry member, the means heat conductively connected to the circuitry member then being operable as the temperature decreases through the specific temperature conditions to allow the biasing means to urge the heat sink and the circuitry member away from the heat sink and out of heat conductive relationship with the heat sink, and wherein the means operational through specific high temperature conditions comprises a cylinder, piston means movable within the cylinder and extending outwardly from the cylinder, and a phase change material within a chamber of the cylinder, the biasing means urging the piston means inwardly of the cylinder into a position dictated by the volume of the phase change material, the phase change material being in a solid phase at temperatures below the specific high temperature conditions and in a liquid phase at temperatures above the specific high temperature conditions, expansion of the material accompanying change to the liquid phase to urge the circuitry member towards the heat sink.
- 6. An electronic unit comprising a housing including a heat sink, an electronic circuitry member within the housing, the electronic circuitry member comprising a planar base element and at least one electronic component carried by the planar base element, heat insulating means disposed between the circuitry member and the heat sink, biasing means normally operable to urge the heat sink and the circuitry member away from relative positions in which the circuitry member is in heat conductive relationship with the heat sink, and means heat conductively connected to the circuitry member and operable as temperature increases through specific temperature conditions to urge the circuitry member towards the heat sink to bring the circuitry member into heat conductive relationship with the heat sink and remove heat from the circuitry member, the means heat conductively connected to the circuitry member then being operable as the temperature decreases through the specific temperature conditions to allow the biasing means to urge the heat sink and the circuitry member away from the heat sink and out of heat conductive relationship with the heat sink.
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20. An electronic unit comprising a housing having at one side a heat sink comprising a planar wall with heat exchange projections extending exteriorly of the housing;
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an electronic circuitry member comprising a planar base element within the housing and disposed parallel to the planar wall, the circuitry member including electronic components mounted upon the planar base element; a heat insulating means comprising a planar heat insulating element extending between the planar base element and the planar wall of the heat sink; biasing means to urge the circuitry member away from the heat sink and into a position of minimal heat conductive relationship with the heat sink; heat conduction means extending through the planar heat insulating element and disposed between the planar base element and the planar wall of the heat sink, the heat conduction means being resiliently compressible and increasing in heat conductivity efficiency as compression increases; and means heat conductively connected to the circuitry member and operable as temperature increases through specific temperature conditions to urge the circuitry member against the force of the biasing means and towards the heat sink so as to progressively compress the heat conduction means and thereby progressively increase heat conduction from the planar base element into the heat sink, said means conductively connected to the heat sink subsequently being operable as temperature decreases through the specific temperature conditions to allow the biasing means to urge the circuitry member away from the heat sink so as progressively to release compression upon the heat conductivity means and thereby progressively decrease heat conduction into the heat sink, the means heat conductively connected comprising a plurality of piston and cylinder means, each of which comprises a cylinder, piston means movable within the cylinder and extending outwardly from the cylinder, and a phase change material within a chamber of the cylinder, the biasing means urging the piston means inwardly of the cylinder into a position dictated by the volume of the phase change material, the phase change material being in a solid phase at temperatures below the specific high temperature conditions and in a liquid phase at temperatures above the specific high temperature conditions, expansion of the phase change material accompanying change to the liquid phase so as to urge the circuitry member towards the heat sink.
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Specification