MXPA98000677A - Apparatus for heat removal from a personal computer card structure - Google Patents

Abstract

The present invention relates to an apparatus for cooling a PC card structure that includes a frame defining a chamber with holes for air. A thermal collector is mounted on the frame within the chamber and has a finned surface to transfer heat to the surrounding environment, a finless surface on one side opposite the finned surface, and thermal tubes that are completely enclosed within the thermal collector , facilitating the conductive thermal transfer between finned surfaces and without fins. A bottom plate mounted to the frame has at least one collector that can be connected mechanically and electrically to at least one PC card, such that a surface of at least one PC card is in immediate vicinity with and substantially parallel to the finned surface of the thermal collector. , thus facilitating thermal transfer between the thermal collector and the PC card at least

Description

APPARATUS FOR REMOVING HEAT FROM A PERSONAL COMPUTER CARD STRUCTURE 1.- Field of the invention The invention relates to the removal of heat from a structure of a personal computer (PC) card and specifically the use of thermal collectors, with pipes embedded thermal to define slots for the insertion of PC cards and to efficiently remove heat from inserted PC cards. BACKGROUND OF THE INVENTION PC cards, for example those that adapt to the PCMCIA standard, are small printed circuit boards that have electronic components. Typically, a PC card includes all the components required to implement a certain electronic function, an example is a fax / odem function. PC cards are widely used in laptops and other applications and are useful due to their small size, durability and ease of insertion into and removal of various machines. PC cards are particularly durable when circumscribed in a metal cover. However, a disadvantage of PC cards is that because they are small and circumscribed, they are limited in the amount of heat they can dissipate. The heat retained in the PC cards causes the temperature of the PC cards and its electronic components REF: 25118 to increase, leading to permanent damage or failure over a certain temperature. The PC cards would be applicable to a wider variety of uses, if they were stacked as multiple card structures and if the heat could effectively be removed from the multiple card structures. Multiple card structures with lamellar metal separators or cages defining slots for inserting PC cards have been implemented. This technique suffers from inefficiency in removing heat generated by the electronic components of PC cards during normal operation. Another technique implements a structure for holding PC cards with a plurality of cold plates that define slots for PC cards. Springing the cold plates are pistons that make contact with heat generating components in the PC cards, thus facilitating the transfer of heat from the PC card to the cold plate. The cold plate is kept cool with internal tubes containing a fluid, held in a vacuum, fluidly connected to a cooling unit by external pipe. This device has the disadvantage of requiring special procedures to move the pistons for insertion into PC cards. In addition, the requirements of an external cooling source contribute to cost and volume to the apparatus.

Other devices for cooling printed circuit boards (PCBs) are based on joining thermal collectors to the PCB or its components. These devices are undesirable for PC cards because the connection of the thermal collector with the PC card undermines the advantages of small size and machine-to-machine portability of the PC card. In addition, once joined, the thermal collector limits the range of applications for which the connected PC card is adapted. SUMMARY OF THE INVENTION In order to overcome the above-identified disadvantages, an economical apparatus for removing heat from a PC card structure is described. The apparatus is adapted to facilitate insertion and removal of PC cards, does not require fluid connection to a refrigeration unit or physical contact with the thermal collector, and is relatively inexpensive to manufacture. The apparatus includes a frame that defines a chamber with holes for air. A thermal collector is mounted to the frame inside the chamber. The thermal collector has a finned surface to transfer heat to an environment surrounding the thermal collector, a finless surface on a side opposite the finned surface, and thermal tubes that are completely enclosed within the thermal collector to facilitate thermal transfer conductive inside the thermal collector, thus making the thermal transfer by convection from the thermal collector to the surrounding environment more efficient. A bottom plate mounted to the frame has at least one electrical connector electrically and electrically connectable to at least one PC card, such that a surface of at least one card is in close proximity with and substantially parallel to the surface without fins of the collector. thermal, thus facilitating the transfer of at least one PC card and the thermal collector. BRIEF DESCRIPTION OF THE DRAWINGS These and other features, objectives and advantages will be more fully appreciated with reference to the accompanying drawings. Figure 1 is an exploded view of a preferred embodiment of the present invention illustrating its component parts. Figure 2 is a view of the invention illustrating the manner of connection of a PC card to the apparatus. DETAILED DESCRIPTION OF THE INVENTION Figures 1 and 2 illustrate a preferred embodiment of an apparatus for maintaining and removing heat from one or more cards PC 8, according to the present invention. The apparatus includes a frame 10, one or more heat collectors 12 and a bottom plate 14.

The frame 10 has four rectangular side walls 16 substantially perpendicular to each other defining an interior chamber 18 with two open ends opposite each other as illustrated in Figure 1. Two of the side walls 16 of the frame 10 include a plurality of threaded holes. and air holes 22. The threaded holes 20 are used to mount one or more heat collectors 12 through coupling threaded holes 24 in the heat collectors, to the frame 10, with screws (not shown) at regular intervals. However, the heat collectors 12 can be mounted to the frame 10 by other techniques including by welding, adhesive and clamping. The air holes 22 expose the interior chamber 18 to the environment outside the frame. In a preferred embodiment, air enters the inner chamber 18 through the air holes 22 and circulates on the thermal collectors 12 cooling them in this way. However, in an alternate embodiment of the invention, the environment in which the inner chamber 18 is exposed can be a gas other than air, for example nitrogen, or it can be a liquid. The heat collectors 12 have a finned surface 26 and a finless surface 28. Preferably, the heat collectors 12 are mounted in such a manner that the finned surfaces 26 all point in the same direction, and in such a manner that the space between Finned surfaces and without respective fins of adjacent thermal collectors 12 define a slot for insertion of one or more PC cards 8. The bottom plate 14 is adapted to receive PC cards 8, and is mounted on the frame 10 at an open end. Assembly can be achieved by screwing the plate 14 to the side walls 16 of the frame 10 through the threaded holes 25 in the bottom plate 14. Alternatively, the bottom plate 14 can be mounted to the frame 10 by techniques including welding, adhesion and clamping. Spaced at intervals on the bottom plate 14 are receptacles 30, each of which receives a coupling end of a PC card 8 that can be plugged into the receptacle 30. The receptacles 30 can be implemented as electrical connectors that both mechanically and electrically couple each PC card 8 to the bottom plate 14. In addition, the bottom plate 14 includes electrical wiring that directs power, ground and signals to and between PC cards 8 of the system. The interval of spacing of the receptacles 30 on the bottom plate 14 is chosen such that each receptacle 30 is located in the slot defined by the space between the adjacent thermal collectors 12. In this way, as illustrated in Figure 2 , a PC card 8 can be plugged into the bottom plate 14 between the heat collectors 12 from the open end of the frame 10 opposite the bottom plate 14. The PC cards 8 should be substantially planar. In a preferred embodiment, the PC cards 8 further include a housing 32 that is securely plugged into and held by a receptacle 30 in the bottom plate 14. The PC cards 8 are then plugged into the housing 32, thereby connecting electrically and mechanically the PC card 8 to the bottom plate 14 by the housing 32. The displacement of the receptacle 30 with respect to the thermal collectors 12 is ideally positioned in such a way that each PC card 8 can be easily inserted inside the thermal collectors 12 and it maintains substantially parallel and close to the finless surface 28 of each thermal collector 12. In a preferred embodiment, PC cards 8 do not make physical contact with thermal collectors 12. However, in an alternate mode, PC cards 8 make contact physical with the thermal collectors 12. The collectors 12 is substantially planar and includes a finned surface 26 and a finless surface 28. The finless surface 28 is substantially smooth. The finned surface 26 has a plurality of substantially parallel fins extending longitudinally from one end of the thermal collector 12 to the other. Between the finned surface 26 and the finned surface 28 of the thermal collector 12 there is a plurality of thermal tubes 29 extending longitudinally and substantially parallel to each other. The thermal pipes improve the thermal transfer by virtue of the fluid for circumscribed boiling. The thermal pipes 29 are hollow passages that maintain fluid, for example water or methanol, which upon boiling greatly improves the heat transfer within the thermal pipes 29. Each thermal pipe 29 is usually in a vacuum such that boiling occurs at low temperatures and essentially acts as a passive cooling device. without moving parts. The thermal pipes 29 also facilitate thermal transfer over the longitudinal and width axes of the thermal collector 12 itself. In a preferred embodiment, the thermal pipes 29 are evacuated after manufacture of the thermal collector 12 filled with the fluid and sealed, thus completely circumscribing the fluid within each of the thermal pipes 29 within each thermal collector 12. An advantage of the thermal collector 12 according to the present invention is that the thermal collector 12 can be manufactured using inexpensive techniques including extrusion, because the fins and the thermal tubes 29 are substantially parallel to one dimension. In a preferred embodiment of the invention, the thermal collector 12 is made of extruded aluminum, is 8.9 cm (3.5") wide and 12.7 cm (5 p) long and has two threaded holes 24 that extend along the collector 12 as illustrated in Figure 1. However, other materials may be used to implement the thermal collector 12. Also, other metals including copper and alloy metals are suitable for use as long as the thermal resistance of the material is low. use, one or more PC cards 8 are inserted into the frame 10 between adjacent thermal collectors 12, and mechanically and electrically connected through the receptacles 30 to the bottom plate 14. Each connected PC card 8 then performs the intended functions. As an operating by-product, heat is generated by the electronic components in each PC card 8 which tends to raise its temperature.The heat of operation of each PC card 8 is transferred to the finless surface 28 of adjacent thermal collector 12 by conduction and radiation. When the PC card é does not touch the surface without fins 28 of the thermal collector 12, the heat is transferred from the PC card 8 to the thermal collector 12 by conduction through the air space between the PC card 8 and the finless surface 28 of the thermal collector 12. Additionally, heat is radiated through the air space from the PC card 8 to the finned surface 28 of the thermal collector 12. In order to increase the efficiency of the thermal transfer by radiation, the optical properties of the Finless surface 28 can be modified. For example, painting an aluminum thermal collector 12 with black paint increases its surface identity from about .1 to about .9 and therefore greatly improves the thermal transfer efficiency by radiation.

Alternatively, if the PC card 8 makes contact with the finned surface 28 of the thermal collector 12 totally or partially, the two transfer mechanisms above combine with the thermal conduction directly from the outside of the PC card 8 to the surface without fins 28 of the thermal collector 12. The thermal collector 12 continuously exchanges heat with the surrounding air in the inner chamber 18 of the frame 10 over the entire surface area of the thermal collector 12. Most of the heat is exchanged between the thermal collector 12 and the air surrounding the finned surface 26, because the finned surface 26 has the greatest surface area to the surrounding air. The air holes 22 in the frame 10 facilitate cold air inlet to displace the heated air surrounding the thermal collectors 12 in the frame 10. Within the thermal collector 12 itself, the thermal pipes 29 tend to significantly reduce the flow resistance of heat, thereby dispersing the heat more evenly over the surface area of the thermal collector 12 for dissipation. This is extremely important, particularly when fans are not used to force air over the thermal collector 12. In this latter scenario, PC 8 cards in the middle of the frame 10 will be at maximum distance from the air holes 22. The low thermal resistance it is provided by the thermal tubes 29, greatly increases the cooling efficiency of the apparatus and specifically improves the capacity by cooling PC cards 8 located in the middle. Additional cooling efficiency can be achieved by implementing a fan to force air over the finned surface 26 of the thermal collectors 12. Although specific embodiments have been described, it will be understood by those of ordinary skill in the art that changes can be made without departing from the scope of the invention. spirit and scope of the invention. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, property is claimed as contained in the following:

Claims (17)

1. CLAIMS 1. An apparatus for removing heat from at least one PC card, characterized in that it comprises a frame defining a chamber with holes for air; a thermal collector mounted to the frame within the chamber, the thermal collector has a finned surface for transferring heat to an environment surrounding the thermal collector, a surface without fins on a side opposite the finned surface, and thermal tubes that are completely enclosed within the thermal collector, the thermal tubes facilitate conductive thermal transfer between finned and non-finned surfaces; and a bottom plate mounted on the frame having at least one electrical connector mechanically and electrically connectable to at least one PC card such that a surface of at least one PC card is in immediate proximity to and substantially parallel to the surface without fins of the thermal collector, facilitating thermal transfer between the PC card at least and the thermal collector.
2. 2. Apparatus according to claim 1, characterized in that a plurality of thermal collectors are mounted at intervals with respect to the frame within the chamber with a space between respective surfaces with fins and without fins of adjacent thermal collectors defining a slot; and wherein at least one electrical connector is located in the bottom plate between each slot.
3. 3. Apparatus according to claim 2, characterized in that the finned surface of the thermal collector is treated to improve radiant heat transfer between the PC card and the thermal collector.
4. 4. Apparatus according to claim 3, characterized in that the surface without fins treated has a surface emissivity of approximately 0.9.
5. 5. Apparatus according to claim 3, characterized in that the thermal collector is treated with black paint.
6. 6. Apparatus according to claim 2, characterized in that the thermal collector is made from extruded material.
7. 7. Apparatus according to claim 6, characterized in that the material is metal.
8. 8. Apparatus according to claim 7, characterized in that the metal is aluminum.
9. 9. Apparatus according to claim 7, characterized in that the metal is copper.
10. 10. Apparatus according to claim 6, characterized in that the material is a metal alloy.
11. 11. Apparatus according to claim 2, characterized in that a PC card connected to an electrical connector physically contacts a finless surface of one of the plurality of thermal collectors.
12. 12. Apparatus according to claim 1, characterized in that a PC card connected to an electrical connector physically contacts a finned surface of the thermal collector.
13. 13. A method for cooling a PC card stack, characterized in that it comprises the steps of: providing thermal collectors, the thermal collectors have finned surfaces without fins and thermal pipes totally circumscribed, and a space between adjacent thermal collectors that define grooves for insertion into PC cards; provide electrical connectors for mechanical and electrical connection of the PC cards to a bottom plate; locate the PC cards eh immediate proximity to the finned surface of the thermal collector, in such a way that heat is transferred from the PC cards to the thermal collector; and cooling the thermal collector by allowing air to circulate on the finned surface of the thermal collector.
14. 14. The method according to claim 13, characterized in that the PC cards touch the finned surface of the thermal collector.
15. 15. The method according to claim 13, characterized in that the thermal collector is made by extruding metal.
16. 16. The method according to claim 13, characterized in that the metal is aluminum.
17. 17. - The method according to claim 13, characterized in that the metal is copper.