Abstract:
An apparatus for cooling a number of electronic components comprises an enclosure within which the components are positioned, an arrangement for circulating a cooling fluid to the components so that the cooling fluid can evaporate on or proximate the components and thereby absorb the heat generated by the components, a mechanism for condensing the evaporated cooling fluid, and a reservoir which is in fluid communication with the circulating means and within which the condensed cooling fluid collects.

Description:
[0001]    This application is based on and claims the benefit of U.S. Provisional Patent Application No. 60/923,480, which was filed on Apr. 13, 2007. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to an apparatus and method for cooling electrical components. In particular, the invention relates to an apparatus and method in which the components are surrounded by an enclosure, a cooling fluid is evaporated onto the components to cool them, and then the heat from the vaporous cooling fluid is dissipated through the enclosure and into the surrounding environment. 
       SUMMARY OF THE INVENTION 
       [0003]    In accordance with the present invention, an apparatus for cooling a number of electronic components comprises an enclosure within which the components are positioned, means for circulating a cooling fluid to the components, wherein the cooling fluid evaporates on or proximate the components and thereby absorbs the heat generated by the components, means for condensing the evaporated cooling fluid, and a reservoir which is in fluid communication with the circulating means and within which the condensed cooling fluid collects. 
         [0004]    In accordance with one aspect of the invention the enclosure defines a hermetically sealed volume within which the components are positioned. In accordance with a further aspect of the invention the components are mounted on a circuit board and the enclosure is secured and sealed to the circuit board over the components. 
         [0005]    The condensing means may comprise a surface of the enclosure. Alternatively, the condensing means may comprise a number of condenser tubes which are connected to or formed integrally with the enclosure. In one embodiment of the invention the condensing means comprises a plurality of condensing tubes which each extend generally vertically from an upper surface of the enclosure. 
         [0006]    In accordance with one embodiment of the invention the circulating means comprises a pump which is fluidly connected to the reservoir, a number of applicators which are positioned proximate the components, and a fluid distribution network which is connected between the pump and the applicators. In this manner, the cooling fluid is circulated by the pump through the fluid distribution network and the applicators to the components. The fluid distribution network may comprise, e.g., a manifold which is formed within one or more surfaces of the enclosure. 
         [0007]    In accordance with another embodiment of the invention the reservoir may comprise a portion of the sealed volume within which the components are positioned. In accordance with another embodiment of the invention the reservoir may comprise a catch tray which is secured to the circuit board opposite the components. In yet another embodiment of the invention the reservoir may communicate with the sealed volume through a number of apertures in the circuit board. 
         [0008]    The present invention is also directed to a method for cooling a number of electronic components. The method comprises the steps of: (a) positioning the components within a sealed enclosure; (b) circulating a cooling fluid to the components; (c) evaporating the cooling fluid on or adjacent the components to thereby absorb the heat generated by the components; (d) condensing the evaporated cooling fluid within the enclosure; (e) collecting the condensed cooling fluid; and (f) repeating steps (a) through (e). 
         [0009]    The objects and advantages of the present invention will be made apparent from the following detailed description, with reference to the accompanying drawings. In the drawings, the same reference numbers are used to denote similar components in the various embodiments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a perspective view of one embodiment of the evaporative cooling apparatus of the present invention shown positioned over an exemplary circuit board; 
           [0011]      FIG. 2  is a perspective view of the evaporative cooling apparatus of  FIG. 1  shown assembled on the circuit board; 
           [0012]      FIG. 3  is a top perspective view of another embodiment of the evaporative cooling apparatus of the present invention; and 
           [0013]      FIG. 4  is a bottom perspective view of the evaporative cooling apparatus shown in  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    Referring to  FIGS. 1 and 2 , the evaporative cooling apparatus of the present invention, which is indicated generally by reference number  10 , is shown in conjunction with an exemplary circuit board  12  which comprises a number of electronic components  14  mounted thereon. The circuit board  12  may be mounted in a device (not shown), such as a computer or a game consol. In use of the device, the electronic components  14  may generate a significant amount of heat which could adversely affect the performance of the components and, thus, the device. In accordance with the present invention, the evaporative cooling apparatus  10  provides an efficient and effective means for dissipating this heat from the components  14 . 
         [0015]    The evaporative cooling apparatus  10  comprises an enclosure  16  which is secured to the circuit board  12  over the electronic components  14 . The enclosure  16  may be configured to cover all or desired ones of the components  14 . Accordingly, the enclosure  16  may have any of a variety of forms. In the embodiment of the invention illustrated in  FIGS. 1 and 2 , for example, the enclosure  16  comprises a front wall  18 , a rear wall  20 , and a pair of side walls  22 ,  24 . The enclosure  16  also comprises a top surface  26  which extends completely between these walls. The top surface  26  may comprise a number of sections at different elevations in order to accommodate electronic components  14  of varying heights. In the embodiment of the invention shown in the Figures, for example, the top surface  26  comprises an upper section  28  and a lower section  30  which are joined by a generally vertical section  32 . 
         [0016]    The enclosure  16  is preferably made of a heat conductive material such as metal. However, other materials, even glass or plastic, may also be used provided that the total surface area of the enclosure  16  is sufficiently large to dissipate a desired amount of the heat generated by the components  14 . Furthermore, depending on the material from which it is made, the enclosure  16  may be manufactured using any of a variety of techniques, such as deep drawing, bulk machining and electroforming. The enclosure  16  may also be assembled from a number of individual components using suitable gluing or brazing techniques. 
         [0017]    The enclosure  16  may be attached to the circuit board  12  using any known means, such as spring clamps, adhesives or, as shown in  FIG. 2 , screws  34 . In addition, the enclosure is ideally hermetically sealed to the circuit board  12  with a suitable, preferably elastomeric, seal  36 . Accordingly, the enclosure  16  and the circuit board  12  will define a sealed volume within which the electronic components  14  are located. 
         [0018]    In accordance with the present invention, a cooling fluid is circulated within this sealed volume and evaporated on or near the components  14  in order to absorb the heat generated by the components. The vaporous cooling fluid then expands against the enclosure  16  and condenses as the heat from the fluid is transmitted through the enclosure and into the surrounding environment. The cooling fluid is preferably a dielectric fluid that will not interfere with the operation of the components  14 . Several known cooling fluids are suitable for use in the present invention, including Fluorinert™, which is sold by 3M Corporation of St. Paul, Minn. 
         [0019]    Referring also to  FIGS. 3 and 4 , which shows another embodiment of the present invention, the enclosure  16  may also comprise a number of condenser tubes  38  to aid in dissipating the heat from the vaporous cooling fluid. In this embodiment, the condenser tubes  38  are cylindrical members which extend generally vertically from the top surface  26  of the enclosure  16 . In addition, the tops of the condenser tubes  38  are closed while their bottoms are open to the sealed volume defined by the enclosure  16  and the circuit board  12 . The number and height of the condenser tubes  38  may vary depending on the volume of cooling fluid used, which in turn depends on the amount of heat which is desired to be dissipated from the individual electronic components  14 . These determinations can be readily made by the person of ordinary skill in the art given a particular cooling application. 
         [0020]    Referring to  FIG. 4 , the cooling fluid may be circulated to the various electronic components  14  by a pump  40 . The pump may derive its power from the circuit board  12  or an external power supply, in which event the power leads for the pump are fed through a sealed feed-through in the enclosure  16 . The pump  40  includes an inlet  42  which is connected to a reservoir for the cooling fluid and an outlet  44  which is connected to a number of applicators  46  by a fluid distribution network. The fluid distribution network may comprise a fluid manifold which is connected to or formed in the enclosure  16  or, in the embodiment of the invention which is shown in  FIG. 4 , separate lengths of a suitable tubing  48 . The reservoir for the cooling fluid may comprise a bottom portion of the sealed volume or, as shown in  FIG. 2 , a separate catch tray  50  which is secured to the opposite side of the circuit board  12  and which communicates with the sealed volume through a number of holes or channels in the circuit board. Each applicator  46  is ideally positioned over or adjacent one or more of the electronic components  14 . The applicators  46  may comprise, for example, small diameter tubes, sprayers, nozzles or atomizers. 
         [0021]    In operation of the embodiment of the invention shown in  FIGS. 3 and 4 , the cooling fluid is pumped through the applicators  46  and onto or adjacent the electronic components  14 . As the cooling fluid absorbs heat from the components  14  it evaporates and thereby cools the components. The vaporous cooling fluid then rises into the condenser tubes and condenses as its heat is transmitted through the condenser tubes and into the surrounding environment. The liquid cooling fluid is then drawn by gravity into the reservoir and the process is repeated to cool the components  14  for as long as desired. 
         [0022]    It should be recognized that, while the present invention has been described in relation to the preferred embodiments thereof, those skilled in the art may develop a wide variation of structural and operational details without departing from the principles of the invention. For example, the various elements shown in the different embodiments may be combined in a manner not illustrated above. Therefore, the appended claims are to be construed to cover all equivalents falling within the true scope and spirit of the invention.