Abstract:
A cooling system ( 10 ) includes a member ( 26 A,  26 B) with an opening ( 27 ) therethrough, and includes first and second heat-conductive sections ( 21, 22 ) disposed adjacent the member on opposite sides thereof. A fluid supply section ( 41 ) is disposed on a side of the first section opposite from the member, and directs a flow of fluid ( 111-114 ) toward the first section. A portion ( 111, 114 ) of the fluid flows through the first section, and a different portion ( 112, 113 ) of the fluid flows through the other section.

Description:
BACKGROUND OF THE INVENTION 
     There are existing applications that include a platelike part which receives heat from a device such as a thermo-electric cooler (TEC) or from high-temperature circuitry. A cooling system is provided to remove heat at a fairly high rate from the platelike part. One existing approach involves the provision of a single layer of fins which have been extruded or machined, which have a wide spacing, and which are relatively thick and tall. An air flow from a fan is directed into the middle of this configuration of fins. While this existing approach has been generally adequate for its intended purposes, it has not been satisfactory in all respects. 
     In this regard, the wide spacing of the fins must be maintained to achieve a low pressure drop, which makes it difficult to provide sufficient convection surface area to facilitate a high rate of heat transfer from the fins to the air flow. The thickness of the fins can also make it difficult to efficiently remove heat from the fins. Also, it is difficult to reliably control air flow past the fins in a manner which results in reasonably efficient and uniform heat transfer throughout the fins. 
     SUMMARY OF THE INVENTION 
     From the foregoing, it may be appreciated that a need has arisen for a method and apparatus for effecting cooling of a heat-conductive part, in a manner which avoids some or all the disadvantages of pre-existing arrangements. According to the present invention, a method and apparatus are provided to address this need, and involve: providing a member having an opening which extends therethrough in a first direction, and first and second sections which are spaced in the first direction, which are disposed adjacent the member on opposite sides thereof, and which are each heat conductive, the first section having a portion which is offset from the opening through the member in a second direction approximately perpendicular to the first direction, and the second section having a portion which is offset from the opening through the member in a third direction approximately perpendicular to the first direction. A fluid is caused to flow toward the first section approximately in the first direction, the fluid flow including a first fluid portion which subsequently flows along the portion of the first section approximately in the second direction to facilitate a transfer of heat from the first section to the first fluid portion, and the fluid flow including a second fluid portion which subsequently flows approximately in the first direction through the opening in the member, and then flows along the portion of the second section approximately in the third direction to facilitate a transfer of heat from the second section to the second fluid portion. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A better understanding of the present invention will be realized from the detailed description which follows, taken in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a diagrammatic perspective view of an apparatus which is a cooling system embodying the present invention, a portion of which has been cut away so that some internal structure is visible; 
     FIG. 2 is a diagrammatic sectional view taken along the section line  2 — 2  in FIG. 1; 
     FIG. 3 is a diagrammatic sectional view taken along the section line  3 — 3  in FIG. 1; 
     FIG. 4 is a diagrammatic sectional view taken along the section line  4 — 4  in FIG. 1; and 
     FIG. 5 is a diagram of the cooling system of FIG. 1, showing how air flows through the cooling system. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 is a diagrammatic view of an apparatus which is a cooling system  10 , a portion of which is cut away so that some internal structure is visible. A coldplate in the form of a base plate  12  conducts heat, and is made of a material such as copper which is highly heat-conductive. The base plate  12  could alternatively be made of a different metal or some other suitable material. The base plate  12  receives heat from not-illustrated structure of a known type located below the base plate  12 . The cooling system  10  dissipates heat from the base plate  12  into ambient air, in a manner discussed in more detail later. 
     The cooling system  10  includes two parallel side walls  16  and  17 , which are vertical metal plates with their lower edges fixedly secured to opposite edges of the top surface of the base plate  12 . In the disclosed embodiment, the side walls  16  and  17  are welded to the base plate  12 , but they could alternatively be secured to the base plate  12  in any other suitable manner. The side walls  16  and  17  are made of metal, but could alternatively be made of any other suitable heat-conductive material. The vertical side walls  16  and  17  each extend parallel to a horizontal direction indicated by an arrow  18 . 
     A lower finstock section  21  is disposed on the base plate  12 , and an upper finstock  22  is disposed above the lower finstock section  21 . The finstock sections  21  and  22  have the same length in a horizontal direction parallel to the direction  18 . They also have the same width, such that each extends the full distance between the side walls  16  and  17 . The finstock sections  21  and  22  each have approximately the same vertical height or thickness, the top of the finstock section  21  being approximately level with the tops of the side walls  16  and  17 . The finstock sections  21  and  22  are each heat conductive, and the structure of each is described in more detail later. 
     Two lower splitter plate sections  26 A and  26 B are disposed vertically between the finstock sections  21  and  22 , at locations which are spaced horizontally in the direction  18 . Each of the lower splitter plate sections  26 A and  26 B is a rectangular plate of metal or some other suitable heat-conductive material, and each has one end disposed against the side wall  16  and the other end disposed against the side wall  17 . The ends of the splitter plate sections  26 A and  26 B may be welded to the side walls  16  and  17 . Although the splitter plate sections  26 A and  26 B are physically separate parts in the disclosed embodiment, for purposes of clarity they are treated herein as if they were respective portions of a single component. Therefore, they are sometimes referred to collectively herein as a lower splitter plate  26 . The region between the splitter plate sections  26 A and  26 B serves as an opening  27  through the lower splitter plate  26 . 
     The upper splitter plate  28  is approximately square, and is made of metal or some other suitable heat-conductive material. The upper splitter plate  28  has an approximately rectangular opening which extends vertically through it. The upper ends of the side walls  16  and  17  engage the underside of the splitter plate  28  adjacent opposite edges of the opening  29 , and are fixedly secured to the plate  29  by welding or in some other suitable manner. It will be noted that the width of the opening  29  in the direction  18  is larger than the width of the opening  27  in the direction  18 . Further, the opening  27  is approximately centered in relation to the opening  29  in the direction  18 . It will also be noted that the finstock sections  21  and  22  each have portions which project outwardly beyond each of the openings  27  and  29  on each side of each opening, in directions parallel to the direction  18 . 
     The base plate  12 , lower finstock section  21 , lower splitter plate  26  and upper finstock section  22  have several sets of aligned holes, one set of aligned holes being identified in FIG. 1 by reference numerals  31 - 34 . A respective bolt, which is not illustrated, can be inserted through each set of aligned holes, in order to physically secure the base plate  12  to a not-illustrated thermal load plate which is located below the base plate  12 . The head of each such bolt engages the top side of the base plate  12 , and the threaded shank of the bolt extends downwardly through the opening  31  in the base plate  12  and engages a threaded opening in the thermal load plate. In order to facilitate heat transfer in the disclosed embodiment, the finstock sections  21  and  22  are each brazed to the lower splitter plate  26  and also to the base plate  12  or the upper splitter plate  28 . 
     A plenum  36  is made of metal or some other suitable material, and is effectively a housing of approximately rectangular shape which has therein a chamber  35  of approximately rectangular shape. The plenum  36  has an approximately square opening  37  in the bottom wall thereof, and an approximately circular opening  38  in the top wall thereof. The opening  37  in the bottom wall is at least as wide and at least as long as the opening  29  in the upper splitter plate. The peripheral edges of the bottom wall of the plenum, which extend around the opening  37 , engage the peripheral edges of the upper splitter plate  28 , and are fixedly secured to the plate  28  by welding, or in some other suitable manner, such as by bolts. 
     An electric fan  41  of a commercially available type has a housing which is fixedly secured to the top wall of the plenum  36  by not-illustrated bolts, or in some other suitable manner. The fan  41  is aligned with the circular opening  38  in the top wall of the plenum  36 , so that operation of the fan  41  will cause air to flow vertically downwardly through the fan and into the plenum  36 . 
     FIG. 2 is a diagrammatic sectional side view taken along the line  2 — 2  in FIG.  1 . FIG. 2 shows the base plate  12 , lower splitter plate section  26 A, upper splitter plate  28 , and finstock sections  21  and  22 . As evident from FIG. 2, the finstock sections  21  and  22  are each defined by a sheet of thin metal which is bent to have a corrugated shape similar to a square wave. In the disclosed embodiment, the metal of the corrugated sheets is approximately 0.006″ thick, but it would alternatively be possible to use some other suitable thickness. Also, each of these corrugated sheets could alternatively be made of a suitable heat-conductive material other than metal. 
     Each of the corrugated sheets has a series of parallel vertical walls which are connected at their ends by bends. For example, the corrugated sheet of the lower finstock section  21  includes vertical walls  61 ,  62  and  63 , the walls  61  and  62  being connected at their upper ends by a bend  66 , and the walls  62  and  63  being connected at their lower ends by a bend  67 . Similarly, three of the walls in the finstock section  22  are designated by reference numerals  71 ,  72  and  73 , the walls  71  and  72  being connected at their lower ends by a bend  76 , and the walls  72  and  73  being connected at their upper ends by a bend  77 . Since the corrugated sheets each have approximately the shape of a square wave, the bends on the underside of the finstock section  21  each have a substantial surface area in contact with the base plate  12 , so as to facilitate heat transfer from the base plate  12  to the finstock section  21 . Similarly, the bends on the upper side of the finstock section  21  and the bends on the lower side of the finstock section  22  each have a substantial surface area in engagement with the splitter plate section  26 A, so as to facilitate heat transfer. 
     FIG. 3 is a diagrammatic sectional view similar to FIG. 2, except it is taken along the section line  3 — 3  in FIG.  1 . In this sectional view, the lower splitter plate section  26 A is present, but the upper splitter plate  28  is not present, because this sectional view is taken within the opening  29  in the upper splitter plate  28 . FIG. 4 is a diagrammatic sectional view similar to FIG. 2, except that it is taken along the section line  4 — 4  in FIG.  1 . It will be noted that neither the lower splitter plate section  26 A nor the upper splitter plate  28  is shown in FIG. 4, because the sectional view of FIG. 4 is taken at a location within each of the openings  27  and  29  of the splitter plates. 
     The top of the upper finstock section  22  has a region which is adjacent and aligned with the opening  29  in the upper splitter plate  28 . Within this region, the bends on the upper side of the finstock section  22  have been removed using a known technique, such as electro-discharge machining (EDM). In FIGS. 3 and 4, the bends which have been removed by EDM are indicated by broken lines. Instead of viewing the removal of this material as complete removal of the bends, it can alternatively be viewed as the creation of slotlike openings within each bend, one example of which is the slotlike opening indicated by reference numeral  86  in FIGS. 3 and 4. 
     In a similar manner, the lower side of the upper finstock section  22  has a region which is aligned with the opening  27  in the lower splitter plate  26 , and the bends within this region of the finstock section  22  have been removed by EDM, as indicated by broken lines in FIG.  4 . This can alternatively be viewed as the creation of slotlike openings within each of these bends, one example of which is indicated by reference numeral  91  in FIG.  4 . Further, the upper side of the lower finstock section  21  has a region which is adjacent and aligned with the opening  27  in the lower splitter plate  26 , and the bends within this region have been removed by EDM, as indicated diagrammatically by broken lines in FIG.  4 . This can alternatively viewed as the creation of slotlike openings within each of these bends, one example which is indicated by reference numeral  92 . As to each of the finstock sections  21  and  22 , material of the bends is removed only where the bends are adjacent and aligned with one of the openings  27  and  29  in the splitter plates. In all other portions of each finstock section, the bends are in place so that the bends can engage the base plate  12  or one of the splitter plates  26  and  28  in order to facilitate heat transfer, and in order to maintain structural rigidity of the finstock sections  21  and  22 . 
     FIG. 5 is a diagrammatic view of the cooling system  10  of FIG. 1, for purposes of showing how air flows through the cooling system  10 . FIG. 5 corresponds to a central portion of the cooling system  10 , where the plane of FIG. 5 corresponds to a vertical plane extending parallel to the direction  18 . The fan  41  has a rotating hub  101  in the center thereof, and air passes through the fan at locations disposed radially outwardly from the hub, as indicated diagrammatically by exemplary air flow lines  111 - 114 . The air flow passes through the plenum  36 , and through the opening  29  in the upper splitter plate  28 . The air flow enters the region between vertical walls of the upper finstock section  22 , facilitated by the slotlike openings  86  provided in the bends  77  on the upper side of the finstock section  22 . 
     The outermost portions of the air flow, indicated by air flow lines  111  and  114 , are routed to flow laterally outwardly in opposite directions through the upper finstock section  22 , due in part to the fact that the opening  27  in the lower splitter plate  26  is not as wide as the opening  29  in the upper splitter plate  28 . The central portion of the air flow passes through the opening  27  in the lower splitter plate  26 , and enters the lower finstock section  21 , due in part to the slotlike openings  91  and  92  provided in the bends  76  and  66  of the finstock sections  21  and  22 . In view of the presence of the base plate  12 , this air flow splits and respective portions of it flow horizontally in opposite directions through the lower finstock section  21 , as indicated diagrammatically by air flow lines  112  and  113 . 
     A plurality of thermoelectric coolers (TECs)  121  are provided on the underside of the base plate  12 . Each TEC  121  is a commercially available component. Heat extracted from the region below the base plate  12  by the TECs  121  is transferred from the TECs to the base plate  12 , and is then dissipated by the cooling system  10 . The thermal load plate discussed earlier, which is not shown in the drawings, is disposed against the underside of the TECs  121 , such that the TECs  121  are sandwiched between the base plate  12  and the thermal load plate. 
     For convenience and clarity, the foregoing discussion assumes that the TECs transfer heat to the cooling system  10 , and that this heat is then transferred to the air flowing through the cooling system  10 . However, it will be recognized that where the region below the base plate  12  needs to be heated, the direction of current flow through the TECs could be reversed so that the TECs extract heat from the base plate  12  and supply it to the region below the base plate. In that case, heat from the air flowing through the cooling system  10  will be transferred to the base plate  12 . 
     The TECs  121  are shown in FIG. 12 by way of example. Persons skilled in the art will recognize that some other structure which is to be cooled or heated could be thermally coupled to the base plate  12 . This other structure could cooperate with the underside of the base plate  12 , or could be thermally coupled to it in some other manner. 
     As discussed above, the lower and upper finstocks  21  and  22  of the disclosed embodiment are made of bent metal sheets that have openings created by EDM techniques. However, it would alternatively be possible to form suitable finstocks by injection molding techniques, using an injection molding material of relatively high thermal conductivity. The molded finstocks would be somewhat less thermally conductive than the illustrated finstocks, and would typically have somewhat thicker fins. On the other hand, forming the finstocks by injection molding would permit the openings in the finstocks to be formed as part of the molding process, thereby avoiding the use of EDM techniques, which in turn would reduce the overall cost of the finstocks. A further consideration is that, as evident from FIGS. 1 and 4, there is a vertical gap between the sheet metal finstocks of the disclosed embodiment in the region of the opening  27  in the lower splitter plate  26 . However, if the finstocks were injection molded, the upper side of the lower finstock and/or the lower side of the upper finstock could be shaped to have a portion that extends into the opening  27 , in a manner so that there is little or no gap between the finstocks in the region of the opening  27 . 
     The present invention provides a number of technical advantages. One such technical advantage results from the use of two finstock sections on opposite sides of a splitter plate with an opening through it, such that the amount of flow through each finstock section can be appropriately controlled with a minimal back pressure on the fan. 
     The width of the opening through the splitter plate disposed between the finstock sections serves as a control on the pressure drop and thus on the division of air flow between the finstock sections. Use of a thin corrugated sheet for each finstock section allows significantly more convection surface area for heat transfer than in the case of tall and/or thick fins of a type used in pre-existing systems. The use of parallel flow paths also facilitates a lower pressure drop for a given air flow. 
     Given that there is a minimal back pressure on the fan, a low-pressure, high-volume, low-noise fan can be used. This can be advantageous in environments where operators or other persons are present, by avoiding the need for such persons to wear ear protectors. A further advantage is that the disclosed cooling system is capable of removing a substantial amount of heat from the base plate, which in turn permits the cooling system to maintain a relatively uniform temperature throughout the base plate. The use of two layers of finstock provides a significantly increase in the convection heat transfer area, in comparison to pre-existing configurations. 
     Although one embodiment has been illustrated and described in detail, it will be understood that various substitutions and alterations are possible without departing from the spirit and scope of the present invention, as defined by the following claims.