Abstract:
An arrangement, for heat dissipation from a component that is to be cooled, features: a pump for pumping a coolant, which pump comprises a pump rotor; a fan that comprises a fan rotor associated with which is an electric motor to drive it, the pump rotor and the fan rotor being separated from one another in fluid-tight fashion and drivingly connected to one another via a magnetic coupling. A corresponding method for heat dissipation from a component that is to be cooled, uses a fan having a fan rotor and a drive motor, a pump having a pump rotor, a coolant that is pumpable by means of the pump, to perform the steps of A) imparting a rotational motion to the fan rotor by means of the drive motor; B) imparting a rotational motion to the pump rotor via the magnetic coupling; and C) causing the coolant to flow by the rotational motion of the pump.

Description:
CROSS REFERENCE 
   This application is a section 371 of PCT/EP2003/010729, filed 26 Sep. 2003, claiming priority from German application DE 102 42 382.9, filed 28 Sep. 2002, the contents of which are incorporated by reference. 
   FIELD OF THE INVENTION 
   The invention concerns an arrangement and a method for cooling a component. 
   BACKGROUND 
   Many components, in particular electrical components such as microprocessors, are becoming more and more powerful and, at the same times are consuming more and more electrical power. 
   SUMMARY OF THE INVENTION 
   It is therefore an object of the invention to make available a new arrangement and a new method for cooling a component. 
   This object is achieved, according to the present invention, by providing a coolant pump, associated with a fan driven by an electric motor, and magnetically coupling the fan rotor and the pump rotor together, so that no separate pump drive is needed. The magnetic coupling separates the pump region from the fan region in fluid-tight fashion. This ensures that the coolant is continuously available for cooling, and that the coolant does not leak out and cause damage. In addition, only one drive system is needed for the fan and the rotor, with a consequent reduction in parts, weight, and cost. 
   According to a further aspect of the invention, the object is also achieved by using a drive motor to impart a rotational motion to the fan rotor, using the magnetic coupling between the fan rotor and the pump rotor to cause the pump rotor to also rotate, and causing the coolant to flow as a result of the rotation of the pump rotor. Transfer of the rotary motion of the fan rotor to the pump rotor simplifies construction and decreases the number of parts required. 
   Further details and advantageous refinements of the invention are evident from the exemplary embodiments, in no way to be understood as a limitation of the invention, that are described below and depicted in the drawings. 
   BRIEF FIGURE DESCRIPTION 
     FIG. 1  is a perspective depiction of a preferred embodiment of a fluid cooling apparatus according to the present invention; 
     FIG. 2  is a side view of a heat absorber according to the present invention; 
     FIG. 3  is a section through the heat absorber, looking along line III-III of  FIG. 2 ; 
     FIG. 4  is a plan view of the heat absorber, looking in the direction of arrow IV of  FIG. 3 ; 
     FIG. 5  is a section through the heat absorber, looking along line V-V of  FIG. 4 ; 
     FIG. 6  is a section through the heat absorber, looking along line VI-VI of  FIG. 4 ; 
     FIG. 7  is a side view of the preferred embodiment of the fluid cooling apparatus according to the present invention shown in  FIG. 1 ; 
     FIG. 8  is a section through the fluid cooling apparatus, looking along line VIII-VIII of  FIG. 7 ; 
     FIG. 9  is an exploded view of a centrifugal pump used as an example in  FIG. 1 ; 
     FIG. 10  is a plan view of a heat exchanger  28  as used in  FIG. 1 ; 
     FIG. 11  shows a plate of a heat exchanger having a bent-out sheet-metal part; 
     FIG. 12  shows a plate of a heat exchanger having a preferred embodiment of a bent-out sheet-metal part; 
     FIG. 13  shows a temperature/rotation speed characteristic curve for determining the necessary rotation speed; and 
     FIG. 14  shows a fan having a fluid conduit for passage of a coolant. 

   DETAILED DESCRIPTION 
     FIG. 1  is a perspective depiction of a preferred embodiment of a fluid cooling apparatus  10  according to the present invention. Fluid cooling apparatus  10  preferably serves to cool an electronic component  12  (depicted only schematically), in particular a microcontroller (μC), processor, or microprocessor (μP). 
   Fluid cooling apparatus  10  comprises a heat absorber  20 , a return hose line  22 , a fluid pump  24 , an interconnecting hose line  26 , a heat exchanger  28 , a fan  30 , and a supply hose line  32 . The flow directions are indicated by arrows  23  and  33 . 
   Heat absorber  20  comprises an inlet  40  and an outlet  42 , pump  24  an inlet  44  and an outlet  46 , and heat exchanger  28  an inlet  48  and an outlet  50 . 
   Outlet  42  of heat absorber  20  is connected via return hose line  22  to inlet  44  of pump  24 . Outlet  46  of pump  24  is connected via interconnecting hose line  26  to inlet  48  of heat exchanger  28 . Outlet  50  of heat exchanger  28  is connected via supply hose line  32  to inlet  40  of the heat absorber. 
   Heat absorber  20 , return hose line  22 , pump  24 , interconnecting hose line  26 , heat exchanger  28 , and supply hose line  32  thus form a cooling circuit in which a coolant  52  can circulate. Coolant  52  can be a fluid, for example a glycol-water mixture (cooling fluid). 
   Manner of Operation of  FIG. 1   
   Coolant  52  flows through heat absorber  20 ; at inlet  40  the coolant has a temperature below the surface temperature of processor  12 , in heat absorber  20  it absorbs heat from processor  12 , and at outlet  42  it has a temperature that is less different from the surface temperature of processor  12  than at inlet  40 . 
   Coolant  52  travels via line  22  to pump  24 , which keeps the coolant circuit in motion and pumps it via line  26  to inlet  48  of heat exchanger  28 . 
   Coolant  52  entering heat exchanger  28  has a higher temperature than the air flow, driven by fan  30 , entering the air side of the heat exchanger. Heat is thereby transferred from coolant  52  to the air, and coolant  52  cools down. 
   Lastly, the cooled coolant is delivered through outlet  50  of heat exchanger  28  and line  32  to heat absorber  20  through the latter&#39;s inlet  40 , in order to cool processor  12 . 
   The arrangement of pump  24  upstream from the inlet of heat exchanger  28  is favorable because a slight heating of coolant  52  takes place during the pumping operation. Because of the greater temperature difference in heat exchanger  28 , the latter works more effectively and achieves a greater cooling capacity than if pump  24  were located downstream from heat exchanger  28 . 
     FIG. 2  is a side view of heat absorber  20 . 
     FIG. 3  is a section through heat absorber  20 , looking along line III-III of  FIG. 2 . 
     FIG. 4  is a plan view of heat absorber  20  from the side facing away from processor  12 . 
     FIG. 5  is a section through heat absorber  20 , looking along line V-V of  FIG. 4 . 
     FIG. 6  is a section through heat absorber  20 , looking along line VI-VI of  FIG. 4 . 
   Heat absorber  20  comprises a heat absorption element  64  having a plurality of plates  66  and conduits  68  located between plates  66 , an inlet-side part  60  having inlet  40 , and an outlet-side part  62  having outlet  42 . 
   An embodiment of heat absorption element  64  that is preferred in economic terms is manufactured by extrusion from a material having good thermal conductivity. The use of aluminum has proven favorable, since it is inexpensive and offers weight advantages. The low weight greatly reduces the risk of damage to component  12  as a result of dynamic stress. 
   Inlet-side part  60  and outlet-side part  62  are connected in fluid-tight fashion to heat absorption element  64 . 
   Coolant  52  travels through inlet  40  into inlet-side part  60 , and from there via conduits  68  of heat absorption element  64  to outlet-side part  62 , which it leaves through outlet  42 . 
   As it flows through conduits  68 , the coolant absorbs heat that was transferred from upper side  13  of processor  12  to side  70  of heat absorption element  64  facing toward the processor, and thus also to plates  66 . 
   A heat transfer improvement medium, in particular a thermally conductive film and/or a thermally conductive paste, is preferably arranged between heat absorber  20  and component  12  that is to be cooled. Better heat transfer is thereby obtained. 
     FIG. 7  is a side view of the preferred embodiment of fluid cooling apparatus  10  according to the present invention shown in  FIG. 1 . 
     FIG. 8  is a schematic section through a preferred embodiment of fluid cooling apparatus  10 . 
   Fan  30  comprises a fan housing  71 , a stator  76  mounted on the latter via a plurality of spokes  74 , and a rotor  78  having fan blades. 
   Pump  24  comprises a magnet cup  80  connected to rotor  78  of fan  30 , a pump housing  82  having a bearing journal  83 , and a pump wheel  84  having pump vanes  86 . 
   Pump housing  82  is connected to fan housing  71  via a retaining spider  72 . 
   Heat exchanger  28  is connected to fan  30  on the opposite side from pump  24 . 
   Pump  24  is driven by rotor  78  of fan  30  via a magnetic coupling. For that purpose, magnet cup  80  is immovably connected to rotor  78 . Pump housing  82  is retained by retaining spider  72  so that it cannot rotate along with magnet cup  80 . Pump wheel  84  is likewise magnetic, and is bearing-mounted in pump housing  82  rotatably via bearing journal  83 . Magnet cup  80  is also bearing-mounted via pump housing  82 . When magnet cup  80  is rotated by motor  76  of fan  30 , pump wheel  84  is therefore also moved, and as a result pump vanes  86  are driven. This causes pumping of coolant  52  on the principle of a centrifugal pump. 
   Because of the coupling of fan  30  and pump  24 , direct regulation of the temperature of component  12  can be accomplished. Lower-noise operation is thus possible if there is less load on processor  12 . 
   The cooling apparatus preferably comprises a rotation speed controller n-RGL  122  for regulating the rotation speed of fan  30 . The target rotation speed for the rotation speed controller is preferably determined as a function of a temperature value, that temperature value being ascertained by a temperature sensor  120  mounted on component  12  that is to be cooled. 
   As alternatives to plastic-on-plastic journal mounting of pump wheel  84  in pump housing  82 , mounting by way of a rolling bearing or also a radial bearing configuration is possible. 
     FIG. 9  is an exploded view of centrifugal pump  24  that is used by way of example. 
   Pump housing  82  comprises a first housing part  82 ′ and a second housing part  82 ″. Inlet  44  and outlet  46  are arranged in first housing part  82 ′, and bearing journal  83  in second housing part  82 ″. First housing part  82 ′ and second housing part  82 ″ are produced from a suitable plastic, for example by injection-molding. Connection of the two housing parts is effected, for example, by ultrasonic welding. 
   Pump wheel  84  comprises pump vanes  86  at its end toward the first housing, and is fabricated from a suitable plastic, for example by injection-molding. Magnet particles or segments, for example hard ferrite powders, are embedded in the plastic, and after injection-molding the desired magnetization is imposed, as indicated in  FIG. 9  by N (north pole) and S (south pole). As a result, in addition to its property as a fluid flow generator, pump wheel  84  also has the capability of transferring the magnetic torque generated by magnet cup  80 , without a stuffing box, to pump wheel  84 . 
   Magnet cup  80  is manufactured as a deep drawn steel part or steel cup having a magnet ring, or preferably, in the same manner as pump wheel  84 , from an injection-moldable plastic having embedded magnetic particles or segments, and the desired magnetization is then imposed as also shown in  FIG. 9 . 
   Upon assembly, pump wheel  84  is inserted into second housing part  82 ″, first housing part  82 ′ is pushed on, and the two housing parts  82 ′,  82 ″ are joined in fluid-tight fashion. Pump housing  82  is then moved into magnet bell  80 . 
   What results is a pump  24  with a very low parts count which can be produced inexpensively. With the magnetic coupling, furthermore, it is much easier than with a continuous shaft to achieve freedom from leaks, which is a necessity for use in the interior of a computing system. 
   Pump wheel  84  and/or magnet cup  80  can alternatively be made not from a plastic having embedded magnet particles but instead, for example, from pressed magnets or pressed magnets injection-embedded in plastic. 
     FIG. 10  is a plan view of a preferred embodiment of heat exchanger  28 . 
   Heat exchanger  28  comprises a housing  88  having an inlet-side part  88  with inlet  48 , an outlet-side part  92  with outlet  50 , a plurality of conduits  94  that extend between inlet-side part  88  and outlet-side part  92 , and a plurality of plate regions  96  extending between conduits  94 . 
   Coolant  72  travels through inlet  48  into inlet-side part  90  of heat exchanger  28 ; from there it travels through conduits  94  into outlet-side part  92 , whence it leaves the heat exchanger through outlet  50 . 
   The air set in motion by fan  30  flows through plate regions  96  that serve to increase the heat-exchange area. For that purpose, the heat exchanger is arranged in the air flow region of fan  30  (see  FIG. 8 ). 
   The heat transferred from coolant  52  to the air ensures cooling of coolant  52 . 
   Fluid cooling apparatus  10  preferably has further connectors (not depicted) through which lines from further heat absorbers  20  can be connected. They are preferably completely preassembled and filled so that, for example, installation in the computer housing can be performed without difficulty. Fan  30  thus simultaneously ventilates other components in the computer housing, e.g. graphics cards, chipset modules, and hard drives. Overall cooling of the system is thereby improved. 
   The flow direction of the air preferably proceeds from the heat exchanger outflow side, i.e. the side at which air emerges, directly out of the housing, e.g. out of a computing system. Other components located in the housing are thereby cooled more effectively, which increases the service life of the computing system and/or allows less air flow. This minimizes noise. 
   Ventilation slots are preferably located in the housing on the side opposite the heat exchanger, so that the components located in the housing are continuously cooled in the resulting air flow. The heat exchanger functions simultaneously as a noise suppressor for the air flowing out of the housing. 
   Fluid cooling apparatus  10  requires very little space and has very little mass in the vicinity of component  12  to be cooled. 
   The magnetic coupling of fan  30  and pump  24  reduces the space requirement, parts count, and therefore manufacturing costs. There is moreover no need for an additional electrical connector for pump  24 . 
   Electric motor  76 , for example an electronically commutated external- or internal-rotor motor, can preferably be regulated in terms of its rotation speed, for example as a function of the temperature of component  12  to be cooled (see  FIG. 7 ). As a result, the cooling capacity or rotation speed can be kept as low as is necessary, and needs to be increased only if the ambient temperature and/or computing power is correspondingly high. The noise generated is thus likewise diminished; this is very advantageous, for example, in the context of a computing system in an office. 
   The heat absorber and heat exchanger are preferably implemented using flat-tube technology. An extremely compact configuration, maximum power density, and decreased weight can thereby be achieved. This is very advantageous when the heat absorber is placed directly on a processor to be cooled in a computer, since processors have little capacity for mechanical stress and the available heat transfer area is very small. 
   Deep drawn parts are preferred for inlets and outlets  60 ,  62 ,  90 ,  92 . 
   Plates  96  are preferably used in order to improve the efficiency of the flat tubes. 
   The flat tubes are preferably extruded parts. 
   It is advantageous in terms of heat transfer that the base surface of the heat absorber is flat and exhibits little surface roughness. 
   All the aforementioned elements can be manufactured and assembled very economically, so that the product as a whole can be manufactured inexpensively. 
   A radial fan is preferably selected as the fan, in which context the heat exchanger can preferably be arranged around the enveloping surface of the radial fan. Mounting the heat exchanger around the enveloping surface of the radial fan increases the heat exchanger area and therefore the cooling capacity. The heat exchanger comprises, for example, fluid conduits that extend on the enveloping surface from one end face of the radial fan to the opposite end face. 
     FIG. 11  shows a portion of a plate  96  of heat exchanger  28  having a bent-out sheet-metal part  130  that is referred to as a “shutter.” Bent-out sheet-metal part  130  is produced by stamping out three sides  131 ′,  131 ″, and  131 ′″ forming a “U,” and then bending out sheet-metal part  130  defined by the three sides  131 ′,  131 ″, and  131 ′″. Application of a plurality of such bent-out sheet-metal parts  130  to plates  96  results, for example, in an 80% improvement in the cooling capacity of the heat exchanger. Open end  132  of bent-out sheet-metal part  130  preferably faces the opposite way from direction  134  of the air flow through heat exchanger  28 . 
     FIG. 12  shows a portion of a plate  96  of heat exchanger  28  having a further embodiment of a bent-out sheet-metal part  135 . The latter is produced by making a cut  136  into plate  96 , followed by deep-drawing and bending out. The bending-out operation creates an opening  138  through which air can flow. Open side  137  of the bent-out sheet-metal part is preferably oriented oppositely to direction  139  of the air flow. 
     FIG. 13  shows a preferred exemplifying embodiment of a temperature/rotation speed characteristic curve  150  that indicates rotation speed n of fan  30  of liquid cooling system  10 , and thus also the rotation speed of pump  24 . This temperature/rotation speed characteristic curve  150  is preferably used in conjunction with a measurement of the temperature of coolant  52 . For that purpose, sensor  120  (see  FIG. 7 ) is preferably positioned in the vicinity of microprocessor  12  at a point in the coolant circuit at which the coolant has already absorbed the heat of microprocessor  12 . 
   The rotation speed of fan  20  is controlled in open- or, preferably, closed-loop fashion as a function of rotation speed value n resulting from temperature/rotation speed characteristic curve  150 . A Negative Temperature Coefficient (NTC) resistor can be used as sensor  120 . 
   According to the temperature/rotation speed characteristic curve, up to a first temperature T 1  (e.g. 30 degrees C.) a minimum rotation speed n 1  is defined at which fan  30  works very quietly. The result is that a minimum cooling level is continuously maintained, as experience has indicated is necessary. If temperature T in the coolant rises to T&gt;T 1 , rotation speed n of fan  30  is then increased until at a temperature T 2  (e.g. 70 degrees C.), maximum rotation speed n 2  of fan  30  is reached. At this operating point the flow velocities in both the closed-circuit fluid flow and the open-circuit fan flow are maximal, and maximum heat transfer is established. The maximum heat load is therefore also being dissipated. The dependence of rotation speed n on temperature T is shown as being linear, but in other instances can have a different, e.g. exponential, character. 
   In the case of components to be cooled that have an internal temperature sensor, in particular microprocessors, the sensor&#39;s temperature information can also be utilized to determine rotation speed n. The temperature information is picked off for this purpose, for example, at a suitable location on the main circuit board. 
     FIG. 14  shows a preferred exemplifying embodiment of a fan  30  for use in a fluid cooling apparatus  10 . Only fan  30  is depicted, without pump  24 . 
   Fan housing  71  of fan  30  comprises a fluid conduit  100  through which a coolant  52  can be conveyed. Fluid conduit  100  comprises an inlet  102  and an outlet  104 . Coolant can flow into fan housing  71  through inlet  102 , and flow out through outlet  104 . 
   Because coolant  52  is being pumped through fan housing  71 , on the one hand a further cooling of coolant  52  takes place (i.e. the fan also acts as a heat exchanger), and on the other hand fan  30  is effectively protected from overheating. For this purpose, fluid conduit  100  is preferably additionally routed past the electrical components of stator  76 . The fan preferably comprises further fluid conduits in addition to fluid conduit  100 . 
   For better heat transfer, the fan housing preferably comprises cooling fins that are arranged on the surface of fan  30  and/or project into fluid conduit  100 . 
   Fan housing  71  is preferably made from a thermally conductive plastic. This enables better heat transfer between coolant  52  and the fan housing surface at which heat dissipation takes place. 
   In a preferred embodiment of the invention, pump  24  is removable from fan  30  ( FIG. 8 ), i.e. pump  24  and fan  30  are connected detachably. This is achieved, for example, by way of a screw connection or quick-release coupling between pump  24  and fan  30 . Pump retaining member  72 , in particular, is detachable from pump  24  and/or from fan  30  for this purpose. This embodiment has the advantage that fan  30  can be replaced independently of the coolant circuit. It is thus unnecessary to drain the coolant when replacing fan  30 . 
   Heat absorber  20  ( FIG. 2  and  FIG. 3 ) preferably comprises, on its outer side, cooling fins (not depicted) with which additional cooling of coolant  52  flowing through heat absorber  20  is achieved. It is also preferred if heat absorber  20  comprises on its outer side an additional fan (not depicted) with which additional cooling of coolant  52  flowing through heat exchanger  20  can likewise be achieved. 
   Coolant lines  22 ,  26 ,  28  are preferably constituted by metal hoses, since the latter exhibit good aging resistance, fluid-tightness, and heat dissipation. Bendable corrugated tubes are also preferably used.