US20060171801A1 - Heatsink apparatus - Google Patents

Abstract

A heatsink apparatus has a radiator and a centrifugal pump in a closed circulation channel for circulating a coolant, wherein the centrifugal pump contacting a heat-generating component dissipates heat from the heat-generating component through heat exchange with the coolant. The centrifugal pump includes: a lower casing provided with a contact surface that contacts the heat-generating component; an upper casing; a ring-shaped sealing member provided between the lower and upper casings so as to form a round heat transfer chamber between the ring-shaped sealing member and the lower casing and to form a pump chamber that houses an impeller between the ring-shaped sealing member and the upper casing; a guiding member provided protruding on the lower casing to make the round heat transfer chamber a circulation channel; and the round heat transfer chamber connecting to a through-hole formed in a central portion of the ring-shaped sealing member.

Description

BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• The present invention relates to a heatsink apparatus that circulates a coolant to cool heat-generating semiconductors, including a micro processing unit (hereinafter referred to as an MPU) used in a personal computer and the like, and other electronic components having heat-generating portions.
• 2. Description of Related Art
• Recent electronic devices include highly integrated electronic components and generate high operating clock frequencies, thereby producing a larger amount of heat from the electronic components. Due to the heat increase, temperatures at contact points of the electronic components surpass an operating temperature range, resulting in more than a few malfunctions of the electronic components. It is thus a critical issue to maintain the temperatures of the electronic components within the operating temperature range so that the electronic components function properly.
• Conventional air-cooling using a heatsink alone, however, is insufficient to cool the heat-generating electronic components. Thus, a heatsink apparatus having higher performance and higher efficiency as shown inFIG. 18, for instance, is disclosed (Related Art 1).FIG. 18 shows a cross-sectional view of acooling module301 that uses a centrifugal pump.
• [Related Art 1] Japanese Patent Laid-Open Publication 2004-134423
• However, the heatsink apparatus disclosed inRelated Art 1, in which a coolant flows through the center of animpeller302 toward a heat-generatingcomponent303, has the following problems: a complex impeller bearing structure declines reliability; low rigidity of the impeller bearing causes noise or declines reliability; and resistance of the coolant running through a small hole at the center of the impeller causes difficulty in ensuring flow rate of the coolant, thus impeding improvement in cooling performance.
• To overcome the above-described problems, a compact heatsink apparatus as shown inFIG. 14, for example, is proposed in which a combined heatsink portion and pump circulates a coolant so as to cool a heated electronic component in a highly efficient manner.
• FIG. 14 is a cross-sectional view of a centrifugal pump of a conventional heatsink apparatus;FIG. 15 illustrates a flow direction of the coolant in the centrifugal pump of the conventional heatsink apparatus; andFIGS. 16 and 17 show structures of an electronic device having a heatsink apparatus.
• The structure of the electronic-device having the heatsink apparatus is first described with reference toFIG. 16. As shown inFIG. 16, the electronic device includes:body1 of a laptop computer as the electronic device having the heatsink apparatus;keyboard2 of the laptop computer;centrifugal pump3 constituting the heatsink apparatus and contacting a heat-generating component for heat exchange; heat-generatingelectronic component4 such as an MPU and the like;board5 mounted with heat-generatingelectronic component4;radiator6 provided on a rear side of a laptop computer display and dissipating heat of the coolant to the exterior, the heat received from heat-generatingelectronic component4; and closedcirculation channel7 connectingcentrifugal pump3 andradiator6 and circulating the coolant. A description ofFIG. 17, which shows a desktop computer having the heatsink apparatus, is omitted since the structure of the heatsink apparatus is the same as that in the laptop computer.
• An internal structure of conventionalcentrifugal pump3 is described below with reference toFIGS. 14 and 15. As shown inFIGS. 14 and 15,centrifugal pump3 includes: open-type impeller211 ofcentrifugal pump3; open-type blades211aofimpeller211;magnet rotor212 provided on an inner peripheral surface ofimpeller211; stator213 provided on an inner peripheral side ofmagnet rotor212; coil214 wound around stator213;circuit board215 mounted with electric circuits that provide a current to coil214;upper casing216; discharge channel216aformed inupper casing216;suction channel216balso formed inupper casing216; heat-receivinglower casing218 fitted toupper casing216 and contacting heat-generatingelectronic component4; thick portion218a;brim218btouchingupper casing216;recess218c;contact surface218dcontacting heat-generatingelectronic component4; and heat-dissipating fins218etransferring heat received from heat-generatingelectronic component4 to the coolant.
• Centrifugal pump3 further includes: shaft219 forming a rotating axis ofimpeller211 and fixed toupper casing216; ring-shaped sealing member220 fitted toupper casing216 so as to formpump chamber217, as also shown inFIG. 15; cylindrical portion220afitted to a side face of thick portion218aoflower casing218; and waterchannel sealing portion220bprovided betweenupper casing216 andlower casing218 and coveringrecess218cso as to form a water channel. AsFIG. 15 shows,discharge connection220cprovided on an upper side of ring-shaped sealing member220 connectspump chamber217 and discharge channel216a;suction connection220dprovided on a lower side of ring-shaped sealing member220 connectspump chamber217 andsuction channel216b. Sealingmember221 such as an o-ring seals a portion betweenupper casing216 andlower casing218.
• Functions ofcentrifugal pump3 of the heatsink apparatus are described below. The coolant is drawn intosuction channel216band forced throughsuction connection220d. The coolant is then led toward the center ofpump chamber217 by waterchannel sealing portion220band propelled to an outer periphery ofpump chamber217 by rotation of blades211a. Then, the coolant is forced throughdischarge connection220cand discharged from discharge channel216a. Meanwhile, the heat emitted from heat-generatingelectronic component4 is transferred fromcontact surface218dto radiatingfins218eand thick portion218a. The coolant dissipates the heat from surfaces of heat-dissipatingfins218eand thick portion218aas flowing insidecentrifugal pump3.FIG. 15 illustrates the flow direction of the coolant incentrifugal pump3, wherein the coolant enters in a direction of arrow X, runs along a heavy line and discharges in a direction of arrow Y.
• In the heatsink apparatus shown inFIGS. 14 and 15, the coolant enters fromrecess218coflower casing218 and flows on the surface of thick portion218a, thereby not required to pass through the center ofimpeller211. The structure thus allows the heatsink apparatus to provide higher reliability and higher cooling performance than the heatsink apparatus disclosed inRelated Art 1.
• The conventional heatsink apparatus having combinedcentrifugal pump3 reduces its size and provides high heat transfer performance in a central portion oflower casing218. However, the conventional heatsink apparatus has low heat transfer efficiency on an outer peripheral side away from the central portion, thus falling short of achieving highly efficient heat transfer across the pump. Providing heat-dissipating fins on the surface of thick portion218acan increase the heat transfer efficiency on the outer peripheral side, but also increases a gap between the surface of thick portion218aand blades211a, which causes a leakage flow of the coolant and thereby degrades pumping capability.
SUMMARY OF THE INVENTION
• The present invention is provided to address the above-described problems. A purpose of the present inventor is to provide a heatsink apparatus that has low thermal resistance on a pump side face and thereby improves overall cooling efficiency and maintains a temperature of a heat-generating electronic component low.
• The present invention relates to a heatsink apparatus having a radiator and a centrifugal pump in a closed circulation channel for circulating a coolant, the centrifugal pump contacting a heat-generating component and releasing heat from the heat-generating component through heat exchange of the coolant thereinside, the radiator dissipating the heat. The centrifugal pump includes: a first casing provided with a contact surface that contacts the heat-generating component; a second casing fitted to the first casing so as to form a space wherein the coolant flows; a partition wall member provided between the first and second casings so as to form a heat transfer chamber between the partition wall member and the first casing and to form a pump chamber that houses an impeller between the partition wall member and the second casing; a coolant inlet connected to the heat transfer chamber; a coolant outlet connected to the pump chamber; and the heat transfer chamber connected to the pump chamber through a through-hole formed in a central portion of the partition wall member.
BRIEF DESCRIPTION OF THE DRAWINGS
• The present invention is further described in the detailed description which follows, with reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments of the present invention, in which like reference numerals represent similar parts throughout the several views of the drawings, and wherein:
• FIG. 1 is a cross-sectional view of a centrifugal pump in a heatsink apparatus according to a first embodiment of the present invention;
• FIG. 2 is an exploded cross-sectional view of the centrifugal pump in the heatsink apparatus according to the first embodiment of the present invention;
• FIG. 3 is a perspective view of a lower casing according to the first embodiment of the present invention;
• FIG. 4 is a perspective view of the lower casing according to the first embodiment of the present invention;
• FIG. 5 is a perspective view of the lower casing according to the first embodiment of the present invention;
• FIG. 6 is a perspective view of a ring-shaped sealing member as a single unit according to the first embodiment of the present invention;
• FIG. 7 illustrates a flow direction of a coolant in the centrifugal pump according to the first embodiment of the present invention;
• FIG. 8 is a cross-sectional view of a centrifugal pump in a heatsink apparatus according to a second embodiment of the present invention;
• FIG. 9 is an exploded cross-sectional view of the centrifugal pump in the heatsink apparatus according to the second embodiment of the present invention;
• FIG. 10 is a perspective view of a lower casing according to the second embodiment of the present invention;
• FIG. 11 is a perspective view of the lower casing according to the second embodiment of the present invention;
• FIG. 12 is a perspective view of a ring-shaped sealing member as a single unit according to the second embodiment of the present invention;
• FIG. 13 illustrates a flow direction of a coolant in the centrifugal pump according to the second embodiment of the present invention;
• FIG. 14 is a cross-sectional view of a centrifugal pump in a conventional heatsink apparatus;
• FIG. 15 illustrates a flow direction of a coolant in the centrifugal pump of the conventional heatsink apparatus;
• FIG. 16 illustrates a structure of an electronic device having a heatsink;
• FIG. 17 illustrates a structure of an electronic device having a heatsink; and
• FIG. 18 is a cross-sectional view of a cooling module that uses a centrifugal pump.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
• The embodiments of the present invention are explained in the following, in reference to the above-described drawings.
First Embodiment
• A centrifugal pump in a heatsink apparatus according to a first embodiment of the present invention is described below.FIG. 1 is a cross-sectional view of the centrifugal pump in the heatsink apparatus according to the first embodiment of the present invention;FIG. 2 is an exploded cross-sectional view of the centrifugal pump in the heatsink apparatus according to the first embodiment of the present invention; FIGS.3 to5 are perspective views of a lower casing according to the first embodiment of the present invention;FIG. 6 is a perspective view of a ring-shaped sealing member as a single unit according to the first embodiment of the present invention; andFIG. 7 illustrates a flow direction of a coolant in the centrifugal pump according to the first embodiment of the present invention. An overall structure of an electronic device having the heatsink apparatus according to the first embodiment is the same as that in the conventional art, thusFIGS. 16 and 17 are also referred in the first embodiment. Detailed explanations of the figures are as described in the conventional art.
• An internal structure ofcentrifugal pump3 is described below with reference to FIGS.1 to7.Centrifugal pump3 includes: open-type impeller11 ofcentrifugal pump3; open-type blades11a;small holes11bformed near the center ofimpeller11; andmagnet rotor12 attached to an inner peripheral surface ofimpeller11.Impeller11 andmagnet rotor12 are separately formed in the first embodiment. However,magnet rotor12 may be integrally formed by magnetizing a portion ofimpeller11, which is made of magnetic material mixed plastics.
• Whenimpeller11 rotates the coolant, a coolant pressure becomes higher on an outer peripheral side of blades11athan on an inner peripheral side of blades11a(K inFIG. 1). Further, the pressure is substantially the same at an entrance ofimpeller11 and on a rear side ofimpeller11 connected throughsmall holes11b. Therefore, the coolant runs on the rear side ofimpeller11 and passes throughsmall holes11b, then a small amount of the coolant is refluxed to the entrance. The structure thus reduces a thrust force toimpeller11, compared to a structure wheresmall holes11bare not provided, and thereby smoothens the rotation ofimpeller11.Centrifugal pump3 of the first embodiment has a thickness of 3 mm to 50 mm, a representative radius of 10 mm to 100 mm, a revolution of 1,000 rpm to 8,000 rpm and a head of 0.5 m to 10 m.
• Centrifugal pump3 further includes:stator13 provided on an inner peripheral side ofmagnet rotor12;coil14 wound aroundstator13 to generate a magnetic field instator13; andcircuit board15 mounted with electric circuits that provide a current tocoil14. It is preferable to layer a plurality of silicon sheets when formingstator13 so as to minimize eddy-current losses. It is further preferable to use an insulation coated copper wire forcoil14. A wire diameter and wire turns ofcoil14 are optimized based on a power voltage and a space factor. Mounted oncircuit board15 are a hole element that detects a rotating position ofmagnet rotor12 and a transistor or a diode that switches a current flow.
• Centrifugal pump3 further includes:upper casing16housing impeller11; discharge channel16aformed inupper casing16;suction channel16bformed inupper casing16;recess16cproviding a space to receive magnetic circuits, includingstator13; andfitting surface16dfitted to a ring-shaped sealing member, which will be described later. When formingupper casing16, it is preferable to mold plastics such as polyphenylene sulfide (PPS) and polyphenylene ether (PPE), sinceupper casing16 has a complex structure and is required to have certain heat resistance. It is not preferable, on the other hand, to formupper casing16 of metal, since fluctuation in magnetic flux generated by the magnetic circuits such asstator13 and the like may cause eddy-current losses.
• Centrifugal pump3 furthermore includespump chamber17 andlower casing18 that contacts heat-generatingelectronic component4 having heat conducting grease and the like (not shown in the figure) therebetween.Lower casing18 is formed of metallic material having high heat conductance and high heat dissipating performance, such as copper, aluminum and the like, and is processed in casting, forging, machining or a combination of the processing methods.Lower casing18 fits toupper casing16 and forms a space wherein the coolant flows, such aspump chamber17.
• To efficiently exchange heat received from heat-generatingelectronic component4 with the coolant,lower casing18 has a structure as shown inFIG. 3.Lower casing18 as shown inFIGS. 3 and 7 includes:base18f; ring-shapedthick portion18a* formed onbase18fand having upper side face18tslanted at an angle identical to are angle ofpartition wall20eof ring-shaped sealingmember20, which will be described later; C-shapedcylindrical portion18gformed onbase18fhaving substantially the same center asimpeller11 and circulating the coolant in the vicinity of through-hole20f, which will be described later;cutout18hformed incylindrical portion18g; linear guidingplate18istanding perpendicularly tobase18fand extending from an outer peripheral side to an inner peripheral side oflower casing18 towardcylindrical portion18g; brim18btouchingupper casing16;cutout18cfor taking in the coolant;contact surface18dcontacting heat-generatingelectronic component4; heat-dissipatingfins18ehaving various shapes and transferring the heat received from heat-generatingelectronic component4 to the coolant; and thrustreceiver18jreceiving the thrust force fromimpeller11. Guidingplate18ihas a height to upper side face18ufacing ring-shaped sealingmember20 lower on thecylindrical portion18gside, slanting at an angle identical to the angle ofpartition wall20eof ring-shaped sealingmember20. In the first embodiment,cylindrical portion18gand guidingplate18iare formed together withlower casing18 in order to maximize an area thatlower casing18 contacts the coolant. Due to manufacturing limitations, however,cylindrical portion18gand guidingplate18imay be formed on a rear side of the ring-shaped sealing member, which will be described later, or formed as separate parts.
• Centrifugal pump3 of the first embodiment has pin-type heat-dissipatingfins18eas shown inFIG. 3. In lieu of the pin-type fins, plate- or rib-type fins having a circular arc shape arranged in a concentric pattern may be formed as shown inFIG. 4. Further, plate- or rib-type fins extending in a radial pattern may be formed as shown inFIG. 5.
• Pin-type heat-dissipatingfins18eas shown inFIG. 3 maximize an area for heat dissipation and thus transfer the heat most efficiently. Plate- or rib-type heat-dissipatingfins18ehaving a circular arc shape as shown inFIG. 4 do not only increase the area for heat dissipation, but also reduce flow resistance of the coolant. Plate- or rib-type heat-dissipatingfins18eextending radially as shown inFIG. 5 reinforce rigidity oflower casing18, thus preventinglower casing18 from being deformed whencentrifugal pump3 is pushed with strong force against heat-generatingelectronic component4, and preventing a gap from developing between heat-generatingelectronic component4 andcontact surface18ddue to deformation. Further, pushing heat-generatingelectronic component4 with strong force thinly spreads the heat conducting grease (not shown in the figure) applied between heat-generatingelectronic component4 andcontact surface18d, thereby minimizing thermal resistance of the heat conducting grease and preventing part separation due to vibrations or shocks to a product.
• Heat-dissipatingfins18emay have a shape other than the above-described shapes. Heat-dissipatingfins18emay also have a mix of different shapes. A shape of fins inside and outside ofcylindrical portion18gneeds not to be the same; i.e., pin-type heat-dissipatingfins18emay be disposed outsidecylindrical portion18gwhile rib-type heat-dissipatingfins18einsidecylindrical portion18g. Other combinations of shapes are also possible.
• Further to the structure ofcentrifugal pump3 of the first embodiment with reference toFIG. 1,shaft19 provided onupper casing16 rotatably supportsimpeller11.Shaft19, made of highly corrosion-resistant material such as stainless, is inserted and molded toupper casing16 to form one piece. Ring-shaped sealingmember20 fits toupper casing16 so as to formpump chamber17. Sealingmember21, such as an o-ring, seals a portion betweenupper casing16 andlower casing18 in order to keep the coolant from leaking therefrom. Roundheat transfer chamber22, provided between ring-shaped sealingmember20, which will be described later, andlower casing18, forms a circulation channel withcylindrical portion18gand ring-shapedthick portion18a* oflower casing18, and connects to through-hole20f, which will be described later, of ring-shaped sealingmember20.
• When forming ring-shaped sealingmember20 having a structure as shown inFIG. 6, it is preferable to mold plastics such as polyphenylene sulfide (PPS) and polyphenylene ether (PPE), since, similar toupper casing16, ring-shaped sealingmember20 has a complex structure and is required to have certain heat resistance. AsFIG. 6 shows, cylindrical portion20ais fitted to a side face of ring-shapedthick portion18a* oflower casing18;partition wall20eis provided having a narrow gap with blades11a; through-hole20fis formed in a central portion ofpartition wall20e; discharge-connection20c, formed on the upper side of ring-shaped sealingmember20, connectspump chamber17 and discharge channel16a; andsuction connection20d, provided on the lower side of ring-shaped sealingmember20, connects roundheat transfer chamber22 andsuction channel16b.
• In the first embodiment,partition wall20ethat formspump chamber17 is formed together with ring-shaped sealingmember20 to facilitate manufacturing. For ensuring the rigidity ofpartition wall20eor other purposes, however,partition wall20emay be formed separately from ring-shaped sealingmember20. Further,partition wall20ehas a conic surface in the first embodiment, but may have a flat surface instead. Flat-shapedpartition wall20erequires blades11ato have a flat-shaped end accordingly. However, conic-shapedpartition wall20 lowers a height of roundheat transfer chamber22, which is located in a central portion oflower casing18 and has the highest temperature, and thereby locally accelerates a current speed of the coolant in the portion. A high current speed of the coolant reduces a temperature boundary layer, thus improving heat transfer efficiency. Meanwhile, lowering the entire height of roundheat transfer chamber22 increases the flow resistance and reduces the flow rate of the coolant that runs through the heatsink apparatus, thus adversely increasing the thermal resistance. Conic-shapedpartition wall20e, however, hardly increases the total flow resistance and thereby improves the heat transfer efficiency.
• Assembly procedures of above-describedcentrifugal pump3 are explained below with reference toFIG. 2. First,coil14 is wound aroundstator13, andcircuit board15 mounted with electronic components is attached tostator13. The assembledpart having stator13 is then inserted intorecess16cofupper casing16. A filler (not shown in the figure) is injected intorecess16cand hardened in a temperature-controlled bath and the like. The filler is used to dissipate the heat from the electronic components mounted oncircuit board15 and to keep the coolant from contactingcircuit board15 in case of leakage. It is desirable to use an epoxy potting agent as the filler. Then,impeller11 is inserted intoshaft19 formed together withupper casing16. Ring-shaped sealingmember20 is then inserted intoupper casing16 so that an outer peripheral surface of cylindrical portion20afits to fittingsurface16d. When ring-shaped sealingmember20 is inserted,suction connection20dandsuction channel16bare set to connect, so aredischarge connection20cand discharge channel16a. Finally, sealingmember21 is set to an outer peripheral surface of ring-shapedthick portion18a*, andlower casing18 is fitted and screwed (not shown in the figure) toupper casing16. Whenlower casing18 is fitted toupper casing16, the outer peripheral surface of ring-shapedthick portion18a* and an inner peripheral surface of cylindrical portion20aare set to fit- andsuction connection20dandcutout18care set to connect. Asupper casing16 fits to lower casing18, a lower surface ofpartition wall20eof ring-shaped sealingmember20 fits to upper side face18toflower casing18 and upper side face18uof guidingplate18i. Thereby, ring-shaped sealingmember20 andlower casing18 form roundheat transfer chamber22.
• Functions ofcentrifugal pump3 in the heatsink apparatus according to the first embodiment are described below. Activatingcircuit board15 generates an alternating magnetic field instator13. The magnetic field rotatesimpeller11 combined withmagnet rotor12, thereby providing momentum to the coolant and causing a negative-pressure in the central portion. Then, the coolant is drawn in fromsuction channel16b. The coolant is forced throughsuction connection20dthen into roundheat transfer chamber22 provided on an outer peripheral side ofcylindrical portion18gand betweenbase18fandpartition wall20e. The coolant then circulates onbase18f. Led by guidingplate18i, the coolant is forced throughcutout18hto insidecylindrical portion18g, then through through-hole20f. The rotation of blades11apropels the coolant to an outer periphery ofpump chamber17. The coolant is then forced throughdischarge connection20cand discharged from discharge channel16a.FIG. 7 shows the above-described flow direction of the coolant insidecentrifugal pump3. The coolant enters in a direction of arrow P, runs along a heavy line, then discharges in a direction of arrow Q.
• Providing substantially C-shapedcylindrical portion18gso as to allow roundheat transfer chamber22 to work as the circulation channel prevents the coolant that enterscentrifugal pump3 from being directly drawn in through-hole20f, thus allowing the coolant to contact a larger area oflower casing18. Further, providing guidingplate18iprevents the coolant that enterscentrifugal pump3 from repeatedly circulating onbase18f, thus smoothly directing the coolant to through-hole20fbefore turning full circle onbase18f.
• Lower casing18 meanwhile receives oncontact surface18dthe heat emitted from heat-generatingelectronic component4. Unlikelower casing218 in the conventional heatsink apparatus formed itself of a thick portion,lower casing18 of the first embodiment hasbase18fhaving a flat shape even on the outer peripheral side oflower casing18.Lower casing18 of the first embodiment thereby allows the heat to transfer extensively on a short heat transfer path insidelower casing18 and to reach surfaces of heat-dissipatingfins18e,base18fandcylindrical portion18g. Since the heat transfer path is short, the thermal resistance is low during the transfer. Thus, surface temperatures of heat-dissipatingfins18e,base18fandcylindrical portion18gapproach a temperature of heat-generatingelectronic component4.
• As flowing into, circulating on and flowing out frombase18fof roundheat transfer chamber22, the coolant contacts at a high speed the surfaces of heat-dissipatingfins18e,base18fandcylindrical portion18gthat have high temperatures after receiving the heat. Thereby, a temperature boundary layer forms thin and the coolant efficiently receives the heat fromlower casing18. The conventional heatsink apparatus, which has blades211aproximate to a surface of thick portion218a(refer toFIG. 14), does not allow forming of fins thereon to expand the surface area, though forming of dimples at best. Unlikelower casing218 as shown inFIG. 14, which haspump chamber217 on an outer peripheral side oflower casing218 and substantially the same curved surface as a rotating surface of blades211a,lower casing18 of the first embodiment is able to have large heat-dissipatingfins18eon the outer peripheral side oflower casing18.Lower casing18 of the first embodiment thereby significantly increases an area contacting the coolant and greatly reduces a weight ofcentrifugal pump3.
• In the centrifugal pump of the conventional heatsink apparatus, the surface of thick portion218aoflower casing218 provides two functions as shown inFIG. 14: a function to transfer the heat to the coolant and a function to form a wall ofpump chamber217. In the first embodiment, whereinpartition wall20eis provided betweenimpeller11 andlower casing18, the function to transfer the heat to the coolant is provided to the surfaces ofbase18fand heat-dissipatingfins18eoflower casing18, and the function to formpump chamber17 to partitionwall20eof ring-shaped sealingmember20. Thereby, the heatsink apparatus of the first embodiment enjoys highly efficient heat transfer performance, without negatively affecting pumping performance.
• According to the first embodiment of the present invention as described above, integrating the heatsink portion that receives the heat from heat-generatingelectronic component4 and the pump provides high flexibility in placing the heatsink apparatus in a body of a small personal computer and the like. Further, the structure described above allows the coolant to contactlower casing18 on the short heat transfer path from heat-generatingelectronic component4, on the outer periphery oflower casing18 as well as in the central portion. Thus, the thermal resistance is kept low not only in the central portion, but also on the outer peripheral side. The overall cooling efficiency is thereby increased and the temperature of heat-generatingelectronic component4 is maintained low.
• As the coolant, an antifreeze solution is suitable, including an ethylene glycol solution and a propylene glycol solution. Further, it is desirable to add an anti-corrosion additive since copper or the like is used as lower casing material.
• Radiator6 as shown inFIGS. 16 and 17 is made of material having high heat conductance and high heat dissipating performance, such as lamellar material of copper and aluminum, and is integrally provided with a coolant channel and a reserve tank thereinside. The reserve tank may be formed separately fromradiator6. Further, a fan may be provided to blow air againstradiator6 to accelerate the cooling efficiency.Circulation channel7 is made of a flexible rubber tube having low gas permeability, such as a butyl rubber tube, so as to ensure flexibility in piping layout.
Second Embodiment
• A centrifugal pump in a heatsink apparatus according to a second embodiment of the present invention is described below.FIG. 8 is a cross-sectional view of the centrifugal pump in the heatsink apparatus according to the second embodiment of the present invention;FIG. 9 is an exploded cross-sectional view of the centrifugal pump in the heatsink apparatus according to the second embodiment of the present invention;FIGS. 10 and 11 are perspective views of a lower casing according to the second embodiment of the present invention;FIG. 12 is a perspective view of a ring-shaped sealing member as a single unit according to the second embodiment of the present invention; andFIG. 13 illustrates a flow direction of a coolant in the centrifugal pump according to the second embodiment of the present invention. An overall structure of an electronic device having the heatsink apparatus according to the second embodiment is the same as that in the conventional art, thusFIGS. 16 and 17 are also referred in the second embodiment. Detailed explanations of the figures are as given in the conventional art.
• An internal structure ofcentrifugal pump3 is described below with reference to FIGS.8 to13.Centrifugal pump3 includes: open-type impeller111 ofcentrifugal pump3; open-type blades111a;small holes111bformed near the center ofimpeller111; andmagnet rotor112 attached to an inner peripheral surface ofimpeller111.Impeller111 andmagnet rotor112 are separately formed in the second embodiment. However,magnet rotor112 may be integrally formed by magnetizing a portion ofimpeller111, which is made of magnetic material mixed plastics.
• Whenimpeller111 rotates the coolant, a coolant pressure becomes higher on an outer peripheral side of blades111athan on an inner peripheral side of blades111a(L inFIG. 8). Further, the pressure is substantially the same at an entrance ofimpeller111 and on a rear side ofimpeller111 connected throughsmall holes111b. Therefore, the coolant runs on the rear side ofimpeller111 and passes throughsmall holes111b, then a small amount of the coolant is refluxed to the entrance. The structure thus reduces a thrust force toimpeller111, compared to a structure wheresmall holes111bare not provided, and thereby smoothens the rotation ofimpeller111.Centrifugal pump3 of the second embodiment has a thickness of 3 mm to 50 mm, a representative radius of 10 mm to 100 mm, a revolution of 1,000 rpm to 8,000 rpm and a head of 0.5 m to 10 m.
• Centrifugal pump3 further includes:stator113 provided on an inner peripheral side ofmagnet rotor112;coil114 wound aroundstator113 to generate a magnetic field instator113; andcircuit board115 mounted with electric circuits that provide a current tocoil114. It is preferable to layer a plurality of silicon sheets when formingstator113 so as to minimize eddy-current losses. It is further preferable to use an insulation coated copper wire forcoil114. A wire diameter and wire turns ofcoil114 are optimized based on a power voltage and a space factor. Mounted oncircuit board115 are a hole element that detects a rotating position ofmagnet rotor112 and a transistor or a diode that switches a current flow.
• Centrifugal pump3 further includes:upper casing116housing impeller111; discharge channel116aformed inupper casing116;suction channel116bformed inupper casing116;recess116cproviding a space to receive magnetic circuits, includingstator113; andfitting surface116dfitted to a ring-shaped sealing member, which will be described later. When formingupper casing116, it is preferable to mold plastics such as polyphenylene sulfide (PPS) and polyphenylene ether (PPE), sinceupper casing116 has a complex structure and is required to have certain heat resistance. It is not preferable, on the other hand, to formupper casing116 of metal, since fluctuation in magnetic flux generated by the magnetic circuits such asstator113 and the like may cause eddy-current losses.
• Centrifugal pump3 furthermore includes: pumpchamber117 andlower casing118 that contacts heat-generatingelectronic component4 having heat conducting grease and the like (not shown in the figure) therebetween.Lower casing118 is formed of metallic material having high heat conductance and high heat dissipating performance, such as copper, aluminum and the like, and is processed in casting, forging, machining or a combination of the processing methods.Lower casing118 fits toupper casing116 and forms a space wherein the coolant flows, such aspump chamber117.
• To efficiently exchange heat received from heat-generatingelectronic component4 with the coolant,lower casing118 has a structure as shown inFIG. 10.Lower casing118 includes: brim118btouchingupper casing116;recess118cfor taking in the coolant;contact surface118dcontacting heat-generatingelectronic component4; heat-dissipatingfins118etransferring the heat received from heat-generatingelectronic component4 to the coolant, similar to those in the conventional heatsink apparatus, and expanding an area contacting the coolant so as to facilitate heat transfer;base118f; ring-shapedthick portion118a* formed onbase118fand havingupper side face118tslanted at an angle identical to an angle ofpartition wall120eof ring-shapedsealing member120, which will be described later; and guidingportions118kprovided standing substantially perpendicularly tobase118f, for directing the coolant entering ontolower casing118 so that the coolant runs through a central portion of a suction heat transfer chamber, which will be described later, provided onbase118f.
• In the second embodiment, guidingportions118kare formed together withlower casing118 in order to maximize an area thatlower casing118 contacts the coolant. Due to manufacturing limitations, however, guidingportions118kmay be formed on a rear side of ring-shapedsealing member120, which will be described later, or formed as separate parts. Also in the second embodiment, flow separation wall118lis provided on ring-shapedthick portion118a* facing an inflow direction, so as to separate an incoming flow from guidingportions118kinto two directions in roundheat transfer chamber122, which will be described later.
• Centrifugal pump3 of the second embodiment has pin-type heat-dissipatingfins118eas shown inFIG. 10. In lieu of the pin-type fins, a combination of the pin-type fins and plate- or rib-type fins may be formed as shown inFIG. 11. One of the plate- and rib-type fins may also be formed.
• Pin-type heat-dissipatingfins118eas shown inFIG. 10 maximize an area for heat dissipation and thus transfer the heat most efficiently. Heat-dissipatingfins118ehaving the combination of the pin-type and the plate- or rib-type as shown inFIG. 11 do not only increase the area for heat dissipation, but also reduce flow resistance of the coolant. Further, heat-dissipatingfins118ehaving the combination of the pin-type and the plate- or rib-type reinforce rigidity oflower casing118, thus preventinglower casing118 from being deformed whencentrifugal pump3 is pushed with strong force against heat-generatingelectronic component4, and preventing a gap from developing between heat-generatingelectronic component4 andcontact surface118ddue to deformation. Furthermore, pushing heat-generatingelectronic component4 with strong force thinly spreads the heat conducting grease (not shown in the figure) applied between heat-generatingelectronic component4 andcontact surface118d, thereby minimizing thermal resistance of the heat conducting grease and preventing part separation due to vibrations or shocks to a product.
• Heat-dissipatingfins118emay have a shape other than the pin-type, the plate-type and the rib-type. The description above, which relates to heat-dissipatingfins118eprovided between guidingportions118k, also applies to heat-dissipatingfins118eprovided outside guidingportions118k. Heat-dissipatingfins118eoutside guidingportions118kmay be the pin-type, the plate-type, the rib-type, other type or a mix of the types.
• Further to the structure ofcentrifugal pump3 of the second embodiment with reference toFIG. 8,shaft119 provided onupper casing116 rotatably supportsimpeller111.Shaft119, made of highly corrosion-resistant material such as stainless, is inserted and molded toupper casing16 to form one piece. Ring-shapedsealing member120 fits toupper casing116 so as to formpump chamber117. Sealingmember121, such as an o-ring, seals a portion betweenupper casing116 andlower casing118 in order to keep the coolant from leaking therefrom. Roundheat transfer chamber122, provided between ring-shapedsealing member120 andlower casing118 and formed by guidingportions118kand ring-shapedthick portion118a* oflower casing118, connects to two through-holes120f, which will be described later, of ring-shapedsealing member120. Heattransfer guiding channel123 is sandwiched by a pair of guidingportions118kand formed betweenlower casing118 andtop panel120g, which will be described later.
• When forming ring-shapedsealing member120 having a structure as shown inFIG. 12, it is preferable to mold plastics such as polyphenylene sulfide (PPS) and polyphenylene ether (PPE), since, similar toupper casing116, ring-shapedsealing member120 has a complex structure and is required to have certain heat resistance. AsFIG. 12 shows, cylindrical portion120ais fitted to a side face of ring-shapedthick portion118a* oflower casing118;partition wall120eis provided having a narrow gap with blades111a;top panel120gcloses an upper part of guidingportions118kand forms heattransfer guiding channel123 that directs the coolant to roundheat transfer chamber122; two half-moon-shaped through-holes120fare formed on both sides oftop panel120g;thrust receiver120hreceives the thrust force fromimpeller111;discharge connection120c, formed on the upper side of ring-shapedsealing member120, connectspump chamber117 and discharge channel116a; andsuction connection120d, provided on the lower side of ring-shapedsealing member120, connects roundheat transfer chamber122 andsuction channel116b. Heattransfer guiding channel123 and roundheat transfer chamber122 as a whole form the suction heat transfer chamber of the present invention, and the pair of guidingportions118kform a partition member of the present invention.
• In the second embodiment,partition wall120ethat formspump chamber117 is formed together with ring-shapedsealing member120 to facilitate manufacturing. For ensuring the rigidity ofpartition wall120eor other purposes, however,partition wall120emay be formed separately from ring-shapedsealing member120. Further,partition wall120ehas a conic surface in the second embodiment, but may have a flat surface instead. Flat-shapedpartition wall120erequires blades111ato have a flat-shaped end accordingly. However, conic-shapedpartition wall120elowers a height of roundheat transfer chamber122, which is located in a central portion oflower casing118 and has the highest temperature, and thereby locally accelerates a current speed of the coolant in the portion. A high current speed of the coolant reduces a temperature boundary layer, thus improving heat transfer efficiency. Meanwhile, lowering the entire height of roundheat transfer chamber122 increases the flow resistance and reduces the flow rate of the coolant that runs through the heatsink apparatus, thus adversely increasing the thermal resistance. Conic-shapedpartition wall120e, however, hardly increases the total flow resistance and thereby improves the heat transfer efficiency.
• Assembly procedures of above-describedcentrifugal pump3 are explained below with reference toFIG. 9. First,coil114 is wound aroundstator113, andcircuit board115 mounted with electronic components is attached tostator113. The assembledpart having stator113 is then inserted intorecess116cofupper casing116. A filler (not shown in the figure) is injected intorecess116cand hardened in a temperature-controlled bath and the like. The filler is used to dissipate the heat from the electronic components mounted oncircuit board115 and to keep the coolant from contactingcircuit board115 in case of leakage. It is desirable to use an epoxy potting agent as the filler. Then,impeller111 is inserted intoshaft119 formed together withupper casing116. Ring-shapedsealing member120 is then inserted intoupper casing116 so that an outer peripheral surface of cylindrical portion120afits tofitting surface116d. When ring-shapedsealing member120 is inserted,suction connection120dandsuction channel116bare set to connect, so aredischarge connection120cand discharge channel116a. Finally, sealingmember121 is set to an outer peripheral surface of ring-shapedthick portion118a*, andlower casing118 is fitted and screwed (not shown in the figure) toupper casing116. Whenlower casing118 is fitted toupper casing116, the outer peripheral surface of ring-shapedthick portion118a* and an inner peripheral surface of cylindrical portion120aare set to fit, andsuction connection120dand recess118care set to connect. Asupper casing116 fits to lower casing118, a lower surface ofpartition wall120eof ring-shapedsealing member120 fits toupper side face118toflower casing118, and a lower surface oftop panel120gof ring-shapedsealing member120 fits toupper side face118uof guidingportions118k. Thereby, ring-shapedsealing member120 andlower casing118 form roundheat transfer chamber122.
• Functions ofcentrifugal pump3 in the heatsink apparatus according to the second embodiment are described below. Activatingcircuit board115 generates an alternating magnetic field instator113. The magnetic field rotatesimpeller111 combined withmagnet rotor112, thereby providing momentum to the coolant and causing a negative-pressure in the central portion. Then, the coolant is drawn in fromsuction channel116b. The coolant is forced throughsuction connection120dthen to heattransfer guiding channel123 formed betweenlower casing118 andtop panel120g. The entered coolant efficiently dissipates the heat from high-temperature base118flocated directly above heat-generatingelectronic component4.
• Then the coolant reaches an end ofbase118fand is separated into two directions to right and left. The two flows of the separated coolant respectively circulate in roundheat transfer chamber122 provided between guidingportions118kand ring-shapedthick portion118a*. The negative-pressure in the central portion ofimpeller111 draws in the coolant again to the central portion ofbase118fand forces the coolant through two through-holes120f. During the process, the coolant dissipates the heat that travels a short distance from heat-generatingelectronic component4 tobase118f.
• Although the coolant is separated into two directions at the flow separation wall as reaching the end ofbase118fin the second embodiment, the coolant may flow in one direction. Separating the coolant into two directions, however, reduces the flow resistance and evenly cools an outer periphery oflower casing118. Finally, the coolant provided with the momentum by the rotation ofimpeller111 is propelled to an outer periphery ofpump chamber117, forced throughdischarge connection120cand then discharged from discharge channel116a.FIG. 13 shows the above-described flow direction of the coolant insidecentrifugal pump3. The coolant enters in a direction of arrow R, runs along a heavy line, then discharges in a direction of arrow S.
• Unlike the conventional heatsink apparatus wherein the coolant is drawn straight intoimpeller211,centrifugal pump3 of the second embodiment, provided with guidingportions118kandtop panel120gthat form heattransfer guiding channel123, directs the entered coolant linearly from end to end in the central portion oflower casing118 with no leakage to other portions. Thereby, the coolant contacts at a high speed a wide surface area of the central portion oflower casing118 that has the highest temperature. Further, unlike the conventional heatsink apparatus wherein the coolant stagnates inpump chamber217,centrifugal pump3 of the second embodiment has no adverse impact on cooling efficiency.
• Furthermore, unlikelower casing218 in the conventional heatsink apparatus formed itself of a thick portion,lower casing118 of the second embodiment, provided with roundheat transfer chamber122 surrounding heattransfer guiding channel123, hasflat base118f.Lower casing118 of the second embodiment thereby allows the heat to transfer extensively on a short path insidelower casing118 and to reach surfaces of heat-dissipatingfins118eandbase118f. Since the heat transfer path is short, the thermal resistance is low during the transfer. Thus, surface temperatures of heat-dissipatingfins118eandbase118fapproach a temperature of heat-generatingelectronic component4.
• As flowing into the central portion oflower casing118 and circulating in and flowing out from roundheat transfer chamber122 oflower casing118, the coolant contacts at a high speed the surfaces of heat-dissipatingfins118eandbase118fthat have high temperatures after receiving the heat. Thereby, a temperature boundary layer forms thin and the coolant efficiently receives the heat fromlower casing118. The conventional heatsink apparatus, which has blades211aproximate to a surface of thick portion218a(refer toFIG. 14), does not allow forming of fins thereon to expand the surface area, though forming of dimples at best. Unlikelower casing218 as shown inFIG. 14, which has thick portion218a,lower casing118 of the second embodiment is able to have large heat-dissipatingfins118eon the outer peripheral side oflower casing118, thereby significantly increasing an area contacting the coolant.
• In the centrifugal pump of the conventional heatsink apparatus, the surface of thick portion218aoflower casing218 provides two functions as shown inFIG. 15: a function to transfer the heat to the coolant and a function to form a wall ofpump chamber217. In the second embodiment, whereinpartition wall120eis provided betweenimpeller111 andlower casing118, the function to transfer the heat to the coolant is provided to the surfaces ofbase118fand heat-dissipatingfins118eoflower casing118, and the function to form the wall ofpump chamber117 to partitionwall120eof ring-shapedsealing member120. Thereby, the heatsink apparatus of the second embodiment enjoys highly efficient heat performance, without negatively affecting pumping performance.
• According to the second embodiment of the present invention as described above, integrating the heatsink portion that receives the heat from heat-generatingelectronic component4 and the pump provides high flexibility in placing the heatsink apparatus in a body of a small personal computer and the like. Further, the structure described above allows the coolant to contact the entire central portion of the lower casing at a high speed and to contact the lower casing on a short heat transfer path from the heat-generating electronic component in the round heat transfer chamber on the outer periphery of the lower casing. Thus, the thermal resistance is kept low both in the central portion and on the outer periphery, thereby maintaining the temperature of the heat-generating electronic component low.
• As the coolant, an antifreeze solution is suitable, including an ethylene glycol solution and a propylene glycol solution. Further, it is desirable to add an anti-corrosion additive since copper or the like is used as lower casing material.
• Radiator6 as shown inFIGS. 16 and 17 is formed of material having high heat conductance and high heat dissipating performance, such as lamellar material of copper and aluminum, and is integrally provided with a coolant channel and a reserve tank thereinside. The reserve tank may be formed separately fromradiator6. Further, a fan may be provided to blow air againstradiator6 to accelerate the cooling efficiency.Circulation channel7 is made of a flexible rubber tube having low gas permeability, such as a butyl rubber tube, so as to ensure flexibility in piping layout.
• It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the present invention has been described with reference to exemplary embodiments, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular structures, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.
• The present invention is not limited to the above described embodiments, and various variations and modifications may be possible without departing from the scope of the present invention.
• This application is based on the Japanese Patent Applications No. 2004-376062 and No. 2004-376063 filed on Dec. 27, 2004, entire content of which is expressly incorporated by reference herein.

Claims (11)

1. A heatsink apparatus having a radiator and a centrifugal pump in a closed circulation channel for circulating a coolant, the centrifugal pump contacting a heat-generating component and releasing heat from the heat-generating component through heat exchange of the coolant thereinside, the radiator dissipating the heat, the centrifugal pump comprising:

a first casing provided with a contact surface that contacts the heat-generating component;

a second casing fitted to be first casing so as to form a space wherein the coolant flows;

a partition wall member provided between the first and second casings so as to form a heat transfer chamber between the partition wall member and the first casing and to form a pump chamber that houses an impeller between the partition wall member and the second casing;

a coolant inlet connected to the heat transfer chamber;

a coolant outlet connected to the pump chamber; and

the heat transfer chamber connected to the pump chamber through a through-hole formed in a central portion of the partition wall member.

2. The heatsink apparatus according toclaim 1, further comprising a guiding member provided between the first casing and the partition wall member of the heat transfer chamber so as to form a flow channel of the coolant.

3. The heatsink apparatus according toclaim 2, wherein the guiding member comprises:

a C-shaped cylindrical portion that circulates the incoming coolant in the vicinity of the through-hole; and

a linear guiding plate that directs the coolant from an outer peripheral side of the first casing to the through-hole located on an inner side of the first casing.

4. The heatsink apparatus according toclaim 3, wherein a plurality of heat-dissipating fins are provided in the heat transfer chamber on a surface opposite to the contact surface, protruding from the first casing toward the partition wall member.

5. The heatsink apparatus according toclaim 1, wherein the partition wall member is slanted so that a distance between the first casing and the partition wall member in the heat transfer chamber is shorter in a central portion of the heat transfer chamber.

6. A heatsink apparatus having a radiator and a centrifugal pump in a closed circulation channel for circulating a coolant, the centrifugal pump contacting a heat-generating component and releasing heat from the heat-generating component through heat exchange of the coolant thereinside, the radiator dissipating the heat, the centrifugal pump comprising:

a first casing provided with a contact surface that contacts the heat-generating component;

a second casing fitted to the first casing so as to form a space wherein the coolant flows;

a partition wall member provided between the first and second casings so as to form a heat transfer chamber between the partition wall member and the first casing and to form a pump chamber that houses an impeller between partition wall member and the second casing;

a coolant inlet connected to the heat transfer chamber;

a coolant outlet connected to the pump chamber;

through-holes formed in the partition wall member so as to connect the heat transfer chamber and the pump chamber; and

a pair of guiding plates provided in the heat transfer chamber so as to direct the coolant from the inlet to a central portion of the heat transfer chamber.

7. The heatsink apparatus according toclaim 6, wherein the though-holes in the partition wall member are disposed outside the pair of guiding plates.

8. The heatsink apparatus according toclaim 6, wherein the guiding plates extend from the inlet of the heat transfer chamber beyond the center of the heat transfer chamber.

9. The heatsink apparatus according toclaim 6, wherein a flow separation wall is provided in the heat transfer chamber so as to separate the coolant passing through the guiding plates into two directions in the heat transfer chamber.

10. The heatsink apparatus according toclaim 6, wherein the though holes in the partition wall member are disposed in two locations outside the pair of guiding plates.

11. The heatsink apparatus according toclaim 6, wherein a plurality of heat-dissipating fins are provided in the heat transfer chamber on a surface opposite to the contact surface, protruding from the first casing toward the partition wall member.

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