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 in
[Related Art 1] Japanese Patent Laid-Open Publication 2004-134423
However, the heatsink apparatus disclosed in Related Art 1, in which a coolant flows through the center of an impeller 302 toward a heat-generating component 303, 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 in
The structure of the electronic-device having the heatsink apparatus is first described with reference to
An internal structure of conventional centrifugal pump 3 is described below with reference to
Centrifugal pump 3 further includes: shaft 219 forming a rotating axis of impeller 211 and fixed to upper casing 216; ring-shaped sealing member 220 fitted to upper casing 216 so as to form pump chamber 217, as also shown in
Functions of centrifugal pump 3 of the heatsink apparatus are described below. The coolant is drawn into suction channel 216b and forced through suction connection 220d. The coolant is then led toward the center of pump chamber 217 by water channel sealing portion 220b and propelled to an outer periphery of pump chamber 217 by rotation of blades 211a. Then, the coolant is forced through discharge connection 220c and discharged from discharge channel 216a. Meanwhile, the heat emitted from heat-generating electronic component 4 is transferred from contact surface 218d to radiating fins 218e and thick portion 218a. The coolant dissipates the heat from surfaces of heat-dissipating fins 218e and thick portion 218a as flowing inside centrifugal pump 3.
In the heatsink apparatus shown in
The conventional heatsink apparatus having combined centrifugal pump 3 reduces its size and provides high heat transfer performance in a central portion of lower casing 218. 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 portion 218a can increase the heat transfer efficiency on the outer peripheral side, but also increases a gap between the surface of thick portion 218a and blades 211a, which causes a leakage flow of the coolant and thereby degrades pumping capability.
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.
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:
The embodiments of the present invention are explained in the following, in reference to the above-described drawings.
A centrifugal pump in a heatsink apparatus according to a first embodiment of the present invention is described below.
An internal structure of centrifugal pump 3 is described below with reference to FIGS. 1 to 7. Centrifugal pump 3 includes: open-type impeller 11 of centrifugal pump 3; open-type blades 11a; small holes 11b formed near the center of impeller 11; and magnet rotor 12 attached to an inner peripheral surface of impeller 11. Impeller 11 and magnet rotor 12 are separately formed in the first embodiment. However, magnet rotor 12 may be integrally formed by magnetizing a portion of impeller 11, which is made of magnetic material mixed plastics.
When impeller 11 rotates the coolant, a coolant pressure becomes higher on an outer peripheral side of blades 11a than on an inner peripheral side of blades 11a (K in
Centrifugal pump 3 further includes: stator 13 provided on an inner peripheral side of magnet rotor 12; coil 14 wound around stator 13 to generate a magnetic field in stator 13; and circuit board 15 mounted with electric circuits that provide a current to coil 14. It is preferable to layer a plurality of silicon sheets when forming stator 13 so as to minimize eddy-current losses. It is further preferable to use an insulation coated copper wire for coil 14. A wire diameter and wire turns of coil 14 are optimized based on a power voltage and a space factor. Mounted on circuit board 15 are a hole element that detects a rotating position of magnet rotor 12 and a transistor or a diode that switches a current flow.
Centrifugal pump 3 further includes: upper casing 16 housing impeller 11; discharge channel 16a formed in upper casing 16; suction channel 16b formed in upper casing 16; recess 16c providing a space to receive magnetic circuits, including stator 13; and fitting surface 16d fitted to a ring-shaped sealing member, which will be described later. When forming upper casing 16, it is preferable to mold plastics such as polyphenylene sulfide (PPS) and polyphenylene ether (PPE), since upper casing 16 has a complex structure and is required to have certain heat resistance. It is not preferable, on the other hand, to form upper casing 16 of metal, since fluctuation in magnetic flux generated by the magnetic circuits such as stator 13 and the like may cause eddy-current losses.
Centrifugal pump 3 furthermore includes pump chamber 17 and lower casing 18 that contacts heat-generating electronic component 4 having heat conducting grease and the like (not shown in the figure) therebetween. Lower casing 18 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 casing 18 fits to upper casing 16 and forms a space wherein the coolant flows, such as pump chamber 17.
To efficiently exchange heat received from heat-generating electronic component 4 with the coolant, lower casing 18 has a structure as shown in
Centrifugal pump 3 of the first embodiment has pin-type heat-dissipating fins 18e as shown in
Pin-type heat-dissipating fins 18e as shown in
Heat-dissipating fins 18e may have a shape other than the above-described shapes. Heat-dissipating fins 18e may also have a mix of different shapes. A shape of fins inside and outside of cylindrical portion 18g needs not to be the same; i.e., pin-type heat-dissipating fins 18e may be disposed outside cylindrical portion 18g while rib-type heat-dissipating fins 18e inside cylindrical portion 18g. Other combinations of shapes are also possible.
Further to the structure of centrifugal pump 3 of the first embodiment with reference to
When forming ring-shaped sealing member 20 having a structure as shown in
In the first embodiment, partition wall 20e that forms pump chamber 17 is formed together with ring-shaped sealing member 20 to facilitate manufacturing. For ensuring the rigidity of partition wall 20e or other purposes, however, partition wall 20e may be formed separately from ring-shaped sealing member 20. Further, partition wall 20e has a conic surface in the first embodiment, but may have a flat surface instead. Flat-shaped partition wall 20e requires blades 11a to have a flat-shaped end accordingly. However, conic-shaped partition wall 20 lowers a height of round heat transfer chamber 22, which is located in a central portion of lower casing 18 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 round heat transfer chamber 22 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-shaped partition wall 20e, however, hardly increases the total flow resistance and thereby improves the heat transfer efficiency.
Assembly procedures of above-described centrifugal pump 3 are explained below with reference to
Functions of centrifugal pump 3 in the heatsink apparatus according to the first embodiment are described below. Activating circuit board 15 generates an alternating magnetic field in stator 13. The magnetic field rotates impeller 11 combined with magnet rotor 12, thereby providing momentum to the coolant and causing a negative-pressure in the central portion. Then, the coolant is drawn in from suction channel 16b. The coolant is forced through suction connection 20d then into round heat transfer chamber 22 provided on an outer peripheral side of cylindrical portion 18g and between base 18f and partition wall 20e. The coolant then circulates on base 18f. Led by guiding plate 18i, the coolant is forced through cutout 18h to inside cylindrical portion 18g, then through through-hole 20f. The rotation of blades 11a propels the coolant to an outer periphery of pump chamber 17. The coolant is then forced through discharge connection 20c and discharged from discharge channel 16a.
Providing substantially C-shaped cylindrical portion 18g so as to allow round heat transfer chamber 22 to work as the circulation channel prevents the coolant that enters centrifugal pump 3 from being directly drawn in through-hole 20f, thus allowing the coolant to contact a larger area of lower casing 18. Further, providing guiding plate 18i prevents the coolant that enters centrifugal pump 3 from repeatedly circulating on base 18f, thus smoothly directing the coolant to through-hole 20f before turning full circle on base 18f.
Lower casing 18 meanwhile receives on contact surface 18d the heat emitted from heat-generating electronic component 4. Unlike lower casing 218 in the conventional heatsink apparatus formed itself of a thick portion, lower casing 18 of the first embodiment has base 18f having a flat shape even on the outer peripheral side of lower casing 18. Lower casing 18 of the first embodiment thereby allows the heat to transfer extensively on a short heat transfer path inside lower casing 18 and to reach surfaces of heat-dissipating fins 18e, base 18f and cylindrical portion 18g. Since the heat transfer path is short, the thermal resistance is low during the transfer. Thus, surface temperatures of heat-dissipating fins 18e, base 18f and cylindrical portion 18g approach a temperature of heat-generating electronic component 4.
As flowing into, circulating on and flowing out from base 18f of round heat transfer chamber 22, the coolant contacts at a high speed the surfaces of heat-dissipating fins 18e, base 18f and cylindrical portion 18g that have high temperatures after receiving the heat. Thereby, a temperature boundary layer forms thin and the coolant efficiently receives the heat from lower casing 18. The conventional heatsink apparatus, which has blades 211a proximate to a surface of thick portion 218a (refer to
In the centrifugal pump of the conventional heatsink apparatus, the surface of thick portion 218a of lower casing 218 provides two functions as shown in
According to the first embodiment of the present invention as described above, integrating the heatsink portion that receives the heat from heat-generating electronic component 4 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 lower casing 18 on the short heat transfer path from heat-generating electronic component 4, on the outer periphery of lower casing 18 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-generating electronic component 4 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.
Radiator 6 as shown in
A centrifugal pump in a heatsink apparatus according to a second embodiment of the present invention is described below.
An internal structure of centrifugal pump 3 is described below with reference to FIGS. 8 to 13. Centrifugal pump 3 includes: open-type impeller 111 of centrifugal pump 3; open-type blades 111a; small holes 111b formed near the center of impeller 111; and magnet rotor 112 attached to an inner peripheral surface of impeller 111. Impeller 111 and magnet rotor 112 are separately formed in the second embodiment. However, magnet rotor 112 may be integrally formed by magnetizing a portion of impeller 111, which is made of magnetic material mixed plastics.
When impeller 111 rotates the coolant, a coolant pressure becomes higher on an outer peripheral side of blades 111a than on an inner peripheral side of blades 111a (L in
Centrifugal pump 3 further includes: stator 113 provided on an inner peripheral side of magnet rotor 112; coil 114 wound around stator 113 to generate a magnetic field in stator 113; and circuit board 115 mounted with electric circuits that provide a current to coil 114. It is preferable to layer a plurality of silicon sheets when forming stator 113 so as to minimize eddy-current losses. It is further preferable to use an insulation coated copper wire for coil 114. A wire diameter and wire turns of coil 114 are optimized based on a power voltage and a space factor. Mounted on circuit board 115 are a hole element that detects a rotating position of magnet rotor 112 and a transistor or a diode that switches a current flow.
Centrifugal pump 3 further includes: upper casing 116 housing impeller 111; discharge channel 116a formed in upper casing 116; suction channel 116b formed in upper casing 116; recess 116c providing a space to receive magnetic circuits, including stator 113; and fitting surface 116d fitted to a ring-shaped sealing member, which will be described later. When forming upper casing 116, it is preferable to mold plastics such as polyphenylene sulfide (PPS) and polyphenylene ether (PPE), since upper casing 116 has a complex structure and is required to have certain heat resistance. It is not preferable, on the other hand, to form upper casing 116 of metal, since fluctuation in magnetic flux generated by the magnetic circuits such as stator 113 and the like may cause eddy-current losses.
Centrifugal pump 3 furthermore includes: pump chamber 117 and lower casing 118 that contacts heat-generating electronic component 4 having heat conducting grease and the like (not shown in the figure) therebetween. Lower casing 118 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 casing 118 fits to upper casing 116 and forms a space wherein the coolant flows, such as pump chamber 117.
To efficiently exchange heat received from heat-generating electronic component 4 with the coolant, lower casing 118 has a structure as shown in
In the second embodiment, guiding portions 118k are formed together with lower casing 118 in order to maximize an area that lower casing 118 contacts the coolant. Due to manufacturing limitations, however, guiding portions 118k may be formed on a rear side of ring-shaped sealing member 120, which will be described later, or formed as separate parts. Also in the second embodiment, flow separation wall 118l is provided on ring-shaped thick portion 118a* facing an inflow direction, so as to separate an incoming flow from guiding portions 118k into two directions in round heat transfer chamber 122, which will be described later.
Centrifugal pump 3 of the second embodiment has pin-type heat-dissipating fins 118e as shown in
Pin-type heat-dissipating fins 118e as shown in
Heat-dissipating fins 118e may have a shape other than the pin-type, the plate-type and the rib-type. The description above, which relates to heat-dissipating fins 118e provided between guiding portions 118k, also applies to heat-dissipating fins 118e provided outside guiding portions 118k. Heat-dissipating fins 118e outside guiding portions 118k may be the pin-type, the plate-type, the rib-type, other type or a mix of the types.
Further to the structure of centrifugal pump 3 of the second embodiment with reference to
When forming ring-shaped sealing member 120 having a structure as shown in
In the second embodiment, partition wall 120e that forms pump chamber 117 is formed together with ring-shaped sealing member 120 to facilitate manufacturing. For ensuring the rigidity of partition wall 120e or other purposes, however, partition wall 120e may be formed separately from ring-shaped sealing member 120. Further, partition wall 120e has a conic surface in the second embodiment, but may have a flat surface instead. Flat-shaped partition wall 120e requires blades 111a to have a flat-shaped end accordingly. However, conic-shaped partition wall 120e lowers a height of round heat transfer chamber 122, which is located in a central portion of lower casing 118 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 round heat transfer chamber 122 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-shaped partition wall 120e, however, hardly increases the total flow resistance and thereby improves the heat transfer efficiency.
Assembly procedures of above-described centrifugal pump 3 are explained below with reference to
Functions of centrifugal pump 3 in the heatsink apparatus according to the second embodiment are described below. Activating circuit board 115 generates an alternating magnetic field in stator 113. The magnetic field rotates impeller 111 combined with magnet rotor 112, thereby providing momentum to the coolant and causing a negative-pressure in the central portion. Then, the coolant is drawn in from suction channel 116b. The coolant is forced through suction connection 120d then to heat transfer guiding channel 123 formed between lower casing 118 and top panel 120g. The entered coolant efficiently dissipates the heat from high-temperature base 118f located directly above heat-generating electronic component 4.
Then the coolant reaches an end of base 118f and is separated into two directions to right and left. The two flows of the separated coolant respectively circulate in round heat transfer chamber 122 provided between guiding portions 118k and ring-shaped thick portion 118a*. The negative-pressure in the central portion of impeller 111 draws in the coolant again to the central portion of base 118f and forces the coolant through two through-holes 120f. During the process, the coolant dissipates the heat that travels a short distance from heat-generating electronic component 4 to base 118f.
Although the coolant is separated into two directions at the flow separation wall as reaching the end of base 118f in 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 of lower casing 118. Finally, the coolant provided with the momentum by the rotation of impeller 111 is propelled to an outer periphery of pump chamber 117, forced through discharge connection 120c and then discharged from discharge channel 116a.
Unlike the conventional heatsink apparatus wherein the coolant is drawn straight into impeller 211, centrifugal pump 3 of the second embodiment, provided with guiding portions 118k and top panel 120g that form heat transfer guiding channel 123, directs the entered coolant linearly from end to end in the central portion of lower casing 118 with no leakage to other portions. Thereby, the coolant contacts at a high speed a wide surface area of the central portion of lower casing 118 that has the highest temperature. Further, unlike the conventional heatsink apparatus wherein the coolant stagnates in pump chamber 217, centrifugal pump 3 of the second embodiment has no adverse impact on cooling efficiency.
Furthermore, unlike lower casing 218 in the conventional heatsink apparatus formed itself of a thick portion, lower casing 118 of the second embodiment, provided with round heat transfer chamber 122 surrounding heat transfer guiding channel 123, has flat base 118f. Lower casing 118 of the second embodiment thereby allows the heat to transfer extensively on a short path inside lower casing 118 and to reach surfaces of heat-dissipating fins 118e and base 118f. Since the heat transfer path is short, the thermal resistance is low during the transfer. Thus, surface temperatures of heat-dissipating fins 118e and base 118f approach a temperature of heat-generating electronic component 4.
As flowing into the central portion of lower casing 118 and circulating in and flowing out from round heat transfer chamber 122 of lower casing 118, the coolant contacts at a high speed the surfaces of heat-dissipating fins 118e and base 118f that have high temperatures after receiving the heat. Thereby, a temperature boundary layer forms thin and the coolant efficiently receives the heat from lower casing 118. The conventional heatsink apparatus, which has blades 211a proximate to a surface of thick portion 218a (refer to
In the centrifugal pump of the conventional heatsink apparatus, the surface of thick portion 218a of lower casing 218 provides two functions as shown in
According to the second embodiment of the present invention as described above, integrating the heatsink portion that receives the heat from heat-generating electronic component 4 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.
Radiator 6 as shown in
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.
Number | Date | Country | Kind |
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2004-376062 | Dec 2004 | JP | national |
2004-376063 | Dec 2004 | JP | national |