JP2006173511A - Cooling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling device having high cooling efficiency, which can increase a refrigerant flow volume, and can control heat generation from a heat generation component and a driving circuit to a low price. <P>SOLUTION: This deals with a cooling device provided with a radiator and a centrifugal pump in its circulation path for circulating the refrigerant, in which if the centrifugal pump is contacted by a heat generating electronic component, heat is drawn from the heat generating electronics through heat exchange with the refrigerant, thus radiating heat from the radiator, wherein the centrifugal pump is provided with a magnetic field generator, composed of a stator 13, a coil 14 and a circuit substrate 15, outside its upper casing 16 for turning the impeller with a magnetic field, the circuit substrate 15 is arranged between the stator 13 and the upper casing 16, and the driving circuit 15a is thermally connected to the upper casing 16 from the outside. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cooling device that cools a semiconductor or other heat generating electronic components such as a microprocessing unit (hereinafter abbreviated as MPU) used in a personal computer or the like by circulating a refrigerant.

  In recent years, electronic components have been highly integrated in electronic devices, and operation clocks have also been increased in frequency, and accordingly, the amount of heat generated from the electronic components has increased. For this reason, the contact temperature of each electronic component exceeds the operating temperature range, and the electronic component malfunctions frequently. Therefore, keeping each electronic component within the operating temperature range has become an important issue for normal operation of each electronic component.

  However, simply by air-cooling with a heat sink as in the prior art, such heat-generating electronic components are insufficient in capacity, and a more efficient and highly efficient cooling device is indispensable. Therefore, as such a cooling device, the present applicant has proposed a cooling device that cools the generated electronic components with high efficiency by circulating the refrigerant (see Patent Document 1).

  Hereinafter, a conventional cooling device that circulates and cools such a refrigerant will be described. FIG. 3 is a sectional view of a centrifugal pump of a conventional cooling device, and FIG. 4 is a configuration diagram of an electronic apparatus provided with the cooling device.

  First, a configuration of a cooling device for an electronic device will be described taking a notebook personal computer as an example. In FIG. 4, 1 is a casing of a notebook computer equipped with a cooling device, 2 is a keyboard of the notebook computer, 3 is a centrifugal pump that contacts the heating element to form a cooling device, and 4 is an MPU. It is a heat generating electronic component. 5 is a substrate on which the heat generating electronic component 4 is mounted, 6 is a refrigerant that conveys heat (not shown), and 7 is the heat of the refrigerant received from the heat generating electronic component 4 provided on the back (back side) of the display of the notebook computer. A heat radiator 8 for radiating heat to the outside is a closed circuit for connecting the centrifugal pump 3 and the heat radiator 7 to circulate the refrigerant.

  In addition, as this refrigerant | coolant 6, antifreezing liquids, such as ethylene glycol aqueous solution and propylene glycol aqueous solution, are suitable, and since it uses copper etc. as a casing material so that it may mention later, it is desirable to add an anticorrosive additive. The radiator 7 is made of a material having high heat conductivity and good heat dissipation, for example, a thin plate material such as copper or aluminum, and has a refrigerant passage and a reserve tank formed therein. Further, a fan may be provided to increase the cooling effect by forcibly applying air to the radiator 7 for cooling. The circulation path 8 is composed of a rubber tube such as a rubber having flexibility and low gas permeability, for example, butyl rubber, in order to ensure the freedom of piping layout. Such a centrifugal pump 3 of a cooling device for a notebook personal computer is suitable for a brushless DC motor system that can be driven easily, and the brushless DC motor system is also adopted in the notebook personal computer shown in FIG.

  Next, the internal configuration of the centrifugal pump 3 will be described with reference to FIG. In FIG. 3, 11 is an open impeller of the centrifugal pump 3, 11 a is a blade of the impeller 11, 12 is a magnet rotor provided on the outer peripheral side of the impeller 11, and 13 is on the inner peripheral side of the magnet rotor 12. The provided stator, 14 is a coil wound around the stator 13, 15 is a circuit board on which an electric circuit for supplying current to the coil 14 is mounted, 15 a is a drive circuit mounted on the circuit board 15, and 16 is an impeller 11. The upper casing for recovering the pressure of the kinetic energy given to the fluid by the impeller 11 and guiding it to the discharge port at the same time, 16a is a discharge passage formed in the upper casing 16, and 17 is a blade 11a which is an open blade. A pump chamber 18 for recovering pressure of given kinetic energy and guiding it to the discharge path, and 18 is a heat receiving member that is fitted to the upper casing 15 and brought into contact with the heat generating electronic component 4. The lower casing 18a is a suction passage formed in the lower casing, 18b is a heat dissipating fin for transferring the heat received from the heat generating electronic component 4 to the refrigerant, and 19 is a rotating shaft of the impeller fixed to the upper casing 16. It is a shaft.

  Here, the operation of the centrifugal pump of the conventional cooling device will be described. The refrigerant 6 flows toward the central portion of the pump chamber 17 through the suction passage 18a. At that time, the refrigerant 6 receives heat from the heat-generating electronic component 4 and receives heat from the heat radiating fins 18b that have reached a high temperature. Thereafter, the refrigerant 6 is guided to the discharge path 16a by the blade 11a.

The drive circuit 15a functions to alternately switch the direction of the current flowing through the coil 14, and is composed of a bipolar type torsion star or the like.
JP 2004-285888 A

  Here, considering a method of transferring the heat of the heat generating electronic component 4 to the refrigerant 6 with higher efficiency, it is conceivable to increase the flow rate of the refrigerant 6. This is because when the flow rate of the refrigerant 6 increases, the flow velocity of the refrigerant 6 increases, so that the temperature boundary layer becomes a turbulent flow and the heat transfer coefficient between the refrigerant 6 and the heat radiation fins 18b increases. Similarly, if the flow rate of the refrigerant 6 increases, the heat transfer efficiency also increases in the radiator 7, so that the increase in the flow rate of the refrigerant 6 greatly contributes to the increase in cooling efficiency as a whole.

  Therefore, when a method of increasing the flow rate of the refrigerant 6 is studied, a method of increasing the driving force for rotating the impeller 11 can be considered as the simplest method. Thereby, the rotation speed of the impeller 11 is increased, and the flow rate of the refrigerant 6 can be increased. In addition, when there is a space, a method of increasing the diameter of the impeller 11 can be considered. If the driving force for rotating the impeller 11 can be sufficiently secured, even if the diameter of the impeller 11 is increased, the rotational speed of the impeller 11 does not decrease and the flow rate of the refrigerant 6 can be increased.

  By the way, in order to increase the driving force for rotating the impeller 11, the current flowing through the coil 14 may be increased. However, if the current passed through the coil 14 is increased, the drive circuit 15a generates heat, the drive circuit 15a becomes high temperature, and the drive circuit 15a is destroyed in the worst case. Therefore, the current passed through the coil 14 is limited. Here, the reason why the drive circuit 15a generates heat is that there is a loss in the bipolar type thruster used when the direction of the current flowing through the coil 14 by the drive circuit 15a is switched alternately. As a current switching element, there is a method of using a field effect transistor (FET) with a small loss instead of a bipolar transistor, but since a field effect transistor is generally much more expensive than a bipolar transistor, the cooling device itself is also expensive. It will become something.

  Therefore, the present invention solves the above-described problems, and provides a cooling device that has high cooling efficiency, can increase the flow rate of refrigerant, and can suppress heat generation from heat-generating electronic components and drive circuits at low cost. With the goal.

  In the present invention, a heat dissipation device and a centrifugal pump are provided in a closed circuit for circulating a refrigerant, and the centrifugal pump is brought into contact with the heat generating electronic component, so that heat is removed from the heat generating electronic component by heat exchange with the refrigerant. A cooling device for radiating heat from a heat radiating device, wherein the centrifugal pump has a magnetic field generating means comprising a stator, a coil wound around the stator, and an electric circuit for supplying a current to the coil. The electric circuit is disposed between the stator and the pump casing, and the heat generating component of the electric circuit is thermally connected to the pump casing from the outside. And

  According to these cooling devices of the present invention, it is possible to increase the driving force for rotating the impeller at low cost, thereby increasing the flow rate of the refrigerant, improving the cooling efficiency, and reducing the temperature of the heat generating electronic component. It becomes possible to keep.

  In order to solve the above problems, a first aspect of the present invention is that a heat dissipation device and a centrifugal pump are provided in a closed circuit for circulating a refrigerant, and the centrifugal pump is brought into contact with a heat generating electronic component, whereby the refrigerant A cooling device that removes heat from the heat-generating electronic component by heat exchange with the heat dissipation device and dissipates heat from the heat dissipation device. The centrifugal pump includes a stator, a coil wound around the stator, and an electric circuit for supplying current to the coil. A magnetic field generating means configured to be provided outside the pump casing for rotating the impeller with a magnetic field, an electric circuit is disposed between the stator and the pump casing, and a heat generating component of the electric circuit is a pump This is a cooling device that is thermally connected to the casing from the outside, and heat generated by the heat generating parts on the electric circuit is transmitted to the pump casing, so that the temperature of the heat generating parts can be kept low. A.

  A second invention of the present invention is an invention subordinate to the first invention, wherein the heat generating component is a cooling device thermally connected to the pump casing by resin potting, and the heat generating component is made of the potted resin. The pump casing is connected without a gap, and heat generated by the heat-generating component is efficiently transmitted to the casing.

  A third invention of the present invention is an invention subordinate to the first invention, wherein the heat generating component is a cooling device thermally connected to the pump casing by a high heat conductive grease, and the heat generating component is formed by the high heat conductive grease. The pump casing is connected without a gap, and the heat generated by the heat generating component is efficiently transmitted to the casing.

  A fourth invention of the present invention is an invention dependent on any one of the first to third inventions, and is a cooling device provided with a through small hole in the vicinity of the center of the impeller, wherein the refrigerant in the outer peripheral portion of the impeller Flows through the rear side of the impeller into the small through hole, so that the heat transmitted through the pump casing is efficiently transmitted to the refrigerant.

  A fifth invention of the present invention is an invention subordinate to the fourth invention, wherein the cooling device is provided with a groove for allowing more refrigerant to flow on the inner surface of the pump casing in the vicinity of the heat generating component. Since the refrigerant flows smoothly through the groove portion and into the through hole of the impeller, a large amount of refrigerant flows through the groove portion, so that the heat transmitted through the pump casing is efficiently transmitted to the refrigerant.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1, 2, and 4.

Example 1
The centrifugal pump of the cooling device according to the first embodiment of the present invention will be described. FIG. 4 is a configuration diagram of an electronic device provided with a cooling device, FIG. 1 is a cross-sectional view of a centrifugal pump of the cooling device according to the first embodiment of the present invention, and FIG. is there.

  In addition, since the whole structure by which the cooling device of Example 1 is used with an electronic device was demonstrated based on FIG. 4 in description of the conventional cooling device, description is abbreviate | omitted.

  Next, the internal configuration of the centrifugal pump 3 will be described with reference to FIGS. 1 and 2, reference numeral 11 denotes an open impeller of the centrifugal pump 3, 11a denotes an open impeller, and 11b denotes a small hole provided near the center of the impeller 11 (near the center of the present invention). , 12 is a magnet rotor provided on the outer peripheral side of the impeller 11.

  The impeller 11 may be configured separately from the magnet rotor 12, but may be an integrated impeller 11 magnetized in a portion that becomes the magnet rotor 13. When the impeller 11 is rotating, the pressure of the refrigerant 6 on the outer peripheral portion of the blade 11a becomes higher than the vicinity of the center portion on the back side of the blade 11a (portion indicated by K in FIG. 1). The refrigerant 6 recirculates a small amount. As a result, excessive thrust force on the impeller 11 is reduced, and the impeller 11 rotates smoothly, and an effect of cooling the upper casing, which will be described later, with the refrigerant 6 is obtained. The specifications of the pump of Example 1 are ultra-compact with a thickness of 3 mm to 50 mm, a representative radial dimension of 10 mm to 100 mm, a rotational speed of 1000 rpm to 8000 rpm, and a head of about 0.5 m to 10 m.

  1, 13 is a stator provided on the inner peripheral side of the magnet rotor 13, 14 is a coil wound around the stator 13 for generating a magnetic field in the stator 13, and 15 is an electric circuit for supplying current to the coil 14. Is a circuit board on which is mounted, and 15 a is a drive circuit mounted on the circuit board 15. The stator 13 is preferably configured by laminating a plurality of silicon steel plates in order to reduce eddy current loss. A copper wire with an insulating film is suitable as the coil 14, and the wire diameter and the number of turns of the coil 14 are optimized in consideration of the power supply voltage used and the line product ratio. The drive circuit 15 a mounted on the circuit board 15 includes a Hall element that detects the rotational position of the magnet rotor 12, a current direction switching transistor, and a diode. In the first embodiment, a bipolar transistor that generates heat due to loss but is available at a low price is used as the transistor. As a result, the cooling device of the first embodiment can be made cheaper than the case where a field effect transistor (FET) is used. An integrated driver IC can also be used for the current direction switching portion.

  Next, 16 is an upper casing for accommodating the impeller 11 and at the same time recovering the kinetic energy given to the fluid by the impeller 11 and guiding it to the discharge port, 16a is a discharge passage formed in the upper casing 16, and 16b. Is a groove provided on the inner surface of the upper casing 16, and is provided at a position substantially opposite to the drive circuit 15 a with respect to the wall of the upper casing 16. By providing the groove 16b, the above-described reflux of the refrigerant 6 on the back surface of the impeller 11 is guided and concentrated in the groove 16b, so that the drive circuit 15a in the short distance of the groove 16b is efficiently cooled. Since the upper casing 16 is complicated in shape and requires a certain degree of heat resistance, it is preferable to manufacture the upper casing 16 by resin molding such as polyphenylene sulfide (PPS) or polyphenylene ether (PPE). It is not preferable to make the upper casing 16 of metal because eddy current loss is caused by fluctuations in magnetic flux generated by a magnetic circuit such as the stator 13.

  Reference numeral 17 denotes a pump chamber for recovering the pressure of the kinetic energy given by the blade 11a and guiding it to the discharge path. Reference numeral 18 denotes a lower casing which is a heat receiving casing to be brought into contact with the heat generating electronic component 4 and is a metal material such as copper or aluminum having high heat conductivity and good heat dissipation, and is constituted by a casting, forging, machining or a combination of these processing methods. Is done. The upper casing 16 and the lower casing 18 constitute the pump casing of the present invention. 18 a is a suction path that is an inlet of the refrigerant 6, 18 b is a heat radiating fin for increasing the heat radiating area with the refrigerant 6, and 18 c is a cone-shaped meat having a mortar-shaped concave conical surface that forms the side surface of the pump chamber 16. A thick portion 18d is a contact surface for making contact with the heat generating electronic component 4, and 18e is a thrust receiving portion for receiving the thrust force of the impeller 11.

  Reference numeral 19 denotes a shaft provided on the upper casing 16 for rotatably supporting the impeller 11 and is integrally fixed to the upper casing 16 with resin. Reference numeral 20 denotes a filler, which eliminates the gap between the drive circuit 15a and the upper casing 16 and functions to efficiently transfer heat generated in the drive circuit 15a to the upper casing. The material of the filler 20 is required to have high thermal conductivity and electrical insulation because it contacts the electric circuit, but an epoxy potting material and thermal conductive grease are suitable.

  When assembling the centrifugal pump 3 described above, first, the impeller 11 is inserted into the shaft 19 formed integrally with the upper casing 16. Next, the lower casing 18 is fitted into the upper casing 16 and fixed using screws or the like (not shown). On the other hand, the coil 14 is wound around the stator 13 in a separate process, and the circuit board 15 on which the drive circuit 15 a is mounted is attached to the wound stator 13. Hereinafter, this assembly is referred to as a magnetic circuit assembly.

  In order to eliminate the gap between the drive circuit 15a and the upper casing 16, the filler 20 is potted. When an epoxy potting material is used as the filler 20, the magnetic circuit assembly is inserted into the recess of the upper casing 16, The filling material 20 is poured, and then the potting material is cured using a thermostatic bath or the like. Thereby, the heat generating component of the drive circuit 15a and the upper casing 16 are connected without a gap, and the heat generated by the heat generating component can be efficiently transferred to the upper casing 16.

  In addition, when thermally conductive grease is used as the filler 20, the thermally conductive grease is applied to the drive circuit 15a of the magnetic circuit assembly and / or the corresponding portion of the upper casing 16 in advance, and then the magnetic circuit is used. The circuit assembly is inserted into the recess of the upper casing 16. Thereby, like the potting material, the heat generating component of the drive circuit 15a and the upper casing 16 are connected without a gap, and the heat generated by the heat generating component can be efficiently transferred to the upper casing 16.

  Next, the operation of the centrifugal pump 3 of the cooling device in Embodiment 1 will be described. First, when a voltage is applied to the drive circuit 15a to generate an alternating magnetic field in the stator 13, the impeller 11 is rotated by this magnetic field, and the centrifugal pump 3 operates as a pump. Then, the refrigerant 6 is sucked into the central portion of the pump chamber 17 through the suction passage 18a, and the circulation of the refrigerant 6 is continued.

  At this time, since the lower casing 18 is in contact with the heat generating electronic component 4 at the contact surface 18d, heat generated in the heat generating electronic component 4 is transmitted. When the refrigerant 6 flows into the pump chamber 17, the low-temperature refrigerant 6 comes into contact with the radiating fins 18 b at a high flow rate, so that a thin turbulent temperature boundary layer is formed in the main flow and the temperature difference is large and the flow is laminar. Since the heat transfer coefficient is larger, the heat of the lower casing 18 is efficiently transferred. Thereafter, the refrigerant 6 whose temperature has risen is guided to the outer peripheral portion of the blade 11a, flows to the discharge passage 16a, and is discharged. At this time, since the pressure of the refrigerant 6 guided to the outer peripheral portion of the blade 11a is higher than that of the central portion of the pump chamber 17, a part of the refrigerant 6 flows around the rear surface of the impeller 11 and flows toward the central portion of the impeller 11. Then, it flows out from a small hole 11 b provided in the impeller 11. Most of the refrigerant 6 flowing on the back surface of the impeller 11 flows along the groove portion 16b provided in the upper casing 16 having a small flow resistance. However, the refrigerant 6 having a high flow rate passing through the groove portion 16b is efficiently used in the upper casing 16. The heat (heat that has received the heat generated by the drive circuit 15a) is taken away. If the impeller 11 is not provided with the small hole 11b, the recirculation of the refrigerant 6 on the rear surface of the impeller 11 as described above does not occur. Since a complicated flow including a circulation flow by the refrigerant 6 is formed and does not stagnate, the heat of the upper casing 16 that has received the heat generated by the drive circuit 15a can be taken away by the refrigerant 6, and the heat generating electronic component 4 and the drive circuit 15a Temperature rise can be suppressed.

  As described above, according to the cooling apparatus of the first embodiment, the flow rate of the refrigerant can be easily increased by using a low-cost bipolar transistor, the cooling efficiency is high, and the heat generation from the heat generating electronic component 4 and the drive circuit 15a. Can be suppressed.

The present invention can be applied to a cooling device for electronic components that cools heat-generating electronic components by circulating a refrigerant.

Sectional drawing of the centrifugal pump of the cooling device in Example 1 of this invention Single-piece | unit perspective view of the upper casing in Example 1 of this invention Sectional view of a centrifugal pump of a conventional cooling device Configuration diagram of electronic equipment with cooling device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Housing | casing 2 Keyboard 3 Centrifugal pump 4 Heat-generating electronic component 5 Substrate 6 Refrigerant 7 Radiator 8 Circulation path 11 Impeller 11a Blade 11b Small hole 12 Magnet rotor 13 Stator 14 Coil 15 Circuit board 15a Drive circuit 16 Upper casing 16a Discharge path 16b Groove portion 17 Pump chamber 18 Lower casing 18a Water absorption path 18b Radiation fin 18c Cone-shaped thick portion 18d Contact surface 18e Thrust receiving portion 19 Shaft 20 Filler

Claims (5)

A heat radiating device and a centrifugal pump are provided in a closed circuit for circulating the refrigerant, and the centrifugal pump is brought into contact with the heat generating electronic component so that heat is removed from the heat generating electronic component by heat exchange with the refrigerant, A cooling device for radiating heat from a heat radiating device, wherein the centrifugal pump includes a magnetic field generating means including a stator, a coil wound around the stator, and an electric circuit for supplying current to the coil. The electric circuit is disposed between the stator and the pump casing, and a heat generating component of the electric circuit is thermally connected to the pump casing from the outside. A cooling device characterized by that. The cooling device according to claim 1, wherein the heat generating component is thermally connected to the pump casing by resin potting. The cooling device according to claim 1, wherein the heat generating component is thermally connected to the pump casing by a high thermal conductive grease. The cooling device according to any one of claims 1 to 3, wherein a through hole is provided near the center of the impeller. The cooling device according to claim 4, wherein a groove for allowing more refrigerant to flow is provided on the inner surface of the pump casing in the vicinity of the heat generating component.

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