TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid cooling system for a small information processing device such as a desktop or notebook personal computer or server.
The related art of a cooling device for an electronic device includes a metal plate or a heat pipe interposed between a heat generating member in the electronic device and a metal housing wall to thermally connect the heat generating member to the metal housing wall. The heat generated by the heat generating member is radiated by the metal housing wall.
Patent Document 1 discloses a technique for liquid-cooling a heat-generating member of an electronic device. According to this technology, heat generated by a semiconductor-element heat-generating member in the electronic device is received by a heat-receiving head, and cooling inside the heat-receiving head is performed. The liquid is transported through the flexible tube to the heat radiating head provided on the metal casing of the display device, and the heat generated by the semiconductor element heating member is efficiently passed from the metal casing through the heat radiating head through the cooling liquid. It has a structure to radiate heat. Furthermore, the heat is transmitted to a heat pipe directly attached to the wall surface of the metal casing that is a heat dissipation surface, and further thermally connected to the other end of the heat pipe that is directly attached to the wall surface of the metal casing that is a heat dissipation surface. A structure for dissipating heat is disclosed.
Patent Documents 2 and 3 disclose heat receiving heads having a meandering flow path.
Patent Document 4 discloses a heat receiving head having a plurality of pipes having the same flow path cross-sectional area.
[Patent Document 1]
JP-A-7-142886 [Patent Document 2]
JP-A-6-266474 [Patent Document 3]
JP 2001-133174 A [Patent Document 4]
JP 2001-102835 A
[Problems to be solved by the invention]
A personal computer or a server generates heat from a CPU, an MPU, or the like (hereinafter, referred to as a CPU) incorporated in a main body. However, the generated heat may cause unstable circuit operation or thermal deformation of mechanisms. is there. In particular, recently, as the operating frequency of the CPU has been further increased, the amount of heat generated has increased, and further improvement of the cooling function is desired.
The prior art discloses a technique for obtaining a substantially constant cooling function over the entire area of a heat receiving surface by a heat receiving method of a liquid cooling system using meandering pipes or a plurality of pipes. However, in general, a CPU or the like has a structure in which a semiconductor element of about 10 mm square that generates heat is mounted on an organic (or ceramic) relay board, which is soldered to a motherboard or mounted in a socket mounted on the motherboard. You. The heat receiving head has a larger structure than the semiconductor element because it forms a flow path. Further, the temperature distribution of the heat receiving head in a state where the heat receiving head is attached to the CPU becomes lower as the distance from the center of the CPU becomes concentric. That is, in a system for efficiently cooling a CPU or the like, it is not necessary to make the heat receiving head uniform, and cooling having a distribution of cooling a hot place is more effective.
It is known that it is effective for cooling to increase the water contact area with the refrigerant flowing in the heat receiving head, increase the flow rate of the refrigerant, and increase the temperature difference between the refrigerant and the heat receiving head. . In order to increase the flow rate, it is necessary to improve the performance of the means for transporting the refrigerant (generally, a pump). To increase the performance, the pump must be increased or the power must be increased.However, the mounting area cannot be secured due to the recent increase in density and power saving of electronic devices, so the pump cannot be enlarged and the power consumption cannot be increased. . In addition, there is a demand for minimizing the capacity of the pump in terms of noise.
In order to increase the water contact area with a meandering pipe, it is conceivable to form a flow path on the entire surface of the heat receiving head, but in this case, the refrigerant reaches the central part of the CPU to receive heat from the heat receiving head while passing through the flow path At this time, the temperature of the refrigerant rises, and the temperature difference between the central part of the CPU and the refrigerant cannot be made large, so that effective cooling cannot be performed.
When a plurality of pipes having the same flow path cross-sectional area are arranged in the heat receiving head, the flow rate of each pipe is the same, so that the flow rate of the ability to cool the central portion of the CPU also flows to the pipes located around the heat receiving head. It is necessary to increase the pump performance because unnecessary cooling is performed so as to cool the part that does not need to be cooled, and the total flow rate becomes several times the number of pipes.
An object of the present invention is to provide a useful liquid cooling technique applied to a local heat-generating component such as a CPU of an information processing apparatus, and to propose a configuration in which a unique heat receiving effect not obtained in the related art can be obtained.
[Means for Solving the Problems]
A first means for achieving the above object is achieved by providing a flow control means in each of the refrigerant flow paths of a heat receiving head having a plurality of pipes. The flow rate control means can be achieved by changing the cross-sectional area of each flow path or by providing a flow-blocking resistor in the flow path. A second means for achieving the above object is to form a resistor that obstructs the flow from a substance (for example, a bimetal) whose shape changes greatly depending on the temperature, and to open the flow path to the resistor when the temperature of the refrigerant is high. This can be achieved by reducing the path resistance and increasing the flow rate, and, when the temperature of the refrigerant is low, blocking the flow path by the resistor to increase the flow path resistance and restricting the flow rate, and allowing the refrigerant to flow intensively in the high temperature part. .
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
A liquid cooling technique for a notebook personal computer according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an overall configuration relating to liquid cooling of a notebook personal computer according to an embodiment of the present invention. Referring to FIG. 1, the notebook computer includes a personal computer main body 1 having a group of operation buttons, and a display unit 2 having a liquid crystal display unit which is rotatably supported by the main body 1. A motherboard (control circuit board) 3 supported by a main chassis is arranged. The motherboard 3 is mounted with various electric / electronic elements, integrated circuits, and electronic circuits necessary for operating the computer. The CPU 4 and the like, which sometimes generate heat, are also arranged on the motherboard 3. In FIG. 1, the CPU 4 is disposed under a W / J (water jacket as a heat receiving head) and transfers heat generated from the CPU 4 to the heat receiving head.
The basic configuration of liquid cooling according to the embodiment of the present invention is as follows. A heat receiving head (W / J) 9 is fixed on a CPU 4 which is a largest heat source housed in a personal computer main body, and heat generated by the CPU is received by the heat receiving head. A tube 10 connected to the heat receiving head 9 and filled with a cooling liquid is collected between the liquid crystal display panel and the front cover and is dissipated through the front cover or housing.
The details of the heat receiving head, which is a feature of the present invention, in the cooling liquid circulation type cooling system having the above configuration will be described below.
FIG. 2 is a top cross-sectional view of one embodiment of the present invention, and arrows indicate the magnitude and direction 22 of the flow rate of the refrigerant flowing through each flow path 21. FIG. 3B is a cross-sectional view taken along line AA of FIG. FIG. 3A shows the temperature distribution 24 of the base 23 of the heat receiving head in FIG. 3B by a solid line and the flow rate characteristic 25 of each flow path by a bar graph.
As shown in FIG. 2, the heat receiving head is an embodiment of a flow path through which the refrigerant flows, a partition plate 26 forming the flow path, an outer frame 27, a base 23 in contact with the heating element, a top plate 28, and a temperature-sensitive flow rate limiting means. It is composed of a certain bimetal 29. The base, the outer frame, and the partition plate may be formed integrally, or may be formed independently of each other and then formed by bonding or the like. Further, they are preferably made of a metal having good heat conductivity. Further, the heat receiving head is provided with an inlet 30 through which the refrigerant flows into the heat receiving head and an outlet 31 through which the refrigerant whose heat has been removed from the heat receiving head flows out on the opposite side. The bimetal is formed by bonding a high expansion metal plate 32 having a large amount of expansion and contraction due to a temperature difference and a low expansion metal plate 33 having a small amount of expansion and contraction due to a temperature difference. As the temperature rises, the amount of extension on the high expansion metal side increases, so that the high expansion metal side is bent in a convex state.
The bimetal is attached to an outer frame or a partition plate with the high expansion metal side on the outflow side of each flow path and the inflow side of each flow path. The bimetal may be attached to the base or top plate.
Hereinafter, the operation of the heat receiving head of the present invention will be described. When the CPU is started, the temperature of the base thermally connected to the CPU starts to rise. As shown in FIG. 2A, the temperature distribution has a peak just above the CPU and decreases toward the periphery. As the temperature of the heat receiving head and the temperature of the refrigerant in the heat receiving head rises, the temperature of the attached bimetal rises and starts to deform toward the outlet. The deformation of the bimetal attached to the high-temperature channel just above the CPU is large, and the deformation becomes small as it goes to the surroundings. Accordingly, since the flow path resistance of the flow path having a bimetal having large deformation decreases, the flow rate can be controlled to increase as the flow path becomes closer to the CPU where the temperature becomes higher. As a result, the flow rate of each flow path can be controlled as shown in the bar graph of FIG. 2A, and the flow rate of the hatched portion 34 can be reduced as compared with the case where the flow rate is not controlled. This eliminates the necessity of flowing an excessive flow rate, so that the capacity of the pump can be reduced. As described above, the size and power consumption of the pump can be reduced.
If the required flow rate is known in advance, it is possible to arrange the partition plates of equal thickness as shown in FIG. It is. Further, it is also possible to realize the embodiment shown in FIG. 5 in which partition plates having different thicknesses are arranged at equal pitches.
As shown in FIGS. 6 to 8, as another method of manufacturing heat receiving heads having different flow path cross-sectional areas, pipes 35 having different diameters of circular, elliptical or square shapes are arranged in a row in a row on a base, and heat conduction bonding is performed. There is also a method of forming by using an agent or soldering 36. According to this manufacturing method, since the flow path becomes the inner diameter of the pipe and is closed as the flow path, the top plate can be eliminated. Further, in the case of using a rectangular pipe, the contact surface with the CPU can be formed flat, so that the base is not required. 6 to 8 show cross sections taken along the line AA in FIG. 2 in the present embodiment.
FIG. 9 shows an embodiment in which the present invention is applied to a modularized heating element 37. In this way, by using the heat receiving heads provided with the bimetals in the respective flow paths, even when the heating element 38 does not exist at the center of the heat receiving head or when the heat generation is distributed in the module, the cooling can be performed at a minimum necessary flow rate. Become. In addition, a module or the like may generate different heat-generating components depending on the function used. Even if the part A generates heat when using a certain function and the part B generates heat when using another function, the flow can be selectively and automatically concentrated at each time. Therefore, it can respond flexibly to heat generation.
【The invention's effect】
As described above, according to the present invention, it is used in a liquid cooling system of an information processing apparatus in which a local heating element such as a CPU is arranged, such as a personal computer or a server, and efficiently removes heat from the local heating element to a radiator. It becomes possible to transport. Since cooling can be performed at a minimum necessary flow rate, the capacity of the pump can be reduced. As a result, miniaturization and power saving of the pump can be expected, and application to a smaller information processing device can be expected.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an overall configuration of a liquid cooling system for a notebook personal computer according to an embodiment of the present invention.
FIG. 2 is a diagram showing a first embodiment of the present invention.
FIG. 3 is a diagram illustrating a flow control operation according to the first embodiment of the present invention.
FIG. 4 is a view showing a second embodiment of the present invention.
FIG. 5 is a view showing a third embodiment of the present invention.
FIG. 6 is a view showing a fourth embodiment of the present invention.
FIG. 7 is a view showing a fifth embodiment of the present invention.
FIG. 8 is a view showing a sixth embodiment of the present invention.
FIG. 9 is a view showing a seventh embodiment of the present invention.
[Explanation of symbols]
1: body part, 2: display part, 3: motherboard, 4: CPU, 9: heat receiving head, 10: tube, 21: flow path, 22: size and direction of flow rate, 23: base, 24: temperature distribution, 25 : Flow characteristics of each flow path, 26: partition plate, 27: outer frame, 28: top plate, 29: bimetal, 30: inlet, 31: outlet, 32: high expansion metal plate, 33: low expansion metal Plate, 34: reducible flow rate, 35: pipe, 36: heat conductive adhesive or soldering, 37: module, 38: heating element,