JP4506483B2 - Liquid cooling system - Google Patents

Description

  The present invention relates to a liquid cooling system for an information processing apparatus, and more particularly to a cooling system that is optimal for priming of a non-self-priming pump that circulates a cooling liquid.

  In recent years, devices and integrated circuits used in personal computers, servers, and the like, particularly CPUs, have been increased in speed, but the amount of heat generation has increased accordingly. Currently, the cooling of the CPU is mainly performed by a direct air cooling method in which a CPU is fixed to a heat sink, a fan is attached to the CPU, and the cooling air is blown onto the heat sink. However, as the density of devices increases, the space around the CPU is limited, and the heat sink size is limited. For this reason, in the direct cooling method, the limit of the cooling capacity is being limited. Further, since the fan size is also limited, it is necessary to rotate the small fan at high speed in order to obtain a high air volume, and noise is increased.

  Therefore, in order to use a large heat sink and a large fan that are more efficient, application of heat transport means such as a liquid cooling system has been attempted. In these liquid cooling systems, since the number of parts is larger than that of the air cooling system, downsizing of the parts is required. For example, a small pump uses a valve type using a piezoelectric element, a piston type by magnetic drive, or a centrifugal type that rotates a propeller.

  Each of the small pumps mentioned above has advantages and disadvantages. The valve type using a piezoelectric element and the piston type by magnetic drive are not limited to liquids, and can be circulated even with gas or a mixture of liquid and gas. However, these pumps circulate the liquid by repetitive movements of valves and pistons, so there is a problem that vibration and noise are large. In addition, the efficiency is lower than that of a centrifugal pump, and the flow rate at the time of low pressure loss tends to be small.

  On the other hand, the centrifugal pump is efficient because it has a small amount of vibration to rotate the propeller. However, if air is mixed into the pump, the propeller is idled and the circulation capacity may be significantly reduced or the circulation may be stopped. In order to improve the problem of this centrifugal pump, Patent Literature 1 and Patent Literature 2 disclose a technique for improving the air discharging capability by devising a propeller shape.

Japanese Patent Laid-Open No. 10-110696 Japanese Patent Laid-Open No. 11-218097

  However, in the techniques disclosed in these documents, the limit value of the amount of aeration until the liquid circulation stops is improved, but when this limit value is exceeded, the liquid circulation also stops. There is a problem. Therefore, when a non-self-priming pump such as a centrifugal pump is used, means for preventing air from entering the pump is necessary. This means is generally carried out by the tank. However, for example, when a strong impact is applied, the liquid and air inside the tank mix and air enters the circulation path, and the circulation may stop.

The present invention solves the problem of the non-self-priming pump, even if the air mixed into the pump occurs, and to provide a free cooling system be circulated coolant is stopped.

In order to solve the above problems, a liquid cooling system of the present invention, a reserve tank for separating the air in the cooling liquid, and a non-self-priming pump for circulating the cooling liquid to radiate the heat generated heat generating portion such as a CPU the have the reserve tank, the so arranged on top of the self-priming pump, further, the liquid inlet of the reserve tank, so as to be positioned on top of the gas-liquid boundary surface of the reservoir tank, the coolant circulation path which corresponds to the difference of the liquid inlet and the gas-liquid interface, and to be recirculated to the non-self-priming pump.

The liquid cooling system of the present invention, comprises a reserve tank for separating the air in the cooling liquid, and a non-self-priming pump for circulating the cooling liquid to radiate the heat generated heat generating portion such as a CPU, the reserve tank, said while being placed on top of the self-priming pump, the reserve tank of the liquid inlet and the liquid volume of the liquid circulation path corresponding to the height of the gas-liquid boundary surface of the reserve tank, the liquid a mixed amount of air pumping of the non-self-priming pump is stopped by aerated, and from the liquid outlet of the reservoir tank to be larger than the sum of the liquid volume of the liquid circulation path to the non-self-priming pump.

The liquid cooling system of the present invention, comprises a reserve tank for separating the air in the cooling liquid, and a non-self-priming pump for circulating the cooling liquid to radiate the heat generated heat generating portion such as a CPU, the reserve tank, said while being placed on top of the self-priming pump, when the flow rate of the coolant is equal to or less than a predetermined value, said stops driving the non-self-priming pump, and the gas-liquid boundary surface the coolant circulation path which corresponds to the difference of the liquid inlet port, and to be recirculated to the non-self-priming pump.

  According to the present invention, it is possible to use a non-self-priming pump even in a liquid cooling system that may be mixed with air, and to prevent a decrease in pumping performance of the pump due to mixed air, thereby providing a stable cooling system. .

The non-self-priming pump, such as centrifugal pumps of the liquid cooling system, the problems coolant and air inlet becomes impossible pumping, to define the installation position of the air release portion of the coolant circulation path and the non-self-priming pump It was solved by.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a perspective view of an electronic apparatus to which the present invention is applied. An outline of a liquid cooling structure will be described using a desktop personal computer (hereinafter referred to as a desktop PC) as an example of an electronic device. In FIG. 1, a mother board 103 is provided on a side surface inside a housing 101, and a CPU 102, a chip set 104, and a memory 105 are mounted thereon. An HDD 106 and a CD-ROM 108 are mounted as external storage devices. In addition, the power source 109 is on the back side of the casing 101, and the PCI board 107 is positioned below the power source 109.

  Next, the configuration of the liquid cooling system 110 will be described. The liquid cooling system 110 is located above the CPU 102. The jacket 111 is attached to the CPU 102 and absorbs heat generated by the CPU. More specifically, the jacket 111 is made of a metal having excellent heat conductivity such as copper or aluminum. The contact surface with the CPU 102 is pressure-bonded with a thermal compound or high thermal conductive silicon rubber sandwiched therebetween, so that heat generated by the CPU 102 is efficiently transmitted to the jacket 111. In addition, a coolant flows inside the jacket, and heat is transferred to the coolant.

  The radiator 112 that cools the coolant that has absorbed the heat generated by the CPU (102) includes pipes 112a and fins 112b. The coolant flows inside the pipe 112a, and heat is transferred to the fins 112b. A fan 113 is attached to the radiator 112, and air is sent to the radiator 112 to cool the fins 112b of the radiator 112.

  There is a tank 114 beside the radiator 112. In the tank 114, the air contained in the cooling liquid is separated from the cooling liquid so that the cooling liquid containing air does not continue to circulate.

  A pump 115 is disposed under the tank 114, and thereby the coolant is circulated. The pump 115 is connected to the mother board 103 by a cable 117. In the motherboard 103, the power supply to the pump 115 and the rotation speed of the impeller inside the pump 115 are detected by the cable 117. Here, the pump 115 is a non-self-priming centrifugal pump. In a centrifugal pump, when air is mixed into the pump, the propeller becomes idle, and the circulation capacity may be significantly reduced or the circulation may be stopped.

  Next, the entire piping will be described. The tube 116a connects the jacket 111 and the radiator 112, and serves as a heat transport path by the coolant flowing through the tube 116a. Further, the tube 116 b connects the radiator 112 and the tank 114, and the tube 116 b is connected at a high position of the tank 114. The tube 116c connects the tank 114 and the pump 115 at a short distance. The tube 116 d connects the pump 115 and the jacket 111. The connection position between the tube 116b and the tank 114 and the length of the tube 116c are according to the present invention, which will be described in detail later.

  Next, the route through which the coolant flows will be described. The coolant circulates from the pump 115 through the tube in the order of the jacket 111, the radiator 112, and the tank 114, and returns to the pump 115 again. As described above, the tank 114 that separates air and liquid is disposed upstream of the pump 115.

Next, the returning means when air is mixed in the non-self-priming pump 115 and the circulation of the coolant is stopped according to the present invention will be described in detail.
First, the state of each part during normal operation will be described with reference to FIG. As described above, the tube 116 b is connected so that the coolant flows back through the radiator 112 and the tank 114. The tube 116b allows the coolant to flow into the tank 114 from the portion 202 above the coolant level 201 inside the tank. In this way, the tube 116b is configured to be provided with the portion 202 positioned above the liquid level 201. Further, the volume inside the upper portion 202 is made larger than the sum of the volume inside the tube 116 c and the liquid flow stop air amount of the pump 115. Here, the liquid flow stop air amount is an air amount inside the pump at which the liquid flow stops. Particularly in the case of this embodiment, the volume inside the tube 116c is 1.25 ml, the liquid flow stop air amount of the pump 115 is 1.5 ml, and the volume inside the upper portion 202 is 3 ml.

  During normal operation, since the coolant flows from the radiator 112 to the tank 114, the upper portion 202 is filled with the coolant. 2, 3, 4, and 7, hatched portions indicate the coolant. The tube 116 c connects the tank 114 and the pump 115, and the port 204 is located at the center of the tank 114. This is because if there is more than half of the cooling liquid inside the tank 114, the mouth 204 will be below the liquid level 201 in any posture in the stationary state. That is, the operation posture of the apparatus is not restricted.

  Next, a state where air is mixed in the pump will be described with reference to FIG. Here, it is assumed that the tank 114 has received a strong impact. The liquid level 201 swells due to a strong impact, whereby the mouth 204 is exposed to air for a moment, and air is sucked into the tube 116 c and the pump 115. Here, if the air sucked into the pump 115 reaches the liquid flow stop air amount of the pump 115, the pump 115 has no pumping capacity and the liquid flow rate is lowered or the liquid flow is stopped.

  Next, referring to FIG. 4, the return of the pumping capacity by discharging the air inside the pump 115 will be described. First, a decrease in the liquid flow rate or a stop of the liquid flow is detected by a pump control means described later. Then, power supply to the pump 115 is stopped and the pump operation is temporarily stopped. Then, the liquid in the upper portion 202 flows back to the height equal to the liquid surface 201 in the direction of the radiator 112 due to its own weight. Due to the reverse flow of the coolant, the air inside the pump 115 and the inside of the tube 116 c is exhausted to the tank 114. The amount of the backflow liquid at this time is the amount of liquid accumulated in the upper portion 202, and as described above, this is equal to or larger than the volume inside the tube 116c + the liquid flow stop air amount of the pump 115. The inside of the tube 116c is again filled with the liquid, and the air contained in these is discharged to the tank 114. After the backflow is completed, the liquid can be circulated again by operating the pump.

  Next, the detection means for stopping the liquid flow will be described. In this embodiment, the stoppage of the liquid flow is determined by detecting the rotational speed of the impeller of the pump. Specifically, when air is mixed into the pump, the area of the impeller that comes into contact with the coolant is reduced, so the load on the impeller is reduced. Accordingly, the rotational speed of the impeller increases. FIG. 5 shows an example of the relationship between the impeller rotational speed and the liquid flow state in this embodiment. As shown in FIG. 5, since there is a clear difference between the rotation speed of the impeller of 1000 rpm or more between the normal time and the air mixing time, it is possible to sufficiently determine the liquid flow stoppage. Since the liquid flow does not need to be completely stopped in order to enter the pump return operation, in this embodiment, the rotational speed at which the pump return operation (pump temporary stop) is entered is 4000 rpm. Hereinafter, this rotational speed is referred to as a return rotational speed. Since the stoppage of the liquid flow is not only the rotational speed of the impeller, but also the current consumption is reduced, the stoppage of the liquid flow can be determined by detecting this pump current.

  Next, a pump control method will be described with reference to the flowchart of FIG. First, the power supply of the entire apparatus is turned on, and in step 601, driving of the pump is started. In the next step 602, a weight is applied until the rotational speed of the impeller is stabilized. Although this time depends on the length of the circulation path, it is usually several seconds, and in this embodiment, it is 3 seconds. In the next step 603, the rotational speed of the impeller is detected, and in the next step 604, it is confirmed whether the rotational speed of the impeller detected previously is equal to or higher than the return rotational speed (4000 rpm in this embodiment). . When the rotational speed of the impeller is equal to or lower than the return rotational speed, the liquid flow is normal, so the process returns to Step 603 again to detect the rotational speed of the impeller.

  On the other hand, if the rotational speed of the impeller is equal to or higher than the return rotational speed in step 604, the pump drive is stopped in step 605. At this time, the reverse flow of the cooling liquid is started by the structure shown in FIG. In the next step 606, a time is waited until the backflow of the liquid is completed, that is, until the height of the liquid in the tube 116b in FIG. Although this time depends on the pressure loss of the entire circulatory system and the volume of the upper portion 202 in FIG. 4, it is 8 seconds in this embodiment. Thereafter, the process returns to step 601, and driving of the pump is started. With the flow described above, even when air is mixed into the non-self-priming pump and the circulation is stopped, the air inside the pump can be discharged, and the pumping capacity of the pump can be restored.

  The upper portion 202 may have a shape as shown in FIG. In short, if the mouth 203 is above the liquid level 201, the shape of the upper portion 202 is arbitrary, and the volume of the upper portion 202 is larger than the sum of the volume inside the tube 116c and the liquid flow stop air amount of the pump 115. do it.

Further, in this embodiment, since the air inside the pump is discharged by one backflow operation, the volume of the upper portion 202 is set to be equal to or larger than the volume inside the tube 116c + the liquid flow stop air amount of the pump 115. When the operation may be performed, the volume of the upper portion 202 only needs to be greater than or equal to the volume inside the tube 116c.
In addition, the volume of the upper portion 202 that is a part of the tube has been used as the amount of liquid at the time of backflow. However, not only the tube but also the radiator itself is disposed at a position higher than the liquid surface 201, thereby increasing the volume inside the radiator. Can be used as the amount of liquid during reverse flow.

  Further, in this embodiment, the circulation of the liquid is caused to flow backward due to the weight of the cooling liquid, but if the pump is not a centrifugal pump but a pump having an axial flow type impeller, by rotating the impeller reversely, It is possible to reverse the circulation of the liquid. In this case, the upper portion 202 is unnecessary.

  As for the control of the pump, when the flow rate is changed not only by turning the pump on and off but also by voltage control, that is, when the rotation speed of the impeller is controlled, the return rotation speed according to the voltage value. By preliminarily investigating and storing this result as data, it is possible to determine whether or not the liquid flow has stopped even when driving each voltage. Moreover, since the rotation speed detection and voltage drive of such an impeller are the same as the fan control generally performed by the present PC, application of this invention is easy.

This embodiment shows an example in which the present invention is applied to a notebook personal computer (hereinafter referred to as a notebook PC) of the present invention. In the description of the present embodiment, the description will focus on parts different from the first embodiment.
FIG. 8 shows this embodiment. Unlike the desktop PC shown in the first embodiment, the notebook PC includes a main body 801 and a display 802, which are connected by a hinge 803. For this reason, a flexible rubber tube is used as the tube 804 passing through the inside of the hinge 803. On the back side of the display unit 802, a heat radiating pipe 806 and a heat radiating plate 805 connected thereto by brazing or caulking are arranged, and the heat of the CPU is cooled by natural heat radiation.

  The inside of the tank 114 is the same as the structure shown in FIGS. 2 to 4 of the first embodiment. That is, the inside of the tank 114 is provided with a tube port 204 connected to the pump 115 at the center of the tank. . For this reason, if there is more than half of the cooling liquid inside the tank 114, the mouth 204 will be below the liquid level 201 in any posture in the stationary state.

  In addition, a tube opening 203 connected to the heat radiating portion is disposed above the liquid level 201. The upper portion 202 occupies most of the heat radiating pipe 806. As for the control of the pump 115, the liquid flow is detected and controlled by the mother board 103 as in the case of the second embodiment. The coolant flows in the order of pump 115-jacket 111-radiating pipe 806-tank 114-pump 115 again. That is, upstream of the pump 115 is a tank 114 that separates air and liquid.

  The tank 114 having means for separating air and liquid located upstream of the pump 115 and the upper portion 202 as means for reversely circulating the liquid are provided. When air enters the pump 115, the pump 115 is temporarily stopped under the control of the mother board 103 to reverse the liquid circulation, and the air inside the pump is discharged to the tank 114. With the structure described above, it is possible to automatically return when air is mixed into the non-self-priming pump and the circulation stops.

  In this embodiment, the heat radiating means including the heat radiating pipe 806 and the heat radiating plate 805 and the tank 114 are prepared separately, but these may be integrally formed by a roll bond method. The roll bond method is a method in which two thin metal plates are bonded together and a part thereof is inflated to form a flow path or the like. An example of this is shown in FIG. The hatched portion is a bonded portion, and the blank portion is a portion that is inflated and formed in a hollow shape.

  Further, in the first and second embodiments, the opening 204 inside the tank 114 is arranged at the center of the tank so as not to restrict the posture during operation of the device, but the device in which the installation posture is determined, for example, a rack mount type It is not necessary for servers. In the assumed installation posture, it is sufficient that the port 204 is below the liquid level 201 inside the tank.

  As described in the first and second embodiments, when the apparatus power is turned off, the coolant flows backward when the pump is stopped, and the coolant inside the pump is discharged, so the air inside the pump is discharged. Thereby, at the next start-up, the pumping capacity of the pump due to the mixing of air is restored, so that stable cooling performance can be provided.

It is a perspective view of Example 1 (desktop PC) of an electronic device using the present invention. It is a figure (steady operation state) which shows the principle of this invention. It is a figure which shows the principle of this invention (air mixing state in a pump inside). It is a figure which shows the principle of the present invention (the state where the liquid flows backward and the air inside the pump is discharged). It is the table | surface which showed the relationship between the state of a liquid flow, and the rotation speed of the impeller of a pump. It is a flow of the pump control in the Example by this invention. FIG. 5 is a diagram showing the principle of the present invention (an upper pipe shape different from that shown in FIGS. 2 to 4). It is a perspective view of Example 2 (notebook PC) of the electronic device using this invention. FIG. 3 is a view of an upper tube and a tank according to the present invention integrally formed by a roll bond method.

Explanation of symbols

102 ... CPU, 103 ... motherboard, 111 ... jacket, 112 ... radiator,
113 ... Fan, 115 ... Pump, 114 ... Tank,
116b: a pipe connecting the radiator and the tank, 116c: a pipe connecting the tank and the pump,
201 ... The liquid level inside the tank, 202 ... The part above the liquid level of the pipe connecting the radiator and the tank,
203 ... Pipe pipe connecting the radiator and tank, 204 ... Pipe pipe connecting the tank and pump,
803 ... Hinge part, 804 ... Flexible tube passing through the hinge part, 806 ... Radiating pipe

Claims (5)

Has a reserve tank for separating the air in the cooling liquid, by circulating cooling fluid by the non-self-priming pump a liquid cooling system to dissipate the heat generated heat generating portion such as a CPU,
The reserve tank is disposed in the upper portion of the non-self-priming pump,
The liquid inlet of the reserve tank is located above the gas-liquid boundary surface of the reserve tank,
The liquid volume of the liquid circulation path on the liquid inflow side of the reserve tank corresponding to the difference between the gas-liquid boundary surface and the liquid inlet is determined by the liquid volume stop air amount of the non-self-priming pump and the liquid flow of the reserve tank. More than the sum of the liquid volume of the liquid circulation path from the outlet to the non-self-priming pump inlet,
Liquid cooling system, characterized in that the coolant circulating path which corresponds to the difference of the liquid inlet and the gas-liquid boundary surface, flows back to the non-self-priming pump. Has a reserve tank for separating the air in the cooling liquid, by circulating cooling fluid by the non-self-priming pump a liquid cooling system to dissipate the heat generated heat generating portion such as a CPU,
The reserve tank, the conjunction is placed on top of the self-priming pump,
The liquid volume of the reserve tank of the liquid inlet and the liquid circulation path corresponding to the height of the gas-liquid boundary surface of the reserve tank, entrained air volume pumping of the non-self-priming pump is stopped by aerating the liquid If, liquid cooling system, characterized in that the liquid outlet of the reservoir tank greater than the sum of the liquid volume of the liquid circulation path to the non-self-priming pump. Has a reserve tank for separating the air in the cooling liquid, by circulating cooling fluid by the non-self-priming pump a liquid cooling system to dissipate the heat generated heat generating portion such as a CPU,
The reserve tank, the conjunction is placed on top of the self-priming pump,
The liquid volume of the liquid circulation path on the liquid inflow side of the reserve tank corresponding to the difference between the gas-liquid boundary surface and the liquid inlet is determined by the liquid volume stop air amount of the non-self-priming pump and the liquid flow of the reserve tank. More than the sum of the liquid volume of the liquid circulation path from the outlet to the non-self-priming pump inlet,
Wherein when the flow rate of the coolant is equal to or less than a predetermined value, said stops driving the non-self-priming pump, a coolant circulation path which corresponds to the difference of the liquid inlet and the gas-liquid boundary surface, liquid cooling system, characterized in that so as to reflux the non self-priming pump. The liquid cooling system of claim 3 wherein the detection of the liquid flow rate of the non-self-priming pumps, which is characterized in that the rotational speed of the pump. It has a reserve tank for separating the air in the cooling liquid and the heat radiating portion of the coolant in the display back, by circulating cooling fluid by the non-self-priming pump installed in the main body radiating heat generated in the heat generating portion such as a CPU A notebook PC liquid cooling system,
When the display is deployed, the liquid inlet of the reserve tank is positioned above the gas-liquid boundary surface of the reserve tank, and the reserve corresponding to the difference between the gas-liquid boundary surface and the liquid inlet. The liquid volume of the liquid circulation path on the liquid inflow side of the tank is such that the liquid volume stop air amount of the non-self-priming pump and the liquid circulation path from the liquid outlet of the reserve tank to the non-self-priming pump inlet not less than the sum of the volume, the liquid cooling system in which coolant circulation path, characterized in that is returned to the non-self-priming pump which corresponds to the difference of the liquid inlet and the gas-liquid interface.

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