Patent Document

BACKGROUND OF THE INVENTION 
     The present invention relates to an electronic apparatus, such as, a personal computer and/or a server, etc., and in particular, it relates to a liquid cooling system, being enable to cool a semiconductor integrated circuit element mounted within an inside thereof, as being a heat-generating element, with using a liquid coolant, effectively. 
     In general, a heat-generating element, for example, a semiconductor integrated circuit element, which generates heat within the electronic apparatus, such as, a personal computer of desk-top type or notebook type, or a server, etc., and in particular, a CPU (i.e., a central processing unit), representatively, it needs a cooling for maintaining the normal operation thereof. Conventionally, for that reason, it is general that such cooling is achieved with using a heat-transfer body, which is built up with fins called by a heat sink, to be a unit, and also a fan for sending a cooling wind upon the surface thereof. However, in recent years, small-sizing and high-integration on the semiconductor integrated circuit element, as being the heat-generating element, causes a problem, such as, localizing portions of generating the heat within the heat-generating element. For that reason, in the place of the conventional cooling system of air-cooling type, attentions are paid upon a cooling system of liquid-type, with using a coolant therein, such as, a water or the like, for example, having a high cooling efficiency. 
     Namely, with the liquid-type cooling system of high cooling efficiency, which is applied in the personal computer and/or the server, etc., as is already known in the following patent documents, for example, in general, a member, being so-called by a heat-receiving (or cooling) jacket, is directly mounted upon the surface of the CPU, being the heat-generating body, while a liquid-like coolant is communicated within a flow passage, which is formed within an inside of that heat-receiving jacket; i.e., transmitting the heat generated from the CPU into the coolant flowing within the jacket mentioned above, thereby cooling down the heat-generating body with high efficiency. Further, within such the cooling system of liquid-cooling type, in general, there is built up a heat cycle, while applying the heat-receiving jacket as a heat-receiving portion thereof, and in more details thereof, comprising a circulation pump for circulating the liquid coolant within the cycle, so-called a radiator, being a heat radiation portion for radiating the heat of the liquid coolant into an outside thereof, and further a coolant tank, being provided in a portion of the cycle if necessary, and wherein those are connected in the structure thereof through tubes, being made of a metal, or an elastic material, such as, rubber, etc., for example.
     Patent Document 1: Japanese Patent Laying-Open No. 2003-304086 (2003);   Patent Document 2: Japanese Patent Laying-Open No. 2003-022148 (2003);   Patent Document 3: Japanese Patent Laying-Open No. 2002-182797 (2002);   Patent Document 4: Japanese Patent Laying-Open No. 2002-189535 (2002);   Patent Document 5: Japanese Patent Laying-Open No. 2002-189536 (2002); and   Patent Document 6: Japanese Patent Laying-Open No. 2002-188876 (2002).   

     On the other hand, generally within such the cooling system relating to the conventional arts mentioned above, so-called a centrifugal pump is applied, widely, to be the circulation pump for driving the liquid coolant, which is provided in a portion of that heat cycle, due to the following reasons; i.e., a flow rate obtained therefrom is relatively large in an amount thereof, and noises are small, which are caused due to contact, etc. With such the circulation pump of applying such the centrifugal pump therein, however there is a necessity of providing an electric motor, separately, for the purpose of rotationally driving such the pump, although being also true for the case of applying a pump of other types therein; and for this reason, the circulation pump as whole comes to be relatively large in the sizes thereof. 
     On the other hand, in recent years, it is of course for the electronic apparatuses, including, such as, the personal computer of the desktop type and the server, etc., that demand or requirement for small-sizing thereof rises up to be higher and higher, in particular, upon the personal computer of the notebook type, for the purpose of improving the portability thereof. For this reason, under the present situation, it is not always possible to deal with such the requirement with the circulation pump of the conventional arts mentioned above. In addition thereto, further there is also demand or requirement increasing up, for lowering the noises generated during when such the electronic apparatus is operating. 
     BRIEF SUMMARY OF THE INVENTION 
     Then, according to the present invention, accomplished by taking the drawbacks of the conventional arts mentioned above into the consideration thereof, an object thereof is to provide a liquid cooling system, enabling the small-sizing thereof, and having a driving means of a new type, to be effective for lowering the noises during when the electronic apparatus is operating; therefore, being suitable to be applied into the personal computers of the desktop type and the notebook type, and also the server, etc. 
     For accomplishing the object mentioned above, according to the present invention, first of all, there is provided a liquid cooling system for an electronic apparatus having a heat-generating element within a housing thereof, comprising: a heat-receiving jacket for transferring heat generated from said heat-generating element to a liquid coolant, to evaporate it, within an inside thereof; a radiator for guiding the evaporated coolant supplied from said heat-receiving jacket into an inside thereof, so as to cool it to be liquefied; and a driving means for applying driving force for circulating said liquid coolant, through repetition of heating and cooling upon a portion of the liquefied liquid coolant supplied from said radiator, while restricting a flow direction of the liquid coolant within an inside thereof into one direction, whereby circulating said liquid coolant within a circulation loop including said heat-receiving jacket, said radiator, and said driving means. 
     According to the present invention, within the liquid cooling system as described in the above, preferably, said driving means includes a portion for storing therein a part of the liquefied liquid coolant supplied from said radiator, interior surface of which is treated with a process for accelerating the evaporation of the liquid coolant, or preferably, said driving means includes an electric heater provided in a portion thereof for storing a part of the liquefied liquid coolant supplied from said radiator. 
     Further, according to the present invention, within the liquid cooling system as described in the above, preferably, said driving means includes a check valve for restricting the flow direction of the liquid coolant within the inside thereof, or preferably, said heat-receiving jacket has interior surface, upon which a process is treated with for accelerating the evaporation of the liquid coolant. 
     According to the present invention mentioned above, there can be obtained an effect of providing a liquid cooling system, enabling the small-size thereof, through building up a transfer mechanism for the coolant with applying a phenomenon, so-called the thermal siphon, therein, and being effective for reducing the noises which are generated during the time when the apparatus is operated; therefore, it is possible to achieve a cooling effect, with certainty, irrespective of the positions where the heat-receiving jacket and the radiator are provided. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       Those and other objects, features and advantages of the present invention will become more readily apparent from the following detailed description when taken in conjunction with the accompanying drawings wherein: 
         FIG. 1  is a view for showing the entire structure of the liquid cooling system, according to an embodiment of the present invention; 
         FIG. 2  is a cross-section view for explaining the detailed structure of an inside of a heat-receiving jacket in the liquid cooling system mentioned above; 
         FIG. 3  is a view for showing waveforms for explaining heat transfer operation of a coolant within the liquid cooling system mentioned above; 
         FIGS. 4(   a ) and  4 ( b ) are views for explaining the operation of a liquid driving portion, for explaining the heat transfer operation of the coolant within the liquid cooling system mentioned above; and 
         FIG. 5  is a view for showing the liquid driving portion, applying a Peltier element, for explaining other embodiment according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, embodiments according to the present invention will be fully explained by referring to the attached drawings. 
     First of all,  FIG. 1  attached herewith shows the entire structures of the liquid cooling system, according to one embodiment of the present invention, and basically, it comprises a heat-receiving jacket  100 , a radiator  200 , and a liquid driving apparatus for circulating a liquid coolant (for example, a pure water, etc.) within the liquid cooling system, wherein pipes or conduits  50 , being made of a metal and so on, are connected between them, thereby building up a closed loop. 
     Explaining in more details thereof, the heat-receiving jacket  100  in the figure has a rectangular plate-like outer configuration, and it is made of a metal, such as, copper, aluminum, or the like, for example, being superior in the thermal or heat conductivity thereof. Internal structures of the heat-receiving jacket  100  is shown by a cross-section view thereof, in  FIG. 2  attached herewith, and as is apparent from this  FIG. 2 , a bottom surface within an inside of the heat-receiving jacket  100  is so formed that it rises up at around the central portion thereof, and further upon the surface thereof, there are formed thin or fine grooves  101  in a large number thereof, intersecting with each other, for the purpose of keeping a liquid film of the coolant liquid thereon and/or accelerating evaporation thereof. Also, within the inside of that heat-receiving jacket  100  is attached a partition plate  102 , thereby being divided into a portion where the liquid coolant flows into (i.e., a chamber at the right-hand side in  FIG. 2 ), and a portion where only the evaporated coolant flows into (i.e., a chamber at the left-hand side in  FIG. 2 ). 
     Further, within this portion where the liquid coolant flows into (i.e., the chamber at the left-hand side in  FIG. 2 ), there is disposed a metal pipe or conduit (or a liquid transfer pipe)  103 , extending up to a central portion thereof, through which flows the liquid coolant driven/supplied from a liquid driving apparatus  300 , which will be explained later. On the other hand, within an inside of the portion where only the evaporated coolant flows into (i.e., the chamber at the left-hand side in  FIG. 2 ), there is disposed a metal pipe or conduit (or a vapor transfer pipe)  104  for guiding the evaporated coolant into the radiator  200  mentioned above. Also, a reference mark W in the figure depicts the coolant within the inside thereof, and a reference numeral  600  depicts a heat-generating element, which is cooled by means of that heat-receiving jacket  100 . 
     Also, the radiator  200  is made up with cooling fins  202  formed on the surface of a pipe of a metal, such as, copper, etc., for example, and it enables to accelerate condensation of the coolant evaporated therein, through treating channeling or cutting on an interior surface of the pipe. As is apparent from  FIG. 1  mentioned above, the radiator introduces the evaporated coolant, which is supplied from the heat-receiving jacket  100 , into the inside thereof through an inlet  201 , which is provided in an upper portion thereof, so as to cool and condense the evaporated coolant through the function of the cooling fins, which are attached onto the wall surface of the radiator in a large number thereof. Thus, the evaporated coolant supplied from the heat-receiving jacket  100  is turned back to the liquid within the inside of that radiator  200 , to be stored on a bottom portion thereof. 
     And, the liquid driving apparatus  300 , for circulating the liquid coolant within that liquid cooling system, comprises a first check valve  301  and a second check valve  302 , and further a liquid driving portion (or a transfer chamber)  303 , having a cylindrical outer configuration, for example. Further, on the interior wall surface of this liquid driving portion  303  is treated so-called a wick machining or processing (indicated by broken lines in the figure), so as to roughen the surface thereof, thereby generating the surface tension thereupon. And, in this liquid driving portion  303 , opening portions  304  and  305  are formed on a bottom wall and a side wall thereof, and they are attached with the first check valve  301  and the second check valve  302 , respectively, in the directions shown in the figure. Further, on an upper portion of the liquid driving portion  303 , there is attached so-called a heater  306 , such as, a nichrome wire being wound around the periphery thereof, for example. Further, a reference numeral  400  in this figure depicts a driver circuit for supplying electric drive power for heating the heater  306  of that liquid driving apparatus  300 . 
     Following to the above, explanation will be made about the operation of the liquid cooling system, in the details thereof, the structures of which are mentioned in the above, by referring to  FIGS. 3 through 4(   b ). In this liquid cooling system, a pulse-like heater current is supplied from the driver circuit  400  to the heater  306  when it operates, as is shown in  FIG. 1 . 
     Also, as is shown in  FIG. 3 , when being supplied with the pulse-like current, the heater  306  of the liquid driving apparatus  300  is heated, thereby heating the liquid driving portion (or the transfer chamber)  303 . For this reason, within the inside of the liquid driving portion  303 , the liquid coolant is evaporated through the heating, thereby rising up the interior pressure thereof (P 1 →P 2 ). In this instance, when the pressure within the inside of the liquid driving portion  303  comes to be higher than the pressure within the heat-receiving jacket  100 , then the second check valve  302  is closed while the first check valve  301  is opened, as is shown in  FIG. 4(   a ); therefore, the liquid coolant flows into the direction of an arrow, i.e., directing to the heat-receiving jacket  100 , passing through the first check valve  301 . 
     Thereafter, when stopping the pulse-like heater current to be supplied, the heater  306  also stops the heating; i.e., the liquid driving portion (i.e., the transfer chamber)  303  is rather cooled down. For this reason, within the inside of that liquid driving portion  303 , the interior pressure therein falls down (P 2 →P 1 ) due to decrease of liquid an amount of evaporation therein, as well as, the condensation of the evaporated coolant. Thus, in this instance, when the interior pressure within the liquid driving portion  303  falls down to be lower than the pressure within the radiator  200 , then the first check valve  301  is closed while the second check valve  302  is opened, as is shown in  FIG. 4(   b ); therefore, the liquid coolant flows into the direction of an arrow, i.e., directing to the inside of the liquid driving portion  303 , passing through the second check valve  302 . Namely, repeating the operations mentioned above, the liquid coolant, being supplied from the heat-receiving jacket  100 , is condensed back into the liquid, while the coolant stored in the bottom portion within the radiator  200  is driven; therefore the coolant can move, sequentially, within the liquid cooling system mentioned above. An amount of heating by the heater  306  and a cycle of ON-OFF are determined upon the basis of an amount of heat transfer (i.e., an amount of heat-generation of the heat generating element  600 ), a sort or kind of the liquid coolant, and the difference in operation pressure of the check valves  301  and  302 . However, an amount of heating by the heater  306  is sufficient to be very small, comparing to that of the amount of heat transfer, since it is enough only to cause an increase in pressure within the inside of the liquid driving portion  303  through evaporation of the liquid. 
     However, in the explanation given in the above, the wick machining or processing is treated on the interior wall surface of the liquid driving portion (i.e., the transfer chamber)  303 , and for this reason, within the inside of the liquid driving portion  303 , the liquid coolant spreads all over the entire wall surface, easily, due to the surface tension thereupon; therefore, the liquid coolant can be evaporated, through the heating by means of the heater  305 , easily. Also, due to the grooves  101  formed in a large number thereof, coming cross with each other, on the bottom surface within an interior of the heat-receiving jacket  100 , in the similar manner, the liquid coolant within the inside thereof can be easily evaporated, and for that reason, an improvement or an increase can be obtained in the efficiency of cooling, when disposing the heat-receiving jacket  100  within a housing of the electronic apparatus, in particular, when attaching it on the surface of the heat-generating element  600 , such as, being the CPU, reprehensibly, as is shown in  FIG. 2 . Further, the opening of the liquid transfer pipe  103 , which is connected to the heat-receiving jacket, is extended up to the vicinity of a center of the evaporating surface thereof, so that the liquid can be easily supplied all over the surface of the evaporation surface. On the other hand, it is preferable, the vapor transfer pipe  104 , which is connected to the heat-receiving jacket, is so constructed that the liquid coolant within the heat-receiving jacket  100  will not be sent out therefrom together with the vapor. For this reason, the opening of the vapor transfer pipe is extended up to a corner portion, along the side wall within the heat-receiving jacket  100 ; i.e., being disposed, so as to remain a gap for letting the vapor to pass through, between the opening and the side wall. Further, as is mentioned in the above, the portion where the liquid coolant flows into (i.e., the chamber at the right-hand side in  FIG. 2 ) and the portion where only the evaporated coolant flows into (i.e., the chamber at the left-hand side in  FIG. 2 ) are divided or separated by the partition plate  102 , so that the liquid coolant W cannot reach to the opening of the vapor transfer pipe  104 . Further, a gap may be provided, for example, for the vapor to pass through, between the partition plate  102  and a ceiling surface of the heat-receiving jacket  100 , so that the vapor generated in the portion where the liquid coolant flows into (i.e., the chamber at the right-hand side in  FIG. 2 ) can move into the portion where only the evaporated coolant flows into (i.e., the chamber at the left-hand side in  FIG. 2 ). However, as was mentioned above, the coolant evaporated within the heat-receiving jacket  100  is guided into the radiator  200  due to the pressure thereof and also the functions of the first check valve  301 . 
     As was mentioned in the above, according to the liquid cooling system mentioned above, it can made to be small in the sizes, through building up a transfer mechanism for the coolant with applying a phenomenon, so-called the thermal siphon, therein, and is effective for reducing the noises which are generated during the time when the apparatus is operated; therefore, it is possible to obtain a cooling effect, with certainty, irrespective of the positions where the heat-receiving jacket and the radiator are provided. 
     Further, in the embodiment mentioned above, although the explanation was given only about an example, wherein the heater  305  is used for heating the liquid driving portion  303  within the liquid driving apparatus  300  mentioned above, however the present invention should not be restricted thereto. As an embodiment other than that, as is shown in  FIG. 5  attached, it is also possible to apply a Peltier element in the place of the heater  305  mentioned above, for example. However, in that case, as is shown in that figure, it is possible to exchange the Peltier element, between heating/cooling (rise-up/fall-down of temperature), actively, through applying an alternating electric power to that Peltier element, as is shown in that figure; thereby it is possible to obtain a preferable effect therefrom. 
     The present invention may be embodied in other specific forms without departing from the spirit or essential feature or characteristics thereof. The present embodiment(s) is/are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the forgoing description and range of equivalency of the claims are therefore to be embraces therein.

Technology Category: h