Patent Publication Number: US-7591121-B2

Title: Fluid filling system

Description:
TECHNICAL FIELD 
     The invention relates to fluid filling systems and, more particularly, to a fluid filling system and method for a vacuum container. 
     BACKGROUND 
     At present, electronic and electrical components such as central processing units (CPUs) are continuing to be developed to have faster operational speeds and greater functional capabilities. A CPU may be mounted in a limited space within a computer enclosure, and when the CPU operates at high speeds, its temperature may increase greatly. Thus, it is desirable to quickly dissipate the heat generated by the CPU. Similarly, many devices such as internal combustion engines of motor vehicles ordinarily generate much heat, and may generate vast amounts of heat when operating at high capacity. It is desirable to quickly dissipate the heat generated by an engine. 
     Numerous kinds of heat dissipation systems have been developed for cooling electronic, electrical and mechanical components. For example, heat pipes are commonly used in computer enclosures. A typical heat pipe includes an evaporation section for absorbing heat and a condensation section for dissipating heat. Working fluid is contained in a wick formed on an inner wall of the heat pipe. The working fluid transfers heat from the evaporation section to the condensation section by way of phase change. 
     In general, the heat pipe is vacuumized at a desired vacuum pressure, e.g., generally between 1.3×10 −1  and 1.3×10 −4  Pa (pascal). This helps speed the flow of the working fluid. When the heat pipe is manufactured and vacuumized, the vacuumizing is generally performed after the working fluid is filled into the heat pipe. However, the working fluid is generally comprised of a volatile fluid, for example, methanol, alcohol, acetone, ammonia, heptane, etc. Thus during the vacuumizing process, a certain small amount of working fluid is usually sucked out of the heat pipe together with air. This results in the actual filling volume of the working fluid being less than the preset desired filling volume. The short fall of the actual filling volume may be significant, as detailed below. 
     The preset filling volume of the working fluid is generally calculated so that the working fluid is accommodated in the wick to an extent whereby the capillary capability of the wick is optimal. If the actual filling volume is less than the preset filling volume, a part of the wick (generally in the evaporation section) is prone to be prematurely dried out. On the contrary, if the actual filling volume is more than the preset filling volume, the wick may be overburdened with working fluid whereby the capillary capability of the wick is limited. In both of these error situations, the thermal efficiency of the heat pipe is decreased. 
     To attain the exact preset filling volume, one approach used is to simultaneously perform the vacuumizing process and the working fluid filling process. However, this approach requires that the two processes be carefully operated and monitored, and in general a large sophisticated apparatus is required. Even then, it can still be difficult to accurately control the filling volume of the working fluid into the heat pipe. 
     What is needed, therefore, is a fluid filling system for a vacuum container, wherein the fluid filling system is relatively compact and is able to accurately control the filling of working fluid into a heat pipe to reach a predetermined filling volume. 
     What is also needed is a fluid filling method for a vacuum container using a fluid filling system having the above-described advantages. 
     SUMMARY 
     In accordance with a preferred embodiment, a fluid filling system for a vacuum container includes a fluid supply system configured for filling fluid into a container to be filled, a vacuum exhaust system configured for vacuumizing the container to a predetermined vacuum pressure, and a refrigeration device configured for freezing the fluid filled in the container. 
     A fluid filling method for a vacuum container includes: filling a fluid into a container; freezing the fluid filled in the container; vacuumizing the filled container to attain a predetermined vacuum pressure therein; and sealing the vacuumized container. 
     Other advantages and novel features will become more apparent from the following detailed description of embodiments when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The components in the system drawing are not necessarily to scale, the emphasis instead being placed upon clearly illustrating the principles of the present fluid filling system. 
         FIG. 1  is a simplified, schematic view of a fluid filling system for a vacuum container in accordance with a preferred embodiment of the present invention. 
         FIG. 2  is a flow chart of a fluid filling method for a vacuum container, in accordance with another preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Embodiments of the present fluid filling system and method for a vacuum container will now be described in detail below with reference to the drawings. 
       FIG. 1  illustrates a fluid filling system  1  for a vacuum container in accordance with a preferred embodiment of the present invention. The fluid filling system  1  has a generally H-shaped configuration, and mainly includes a fluid supply system  10 , a vacuum exhaust system  20 , an inflator  30 , a refrigeration device  40 , a three-way valve  50 , and a heater  60 . 
     The three-way valve  50  generally has three nozzles; i.e., a first nozzle  51 , a second nozzle  52 , and a third nozzle  53 . The fluid supply system  10  is connected with the first nozzle  51 . The vacuum exhaust system  20  and the inflator  30  are commonly connected to the second nozzle  52 . The third nozzle  53  is adapted to connect with a container  70  to be filled. In the illustrated embodiment, the container  70  is a hollow heat pipe preform  71 . The heat pipe preform  71  is generally a hollow pipe with an open end  712  and an opposite sealed end  714 . The heat pipe preform  71  has a wick formed on an inner wall thereof A fluid guide pipe  54  can optionally be used to interconnect the third nozzle  53  and the open end  712  of the heat pipe preform  71 . 
     The fluid supply system  10  preferably includes a fluid container  12 , a micro-valve  14 , and a micro capillary  16  connected in series. The fluid container  12  contains a fluid to be filled in the heat pipe preform  71 . The micro-valve  14  is positioned between the fluid container  12  and the micro capillary  16 , and is used to control flow of the fluid from the fluid container  12  into the micro capillary  16 . The micro capillary  16  is connected with the first nozzle  51 . The micro capillary  16  is advantageously a quantitative capillary or a graduated capillary having a micrometer scale. 
     The quantitative capillary is suitable for use in a quantitative fluid filling process, i.e., where a total fluid volume of the capillary is equal to a predetermined fluid filling volume. This facilitates the performance of the filling process. The graduated capillary is suitable for use in various fluid filling processes requiring different fluid quantities. Micrometer graduations of the graduated capillary are arranged in order from top to bottom like a burette, with an initiation graduation (e.g., a “0” point) being adjacent the micro-valve  14 . Advantageously, smallest graduations of the graduated capillary correspond to very small increments of volume, which may for example be 0.1 milliliters or may for example be as little as 0.01 milliliters. The graduated capillary advantageously can have an inner diameter in the range from approximately 0.1 millimeters to approximately 1 millimeter. 
     The vacuum exhaust system  20  generally includes a vacuum pump  21  and a vacuum gauge  22 . The vacuum gauge  22  is advantageously positioned between the vacuum pump  21  and the second nozzle  52 , and is configured for measuring and monitoring the pressure of vacuum of the container  70  during the vacuumizing process. The vacuum exhaust system  20  and the inflator  30  are each connected to the second nozzle  52  via a common pipe  55 , thereby forming a common gas passage to the container  70 . 
     The inflator  30  is configured for blowing any remaining fluid, generally remaining in the three-way valve  50  and in the fluid guide pipe  54 , into the container  70 . Thereby, any fluid filling error is decreased. During a vacuumizing process, only the vacuum exhaust system  20  is in communication with the second nozzle  52 . During a blowing process, only the inflator  30  is in communication with the second nozzle  52 . 
     The refrigeration device  40  is configured for partially or fully freezing the container  70  so as to freeze the fluid filled therein, thereby preventing the fluid from evaporating and escaping out of the container  70  during the vacuumizing process. The refrigeration device  40  can be in the form of a bath or a loop-cooler. Coolant  42  of the refrigeration device  40  is comprised of a material selected from the group consisting of dry ice, liquid nitrogen, freon™, and refrigerating brine. In the illustrated embodiment, the refrigeration device  40  is in the form of a bath, and the coolant  42  is liquid nitrogen. 
     The heater  60  is configured for preheating the container  70  in order to remove any liquid or vapor contaminants therefrom prior to filling of the fluid therein. The contaminants may, for e.g., be water or waste such as oil. In general, the contaminants are present by way of being adsorbed on an inner wall of the container  70 . For example, when the container  70  is the heat pipe preform  71 , contaminants may be present by way of being adsorbed on the wick of the heat pipe preform  71 . After preheating, the container  70  is cleaned, thereby ensuring that the subsequent filling process is unimpaired. Thus the heater  60  can be any suitable heater such as an immersion water heater or an electrical heater. 
     The H-shaped configuration of the fluid filling system  1  is advantageous in that it can reduce the overall size of and/or the overall space occupied by the fluid filling system  1 . Furthermore, the fluid guide pipe  54  is connected with the fluid supply system  10  or the vacuum exhaust system  20  or the inflator  30  alternatively via the three-way valve  50 . With the H-shaped configuration of the fluid filling system  1 , any fluid remaining in the three-way valve  50  and the fluid guide pipe  54  can be fully utilized relatively easily. Therefore, the volume of the fluid filled into the container  70  can be accurately controlled. 
     Referring also to  FIG. 2 , this shows steps in a preferred fluid filling method for a vacuum container (such as the container  70 ) using the fluid filling system  1 . Briefly, the method includes the steps of: filling a fluid into a container; freezing the fluid filled in the container; vacuumizing the filled container to attain a predetermined vacuum pressure therein; and sealing the vacuumized container. 
     In filling step, in the illustrated embodiment, the fluid is filled into the container  70  via the fluid supply system  10 . The three-way valve  50  is switched and opened to the fluid supply system  10 , and the vacuum exhaust system  20  and inflator  30  sides are shut off. The fluid is accurately controlled by the micro capillary  16  and conducted to the container  70  via the three-way valve  50  and the fluid guide pipe  54 . 
     In addition, preferably, a step of preheating the container  70  is performed prior to filling the fluid into the container  70 , so as to remove liquid or vapor contaminants therefrom (see above). The preheating step is particularly beneficial when the container  70  is the heat pipe preform  71 , because the wick of the heat pipe preform  71  readily adsorbs liquid or vapor contaminants such as water, waste, oil, and so on. 
     After the filling step, some fluid may remain in the three-way valve  50  and the fluid guide pipe  54 . Thus, a step of blowing gas into the container  70  is preferably conducted prior to the freezing step. At this time, the three-way valve  50  is switched and opened only to the inflator  30  while keeping the vacuum exhaust system  20  side shut off. The inflator  30  blows any fluid remaining in the three-way valve  50  and the fluid guide pipe  54  into the container  70 . Thereby, the accuracy of the fluid filling can be increased. At this stage, in the case that the container  70  is the heat pipe preform  71 , the fluid is generally adsorbed inside the wick of the heat pipe preform  71 . 
     In the freezing step, first, the three-way valve  50  is fully closed. Then the fluid filled in the container  70  is frozen by the coolant  42 . In the illustrated embodiment, the sealed end  714  of the heat pipe preform  71  is submerged in the coolant  42 . This effectuates freezing of the fluid by utilizing the typically excellent heat conductivity of the heat pipe preform  71 . Because the unfrozen fluid is generally adsorbed inside the wick of the heat pipe preform  71 , after the freezing step, the fluid is generally solidified inside the wick. 
     In the vacuumizing step, the three-way valve  50  is switched and opened only to the vacuum exhaust system  20  while keeping the inflator  30  side shut off The vacuumizing is performed by the vacuum pump  21  until the vacuum gauge  22  attains a desired vacuum reading. During the vacuumizing, since the fluid is initially frozen in the container  70 , or frozen in the wick of the heat pipe preform  71 , little if any evaporation of the frozen fluid occurs. That is, during the vacuumizing process, fluid loss is minimized. Thereby, a high accuracy of the fluid filling can be maintained. 
     After the vacuumizing step, a step of sealing the container  70  (e.g., the open end  712  of the heat pipe preform  71 ) is preferably performed immediately under high vacuum pressure. Thereby, a low-pressure container filled with the fluid is obtained. For example, a low-pressure heat pipe filled with the fluid is obtained. It is noted that the heat pipe may for example be in a form of a tubular heat pipe or a plate-type heat pipe. The tubular heat pipe may for example be straight, U-shaped, loop-shaped, helical, and so on. 
     It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.