Abstract:
A method of manufacturing a heat pipe, including the steps of: providing a hollow body with an open end and an opposite close end; filling a predetermined quantity of working fluid into the hollow body through the open end thereof after an interior of the hollow body having been evacuated to a predetermined vacuum degree; and sealing the open end of the hollow body.

Description:
CROSS-REFERENCES TO RELATED APPLICATION 
     Relevant subject matter is disclosed in a co-pending U.S. patent application Ser. No. 11/308,376, filed on Mar. 20, 2006 and entitled “METHOD AND APPARATUS FOR MAKING HEAT-DISSIPATION DEVICE HAVING VACUUM CHAMBER AND WORKING FLUID THEREIN”, which is assigned to the same assignee with this application. The disclosures of the co-pending application are wholly incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to a heat pipe for cooling an electronic component, and particularly to an apparatus and a method for manufacturing the heat pipe. 
     DESCRIPTION OF RELATED ART 
     With the ever-increasing density and high power of electronic components, for example, the central processing unit (CPU), memories and logic arrays in high speed computers, the problem of heat generation by the electronic components in close proximate to one another on electronic circuit cards has become of increasing concern to industry. In response to this, over the past several years heat pipes have been developed to help cooling the electronic components. 
     A heat pipe generally includes a container with a cavity therein and a quantity of working fluid sealed in the cavity. The cavity is vacuum-exhausted to make the working fluid easy to evaporate. The heat pipe transfers heat generated from the electronic components away by the phase change of the working fluid in the cavity. The maximum heat transport capability and the useful temperature range are two factors to determine the heat transfer performance of the heat pipe. The maximum heat transport capability is affected by the quantity of the working fluid contained in the cavity, while the useful temperature range is determined by the degree of perfection of the vacuum in the cavity. The more perfect the vacuum in the heat pipe, the lower the temperature at which the heat pipe begins to work. Therefore, methods for manufacturing the heat pipe have to accurately control the quality of the working fluid and the vacuum degree of the heat pipe, simultaneously. 
       FIG. 7  shows a conventional method for manufacturing a heat pipe. The method comprises the following steps: (1) offering a tube body  2  having an open end  3  and a wick structure  4  forming on an inner surface thereof; (2) charging the tube body  2  with a quantity of working fluid  5  from the open end  3  of the tube body  2 ; (3) evacuating air in the tube body  2  to a pre-determined low-pressure vacuum from the open end  3  through a vacuum pump  6 , and then sealing the open end  3  to form a heat pipe shown in  FIG. 8 . The heat pipe comprises an airtight tube body  2  and contains a quantity of working fluid  5  therein. The heat pipe has a sealing portion  7  formed on an end of the body  2 . Since the working fluid  5  is filled into the body  2  before the air in the body  2  is pumped out of the body  2 , this results in some difficulties in accurately controlling the quality of the working fluid  5  whilst ensuring the perfection of the vacuum in the heat pipe. For example, in the step (3), some of the working fluid  5  evaporates into vapor and is drawn out of the heat pipe by the vacuum pump  6 . Thus, the quantity of the working fluid  5  of the heat pipe can be not accurately controlled. Furthermore, the evaporated working fluid  5  results in an increase in pressure in the heat pipe, which leads to errors in checking the degree of perfection of the vacuum in the heat pipe. Therefore, the conventional method for manufacturing heat pipes can not accurately and simultaneously guarantee the quality of the working fluid and the perfection of the vacuum in the heat pipe. 
     SUMMARY OF INVENTION 
     A method of manufacturing a heat pipe, comprising the steps of: providing a hollow body with an open end and an opposite close end; filling a predetermined quantity of working fluid into the hollow body through the open end thereof after an interior of the hollow body has been evacuated to a vacuum of predetermined perfection by a vacuum pump connecting with the hollow body via the open end; and sealing the open end of the hollow body. 
     Other advantages and novel features will become more apparent from the following detailed description of preferred embodiments when taken in conjunction with the accompanying drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagrammatic view illustrating an apparatus for making a heat pipe in accordance with a first embodiment of the present invention; 
         FIG. 2  is a schematic sectional-view of a heat pipe along an axis direction thereof, which is manufactured by the apparatus of  FIG. 1 ; 
         FIG. 3  is a plan view of the heat pipe of  FIG. 2 , showing an outer configuration of the heat pipe; 
         FIG. 4  is a schematic sectional-view of the heat pipe taken along the line A-A of  FIG. 3 ; 
         FIG. 5  is a perspective view of another heat pipe manufactured by the apparatus of  FIG. 1 ; 
         FIG. 6  is a diagrammatic view illustrating an apparatus for making a heat pipe in accordance with a second preferred embodiment of the present invention; 
         FIG. 7  is a diagrammatic view illustrating a process for making a heat pipe according to a conventional method; and 
         FIG. 8  is a heat pipe manufactured by the conventional method. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows an apparatus for manufacturing a heat pipe in accordance with a first preferred embodiment of the invention. The manufacturing apparatus comprises a vacuum pump  20 , two clamping machines  30 , two cutting machines  40 , two soldering machines  50 , a liquid-storage tank  60 , a vacuum gauge  70 , and a pair of valves  80 ,  81 . 
     A method for manufacturing a heat pipe by the manufacturing apparatus in accordance with the first embodiment of the present invention comprises the following steps: 
     (1) Offering a hollow body  10  with a wick structure  11  formed therein, which has a first open end  12  and a second open end  14  opposite to the first open end  12 . Each of the open ends  12 ,  14  is connected with the body  10  via a shrunk portion  15 . 
     (2) Fixing the body  10  to the manufacturing apparatus in such a manner that the vacuum pump  20  is hermetically connected with the first open end  12  of the body  10 , while the liquid-storage tank  60  and the vacuum gauge  70  are commonly and hermetically connected with the second open end  14  of the body  10  via a bifurcated tube. The liquid-storage tank  60  and the vacuum gauge  70  are controlled to asynchronously communicate with the body  10  via the valves  80 ,  81 , respectively. 
     (3) Starting up the vacuum pump  20 , and turning on the valve  80 , and keeping the vacuum pump  20  working to draw the air originally in the body  10  out of the body  10  until the degree of perfection of the vacuum in the body  10  reaches the pre-designed value, which is then checked using the vacuum gauge  70 . 
     (4) Closing the valve  80  and sealing the first open end  12 , that is, using the clamping machine  30  to press the first open end  12  into a flattened configuration; then using the cutting machine  60  to cut away an excessive distal end portion of the flattened open end; then finally, using the soldering machine  70  to solder the flattened open end so as to hermetically and permanently seal the first open end  12  to thereby form a first sealing portion  102  shown in  FIG. 2 . 
     (5). Opening the valve  81  and charging the body  10  with a predetermined quantity of working fluid previously stored in the liquid-storage tank  60 , due to the vacuum condition formed in the body  10 . 
     (6). Sealing the second open end  14  to thereby form a second sealing portion  104  shown in  FIG. 2  in a manner similar to that of the step (4), thereby manufacturing the heat pipe. 
     Referring to  FIG. 2 , a heat pipe manufactured by the above described method is illustrated. The heat pipe comprises an airtight body  10  with the wick structure  11  defined therein and working liquid (not shown) contained therein. A pair of sealing portions  102 ,  104  is formed on opposite ends of the heat pipe; each of the sealing portions  102 ,  104  is connected with the body  10  via a corresponding one of the shrunk portions  15 . Therefore, each of the end portions of the heat pipe has a tapered cross section. The first sealing portion  102  is formed between the steps (4) and (5), while the second sealing portion  104  is formed after the step (5). Thus, the working fluid for the heat pipe is filled into the body  10  after the body  10  is vacuumed. In this manner, the problem found in conventional art of the previously filled working fluid being inadvertently drawn out of the tube body during the following air-drawing step is effectively eliminated. This avails to accurately control the quantity of the working fluid and the degree of perfection of the vacuum in the heat pipe. 
     Additionally, the outer configuration of the sealing portions  102 ,  104  can be changed according to practical requirements. For example, flatten shaped sealing portions shown in  FIGS. 3-4  may be shaped by pressing of a pair of flat shaped dies of the clamping machine  30 ; while arc shaped sealing portions shown in  FIG. 5  may be shaped by pressing of a pair of arc shaped dies of the clamping machine  30 . 
       FIG. 6  shows an apparatus for manufacturing a heat pipe in accordance with a second preferred embodiment of the invention. The manufacturing apparatus comprises similar components to those of the previously described manufacturing apparatus: a vacuum pump  20 , a clamping machine  30 , a cutting machine  40 , a soldering machine  50 , a liquid-storage tank  60 , a vacuum gauge  70 , and three valves  80 ,  81 ,  83 . 
     A method for forming a heat pipe by using the manufacturing apparatus in accordance with the second embodiment of the present invention comprises the following steps: (1) Offering a hollow body  10   a  with a wick structure  11   a  formed therein, which has an open end  14   a  connected with the body  10   a  via a shrunk portion  15   a . An opposite end of the hollow body  10   a  is closed. 
     (2) Fixing the body  10   a  to the manufacturing apparatus in such a manner that the vacuum pump  20 , the liquid-storage tank  60  and the vacuum gauge  70  are commonly and hermetically connected with the open end  14   a  of the body  10  via a trifurcate tube, wherein the vacuum pump  20 , the liquid-storage tank  60  and the vacuum gauge  70  communicate with the body  10   a  via the valves  80 ,  81 ,  83 , respectively. 
     (3) Turning on the valves  80 ,  83 , and turning off the valve  81 , then starting up the vacuum pump  20 , and keeping the vacuum pump  20  working to draw the air originally in the body  10   a  out of the body  10   a  until the degree of perfection of the vacuum in the body  10   a  reaches the pre-designed value, which is then checked by the vacuum gauge  70 . 
     (4) Turning off the valves  80 ,  83  and turning on the valve  81 , then charging the body  10   a  with a predetermined quantity of working fluid previously stored in the liquid-storage tank  60  due to the vacuum condition formed in the body  10   a.    
     (5) Sealing the open end  14   a  to thereby form a sealing portion thereby manufacturing the heat pipe. In this manner, the problem in relation to the conventional art where the previously filled working fluid would inadvertently drawn out of the tube body in the following air-drawing step is also effectively eliminated. 
     Additionally, the heat pipe may have a uniform diameter or gradually changed diameter from one end of the heat pipe to the opposite end. 
     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.