Patent Publication Number: US-2009229790-A1

Title: Radiating fin assembly for thermal module

Description:
FIELD OF THE INVENTION 
     The present invention relates to a radiating fin assembly for thermal module, and more particularly to a radiating fin assembly mounted on a heat radiating base of a thermal module to tightly press a heat pipe against the heat radiating base. 
     BACKGROUND OF THE INVENTION 
     With the highly developed semiconductor technology, the currently available integrated circuits (ICs) have a largely reduced volume than before. To enable the ICs to process more data, the number of elements and components included in the current ICs is often several times of that in the conventional ICs having the same volume. However, heat produced by the ICs during operation thereof increases with the growing number of electronic elements and components in the ICs. For example, the heat produced by a common central processing unit (CPU) at full working load is high enough for burning out the whole CPU. Therefore, it is important to develop effective heat radiating means for the ICs. 
     Generally, a thermal module is made of a metal material with high heat conductivity. In addition to the mounting of a cooling fan to carry away the heat produced by heat-producing elements, the thermal module in the form of a radiating fin assembly is frequently used to obtain an enhanced heat radiating effect. In some other cases, heat pipes are further provided on the thermal module to more quickly transfer and dissipate heat, so that products with ICs are protected against burning out. 
       FIG. 1  is an exploded perspective view of a conventional thermal module  1 , which includes a heat radiating base  11 , on which a tubular groove  111  is provided; a radiating fin assembly  13  mounted on a top of the heat radiating base  11 , and a heat pipe  12  received in the tubular groove  111  to locate between the heat radiating base  11  and the radiating fin assembly  13 . 
     The radiating fin assembly  13  includes a plurality of radiating fins, each of which is bent at a lower edge to form a flange  131 , and a downward opened curved notch  132  is also formed at the lower edge of the radiating fin. 
     When the radiating fin assembly  13  is mounted to the top of the heat radiating base  11 , the curved notches  132  are engaged with the heat pipe  12 , and the flanges  131  are pressed against the top of the heat radiating base  11 . With these arrangements, heat transmitted to the heat radiating base  11  and the heat pipe  12  may be quickly transferred to the plurality of radiating fins of the radiating fin assembly  13  via the flanges  131  to thereby provide upgraded heat dissipating efficiency. 
     However, the following disadvantage is found in manufacturing the above-structured conventional thermal module  1 : 
     Generally, metal parts are connected to one another by way of welding. Therefore, the radiating fin assembly  13  is connected to the heat radiating base  11  by welding the flanges  131  to the top of the heat radiating base  11 . Thereafter, the heat pipe  12  is extended through the tubular groove  111 . Since the heat pipe  12  is not always a fully straight member but might include some bent portions, there are clearances existed between the heat pipe  12  and the tubular groove  111  to create the problem of thermal resistance, resulting in a reduced heat conducting efficiency between the heat radiating base  11  and the radiating fin assembly  13 . 
     In brief, the conventional thermal module  1  has the drawbacks of (a) having excessively large clearances among the heat radiating base, the heat pipe, and the radiating fin assembly; (b) being subject to the problem of thermal resistance; and (c) having relatively poor connection strength among different parts. 
     It is therefore tried by the inventor to develop a radiating fin assembly for thermal module that enables a heat pipe to tightly contact with the heat radiating base of the thermal module to ensure good heat conducting efficiency of the thermal module. 
     SUMMARY OF THE INVENTION 
     A primary object of the present invention is to provide a radiating fin assembly, which is mounted on a heat radiating base of a thermal module while presses against a heat pipe, so that the heat pipe is brought to more tightly contact with the heat radiating base. 
     To achieve the above and other objects, the radiating fin assembly for thermal module according to the present invention includes a plurality of radiating fins being mounted on a top of a heat radiating base of the thermal module with a heat pipe located between the radiating fins and the base. Each of the radiating fins is provided at a lower side with a flange for contacting with the base and a downward opened curved notch for engaging with the heat pipe. A curved extension is provided along an outer edge of the curved notch to outward extend and downward incline from the radiating fin. When the radiating fin assembly is mounted on the top of the heat radiating base, the curved extensions are fitly engaged with an upper portion of the heat pipe and apply uniformly distributed downward pressure to the heat pipe, bringing the heat pipe to more tightly contact with the heat radiating base. 
     The radiating fin assembly for thermal module according to the present invention has the following advantages: (1) the radiating fin assembly may be produced without increasing any additional manufacturing cost of the thermal module; (2) the use of the radiating fin assembly does not affect the manufacturing process for the thermal module; (3) the radiating fin assembly, the heat radiating base, and the heat pipe are in tight contact with one another without leaving clearances among them; and (4) the problem of thermal resistance is avoided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein 
         FIG. 1  is an exploded perspective view of a conventional thermal module; 
         FIG. 2  is an exploded perspective view of a thermal module that adopts a radiating fin assembly according to a preferred embodiment of the present invention; 
         FIG. 3  is an assembled view of  FIG. 2 ; 
         FIG. 4  is a fragmentary sectional view of  FIG. 3 ; 
         FIG. 4B  is an enlarged view of the circled area B in  FIG. 4 ; and 
         FIG. 5  is a front view of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Please refer to  FIGS. 2 and 3  that are exploded and assembled perspective views, respectively, of a thermal module A that adopts a radiating fin assembly  4  according to a preferred embodiment of the present invention, and to  FIG. 4  that is a fragmentary sectional view of  FIG. 3 . As shown, the thermal module A includes a heat radiating base  2 , a heat pipe  3 , and a radiating fin assembly  4 . 
     The heat radiating base  2  is provided on a top with a groove  21  having a curved cross section for receiving a lower portion of the heat pipe  3  therein. 
     The radiating fin assembly  4  includes a plurality of parallelly arranged radiating fins  41 . Each of the radiating fins  41  has one lower side bent into a flange  411 , and a curved notch  412  is formed on the radiating fin  41  at the same lower side with the flange  411 . Along an outer edge of the curved notch  412 , there is formed a curved extension  413  outward extended and downward inclined from the radiating fin  41 . It is noted a cut  414  having a predetermined size is formed between each of two ends of the curved extension  413  and the flange  411 , so that the curved extension  413  is not restricted by the flange  411  and possess a relatively large freeness to elastically deform under an external force applied thereto. 
     To assemble the thermal module A, first position the heat pipe  3  in the curved-section groove  21  on the heat radiating base  2 . Then, attach the radiating fin assembly  4  to the top of the heat radiating base  2  and the heat pipe  3  received in the groove  21 , such that the curved notches  412  on the radiating fins  41  of the radiating fin assembly  4  are fitly engaged with an upper portion of the heat pipe  3  protruded from the groove  21 , and the flanges  411  of the radiating fins  41  are pressed against the top of the heat radiating base  2 . At this point, the curved extensions  413  on the radiating fins  41  are in contact with and apply a downward pressure P against the heat pipe  3 , forcing the heat pipe  3  to be more tightly received in the groove  21  and closely contact with the heat radiating base  2 , so that the clearances between the heat pipe  3  and the heat radiating base  2  and the radiating fin assembly  4  are eliminated to avoid the problem of thermal resistance from occurring on the thermal module A. 
       FIG. 4B  is an enlarged view of the circled area B in  FIG. 4 , and  FIG. 5  is a front view of  FIG. 3 . Please refer to  FIGS. 4 ,  4 B, and  5 . As a mechanical property thereof, a metal material deformed under an externally applied force would restore to an initial shape when the external force is released. Such a mechanical property is referred to as elasticity, and such a restorable deformation is referred to as an elastic deformation of material. In the present invention, the radiating fins  41  are made of a metal material with elasticity. Therefore, when the radiating fins  41  are subject to an external force and deformed, they may still elastically restore to an initial shape so long as the external force is lower than a yielding point of the metal material. As can be clearly seen from  FIGS. 4 ,  4 B, and  5 , each of the extensions  413  is in a curved form adapted to fitly engage with the upper portion of the heat pipe  3 . Therefore, the downward pressure P applied by the curved extensions  413  to the heat pipe  3  is a uniformly distributed pressure. That is, the pressure P applied to the upper portion of the heat pipe  3  is evenly and uniformly distributed over areas at where the heat pipe  3  is in contact with the curved extensions  413 . Meanwhile, the heat pipe  3  generates an upward resistance P 1  to each of the curved extensions  413 . Since the resistance P 1  is smaller than the yielding point of the curved extensions  413  without causing a permanent deformation of the curved extensions  413 , the curved extensions  413  still have elasticity to constantly apply the uniformly distributed downward pressure P against the heat pipe  3 . Meanwhile, since the uniformly distributed downward pressure P applied to the heat pipe  3  via the curved extensions  413  is larger than the upward resistance P 1  from the heat pipe  3  to the curved extensions  413 , the heat pipe  3  is caused to tightly locate in the groove  21  and closely contact with the heat radiating base  2  to ensure the optimal contact of the radiating fin assembly  4 , the heat radiating base  2 , and the heat pipe  3  with one another. 
     The present invention has been described with a preferred embodiment thereof and it is understood that many changes and modifications in the described embodiment can be carried out without departing from the scope and the spirit of the invention that is intended to be limited only by the appended claims.