Abstract:
A heating dissipating device for electronic elements comprises a bottom plate and a plurality of heat dissipating sheets; the bottom plate being formed with a plurality of grooves. A lower end of each heat dissipating sheet is a folded end and the folded end is inserted into a respective groove to be fixed therein tightly. Each groove may be inclined with respect to the surface of the bottom plate and the fold end is also inclined. Moreover, two sides of the bottom plate are punched so that the heat dissipating sheets are tightly engaged to the bottom plate.

Description:
FIELD OF THE INVENTION 
     The present invention relates to heating dissipating devices, and particularly to a heating dissipating device for electronic elements, wherein one end of the heat dissipating sheet is folded to be wider and then the end is fixed to the bottom plate so that the heat dissipating ability is increased. 
     BACKGROUND OF INVENTION 
     Current electronic devices need many high efficiency heating dissipating devices due to the operation speed increment of the electronic devices. Referring to FIGS.  1  and  1 — 1 , it is illustrated that the prior art heating dissipating device, where a fin device with a plurality of heat dissipating sheets is locked to a fan and a bottom at two sides. The bottom plate is used to contact with the electronic device for dissipating heat. The heat dissipating capacity is confined by the number of the fins embedded in the bottom plate and thus the more the fins, the better the heat dissipating ability. Since the sizes of the electronic devices are made more and more compact, the heating dissipating devices must have higher efficiency for dissipating heat. Thereby, it is necessary to implant heat dissipating sheets into a bottom plate as many as possible. However, this is confined by the cutting steel sheets for forming grooves on the bottom plate. The width of the steel sheet is confined. If the steel sheet for cutting the bottom plate to form grooves is too narrow, the steel piece will break. Thereby, the conventional way has a limit in embedding heat dissipating sheets to the bottom plate and thus the heating dissipating ability is confined. 
     SUMMARY OF THE INVENTION 
     Accordingly, the primary object of the present invention is to provide a heating dissipating device for electronic elements which comprises a bottom plate and a plurality of heat dissipating sheets; the bottom plate being formed with a plurality of grooves. A lower end of each heat dissipating sheet is a folded end and the folded end is inserted into a respective groove to be fixed therein tightly. 
     Another object of the present invention is to provide a heating dissipating device for electronic elements, wherein each groove may be inclined with respect to the surface of the bottom plate and the fold end is also inclined. 
     A further object of the present invention is to provide a heating dissipating device for electronic elements, wherein the fold end can have different configurations so that the heat dissipating sheets con be designed with different configurations. 
     The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic view of a prior art heating dissipating device and FIG.  1 — 1  is an assembled lateral view of the prior art. 
     FIG. 2 shows the assembly of a heat dissipating sheet to a bottom plate, where  2 A is a prior art case and  2 B is a case of the present invention. 
     FIG. 3 is an exploded perspective view of the present invention. 
     FIG. 4 is an assembly schematic view of the present invention. 
     FIG. 5 is a cross sectional view of the present invention, where a fan is installed above the heat dissipating sheets. 
     FIG. 6 is an exploded perspective view of the present invention, wherein the grooves are inclined. 
     FIG. 7 is an assembly schematic view of FIG.  6 . 
     FIG. 8 is an assembled cross sectional view of the present invention, wherein a fan is added. 
     FIG. 9 shows another embodiment of the present invention. 
     FIG. 10 shows a further embodiment of the present invention. 
     FIG. 11 shows still an embodiment of the present invention. 
     FIG. 12 shows yet an embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In order that those skilled in the art can further understand the present invention, a description will be described in the following in details. However, these descriptions and the appended drawings are only used to cause those skilled in the art to understand the objects, features, and characteristics of the present invention, but not to be used to confine the scope and spirit of the present invention defined in the appended claims. 
     With reference to FIG. 2, schematic views showing the prior art and the present invention are illustrated in FIG. 2A and 2B, respectively. In the drawings, the heat dissipating sheets A and B have the same length L and the height H, where L is 70 mm and height is 20 mm. The heat dissipating sheet A has a width W 1  of 0.4 mm and B has a width W 2  of 0.2 mm. Thereby, the difference of the heating dissipating areas of heat dissipating sheets A and B is very small, even it can be neglected. The heat dissipating sheets A aid B are installed to respective grooves in a bottom plate. The two grooves have equal widths and thus have the same contact area and thus the heat flow rates from the bottom plates to the heat dissipating sheets A and B are equal. Heat flow rate can be calculated by the formula, H=KAr (T 2 −T 1 )/H, where K is heat conductivity, for example, for copper, K is equal to 0.92; Ar is the heating dissipating area of the heat dissipating sheet; T 1  is the contact temperature of the bottom plate; and T 2  is temperature of the end section of the heat dissipating sheet A or B (temperature of the heat dissipating sheet is changed monotonically with the distance from the end section of the heat dissipating sheet). Thereby, it is shown that the heat flow rates of the heat dissipating sheets A and B are almost equal to one another. 
     Moreover, for heat capacity, Q=mC(T 2 −T 1 ), where m is the mass of the heat dissipating sheet; C is specific heat; T 1  is the contact temperature of the bottom plate; and T 2  is temperature of the end section of the heat dissipating sheet A or B. Since mass of the heat dissipating sheet A is twice of that of heat dissipating sheet B and thus the heat capacity of heat dissipating sheet A is twice of that of heat dissipating sheet B. Therefore, as wind blows the heat dissipating sheets A and B, the temperature of heat dissipating sheet B will descend more rapidly than that of heat dissipating sheet A, and thus B is a larger temperature gradient. Thus temperature differenced of heat dissipating sheet B is larger than heat dissipating sheet A. Heat flow rate is positively proportional to temperature difference. Thus, heat dissipating sheet has a preferred heating dissipating efficiency. 
     In the following, the structure of the present invention will be described, With reference to FIGS. 3 to  5 , the present invention includes a bottom plate  1  and a plurality of heat dissipating sheets  2 . The surface of the bottom, plate  1  has a plurality of grooves  11  (which may has a minimum size allowable in the specification). An end surface  12  is formed between two adjacent grooves. A lower end of each heat dissipating sheet  2  can be inserted into the groove  11  by tightly engagement. An end surface of each heat dissipating sheet  2  inserted into the groove  11  has a reverse fold  21 . Thereby, the lower end of each heat dissipating sheet  2  has an optimum contact area with respect to the groove  11  so that heat of the bottom plate  1  can be transferred to the heat dissipating sheets  2  rapidly. The width of each heat dissipating sheets  2  is one half of the groove  11 , but the reverse fold  21  is exactly received in the groove  11 . Thereby from the discussion above, it is known that the heat dissipating sheets  2  of the present invention have preferred heating dissipating efficiency than those have a width equal to the width of the groove  11  when a fan  3  is used to blow wind to the heat dissipating sheets  2 . 
     With reference to FIGS. 6 to  8 , it is illustrated that a plurality of inclined grooves  11   a  are formed in the bottom plate  1   a . Each two grooves  11   a  are spaced by an end surface  12   a . A lower end of each heat dissipating sheet  2   a  has an inclined reverse fold  21   a , thereby, the heat dissipating sheets  2   a  can be inserted into the inclined grooves  11   a . Then the two sides of the bottom plate  1   a  are punched so that the heat dissipating sheets  2   a  are tightly engaged to the bottom plate  1   a.    
     Referring to FIG. 9, another embodiment of the present invention is illustrated. In this embodiment, the heat dissipating sheet  2   b  has a two-fold end surface  21   b  and the heat dissipating sheets  2   c  has a three-fold end surface  21   c . The heat dissipating sheets  2   b  ( 2   c ) is fixedly inserted into the groove  11   b  ( 11   c ). Thereby, the width of the heat dissipating sheet  2   b  ( 2   c ) is reduced further so as to match the requirement of different integrated circuit. 
     With reference to FIGS. 10 to  12 , another embodiment of the present invention is illustrated. It is illustrated that the heat dissipating sheet  2   d  has a fold portion  21   d . The fold portion  21   d  is firstly revered folded to a height approximately equal to the height of the groove  11   d  and then is further reversely folded to the bottom of the groove  11   d , then it is further reversed folded so that two ends of the heat dissipating sheet  2  have approximately the same height. By above structure, the present invention has a preferred heat dissipating efficiency. 
     The present invention is thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.