Abstract:
An improved structure of a heat sink is disclosed. The heat sink is composed of a ring body, fins and a bottom plate. The fins are radially arranged on the ring body. The bottom plate is fixed in the ring body for being placed a heat source. The heat sink can effectively dissipate the heat from the heat source.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    The invention generally relates heat sinks, more particularly to annular heat sinks. 
         [0003]    2. Related Arts 
         [0004]    Technology of heat dissipation plays an important role in the field of electronic apparatuses. With continuous development of consumer electronic apparatuses, the requirement and challenge of heat dissipation also increase. For example, tungsten lamps and halogen lamps have been replaced by light emitting diodes (LEDs). The main features of the LEDs are less power consumption, long service time, compact size and light weight. The LEDs also can emit various light so they can be extensively applied in many fields for indication and illumination. Although the LEDs generate less heat than conventional lighting devices, the problem of heat dissipation accompanied with high power LEDs still should be dealt with carefully. 
         [0005]    Taiwan Patent Application Publication No. 200716911 discloses a heat dissipating device for LED lamp. &#39;911 connects a high power LED lamp to a heat spreader via a heat pipe so that the heat from the LED lamp can be conducted to the heat spreader. However, &#39;911&#39;s structure is considerably complicated and bulky. 
         [0006]    Taiwan Utility Model Patent No. M317539 discloses an LED lamp. &#39;539 employs a heat conducting post and a plurality of fins annularly connected thereto to constitute a heat dissipating module. The fins are radially disposed on the heat conducting post and form a recess at a top end of the heat conducting post for accommodating an LED. 
         [0007]    In &#39;539, however, the fins and heat conducting post can not be tightly connected so that the heat from the LED can not be effectively conducted to the fins through the heat conducting post. Thus, the heat dissipating efficiency of &#39;539 is not good enough, and the LED tends to be damaged because of overheating. Furthermore, &#39;539 has too many components and lacks secure positioning and connecting arrangement. Therefore, &#39;539 is hard to be assembled and is uneconomical for manufacture. 
       SUMMARY OF THE INVENTION 
       [0008]    A primary object of the invention is to provide an improved heat sink having a ring body and a seat plate, which can be securely and tightly connected to each other. 
         [0009]    Another object of the invention is to simplify a structure of heat sink and to shorten production time in manufacturing process. 
         [0010]    Another object of the invention is to enhance heat dissipation performance. 
         [0011]    To accomplish the objects abovementioned, the heat sink is composed of a ring body, fins and a bottom plate. The fins are radially arranged on the ring body. The bottom plate is fixed in the ring body for being placed a heat source. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is an exploded view of a preferred embodiment according to the invention; 
           [0013]      FIG. 2  is a perspective view of the assembly of  FIG. 1 ; 
           [0014]      FIG. 3  shows a detailed status before the taper slot is pressed  FIG. 4  shows a detailed status after the taper slot is pressed; 
           [0015]      FIGS. 5A and 5B  shows a process of the bottom plate being pressed; 
           [0016]      FIG. 6  is a perspective view of a finished product shown in  FIG. 1 ; 
           [0017]      FIGS. 7A and 7B  show another type of the bottom plate and how it connects the ring body; 
           [0018]      FIGS. 8A and 8B  show another type of the bottom plate and how it connects the ring body; 
           [0019]      FIGS. 9A and 9B  show another type of the bottom plate and how it connects the ring body; 
           [0020]      FIG. 10  shows another embodiment of the bottom plate; 
           [0021]      FIG. 11  shows a connection between the bottom plate and ring body; 
           [0022]      FIGS. 12 and 13  show another connection of the bottom plate and ring body; 
           [0023]      FIG. 14  shows another embodiment of the ring body; 
           [0024]      FIGS. 15 and 16  show another embodiment of the bottom plate having a working fluid; 
           [0025]      FIG. 17  is an exploded view of another embodiment of the ring body; and 
           [0026]      FIG. 18  is a perspective view of assembly of  FIG. 17 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0027]    Referring to  FIG. 1 , the first preferred embodiment in accordance with the invention is shown. The cylindrical heat sink  1  is composed of a ring body  10 , a bottom plate  20  disposed in the ring body  10  and a plurality of fins radially disposed on the ring body  10 . The ring body  10  is, but not limited to, a hollow cylinder. There are a plurality of longitudinally thin grooves  14  and taper slots  12  on an outer surface of the ring body  10 . Both the thin grooves  14  and taper slot  12  are alternatively arranged. The bottom plate  20 , which is made of copper, aluminum or iron, can be a single component or be composed of two components with different materials. A diameter of the bottom plate  20  is approximately equal to an inner diameter of the ring body  10  so that the bottom plate  20  can be fixed within the ring body  10 . In a preproduction process, the fins  30  are arranged outside the ring body  10  and directed at the thin grooves  14  separately, and then the fins  30  can be fixedly embedded in the thin grooves  14 . 
         [0028]    In the shown embodiment, ring body  10  and fins  30  are fixedly connected by an extrusion process. Referring to  FIGS. 3 and 4 , each of the fins  30  is inserted in a thin groove  14 . By using a punch  40  to extrude the taper slot  12 , the thin groove  14  can grip the fin  30 . As shown in  FIG. 2 , fins  30  are fixedly arranged outside the ring body  10 . The taper slots  12  are extruded by the punch  40  to deform. Thin grooves  14  are pressed to tightly grip fins  30  as shown in  FIGS. 3 and 4 . Thus, both fins  30  and ring body  10  are fixed to be integrated as shown in  FIG. 6 . 
         [0029]    Referring to  FIGS. 5A and 5B , bottom plate  20  is pressed by a molding machine  4  from an originally smaller diameter to an extendedly larger diameter, so that bottom plate  20  can be fixed at a predetermined position in the ring body  10  to form an integrated module. As shown in  FIG. 6 , a space  200  is arranged in ring body  10  and bottom plate  20  for accommodating additionally electronic components. 
         [0030]    On the other side, ring body  10 , bottom plate  20  and fins can be made of different materials such as iron, copper, aluminum or alloy of previous metals to satisfy requirement of various circumstances as shown in  FIG. 10 . By using metal or alloy with better extensibility, the extrusion process can be performed more smoothly. 
         [0031]    The junction between bottom plate  20  and ring body  10  can be noncomplete to retain air gaps. As shown in  FIG. 7A , an outer side of bottom plate  22  can be of a regularly or irregularly lumpy shape. After being extruded, the extrusive portions  220  can be tightly connected to an inner wall of the ring body having thin grooves  14  and taper slots  12  as shown in  FIG. 7B . Another available shape of the bottom plate  20  is shown in  FIGS. 8A and 8B . In this embodiment, bottom plate  24  is of a flower shape with multiple petal. By these arrangements, gaps  222  or  242  can be retained after bottom plate  22  or  24  is pressed. The bottom plate  22  or  24  can provide not only to be placed additionally electronic components but also to enhance air convection through the gaps  222  or  242 . 
         [0032]    On the other side, ring body  100  can be rectangular as shown in  FIGS. 9A and 9B . The rectangular ring body  100 , which still has taper slots  12  and thin grooves  14 , can match a rectangular bottom plate  26  with a regularly or irregularly lumpy peripheral. As the round ring body  10  abovementioned, rectangular bottom plate  26  also can be pressed to tightly connect the inner wall of the rectangular ring body  100 . Additionally, ring body  10  or  100  also can be configured in a shape of semicircle, triangle, oval, cone, or irregularity. They can match corresponding bottom plates to form various outlines. 
         [0033]    Referring to  FIG. 11 , besides the abovementioned manner, the connection between bottom plate  20  and ring body  10  also can adopt other processing approaches. A diameter of the bottom plate  20  can be approximately equal to or slightly smaller than an inner diameter of the ring body  10 . The junction between bottom plate  20  and ring body  10  can be soldered or welded together, or infused thermal grease. 
         [0034]    Referring to  FIGS. 12 and 13 , which shows other preferred embodiments according to the invention, cylindrical heat sink  1  includes a ring body  10  and a bottom plate  20  whose diameter is slightly larger than the inner diameter of the ring body  10 . First, bottom plate  20  is aslant placed on an end of the ring body  10 . Molding machine  4  presses bottom plate  20  to fix at a predetermined position as shown in  FIG. 12 . Alternatively, the inner wall of the ring body  10  can be provided with a step  20   a  on a top end thereof. Bottom plate  20  is pressed by the molding machine  4  to insert into ring body  10  along the step  20   a.    
         [0035]    Ring body  10   a  is not limited to a hollow cylinder, it also can be configured into a shape shown in  FIG. 14 . The ring body  10   a  has a bell at an end thereof. Bottom plate  20  is pressed by the molding machine  4  to be gripped at a predetermined position in the bell. A heat source (not shown), such as an LED lamp, can be placed on the bottom plate  20 . 
         [0036]    Furthermore, as shown in  FIGS. 15 and 16 , the bottom plate also can be a heat spreader having a working fluid  280  therein. The bottom plate  28  is fixed at in the ring body  10  and the heat source is placed on one side of the bottom plate  28 . The heat dissipating efficiency can be increased by delivering heat of working fluid  280 . 
         [0037]      FIG. 17  shows another embodiment of the invention. In this embodiment, both ring body  50  and fins  60  are integratedly formed into a single element, and bottom plate  20  is fixed in ring body  50  as shown in  FIG. 18 . Similarly, bottom plate  20  can be placed by a heat source and the heat from the heat source can be dissipated by bottom plate  20 , ring body  50  and fins  60 .