Abstract:
The invention relates to heat transfer apparatus for cooling electronic components. There is a continuously increasing demand for compact electronic systems such as portable laptop computers and thirst for high processing power, leading to high heat generated by components residing within these systems. These electronic systems have to be cooled due to their fixed operating temperature ranges. Operating an electronic component beyond its rated operating temperature range will damage electronic components. Instead of conventionally utilising a bigger fan, a smaller sized solution is required for cooling an electronic component contained in a compact electronic system, for example a notebook computer. A heat transfer apparatus includes a heat carrier for conveying heat away from the electronic system into a radiator for dissipation. The radiator is placed into a cooler for directing air through the radiator and expelling heated air, cooling the radiator in the process.

Description:
FIELD OF INVENTION  
         [0001]    The present invention relates generally to a heat transfer apparatus. In particular, the invention relates to a heat transfer apparatus for portable electronic systems.  
         BACKGROUND  
         [0002]    In recent years, there is a continuously increasing demand for compact electronic systems such as portable laptop computers. Coupled with this demand is a need for further miniaturizing of these electronic systems and the thirst for high processing power. Elevating processing power-to-size ratio results in an elevating level of heat generated by these electronic systems. As these electronic systems have fixed operating temperature ranges, the heat generated by these electronic systems limits the extent to which the processing power-to-size ratio can increase. Operating an electronic component beyond its rated operating temperature range can damage the electronic component.  
           [0003]    Conventionally, a heat sink is attached to the heat generating electronic component, for example a microprocessor, within the electronic system for conducting heat away from the electronic component. The heat sink typically has a base and an array of fins extending away from the base. The array of fins provides increased surface area that facilitates heat dissipation. A fan can be coupled to the heat sink for improving air circulation around the heat sink. The improved air circulation results in more efficient heat transfer from the heat sink to the surrounding environment.  
           [0004]    However, the fan size is limited by the size of the electronic system onto which it is mounted into. The small fan size results in a lower cooling capacity and consequently, lower heat dissipation from the electronic component. Although increasing the amount of fins in the heat sink and the use of a larger fan can substantially improves heat dissipation, the space limitation of these compact electronic systems however constraints such an improvement.  
           [0005]    Hence, this clearly affirms a need for an optimised heat transfer apparatus to improve heat dissipation of an electronic component.  
         SUMMARY  
         [0006]    When a substantial amount of heat is generated by an electronic component, for example a microprocessor, a heat sink is used to remove heat away from the electronic component and a large fan is typically used to cool both the electronic component and the heat sink. However, when the electronic component is contained in a compact electronic system, for example a notebook computer, the size of the cooling system used is constrained.  
           [0007]    A heat transfer apparatus includes a heat carrier for conveying heat away from the electronic system into a radiator for dissipation. The radiator is placed into a cooler for directing air through the radiator and expelling heated air, cooling the radiator in the process.  
           [0008]    Therefore, in accordance with a first aspect of the invention, there is disclosed a heat transfer apparatus for exhausting heat of an electronic component, the heat transfer apparatus comprising:  
           [0009]    a heat carrier for receiving heat generated by the electronic component, the heat carrier being thermally coupled to the electronic component;  
           [0010]    a radiator for receiving heat conveyed by the heat carrier and for emanating heat into air, the radiator being thermally coupled to the heat carrier; and  
           [0011]    a cooler comprising:  
           [0012]    a chamber in fluid communication with the radiator for providing the passage of air therethrough, the radiator being received in the chamber,  
           [0013]    wherein heat received in the radiator is dissipated by airflow through the chamber.  
           [0014]    In accordance with a second aspect of the invention, there is disclosed a method for heat transfer and dissipation comprising the steps of:  
           [0015]    receiving heat generated by an electronic component into a heat carrier, the heat carrier being thermally coupled to the electronic component;  
           [0016]    receiving heat conveyed by the heat carrier into a radiator, the radiator being thermally coupled to the heat carrier;  
           [0017]    emanating heat from the radiator into air; and  
           [0018]    generating airflow through a chamber for dissipating heat received by the radiator, the radiator being disposed within the chamber and the chamber being in fluid communication with the radiator. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    Embodiments of the invention are described hereinafter with reference to the following drawings, in which:  
         [0020]    [0020]FIG. 1 is a partially exploded perspective view of a heat transfer apparatus according to an embodiment of the invention;  
         [0021]    [0021]FIG. 2 is a front view of the heat transfer apparatus of FIG. 1;  
         [0022]    [0022]FIG. 3 is a top view of a radiator of the heat transfer apparatus of FIG. 1 with a partial view of a cooler;  
         [0023]    [0023]FIG. 4 is a front sectional view of a radiator disposed in a cooler of the heat transfer apparatus in FIG. 1;  
         [0024]    [0024]FIG. 5 is a front sectional view of a radiator of the heat transfer apparatus in FIG. 1 enclosed within a pair of coolers; and  
         [0025]    [0025]FIG. 6 is a top view of a plurality of the heat transfer apparatus in FIG. 1 with heat carriers sharing a common heat spreader.  
     
    
     DETAILED DESCRIPTION  
       [0026]    A heat transfer apparatus for addressing the foregoing problems is described hereinafter.  
         [0027]    A first embodiment of the invention, a heat transfer apparatus  20  is described with reference to FIG. 1, which shows a partially exploded perspective view of the heat transfer apparatus  20 , and FIG. 2, which shows a front view of the heat transfer apparatus  20 . The heat transfer apparatus  20  comprises of three main elements: a heat carrier  22 , a radiator  24  and a cooler  26 , with the radiator  24  being encased by the cooler  26 . The heat carrier  22  includes a pair of heat pipes  28  coupled and adjacent to one another, a first heat spreader  30  and a second heat spreader  32 . The pair of heat pipes  28  has two distal ends (not shown) with the first heat spreader  30  coupled to one end and the second heat spreader  32  coupled to the other end. The heat pipes  28  are generally flattened for the purpose of space conservation.  
         [0028]    The first heat spreader  30  is planar and dimensioned for mounting onto a heat producing electronic component  34 , for example a microprocessor mounted on a printed circuit board (‘PCB’). The first heat spreader  30  is mounted to the electronic component  34  to reduce conductive resistance. It is preferred that thermal grease be used at the interface of the first heat spreader  30  and the electronic component  34  to improve thermal conductivity. Heat produced by the electronic component  34  is transmitted through the first heat spreader  30  via conduction. Heat received by the first heat spreader  30  is transmitted to the pair of heat pipes  28 .  
         [0029]    Each heat pipe  28  is an elongated rod with a centrally disposed channel (not shown). The channel is injected with an evaporative fluid (not shown). The evaporative fluid and its vapour circulate in the channel to convey heat from one end of the heat pipe  28  that is warm to the other end of the heat pipe  28  that is cool. Therefore, heat received by the heat pipe  28  from the first heat spreader  30  is conveyed to the second heat spreader  32  in the foregoing manner.  
         [0030]    [0030]FIG. 3 shows a top view of the radiator  24  comprising a base  36  having a first end portion  37   a  and a second end portion  37   b . A plurality of fins  38  protrude from a midsection of an upper face  40  of the base  36  with the plurality of fins  38  being spaced apart with each fin  38  being parallel to the other fin  38 . Each fin  38  is rectangularly shaped, planar and preferably having a thickness  39   a  of 0.3 mm to 0.9 mm and a length  39   b  of preferably 30 mm to 60 mm. Passageways  41  are formed between each pair of adjacent fins  38 , the passageways  41  extending from the first end portion  37   a  towards the second end portion  37   b  of the base  36 . It is preferred that each fin  38  protrude a distance of at least 12 mm from the upper face  40  of the base  36  with the base  36  and each fin  38  having a combined height  39   c  of preferably 15 mm to 25 mm. The radiator  24  has a width of preferably between 45 mm and 55 mm, the width  39   d  of the radiator  24  being a distance between the two furthermost fins  38 . Each passageway  41  has a fin gap  39   e , the fin gap  39   e  being the general distance between each pair of adjacent fins  38 . The ratio of fin gap  39   e  to fin thickness  39   a  ranges from and includes 2 to 4.  
         [0031]    The second heat spreader  32  is coupled to a lower face  42  of the base  36 . The upper face  40  and the lower face  42  of the base  36  are outwardly opposing. The interface between the second heat spreader  32  and the base  36  being preferably flush to minimise contact resistance between the base  36  and the second heat spreader  32 . The fins  38  then receive heat from the base  36 . The array of fins  38  presents a larger surface area that is in contact with air surrounding the fins  38  and between every pair of fins  38 . This facilitates radiating of heat from the fins  38  to the atmosphere, cooling the radiator  24  in the process.  
         [0032]    The radiator  24  is coupled to the cooler  26 , shown in the front sectional view of the cooler  26  in FIG. 4, which has an internally disposed chamber  44  for receiving the array of fins  38  therein, in which the chamber  44  is in fluid communication with the passageways  41 . The cooler  26  is shaped and dimensioned for enclosing the fins  38  and the upper face  40  of the base  36 , forming a rectangular-shaped case. The cooler  26  has a top face  46  being inwardly opposite of the lower face  42  and a side wall  48  depended along a portion of an outer periphery of the cooler  26 .  
         [0033]    A first opening  50  is disposed on the top face  46  of the cooler  26  proximal to the first end portion  37   a  of the base  36 . A second opening  52  is disposed on the side wall  48  of the cooler  26  proximal to the second end portion  37   b  of the base  36 . Air is received into the first opening  50  and expelled from the second opening  52  through the chamber  44 .  
         [0034]    A fan  54 , preferably an axial-type, is disposed in the chamber  44 . Alternatively, the fan  54  can be a blower-type. The fan is disposed on the upper face  40  of the base  36  adjacent to the fins  38  and the first opening  50 . The fan  54  draws air through the first opening  50  and channels the air through the passageways  41  between the fins  38 . Heat is conveyed from the fins  38  into the air passing through the passageways  41 , substantially cooling the fins  38  in the process. The heated air is then expelled through the second opening  52 .  
         [0035]    A wall  56  is disposed adjacent to the second opening  52  and the fins  38 . The wall  56  disposed within the chamber  44  guides the heated air from the passageways  41  of the fins  38  towards the second opening  52 . The wall  56  has a plane that is oblique to the plane of the fins  38 . The wall  56  facilitates the expulsion of heated air from the chamber  44  and greatly reduces the heat dissipation capacity of the cooler  26 . Facilitating the movement of heated air out from the cooler  26  improves cooling efficiency of the cooler and conveyance of heat away from the electronic component  34 .  
         [0036]    The heat transfer apparatus  20  is preferably mounted onto a plate  58  to minimise deflection of and consequentially damage to the heat pipes  28  as shown in FIG. 2.  
         [0037]    A second embodiment of the invention, a heat transfer apparatus  20   a  as seen in FIG. 5, comprises of three main elements: a heat carrier  22   a , a radiator  24   a  and a cooler  26   a . The descriptions in relation to the structural configurations of and positional relationships among the heat pipes  28 , the first heat spreader  30 , the base  36 , the fins  38  and the fan  54  with reference to FIGS.  1  to  5  are incorporated herein, in relation to the equivalent components of the heat transfer apparatus  20   a  of FIG. 5.  
         [0038]    The radiator  24   a  further includes fins  38   a  protruding from the lower face  42   a , the fins  38   a  being uniformly spaced apart as shown in a front sectional view of the heat transfer apparatus  20   a  in FIG. 5. The cooler  26  in the first embodiment of the invention, as shown in FIG. 4, is incorporated in the second embodiment. Referring to FIG. 5, the cooler  26   a  encloses and cools the fins  38   a  protruding from both the upper face  40   a  and the lower face  42   a  of the base  36   a . The cooler  26   a  includes a chamber  44   a , a fan  54   a  and a wall  56   a  as described in the first embodiment.  
         [0039]    The dimensions in relation to the thickness  39   a  of each fin  38   a , the length  39   b  of each fin  38   a  and the width  39   d  of the radiator  24   a  with reference to the first embodiment is incorporated in the second embodiment. However, the combined height  39   f  of the base  36   a  and the fins  38   a  protruding from both the upper face  40   a  and the lower face  42   a  of the base  36   a  is preferably 15 mm to 25 mm.  
         [0040]    Instead of coupling the heat pipes  28   a  to a second heat spreader  32   a  as in the first embodiment, the heat pipes  28   a  are received into the base  36   a  of the radiator  24   a.    
         [0041]    A third embodiment of the invention, a heat transfer apparatus  20   c  as seen in FIG. 6, comprises of three main elements: a heat carrier  22   c , a radiator  24 / 24   a  and a cooler  26 / 26   a . The descriptions in relation to the structural configurations of and positional relationships among the heat pipes  28 / 28   a , the first heat spreader  30 / 30   a , the second heat spreader  32 / 32   a , the base  36 / 36   a , the fins  38 / 38   a  and the fan  54 / 54   a  with reference to FIGS.  1  to  5  are incorporated herein.  
         [0042]    [0042]FIG. 6, shows a top view of the heat transfer apparatus  20   c  further including a plurality of heat carriers  22   c  sharing a common first heat spreader  30 / 30   a . Each heat carrier  22   c  has a pair of heat pipes  28 / 28   a  and a second heat spreader  32 / 32   a . Each second heat spreader  32 / 32   a  of the heat transfer apparatus  20   c  is coupled to an independent radiator  24 / 24   a  coupled to an independent cooler  26 / 26   a.    
         [0043]    In the foregoing manner, a heat transfer apparatus is described according to three embodiments of the invention for addressing the foregoing disadvantages of conventional heat transfer apparatus. Although only three embodiments of the invention are disclosed, it will be apparent to one skilled in the art in view of this disclosure that numerous changes and/or modification can be made without departing from the scope and spirit of the invention.