Patent Publication Number: US-6700781-B2

Title: Heat-dissipating module for removing heat generated from heat-generating device

Description:
FIELD OF THE INVENTION 
     The present invention relates to a heat-dissipating module, and more particularly to a heat-dissipating module for removing heat generated from a heat-generating device. 
     BACKGROUND OF THE INVENTION 
     Typically, electronic components are mounted onto a printed circuit board in accordance with a surface mounting technology (SMT). For example, such electronic components include capacitors, resistors, inductors, transformers, diodes, MOSFETs, bare dice and integrated chips. When operating, such electronic components generate energy in the form of heat. If the generated heat could not be effectively removed to the ambient air, the elevated operating temperature might result in a failure of the electronic component or the breakdown of the whole system. 
     The customarily used heat-dissipating mechanism are divided into the types: an active-type heat-dissipating mechanism and a passive-type heat-dissipating mechanism. 
     FIG.  1 ( a ) is an exploded view showing a commonly active-type heat-dissipating mechanism, which is employed for removing heat generated from a central processing unit (CPU)  11 . Such active-type heat-dissipating mechanism includes a heat sink  12  and a fan  13 . The heat sink  12  is made of a highly thermal conductive material, for example aluminum, copper, aluminum alloy and copper alloy. The heat sink  12  includes a base  121  and a plurality of sheet-shaped fins  122 . The base  121  is attached on and spreads over the top surface of the CPU  11 , and the fan  13  is disposed on the heat sink  12 . The fan  13  is usually coupled with the heat sink  12  by the engagement of screws  16  with fins  122 . By means of the fans  13 , the ambient air is inhaled to be in contact with the fins  122  so as to remove most generated heat. Such active-type heat-dissipating mechanism could dissipate heat effectively. However, due to hindrance of the fan hub  131 , the inhaled air could not sufficiently remove heat at the position under the hub  131 . Therefore, partially generated heat accumulates locally at such position and might result in a failure of the CPU  11  for a long-term period. 
     Referring to FIG.  1 ( b ), the typical passive-type heat-dissipating mechanism is implemented by a blower  23  separated from a heat source  21 . The housing of the blower  23  is made of plastic materials, and a blade portion  232  is disposed in the center thereof. When the blower  23  is turned on, the blade portion  232  is rotated to inhale ambient air, which is heated by the heat source  21 , into the blower  23  via an inlet  231 , and then exhaled via an outlet  233 . Such passive-type mechanism can facilitate guiding the air flow and avoid the local accumulation of heat. However, because no heat sink is used, the blower  23  could not remove heat effectively. Therefore, for example in a computer, several blowers  23  are needed, which occupies much space. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a heat-dissipating module having both the functions of active-type and passive-type heat-dissipating mechanisms. 
     It is another object of the present invention to provide a heat-dissipating module for removing heat generated from electronic components in operation by both heat conduction and heat convection. 
     It is another object of the present invention to provide a heat-dissipating module for enhancing heat-dissipating efficiency. 
     In accordance with an aspect of the present invention, there is provided a heat-dissipating module for removing heat generated from a heat-generating device. The heat-dissipating module includes a lower housing, a first magnet portion, a second magnet portion and a circuit board. The lower housing is made of a highly thermal conductive material. The upper housing has an opening in the center thereof, wherein when the upper housing and the lower housing are jointed together, an outlet is defined. The first magnet portion includes a plurality of first magnets. The second magnet portion has a plurality of second magnets, wherein a permanent magnetic field is formed between the plurality of first magnets and the plurality of second magnets. The circuit board is disposed between the first magnet portion and the second magnet portion and having a plurality of winding coils, wherein when a current is applied to the plurality of winding coils, the permanent magnetic field is repulsed to rotate the blade portion, and an ambient air flow is inhaled from the opening and exhaled via the outlet. 
     In an embodiment, the heat-generating device is a CPU (central processing unit) in operation. The heat-generating device is attached on a first surface of the lower housing. Preferably, a plurality of pin-shaped fins are disposed on a second surface of the lower housing. 
     In an embodiment, the highly thermal conductive material is one selected form a group consisting of aluminum, copper, aluminum alloy and copper alloy. 
     In an embodiment, the blade portion includes a frame and a plurality of blades, the frame being ring-shaped and the plurality of blades being coupled to a bottom surface of the frame. An inner edge of the frame has a protrusion coupled to the second magnet portion. The second magnet portion includes a support, a shaft and at least one rib, a free end of the shaft being inserted into a sleeve of the lower housing, and the at least one rib being interconnected with the other end of the shaft and the support. Preferably, the number of the at least one rib is three, and the ribs are sheet-shaped and symmetrical about the shaft. 
     Preferably, each of the plurality of winding coils is a conducting line patterned on the circuit board for a plurality of turns. 
     The above objects and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG.  1 ( a ) is an exploded view showing an active-type heat-dissipating mechanism in the prior art; 
     FIG.  1 ( b ) is a schematic diagram showing a passive-type heat-dissipating mechanism in the prior art; 
     FIG. 2 is an exploded view showing the heat-dissipating module according to a preferred embodiment of the present invention; and 
     FIGS.  3 ( a ) to  3 ( d ) are views illustrating the steps for assembling the heat-dissipating module according to a preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Please refer to FIG.  2 . The heat-dissipating module of the present invention includes a lower housing  3 , an upper housing  4 , a circuit board  5  and a fan, wherein the fan includes a blade portion  61 , a first magnet portion  62  and a second magnet portion  63 . 
     The lower housing  3  is made of a highly conductive material, for example aluminum, copper, aluminum alloy and copper alloy. The lower housing  3  has a plurality of fins  31  on the top surface thereof. A CPU chip (not shown) will be attached on the bottom surface of the lower housing  3  by using an anchor belt or by gluing, and thus the heat generated from the CPU chip will be transferred to the fins  31  by means of heat conduction. It is of course that the fins  31  can be in any shape such as sheet-shaped or pin-shaped. 
     The fan blade portion  61  includes a frame  611  and a plurality of blades  612 . The frame  612  is ring-shaped, wherein the inner edge thereof has a protrusion  613 , and the plurality of blades  612  are disposed on the bottom surface thereof. The first magnet portion  62  includes a plurality of first magnets  620 . The second magnet portion  63  includes a support  631 , a shaft  632  and at least one rib  633 . The free end of the shaft  632  will be inserted into a sleeve (not shown) on the top surface of the lower housing  3 , while the ribs  633  are interconnected with the other end of the shaft  631  and the support  631 . The number of the ribs  633  is preferably three, and such ribs  633  are sheet-shaped and symmetrical about the shaft  632 , such that the fan can rotate smoothly. There are intervals between ribs  633  for air flow therethrough. Depending on the first magnets  620 , the support  631  of the second magnet portion  63  has a plurality of second magnets (not shown) attached on the bottom surface thereof, thereby forming a permanent magnetic field between the first magnets  620  and the second magnets. 
     The circuit board  5  is equipped with electronic components and winding coils  52  required for controlling and running the fan. The winding coils  52  are employed as a stator part. When an electrical current is applied to the winding coils  52 , an electric magnetic field is created to repulse the permanent magnetic field caused from the rotor part, i.e. the combination of the first magnet portion  62  and the second magnet portion  63 , thereby driving the blade portion  63  to rotate. In addition, for a purpose of reducing the volume occupied, each winding coil might be a conducting line patterned on the circuit board  5  for a plurality of turns. The operation and principle of the stator part and the rotor part are well known in the art and need not be further described in details herein. 
     The shape of the upper housing  4  is similar to that of the lower housing  3 ; however, the upper housing  4  has an opening  41  in the center thereof. The upper housing  4  can be made of any appropriate material, for example either a highly thermal conductive material or a heat-resistant material such as plastic resin. 
     The steps for assembling the heat-dissipating module of the present invention will be illustrated hereinafter. In FIG.  3 ( a ), the plurality of first magnets  620  are attached on the top surface of the fan frame  611 . In FIG.  3 ( b ), the protrusion  613  of the blade portion  61  penetrates through an opening  51  in the center of the circuit board  51  to be coupled with a bottom surface of the support  631  of the second magnet portion  63 . In such way, the fan is substantially finished. In FIG.  3 ( c ), The free end of the shaft  632  is inserted into a sleeve (not shown) on a top surface of the lower housing  3 . Subsequently, the circuit board  5  should be positioned in order to avoid sliding when the fan is rotated. For example, the top surface of the lower housing  3  and the bottom surface of the upper housing  4  can be respectively equipped with the corresponding engaging elements (not shown), such that the circuit board  5  is fixed when the upper housing  4  and the lower housing  3  are jointed together. In FIG.  3 ( d ), when the upper housing  4  and the lower housing  3  are jointed together, an inlet  71  and an outlet are simultaneously formed and defined. 
     The heat transfer procedures for the heat-dissipating module according to the present invention will be illustrated thereinafter. Since the bottom surface of the lower housing is attached on a CPU chip, the generated heat in operation will be transferred via the lower housing  3  to the fins  31  by heal conduction. Since the winding coils  52  installed on the circuit board  5  are employed as a stator part, the permanent magnetic field formed between the first magnet portion  62  and the second magnet portion  63  will be repulsed so as to drive the blade portion  61  to rotate, when a current is applied to the winding coils  52 . Thus, the ambient air is forced to be inhaled via the inlet  71  and in contact with the fins  31  (the fins  31  are disposed substantially under the inlet  71  in this embodiment), and the heated, air flow is guided to be exhaled via the outlet  72 . 
     As will be apparent from the above description according to the present invention, the heat-dissipating module has the following advantages over the prior art: 
     1. The problem of the local heat accumulation under the fan hub  131 , which is occurred in the active-type heat-dissipating mechanism, could be avoided because the lower housing  3  in combination with the fins  31  could be regarded as a heat sink and the inhaled air contacts the fins  31  fully. 
     2. In the active-type heat-dissipating mechanism, the efficiency for removing heat is still required to be improved because the inhaled air is not well-guided. However, in the present invention, the inhaled air flow is enclosed within the space between the lower housing  3  and the upper housing  4 , and then guided by means of a channel defined between the housing and the blade portion  61 . Therefore, the heat-dissipating efficiency is also increased. 
     3. In the typical passive-type heat-dissipating mechanism, the blower  23  is distant from the heat source  21 . The passive-type heat-dissipating mechanism has poor heat-dissipating efficiency due to heat convection. However, the heat-dissipating module of the present invention removes heat by both heat conduction and heat convection to enhance heat dissipation. 
     4. If the generated heat from a CPU chip  11  and lower power electronic components  21  are needed to be removed, both the active-type and the passive-type heat-dissipating mechanism are required in the prior art. However, only a heat-dissipating module is needed in the present invention, for example the heated air flow from the low power electronic components  21  is inhaled via the inlet  71 . Therefore, the present heat-dissipating module has potential for being a standard type of heat-dissipating apparatus. 
     While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.