Patent Publication Number: US-2010116462-A1

Title: Heat dissipation system

Description:
BACKGROUND 
     1. Technical Field 
     The disclosure relates to a heat dissipation system and, more particularly, to a heat dissipation system for dissipating heat generated by two electronic devices. 
     2. Description of Related Art 
     A computer system, such as a server, a workstation, often includes two electronic devices, such as two central processing units (CPUs). The CPUs produce a large amount of heat during operation. The heat must be quickly removed from the CPUs to prevent them from becoming unstable or being damaged. Typically, two heat dissipation devices are attached to outer surfaces of the CPUs, respectively. 
       FIG. 6  shows a heat dissipation system  2  for dissipating heat generated by the computer system mentioned above. The heat dissipation system  2  includes two heat dissipation devices  50   a ,  50   b . The heat dissipation devices  50   a ,  50   b  are respectively attached to outer surfaces of the CPUs (not shown) mounted on a printed circuit board  60  in the computer system. The heat dissipation devices  50   a ,  50   b  include a substrate  51   a ,  51   b  and a plurality of fins  52   a ,  52   b  extending upwardly from the substrate  51   a ,  51   b , respectively. These fins  52   a ,  52   b  are spaced from each other to form a plurality of passages  521   a ,  521   b  through which a cooling airflow flows. The heat dissipation devices  50   a ,  50   b  and a plurality of accessories  70  around the CPUs cooperatively form a path  80 . The airflow flows through the path  80  along a direction indicated by arrows in the  FIG. 6 , in other words, the airflow flows through the heat dissipation device  50   a  firstly, and then flows through the heat dissipation device  50   b.    
     During the airflow flowing through the path  80 , the airflow is heated by the heat dissipation device  50   a , and a speed of the airflow is decreased. The heated and low-speed airflow flows through the heat dissipation device  50   b , and carry away little heat absorbed by the heat dissipation device  50   b  from the CPU. Thus the heat dissipation capability of the heat dissipation device  50   b  is lower than that of the heat dissipation device  50   a . That is to say, if the heat dissipation device  50   a  has a heat dissipation capability that the computer system requires, the heat dissipation capability of the heat dissipation device  50   b  is lower than the required heat dissipation capability, if the heat dissipation device  50   b  achieve the required heat dissipation capability, an excessive heat dissipation performance of the heat dissipation device  50   a  are used, representing considerable cost and material burdens. 
     What is needed, therefore, is a heat dissipation system having a balanceable heat dissipation capability. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is an isometric, assembled view of a heat dissipation device in accordance with an embodiment of the disclosure. 
         FIG. 2  is a partially exploded view of the heat dissipation device of  FIG. 1 . 
         FIG. 3  is an isometric, sectional view of an air guiding member of the heat dissipation device of  FIG. 1 . 
         FIG. 4  is an isometric, assembled view of a heat dissipation system utilizing the heat dissipation device of  FIG. 1 . 
         FIG. 5  is a schematic view showing air flow of the heat dissipation system of  FIG. 4 . 
         FIG. 6  is an isometric, assembled view of a heat dissipation system utilizing a heat dissipation device in accordance with related art. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a heat dissipation device  10   a  is illustrated in accordance with an embodiment of the disclosure. The heat dissipation device  10   a  comprises a rectangular base  11 , a plurality of parallel fins  12  extending upwardly from a top face of the base  11 , four fasteners  13  fastening the base  11  on a printed circuit board  20  (see  FIG. 4 ) and an air guiding member  15  mounted on the base  11  via one of the fasteners  13 . The base  11  and the fins  12  are made of materials having a good thermal conductivity, such as copper, aluminum for efficiently absorbing heat generated by an electronic member (not shown) mounted on the printed circuit board  20  and dissipating it to the exterior. These fins  12  are spaced from each other to form a plurality of heat exchange passages  121  for heat exchanging with a cooling airflow flowing therethrough. There is non-fins disposed at a side of the base  11  to form a blank region (not labeled) for defining a cooling air passage  122  through which a branch of the cooling airflow passes. Width of the cooling air passage  122  is larger than that of the heat exchange passage  121 , whereby a sufficient amount of cool air of the cooling airflow can flow through the cooling air passage  122 . 
     Referring also to  FIG. 2 , each fastener  13  comprises a blot  131  with an upper head (not labeled) having a cross groove (not labeled) at a top end thereof for facilitating operation of a tool, a helical spring  132  and a gasket  133  sequentially coiled around the bolt  131 . When the fastener  13  is used, the fastener  13  extends through a through hole  111  in the base  11  and the printed circuit board  20 , and engages with a back plate (not shown) located below the printed circuit board  20 . Simultaneously, the helical spring  132  is elastically sandwiched between the upper head of the bolt  131  and the gasket  133 , such that the base  11  is secured on the printed circuit board  20  and attached to an outer, top surface of the electronic member on the printed circuit board  20 . 
     The air guiding member  15  is made of materials having a certain elasticity, such as plastic or rubber. The air guiding member  15  is rested in the cooling air passage  122  on the base  11  for controlling open and close of the cooling air passage  122 . In this illustrated embodiment, the air guiding member  15  is located at an intake of the cooling air passage  122  and mounted at a corner of the base  11  via one of the fasteners  13 . In other uses, the air guiding member  15  can be located at any position of the cooling air passage  122  by other means. 
     The air guiding member  15  comprises a cylindrical holder  153 , a cylindrical body  152  pivotally engaging with a top of the holder  153 , and a wing  151  integrally extending from an outer surface of the cylindrical body  152 . 
     Referring also to  FIG. 3 , four evenly spaced substantially V-shaped slots  1532  are defined in an inner wall of the holder  153 . Two adjacent V-shaped slots  1532  each have an acute angle or a right angle (i.e., not larger than 90 degrees), and the other two adjacent V-shaped slots  1532  each have an obtuse angle (i.e. larger than 90 degrees). The body  152  is cylinder and has a tie-in  1521  at a bottom end thereof. The tie-in  1521  protrudes two clasps  1522  at two opposite sides thereof for selectively engaging in one of the two adjacent slots  1532  having an angle not larger than 90 degrees and one of the other two adjacent slots  1532  having an angle larger than 90 degrees, respectively. The wing  151  is a rectangular board. A height of the wing  151  is identical to that of the fins  12 , and a width thereof is identical to that of the cooling air passage  122 . In this embodiment, a top of the wing  151  is flush with a top of the body  152 . The height of the wing  151  is identical to a sum of a height of the holder  153  and a height of the body  152  minus a height of the tie-in  1521 . The bolt  131  of the fastener  13  extends through the spring  132 , the body  152 , the holder  153 , and the gasket  133  in sequence to secure the air guiding member  15  on the base  11  and prevent it from rotating with respect to the base  11 . 
     When one of the clasps  1522  of the body  152  is blocked in a corresponding acute-angled or right-angled slot  1532  of the holder  153 , the wing  151  is positioned parallel to the cooling air passage  122  of the heat dissipation device  10   a , and the cooling air passage  122  is open so that the branch of the cooling airflow can flow through the cooling air passage  122 ; when the body  152  rotates 90 degrees with respect to the holder  153  to make the one of the clasps  1522  of the body  152  is blocked in the other one acute-angle or right-angled slot  1532 , the wing  151  is positioned perpendicular to the cooling air passage  122 , and the cooling air passage  122  is closed so that the branch of the cooling airflow is blocked by the wing  151 . The body  152  is pivotably connected to the holder  153 , and the wing  151  is located at the required position by a rotation of the body  152  relative to the holder  153 . 
     Referring to  FIG. 4 , a heat dissipation system  1  utilizing the heat dissipation device  10   a  is illustrated. The heat dissipation system  1  comprises a heat dissipation device  10   a  disclosed above, a heat dissipation device  10   b  similar to the heat dissipation device  10   a , the printed circuit board  20  and a plurality of accessories  30  around the heat dissipation devices  10   a ,  10   b . The accessories  30  in this embodiment are DRAM modules. The heat dissipation devices  10   a ,  10   b  are mounted on the printed circuit board  20  via the fasteners  13 ,  13   b  side by side for dissipating heat generated by two electronic members on the printed circuit board  20 . The heat dissipation device  10   a ,  10   b  and the accessory  30  cooperatively form a path  40  through which the cooling airflow passed. The heat dissipation device  10   a  is located at an intake of the path  40 , and the heat dissipation device  10   b  is located at an outtake of the path  40 . The wing  151  of the heat dissipation device  10   a  is rotated to a position parallel to the fins  12 , whereby the cooling air passage  122  is opened. Simultaneously, the wing  151   b  of the heat dissipation device  10   b  is rotated to a position perpendicular to the fin  12 , whereby the cooling air passage  122   b  is closed. Each of the air guiding members  15  is located at a corner of a windward side of the base  11  of the corresponding heat dissipation device  10   a  ( 10   b ), whereby an entrance of the cooling passage  122   b  is closed, and the cooling air which flows through the cooling passage  122   a  can almost flow into the heat exchange passages  121   b  to effectively take heat away from the heat dissipation device  10   b.    
     Referring also to  FIG. 5 , the cooling airflow flows along a direction indicated by arrows in the path  40 . A part of the cooling airflow flows through the heat exchange passages  121  of the fins  12  of the heat dissipation device  10   a  and exchanges heat therewith, and the other part of the cooling airflow, that is to say, the branch of the cooling airflow directly flows through the cooling air passage  122  without being blocked by the wing  151 . Then, the heated airflow by the fins  12  of the heat dissipation device  10   a  and the branch of the cooling airflow together flow through the heat dissipation device  10   b . As blocked by the wing  151   b  of the heat dissipation device  10   b , all of the airflows flowing through the heat dissipation device  10   a  flow through the cooling air passages  121   b  of the fins  12   b  and exchanging heat therewith. Accordingly, the heat dissipation system  1  can more effectively cool two electronic members arranged in series along an airflow path. 
     In the heat dissipation system  1 , amount of airflow flowing through the heat exchange passages  121  of the heat dissipation device  10   a  is smaller than that flowing through the heat exchange passage  121   b  of the heat dissipation device  10   b . The increased amount of airflow through the heat dissipation device  10   b  compensates the increase of temperature of the airflow through the heat dissipation device  10   b , to thereby achieve a balance of heat dissipation capabilities between the heat dissipation devices  10   a ,  10   b . To improve heat-dissipating efficiency of the heat dissipation system  1 , the exit of the cooling air passage  122  of the heat dissipation device  10   a  faces the heat exchange passages  121   b  of the heat dissipation device  10   b . The heat dissipation devices  10   a ,  10   b  are the same from each other regarding the configuration and structure to improve an interchangeability of the heat dissipation devices  10   a ,  10   b  for further reducing a designing cost of the heat dissipation system  1 . 
     Alternatively, when one electronic member which engages the heat dissipation device  10   a  works and the other one electronic member which engages the heat dissipation device  10   b  stops, the wing  151  of the heat dissipation device  10   a  is rotated perpendicular to the fins  12  to close the cooling air passage  122 , and the wing  151   b  of the heat dissipation device  10   b  is rotated parallel the fins  12  to open the cooling air passage  122   b . Thus, the amount of the airflow flowing through the heat exchange passages  121  of the heat dissipation device  10   a  is increased whereby the heat dissipation devices  10   a  has a great heat dissipation capability. Simultaneously, the airflow heated by the heat dissipation device  10   a  flows through the heat dissipation device  10   b  and exchanges heat with the heat dissipation device  10   b  to decrease the temperature of the heat dissipation system  1 . The temperature of the dissipation system  1  can be kept as low as possible. 
     It is to be understood, however, that even though numerous characteristics and advantages of the present embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.