Patent Publication Number: US-2004045701-A1

Title: Radiator

Description:
FIELD OF THE INVENTION  
       [0001] The invention relates to a radiator for dispersing heat from a heat source located in an electronic device that has elements generating thermal energy during operation, such as a central processing unit (CPU).  
       BACKGROUND OF THE INVENTION  
       [0002] A computer consists of many electronic elements, including a main board, a power supply, hard disk drives, a floppy disk drive, and an optical disk drive. These electronic elements unavoidably generate thermal energy during operation. This thermal energy must be dispersed to the surrounding environment through selected channels such as thermal conduction, thermal convection or thermal radiation to prevent the electronic elements from overheating and the resulting impact on product stability and reliability. In the computer system, the heat dissipation problem of the main processing element—the CPU—is most critical. Hence heat dissipation for the CPU is a heavily focused issue for most computer manufacturers.  
       [0003] With the continuous advance of processor technology, CPU operation frequency has increased to 1 GHz or more. Its heat generation power is more than 50W. If the heat generated by the CPU cannot be discharged effectively, computer performance will be negatively impacted and the computer&#39;s service life will be shortened. Thus heat dissipation becomes more critical when the computer processing frequency increases.  
       [0004] Present heat dissipation devices for CPUs are mostly radiators and radiation air fans. The radiator is made from metal and includes a base and a plurality of radiation fins mounted onto the base. The base is mounted onto and in contact with the CPU. Thermal energy generated by the CPU during operation is transmitted through the base to the radiation fins. The radiation air fan is located above the radiation air fins to generate airflow to flow into the radiation fins. Heat exchange occurs between the airflow and the high temperature radiation fins to carry away the thermal energy from the radiator and to reduce the temperature of the CPU to achieve the object of heat dissipation.  
       [0005] In the past, radiators were mostly made from aluminum because of its lower thermal resistance, lighter weight and lower cost. However, with the continual increase of CPU operation frequency, effectiveness of the radiator also must increase. Thus some vendors are trying to make radiators from copper.  
       [0006] The coefficient of heat transmission of copper is 1.8 times that of aluminum, and the density of copper is three times that of aluminum. With a radiation fin of the same size and volume, the weight of copper is three times that of aluminum. Hence although the radiator made from copper has better heat conduction than the radiator made from aluminum, its weight is much greater. The main board that holds the CPU has to withstand a greater weight when a copper radiator is used. Therefore to utilize the advantage of better heat conduction of the copper radiator, the loading of the main board is an issue that must be properly addressed.  
       [0007] Selection of radiation materials has to consider material properties. How to improve radiation effectiveness through structural design is an object of the invention. Most radiation fins now being used on radiators are mounted vertically onto the base of the radiators. Thermal energy of the CPU is transmitted through the base to the radiation fins. Hence the temperature at the base is the highest in the entire radiator. However, lower temperature airflow generated by the air fan is channeled from top to bottom in the radiation fins. After heat exchange with the top ends of the radiation fins, the temperature of the airflow is higher, and the airflow of higher temperature is directed downwards. As a result, the bottom of the radiation fins and the base that have higher temperatures cannot receive the lower temperature airflow. Such a design cannot effectively reduce the temperature of the higher temperature portions of the radiator.  
       SUMMARY OF THE INVENTION  
       [0008] In view of the aforesaid problems, the primary object of the invention is to provide a radiator that can channel cooling airflow to the higher temperature portions of the radiator to improve radiation efficiency. The radiator of the invention is adopted for dissipating heat of a heat source. The radiator includes a conductive base board and a plurality of radiation fins. The radiation fins are segmented to a first fin section and a second fin section. The first fin section and the second fin section have corresponding sides to form an acute angle with the bottom side. Hence there is an airflow space formed between the first fin section and the second fin section, and the airflow space has a wider upper end and a narrower lower end. By means of such a design, airflow generated by the air fan can directly flow to the conductive base board to enable a portion of the airflow to perform heat exchange directly with the bottom section of the radiation fins and the conductive base board, thereby heat exchange efficiency can be improved.  
       [0009] In addition, the airflow space of the wide upper end and the narrow lower end in the radiator of the invention enables the air fan to generate a pressure boosting effect to discharge airflow more smoothly.  
       [0010] The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0011]FIG. 1 is a perspective view of the radiator of the invention.  
     [0012]FIG. 2 is a side view of the radiator of the invention.  
     [0013]FIG. 3 is a schematic view of the radiator of the invention in use.  
     [0014]FIG. 4 is a schematic view of the airflow path of the invention.  
     [0015]FIG. 5 is a schematic view of another embodiment of the radiator of the invention.  
     [0016]FIG. 6 is a schematic view of the assembly of a second embodiment of the invention.  
     [0017]FIG. 7 is an exploded view of the second embodiment of the invention.  
     [0018]FIG. 8 is a perspective view of the second embodiment of the invention in use.  
     [0019]FIG. 9 is a schematic view of the airflow path in the radiation module of the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0020] The invention aims at providing a radiator to make contact with a heat source to perform heat transfer and through a radiation air fan located above the radiator to deliver cooling air to perform heat exchange with the radiator, to thereby disperse heat from the heat source. The heat source is mainly the CPU of the computer system. However, the embodiments according to the invention are not limited to a CPU. They can also be used on other electronic elements that generate thermal energy during operation. The following embodiments are based on a CPU for explanation. Refer to FIG. 1 for a first embodiment of the invention. The radiator  10  is bonded to a CPU  20  (also shown in FIG. 3) to conduct thermal energy from the CPU to prevent the CPU from overheating and becoming damaged. The radiator  10  is made from metal of a high coefficient of heat transmission such as aluminum, copper or the like. It consists of a conductive base board  11  and a plurality of radiation fins  12 . The radiation fins  12  include a first fin section  121  and a second fin section  122 . The conductive base board  11  is a rectangular member (other shapes may be adopted) matching the shape of the CPU  20 . It has a flat bottom surface to bond to and make contact with the CPU  20 . In actual fabrication a layer of heat insulation adhesive (not shown in the drawing) is coated between the conductive base board  11  and the CPU  20  to ensure that the conductive base board  11  and the CPU  20  are in contact in the optimal manner to increase heat transmission efficiency. The radiation fins  12  are vertically mounted onto the top surface of the conductive base board  11 . The bonding of the radiation fins  12  to the conductive base board  11  may be accomplished by means of adhesive or machining such as cutting, extrusion or the like. The first fin section  121  and the second fin section  122  are located on two sides of the conductive base board  11  and are spaced from each other at a selected distance. The first fin section  121  and the second fin section  122  have respectively an outer side  1211  and  1221  that are aligned with the outer side of the conductive base board  11 . The first fin section  121  and the second fin section  122  further have respectively an inner side  1212  and  1222  spaced from each other at a selected distance to form an airflow space  13 .  
     [0021] Referring to FIG. 2, the inner side  1212  and a bottom side  1213  of the first fin section  121  form an acute angle θ (the second fin section  122  is symmetrical to the first fin section  121 ) such that the first fin section  121  is narrower at the upper end and becomes gradually wider at the lower end to make the inner side  1212  a slope. The second fin section  122  is formed like the first fin section  121  in a symmetrical fashion. Thus the airflow space  13  formed between the first fin section  121  and the second fin section  122  has a wider upper end and a narrower lower end.  
     [0022] Referring to GIG.  3 , when the invention is in use, the radiator  10  is bonded to the CPU  20 , and a radiation air fan  30  is mounted above the radiator  10 . The conductive base board  11  of the radiator  10  is in contact with the CPU  20  so that thermal energy generated by the CPU  20  during operation is transmitted to the conductive base board  11  and to the radiation fins  12 . The radiation air fan  30  rotates and generates downward airflow, which has a lower temperature than the radiator  10 . Thus heat exchange occurs between the airflow and the radiator  10 . The heated air is discharged through two sides of the radiation fins  12  to dissipate heat from the CPU  20 . Referring to FIG. 4, the main difference between the invention and the conventional technique is that in the latter, air flows from the upper portions of the radiation fins  12  to the lower portions and the conductive base board  11 . As the higher temperature portion of the radiator  10  is located on the conductive base board  11  and the bottom section of the radiation fins  12  close to the CPU  20 , the conventional design cannot effectively and directly channel the airflow to the bottom section of the radiation fins  12  or the conductive base board  11 . Therefore radiation efficiency is not desirable.  
     [0023] The airflow space  13  of the invention has a wider upper end and a narrower lower end, thus enabling the airflow generated by the radiation air fan  30  to be directly channeled to the bottom section of the air fins  12  or the conductive base board  11  to perform heat exchange with the portions that are of a higher temperature. Thus the heat dissipation problem at the higher temperature portions of the radiator  10  can be resolved effectively and total radiation efficiency is improved.  
     [0024] In addition, the design of airflow space  13  that is wider at the top and narrower at the bottom also has the effect of guiding and compressing the airflow. By compressing airflow to a smaller volume and a greater pressure, the temperature in the surrounding fluid field may be reduced to carry away the thermal energy accumulated on the conductive base board  11 .  
     [0025] Refer to FIG. 5 for another embodiment of the invention. The radiator  10  of the invention aims at providing an airflow space that is wider at the top and narrower at the bottom to directly channel airflow generated by the radiation air fan  30  to the bottom section of the radiation fins  12  and the conductive base board  11 . Based on this principle, the inner sides  1212  and  1222  of the first fin section  121  and the second fin section  122  may be formed in arched shapes to achieve the object of the invention.  
     [0026] Refer to FIG. 6 for a second embodiment of the invention. A radiation module  40  includes an air mask  50  to surround the radiator  10  described above. The air mask  50  is spaced from the radiator  10  at a desired height. The air mask  50  is fastened to the conductive base board  11  by means of fastening elements  60  (with corresponding fastening holes  111  formed on the conductive base board  11 ). The spaced air mask  50  with a desired height enables the airflow channeled from the air fan  30  located above to generate an air mask effect to reduce airflow friction, and through air pressure, to channel the airflow to the conductive base board  11 . Thus air reflux resulting from airflow directly hitting the radiation fins  12  and flowing backwards to the air fan  30  may be avoided.  
     [0027] The radiator  10  of the second embodiment is the same as that of the first embodiment, so details are omitted. The air mask  50  is constructed to match and encase the radiator  10 . It is substantially a rectangular frame having two long sides  51  and  53 , and two short sides  52  and  54 . The long sides  51  and  53  correspond to the lateral sides of the radiation fins  12 , while the short sides  52  and  54  correspond to the spaced portions of the radiation fins  12 . The height of the short sides  52  and  54  just covers the top rim of the radiation fins  12  to enable airflow to be discharged through the interval space of the radiation fins  12 . The lower sections of the short sides  52  and  54  form two air outlets  55 . The top side of the air mask  50  has four fastening apertures  56  formed on the periphery thereof for fastening the air fan  30  and enabling the air fan  30  to provide airflow for heat dissipation.  
     [0028] Refer to FIGS. 8 and 9 for the application of the radiation module  40 . First, the radiator  10  is bonded to the CPU  20 . Next, the air mask  50  is disposed to encase the radiator  10 . Then the air fan  30  is fastened to the top end of the air mask  50  with the air fan  30  spaced from the radiation fins  12  at a selected distance. Then wind generated by the air fan  30  can be channeled directly to the conductive base board  11  to perform heat exchange and effectively increase radiation efficiency.  
     [0029] In summary, the invention can achieve the following effects:  
     [0030] 1. The radiator has an airflow space that is wider at the top end and narrower at the bottom end, thus wind may be channeled smoothly to the bottom section of the radiation fins and conductive base board to increase radiation efficiency.  
     [0031] 2. The design of the airflow space, being wider at the top end and narrower at the bottom end, increases pressure due to gradually narrowing space. Therefore airflow in the surrounding fluid fields may have a lower temperature to carry away thermal energy accumulated on the conductive base board and can prevent the CPU from overheating and being damaged.  
     [0032] 3. The design of the airflow space can increase radiation efficiency of the entire radiator. If the radiator is made from aluminum, the design enables it to achieve the same performance as a radiator made from copper. The load on the CPU or main board resulting from the radiator may be reduced. If the radiator is made from copper, radiation effectiveness can be greatly improved to meet the heat dissipation requirements of high speed operation.  
     [0033] While the preferred embodiments of the invention have been set forth for the purpose of disclosure, modifications of the disclosed embodiments of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention.