Abstract:
A heat dissipating device for taking away heat from a plurality of heat sources is disclosed. It includes a plurality of heat sinks installed on heat sources and a heat conductor connected to the heat sinks. When a temperature difference is generated among the heat sources in work, the heat conductor can pass the heat from a hot heat sink to cooler ones. This enables heat transfers among the heat sinks to increase the heat dissipating efficiency.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of Invention 
   The invention pertains to a heat dissipating device used in an electronic device for taking heat away from a hot element therein (such as the CPU in a computer system). In particular, it relates to a heat dissipating device that can take away heat from several heat-generating elements. 
   2. Related Art 
   In a computer system, the central processing unit (CPU) is in charge of data processing and generates heat during operations. If its temperature is too high, the heat may damage the CPU. Therefore, a heat sink is usually installed on the CPU in the computer system. A fan is further installed on top of or on one side of the heat sink. Therefore, the heat produced by the working CPU is passed to the heat sink and then taken away by the air blown in by the fan. This means can lower the working temperature of the CPU, maintaining the normal operations. 
   With the increase of multi-tasking demands, the computer system requires a more powerful operational ability. A more powerful CPU is thus needed to process complicated data. In addition to the increasing operational frequency, some manufacturers even propose computer systems with double CPU&#39;s. The double-CPU system uses two CPU&#39;s to process different tasks. The heat dissipation design for the double-CPU system is still the same as that of the single-CPU ones. Each processor is independently installed with a heat sink and a fan. Since the two CPU&#39;s in the double-CPU system perform their jobs according to system requests, sometimes only one CPU is running while the other is idle. Even if both of them are running at the same time, they may produce different amounts of heat due to the different operations. In such cases, the idle CPU also has an idle heat sink or the CPU running less diligently has a lower temperature. Therefore, the corresponding heat sink does not reach its maximal efficiency. 
   SUMMARY OF THE INVENTION 
   The heat dissipation design of the conventional double-CPU computer system is only for individual processors. The heat sinks cannot support each other when the two processors are running under different loads. Thus, the whole heat dissipating system is not optimized. 
   In view of the foregoing, an objective of the invention is to provide a heat dissipating device that enables individual heat sinks to support one another according to the actual loads of the processors for increasing the heat dissipation efficiency of the whole system. 
   The disclosed heat dissipating device includes several heat sinks and a heat conductor. Each heat sink is installed on a corresponding heat source. The heat conductor connects the heat sinks so that the heat absorbed by the heat sinks can be transferred from one with a relatively high temperature to another with a relatively low temperature. Therefore, the heat sinks can share the heat produced by the heat sources. 
   The disclosed heat dissipating device makes use of the principle that heat always flow from a high-temperature place to a low-temperature one. A heat conductor connects the plurality of heat sinks so that any idle heat sink can help dissipating heat from hotter ones. The efficiency of the whole heat sink system is thus higher. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will become more fully understood from the detailed description given hereinbelow illustration only, and thus are not limitative of the present invention, and wherein: 
       FIG. 1  is a first embodiment of the invention; 
       FIGS. 2A and 2B  are side and top views of  FIG. 1 ; 
       FIG. 3  is a second embodiment of the invention; 
       FIG. 4  is a third embodiment of the invention; 
       FIG. 5  is a fourth embodiment of the invention; 
       FIG. 6  is a fifth embodiment of the invention; 
       FIG. 7  is a sixth embodiment of the invention; and 
       FIG. 8  is a seventh embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The disclosed heat dissipating device is used in an electronic device that generates heat during work. The electronic device can be a personal computer (PC), a laptop computer, or other similar products. The PC or laptop computer has at least one main heat source, which is the central processing unit (CPU). The CPU generates a certain amount of heat during operations. Therefore, the heat has to be carried away in order for the CPU to run normally. The disclosed heat dissipating device is mainly used in a computer system with two processors. However, the invention is not limited to the CPU as the heat sources. The number of heat sources is not limited to two, either. 
   As shown in  FIGS. 1 ,  2 A, and  2 B, the electronic device  10  is a computer system, whose technical details are well known and not repeated herein. The electronic device  10  has at least two heat sources  11 ,  12 , which are the CPU&#39;s. Thy generate heat during work. 
   First Embodiment 
   The heat dissipating device in this embodiment has two heat sinks  21 ,  22  corresponding to the two heat sources  11 ,  12 , two fans  31 ,  32  corresponding to the heat sinks  21 ,  22 , respectively, and a heat conductor  40 . The heat sink  21  (similarly for the heat sink  22 ) is made of aluminum or copper that is highly thermal conductive. It consists of a base  211  and several fins  212  on the base  211 . The base  211  is in direct contact with the heat source  11 . The purpose of the fins  212  is to increase the heat dissipation area. When the heat source  11  generates heat during operations, the heat is transferred to the base  211  and in turn to the fins  212 . The fins  212  exchange heat with the ambient air to lower its temperature. 
   The fans  31 ,  32  can be installed on one side of the heat sinks  21 ,  22 , respectively (see FIG.  1 ), or directly on the heat sinks  21 ,  22  (not shown). The fans  31 ,  33  blow ambient air toward the fins  212  so that the heat thereon can be brought away. 
   The heat conductor  40  is a plate made of aluminum or copper that is highly thermal conductive. It can be attached onto the heat sinks  21   22  using a heat-conductive adhesive (not shown), so that the heat sinks  21 ,  22  can exchange heat via the heat conductor  40 . 
   Heat transfers from a high-temperature place to a low-temperature one. Suppose the heat source  11  has a larger load in operation and the heat source  12  has a lower one (or is even idle), then the heat sink  21  has a relatively higher temperature and the heat sink  22  lower. The temperature difference between the heat sinks  21 ,  22  makes the heat transfer from the heat sink  21  to the heat sink  22  via the heat conductor  40 . Consequently, the heat dissipation area of the heat source  21  with a larger load is increased. 
   Please refer to Attachments 1 and 2. Attachment 1 is a test plot of the internal heat distribution of a running electronic device  10  that uses a conventional heat dissipating device; attachment 2 is that of a running electronic device  10  that uses the disclosed heat dissipating device. Comparing Attachments 1 and 2, one sees that the disclosed heat dissipating device can indeed greatly increase the heat dissipation efficiency of the system. 
   Second Embodiment 
   In the first embodiment, the heat conductor  40  is attached to the heat sinks  21 ,  22  by a heat-conductive adhesive. Since there is little possibility for a normal user to replace the CPU for upgrading the hardware equipment, such a method will not cause any trouble. Even for a professional computer user, he or she can use appropriate tools to take off the heat conductor  40  if necessary. After the replacement, the user only need to stick the heat conductor  40  on the heat sinks  21 ,  22  using the heat-conductive adhesive again (as shown in FIG.  3 ). In the second embodiment of the invention, the heat conductor  40  is installed on the heat sinks  21 ,  22  in a dismountable way. The base  211  of the heat sink  21  (similarly for the heat sink  22 ) has a click slot  2111 . The heat conductor  40  has a corresponding clicking block  41  that matches with the clicking slot  2111 . Therefore, when the user wants to upgrade the CPU, the heat conductor  40  can be directly taken off or installed on the heat sinks  21 ,  22  without using any tool. 
   Third Embodiment 
   In the first and second embodiments, the two heat sinks  21 ,  22  correspond to two heat sources  11 ,  12 . The two heat sinks  21 ,  22  exchange heat according to the temperature condition via the heat conductor  40 . As shown in  FIG. 4 , the electronic device  10  has an additional heat source  13  that require heat dissipation in the third embodiment. Thus, an additional heat sink  23  is needed. The heat conductor  40  is attached to all the heat sinks  21 ,  22 ,  23 . Similarly, when any heat sink has a high temperature than others, heat is transferred from it to the others via the heat conductor  40  to increase the heat dissipation efficiency. 
   Fourth Embodiment 
   As shown in  FIG. 5 , the fourth embodiment uses a heat duct as the heat conductor  40 . 
   The heat duct is a metal duct packaged in vacuum. A fluid with 90% of water is filled inside the duct. The pressure inside the duct is very low so that the fluid can be vaporized at about 30° C. to provide a better heat conduction efficiency. 
   Fifth Embodiment 
   In the fifth embodiment shown in  FIG. 6 , the heat conductor  40  is a block. Both sides of the block are directly attached to the fins  212  to increase the heat dissipation area. 
   Sixth Embodiment 
   As shown in  FIG. 7 , the heat conductor  40  can be further installed with heat dissipating fins  42  so that the heat conductor  40  also has the function of dissipating heat. 
   In the above-mentioned embodiments, the heat sources and the heat sinks of the 
   electronic device  10  have one-to-one correspondence. In principle, such an electronic device  10  has two processors. The disclosed heat dissipating device can be used in electronic devices with only a single processor. The seventh embodiment defines the first heat sink  21 ′ and the second heat sink  22 ′. The first sink  21 ′ is in contact with the heat source  11  and the second heat sink  22 ′ is installed on one side of the first sink  21 ′. Using the heat conductor  40 , the heat on the first heat sink  21 ′ is transferred to the second heat sink  22 ′, providing a larger heat dissipation area for the heat source  11 . 
   Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments, will be apparent to persons skilled in the art. It is, therefore, contemplated that the appended claims will cover all modifications that fall within the true scope of the invention.